Image forming apparatus

Abstract

The present invention provides an image forming apparatus capable of recovering a fixing liquid that is not attached to a sheet. The image forming apparatus (1) includes a photosensitive drum (4), a developing device (7), a transfer device (8), a spraying device (9), and a recovery device (12). The spraying device (9) sprays a fixing liquid for fixing toner onto a sheet (S) onto which toner has been transferred. The recovery device (12) includes a recovery tray (121), a recovery pipe (122), and a recovery pump (123). The recovery tray (121) can accommodate the fixing liquid that is not attached to the sheet (S). The recovery pipe (122) is connected to the recovery tray (121) and allows the fixing liquid in the recovery tray (121) to pass through. The recovery pump (123) conveys the fixing liquid in the recovery pipe (122) toward the spraying device (9).

Description

Technical Field

[0001] The present invention relates to an image forming apparatus. Background Art

[0002] Conventionally, an image forming apparatus includes a photosensitive drum, a developing device, a transfer device, a spraying device, and a recovery tray. The spraying device sprays a fixing liquid for fixing toner onto a sheet toward the sheet on which toner is transferred. The recovery tray accommodates the fixing liquid that has not adhered to the sheet (see Patent Document 1 below).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-68103

[0006] Problems to be Solved by the Invention

[0007] In an image forming apparatus as described in Patent Document 1, there is a demand for recovering the fixing liquid accumulated in the recovery tray. Summary of the Invention

[0008] An object of the present invention is to provide an image forming apparatus capable of recovering the fixing liquid that has not adhered to a sheet.

[0009] Means for Solving the Technical Problems

[0010] (1) The image forming apparatus of the present invention includes a photosensitive drum, a developing device, a transfer device, a spraying device, and a recovery device.

[0011] The developing device supplies toner to the photosensitive drum. The transfer device transfers the toner supplied to the photosensitive drum to a sheet. The spraying device sprays a fixing liquid for fixing toner onto a sheet toward the sheet on which toner is transferred. The spraying device includes a housing and a nozzle. The housing can accommodate the fixing liquid. The nozzle sprays the fixing liquid in the housing.

[0012] The recovery device recovers the fixing liquid that has been sprayed from the nozzle and has not adhered to the sheet. The recovery device has a recovery tray, a recovery pipe, and a recovery pump. The recovery tray can accommodate the fixing liquid. The recovery pipe is connected to the recovery tray and allows the fixing liquid in the recovery tray to pass through. The recovery pump conveys the fixing liquid in the recovery pipe toward the housing.

[0013] With such a configuration, the fixing liquid that has been sprayed from the nozzle and has not adhered to the sheet can be accommodated in the recovery tray and conveyed to the housing through the recovery pipe.

[0014] Accordingly, the fixing liquid that has not adhered to the sheet can be recovered and sprayed again from the nozzle.

[0015] As a result, the consumption of the fixing liquid can be suppressed.

[0016] (2) The spraying device may further include a nozzle electrode and a counter electrode. The nozzle electrode charges the fixing liquid in the housing. The counter electrode is located at a position spaced apart from the nozzle electrode. The nozzle is located between the nozzle electrode and the counter electrode.

[0017] (3) The counter electrode may be located in the recovery tray.

[0018] According to such a structure, the fixing liquid sprayed from the nozzle can be attracted into the recovery tray by the counter electrode.

[0019] As a result, the fixing liquid not attached to the sheet can be reliably accommodated in the recovery tray.

[0020] (4) The recovery pump may be a gear pump.

[0021] (5) The image forming apparatus may further include a main body housing and a supply device. The supply device supplies the fixing liquid to the housing. The supply device includes a fixing liquid cartridge, a replenishing tube, a supply tank, and a supply tube. The fixing liquid cartridge stores the fixing liquid. The fixing liquid cartridge can be installed in the main body housing. The replenishing tube is connected to the fixing liquid cartridge in a state where the fixing liquid cartridge is installed in the main body housing. The replenishing tube allows the fixing liquid in the fixing liquid cartridge to pass through. The supply tank is connected to the replenishing tube. The supply tank can store the fixing liquid that has passed through the replenishing tube. The supply tube is connected to the supply tank. The supply tube allows the fixing liquid in the supply tank to pass through. The housing is connected to the supply tube. The housing can store the fixing liquid that has passed through the supply tube.

[0022] According to such a structure, the fixing liquid in the fixing liquid cartridge can be supplied to the housing via the supply tank.

[0023] Therefore, by keeping the amount of the fixing liquid in the supply tank constant, even if the fixing liquid in the fixing liquid cartridge decreases, the fixing liquid can be stably supplied to the housing.

[0024] As a result, the spraying state of the fixing liquid from the nozzle can be stabilized.

[0025] (6) The recovery tube may be connected to the supply tank. The recovery pump transports the fixing liquid in the recovery tube to the housing via the supply tank.

[0026] According to such a structure, the fixing liquid from the recovery tray and the fixing liquid from the fixing liquid cartridge can be stored in the supply tank together.

[0027] As a result, the fixing liquid from the recovery tray can be reused while stabilizing the spraying state of the fixing liquid from the nozzle.

[0028] (7) The image forming apparatus may include a replenishing pump. The replenishing pump transports the fixing liquid in the replenishing tube to the supply tank.

[0029] (8) The supply pump may be a gear pump.

[0030] (9) The image forming apparatus may include a sensor and a control device. The sensor detects the liquid level position of the fixing liquid in the supply tank. The control device can execute a pump driving process and a pump stopping process. In the pump driving process, when the liquid level position of the fixing liquid in the supply tank detected by the sensor is lower than a threshold value, the control device drives the supply pump to supply the fixing liquid from the fixing liquid cartridge to the supply tank. In the pump stopping process, when the liquid level position of the fixing liquid in the supply tank detected by the sensor is equal to or higher than the threshold value, the driving of the supply pump is stopped to stop the supply of the fixing liquid from the fixing liquid cartridge to the supply tank.

[0031] According to such a configuration, the amount of the fixing liquid in the supply tank can be made constant based on the liquid level position detected by the sensor.

[0032] As a result, the spraying state of the fixing liquid from the nozzle can be stabilized.

[0033] (10) The control device may execute the pump driving process after the printing operation is completed.

[0034] (11) The image forming apparatus may further include a stirring member. The stirring member stirs the fixing liquid in the supply tank.

[0035] (12) The recovery device may have a recovery valve. The recovery valve suppresses the case where the fixing liquid in the recovery tray is transported to the supply tank through the inside of the recovery pipe.

[0036] (13) The recovery pipe may have a filter.

[0037] According to such a configuration, even if foreign matters such as toner and paper dust are mixed in the fixing liquid in the recovery tray, the foreign matters can be removed by the filter and the fixing liquid can be reused.

[0038] (14) At least a part of the recovery pipe may extend in the vertical direction. The filter may extend in a direction crossing the vertical direction.

[0039] According to such a configuration, the fixing liquid passes through the filter in the vertical direction, whereby the entire surface of the filter can be brought into contact with the fixing liquid.

[0040] As a result, the case where only a part of the filter is clogged can be suppressed and the replacement frequency of the filter can be reduced.

[0041] (15) The recovery pipe may be connected to the supply pipe. The supply pipe allows the fixing liquid that has passed through the recovery pipe to pass through.

[0042] (16) The image forming apparatus may include a recovery tank and a second recovery pipe. The recovery tank is connected to the recovery pipe. The recovery tank is capable of storing the fixing liquid that has passed through the inside of the recovery pipe. The second recovery pipe is connected to the recovery tank. The second recovery pipe allows the fixing liquid in the recovery tank to pass through. The housing may be connected to the second recovery pipe. The housing may also be capable of storing the fixing liquid that has passed through the second recovery pipe.

[0043] (17) The housing may be connected to the supply pipe and the recovery pipe, and be capable of storing the fixing liquid that has passed through the supply pipe and the fixing liquid that has passed through the recovery pipe.

[0044] (18) The control device may perform a recovery process when the execution of the printing operation is completed. In the recovery process, the control device drives the recovery pump to convey the fixing liquid in the recovery tray toward the housing.

[0045] According to such a structure, when all the printing operations are completed, the fixing liquid in the recovery tray can be conveyed to the housing.

[0046] Therefore, it is possible to suppress the enlargement of the recovery tray and recover the fixing liquid not attached to the sheet.

[0047] (19) The control device may count the first cumulative page number, which is the cumulative number of pages printed after the previous recovery process.

[0048] (20) It may also be that the more the first cumulative page number is, the longer the control device extends the driving time of the recovery pump in the recovery process.

[0049] According to such a structure, when the first cumulative page number is small and the fixing liquid in the recovery tray is small, the time of the recovery process can be shortened and the printing waiting time can be shortened.

[0050] In addition, when the first cumulative page number is large and the fixing liquid in the recovery tray is large, the time of the recovery process can be extended to reliably convey the fixing liquid in the recovery tray to the housing.

[0051] (21) The supply device may have a supply tank and a sensor. The supply tank houses the fixing liquid supplied to the spraying device. The sensor detects whether the amount of the fixing liquid in the supply tank is less than a specified amount. The control device may store a first set value and a second set value. The first set value is the number of pages that can be continuously printed with a specified amount of the fixing liquid. The second set value is set based on the capacity of the recovery tray. When the first cumulative number of pages is less than the first set value and the control device receives a new printing job during the recovery process, if the first cumulative number of pages is equal to or more than the second set value, the control device executes the new printing job after the recovery process. When the first cumulative number of pages is less than the first set value and the control device receives a new printing job during the recovery process, if the first cumulative number of pages is less than the second set value, the control device executes the recovery process after executing the new printing job.

[0052] When the first cumulative number of pages is equal to or more than the second set value, there is a high possibility that the recovery tray will overflow.

[0053] In this regard, by giving priority to the recovery process over the new printing job, it is possible to suppress the situation where the recovery tray overflows.

[0054] On the other hand, when the first cumulative number of pages is less than the second set value, there is a low possibility that the recovery tray will overflow.

[0055] Therefore, by giving priority to the new printing job over the recovery process, it is possible to shorten the printing waiting time.

[0056] (22) It may also be that when the first cumulative number of pages is less than the first set value and the control device receives a new printing job during the recovery process and the first cumulative number of pages is less than the second set value, during the recovery process after the new printing job, based on the first cumulative number of pages after adding the number of pages printed in the new printing job, the more the first cumulative number of pages, the longer the control device extends the driving time of the recovery pump during the recovery process.

[0057] According to such a structure, when giving priority to the new printing job over the recovery process, it is possible to extend the recovery process time by the amount of the number of pages printed in the new printing job.

[0058] Therefore, when giving priority to the new printing job over the recovery process, it is also possible to reliably transport the fixing liquid in the recovery tray to the housing.

[0059] (23) It may also be that when the first cumulative number of pages becomes equal to or more than the first set value during the execution of the printing job, the control device interrupts the execution of the printing job and executes the recovery process.

[0060] According to such a structure, it is possible to suppress the following situation: continuing the printing operation in a state where the fixing liquid in the supply tank has become empty, which may cause air to enter the nozzle.

[0061] (24) The control device can reset the first cumulative page count when the recovery process is completed.

[0062] (25) The supply device may further include a fixing liquid cartridge, a supply pipe, and a supply pump. The fixing liquid cartridge can accommodate the fixing liquid to be supplied to the supply tank. The supply pipe is connected to the fixing liquid cartridge and the supply tank. The supply pipe allows the passage of the fixing liquid from the fixing liquid cartridge to the supply tank. The supply pump conveys the fixing liquid in the supply pipe toward the supply tank.

[0063] (26) Alternatively, after the recovery process, when the sensor detects that the amount of the fixing liquid in the supply tank is less than a specified amount, the control device performs a replenishment process. In the replenishment process, the control device drives the supply pump to convey the fixing liquid stored in the fixing liquid cartridge to the supply tank.

[0064] Here, if the recovery process is performed after the replenishment process, after the supply tank is filled by the replenishment process, the fixing liquid is conveyed from the recovery tray to the supply tank by the recovery process, and there is a possibility that the supply tank may overflow.

[0065] In this regard, according to such a structure, the replenishment process is performed after the recovery process, so it is possible to prevent the supply tank from overflowing due to the recovery process.

[0066] (27) Alternatively, during the preheating process of the image forming apparatus, when the sensor detects that the amount of the fixing liquid in the supply tank is less than a specified amount, the control device performs a replenishment process.

[0067] (28) Alternatively, when the second cumulative page count is equal to or greater than a third set value and the sensor does not detect that the amount of the fixing liquid in the supply tank is less than a specified amount, the control device performs an error display process. The second cumulative page count is the cumulative number of pages printed after the last replenishment process. In the error display process, the control device causes the display device to display an error.

[0068] According to such a structure, when it is assumed that the amount of the fixing liquid in the supply tank is decreasing, but the sensor does not detect the decrease in the amount of the fixing liquid in the supply tank, it is possible to cause the display device to display a malfunction of the sensor.

[0069] (29) Alternatively, after the control device has completed the execution of the printing operation, when the second cumulative page count is equal to or greater than a third set value and the sensor does not detect that the amount of the fixing liquid in the supply tank is less than a specified amount, the control device performs an error display process.

[0070] (30)Alternatively, during the preheating process of the image forming apparatus, when the second cumulative number of sheets is equal to or greater than a third set value and the sensor does not detect that the amount of fixing liquid in the supply tank is less than a specified amount, the control device performs an error display process.

[0071] (31)Alternatively, during the recovery process after the sheet jammed in the image forming apparatus is removed, when the second cumulative number of sheets is equal to or greater than a third set value and the sensor does not detect that the amount of fixing liquid in the supply tank is less than a specified amount, the control device performs an error display process.

[0072] (32) The image forming apparatus may include a disconnection instruction receiving unit that receives an instruction to disconnect the power supply. When the disconnection instruction receiving unit receives an instruction to disconnect the power supply, the control device sprays the fixing liquid in the housing from the nozzle. And, the recovery pump is driven to convey the fixing liquid in the recovery tray toward the housing.

[0073] According to such a configuration, it is possible to suppress the following situation: when the power supply is in a disconnected state, the fixing liquid remaining inside the housing or the recovery unit leaks to the outside.

[0074] (33) The recovery pump may be configured to convey the fixing liquid in the recovery pipe to the housing via the supply tank.

[0075] (34) The supply device may include a first sensor. The first sensor detects the accommodation state of the fixing liquid in the housing. When the image forming apparatus is started, if the detection result of the first sensor indicates that a specified amount of fixing liquid is not accommodated in the housing, the control device performs the supply of the fixing liquid from the supply tank to the housing by the supply pump.

[0076] According to such a configuration, when a specified amount of fixing liquid is not accommodated in the housing when the image forming apparatus is started, the control unit supplies the fixing liquid from the tank to the housing. Therefore, printing can be performed using the image forming apparatus.

[0077] (35) The image forming apparatus may include a second sensor that detects the accommodation state of the fixing liquid in the supply tank. When the image forming apparatus is started, if the detection result of the second sensor indicates that a specified amount of fixing liquid is not accommodated in the supply tank, the control device performs the replenishment of the fixing liquid from the fixing liquid cartridge to the supply tank by the replenishment pump.

[0078] According to such a configuration, when a specified amount of fixing liquid is not accommodated in the supply tank when the image forming apparatus is started, the control device replenishes the fixing liquid from the fixing liquid cartridge to the supply tank. Therefore, the fixing liquid can be supplied from the supply tank to the housing, and further printing can be performed using the image forming apparatus.

[0079] (36) The image forming apparatus may include a cancellation instruction receiving unit. The cancellation instruction receiving unit receives instructions for canceling the recycling process and releasing the cancellation of the recycling process. When the cancellation instruction receiving unit receives an instruction to cancel the recycling process, the control device does not perform the recycling process until the cancellation instruction receiving unit subsequently receives an instruction to release the cancellation of the recycling process.

[0080] With such a configuration, the recycling process can be not performed by the user's selection. Therefore, the time required for performing the recycling process or supplying the fixing liquid to the housing etc. at startup can be reduced.

[0081] (37) The spraying device may have a nozzle electrode and a counter electrode. Further, the image forming apparatus may further include a first voltage generation circuit, a second voltage generation circuit, and a current detection circuit. The nozzle electrode charges the fixing liquid in the housing. The counter electrode is located at a position spaced apart from the nozzle electrode, and a potential difference is formed between the counter electrode and the nozzle electrode. The first voltage generation circuit is connected to the nozzle electrode and generates a first voltage applied to the nozzle electrode. The second voltage generation circuit is connected to the counter electrode and generates a second voltage applied to the counter electrode. The current detection circuit detects the current flowing between the first voltage generation circuit and the nozzle electrode or between the second voltage generation circuit and the counter electrode. Before spraying the fixing liquid using the nozzle, the control device controls the first voltage generation circuit and the second voltage generation circuit so that the potential difference between the nozzle electrode and the counter electrode is less than a specified value. The control device also calculates the resistance value of the bypass circuit from the nozzle electrode to the counter electrode via the supply device and the recycling device based on the current value detected by the current detection circuit and the potential difference between the nozzle electrode and the counter electrode that is less than the specified value.

[0082] When spraying the fixing liquid using the nozzle, the control device further calculates a correction current value based on the potential difference between the nozzle electrode and the counter electrode that is equal to or greater than the specified value and the resistance value of the bypass circuit. In addition, the control device sprays the fixing liquid using the nozzle by controlling the first voltage generation circuit and the second voltage generation circuit so that the potential difference between the nozzle electrode and the counter electrode is equal to or greater than the specified value. And the control device determines whether the corrected current obtained by correcting the current value detected by the current detection circuit with the correction current value is within the target current range. If the corrected current is outside the target current range, the control device controls the first voltage generation circuit and the second voltage generation circuit so that the corrected current is within the target current range.

[0083] The resistance value in the state where no spray current is flowing is the resistance value of the detour circuit from the nozzle electrode, via the supply device and the recovery device, towards the counter electrode. The current value for correction is the current value flowing in the detour circuit when spraying the fixing liquid. The current after being corrected by the current value for correction is the net spray current when spraying the fixing liquid. Therefore, the control device can appropriately control the magnitude of the net spray current by controlling the first voltage generation circuit and the second voltage generation circuit so that the current after being corrected by the current value for correction is within the target current range.

[0084] (38) The control device can determine whether the current value detected by the current detection circuit is within the corrected target current range obtained by correcting the target current range with the current value for correction, and the control device can control the first voltage generation circuit and the second voltage generation circuit when the current is outside the corrected target current range so that the current is within the corrected target current range.

[0085] The resistance value in the state where no spray current is flowing is the resistance value of the detour circuit from the nozzle electrode, via the supply device and the recovery device, towards the counter electrode. The current value for correction is the current value flowing in the detour circuit when spraying the fixing liquid. The corrected target current range with the current value for correction is the target current range regarding the sum of the spray current and the current flowing in the above circuit. Therefore, the control device can appropriately control the magnitude of the net spray current by controlling the first voltage generation circuit and the second voltage generation circuit so that the current value detected by the current detection circuit is within the corrected target current range.

[0086] (39) Before spraying the fixing liquid using the nozzle, the control device uses the second voltage generation circuit to apply a negative voltage to the counter electrode. Moreover, the control device controls the second voltage generation circuit without causing the first voltage generation circuit to apply a voltage to the nozzle electrode so that the potential difference between the nozzle electrode and the counter electrode is less than the specified value.

[0087] With such a structure, the control device can cause a potential difference to be generated between the nozzle electrode and the counter electrode without spraying the fixing liquid using the nozzle.

[0088] (40) Before spraying the fixing liquid using the nozzle, the control device can use the first voltage generation circuit to apply a positive voltage to the nozzle electrode, and control the first voltage generation circuit without causing the second voltage generation circuit to apply a voltage to the counter electrode so that the potential difference between the nozzle electrode and the counter electrode is less than the specified value.

[0089] (41) The image forming apparatus may include a voltage generation circuit having a first voltage generation circuit and a second voltage generation circuit.

[0090] With such a configuration, the first voltage generation circuit and the second voltage generation circuit can be made into a single component, and the number of parts can be reduced.

[0091] (42) The supply device may include: a supply tank that can store a fixing liquid; and a supply pipe that is connected to the supply tank and allows the fixing liquid stored in the supply tank to pass through.

[0092] Effects of the Invention

[0093] According to the image forming apparatus of the present invention, it is possible to recover the fixing liquid that has not adhered to the sheet. Description of the Drawings

[0094] Figure 1 It is a schematic configuration diagram of the image forming apparatus according to the first embodiment of the present invention.

[0095] Figure 2 It is a piping diagram of the supply device and the recovery device according to the first embodiment.

[0096] Figure 3 It is a flowchart for explaining the control of the first supply pump according to the first embodiment.

[0097] Figure 4 It is an explanatory diagram for explaining the first modification example of the image forming apparatus according to the first embodiment.

[0098] Figure 5 It is an explanatory diagram for explaining the second modification example of the image forming apparatus according to the first embodiment.

[0099] Figure 6 It is an explanatory diagram for explaining the third modification example of the image forming apparatus according to the first embodiment.

[0100] Figure 7 It is a schematic configuration diagram of the image forming apparatus according to the second embodiment of the present invention.

[0101] Figure 8 It is a piping diagram of the supply device and the recovery device according to the second embodiment.

[0102] Figure 9 It is a flowchart for explaining the control of the control device according to the second embodiment.

[0103] Figure 10 It is continued Figure 9 from the flowchart.

[0104] Figure 11 is a flowchart in the case where an embedding job is received during the recycling process shown in Figure 10

[0105] Figure 12 is a flowchart in the case where the first cumulative page count becomes equal to or greater than the first set value during the execution of the printing job shown in Figure 9

[0106] Figure 13 is a flowchart of the recovery process after the jammed sheet in the image forming apparatus according to the second embodiment is removed.

[0107] Figure 14 is a flowchart of the preheating process of the image forming apparatus according to the second embodiment.

[0108] Figure 15 is Figure 10 , Figure 12 , Figure 13 , Figure 14 is a flowchart of the supply process shown in

[0109] Figure 16 is a diagram showing the structure of the laser printer according to the third embodiment of the present invention.

[0110] Figure 17 is a diagram showing the structure of the fixing device according to the third embodiment.

[0111] Figure 18 is a diagram showing an example of the structure of the second sensor according to the third embodiment.

[0112] Figure 19 is a flowchart showing an example of the process in the fixing device according to the third embodiment.

[0113] Figure 20 is showing Figure 19 is a flowchart showing the content of the "preparation process" in the flowchart shown in

[0114] Figure 21 is a diagram showing a modified example of the fixing device according to the third embodiment.

[0115] Figure 22 is a diagram showing the structure of the laser printer according to the fourth embodiment of the present invention.

[0116] Figure 23 is a diagram showing the specific structure of the fixing device included in the laser printer according to the fourth embodiment.

[0117] Figure 24 ​​It is a diagram showing a bypass circuit in a fixing device included in a laser printer according to a fourth embodiment.

[0118] Figure 25 It is a schematic diagram showing the circuit structure of a fixing device included in a laser printer according to a fourth embodiment.

[0119] Figure 26 It is a flowchart showing the processing of a control unit when forming an image on a sheet in a laser printer according to a fourth embodiment.

[0120] Figure 27 It is a flowchart showing the processing of a control unit for calculating a loop resistance value according to a fourth embodiment.

[0121] Figure 28 It is a flowchart showing the processing of a control unit for controlling a first voltage generation circuit and a second voltage generation circuit for spraying a fixing liquid according to a fourth embodiment.

[0122] Figure 29 It is a modified example of a flowchart showing the processing of a control unit for controlling a first voltage generation circuit and a second voltage generation circuit for spraying a fixing liquid according to a fourth embodiment. Detailed Embodiments

[0123] [First Embodiment]

[0124] While referring to Figures 1 - 6 , the image forming apparatus according to the first embodiment of the present invention will be described in detail.

[0125] Referring to Figure 1 , an overview of the image forming apparatus 1 will be described.

[0126] The image forming apparatus 1 includes a main body housing 2, a sheet cassette 3, a photosensitive drum 4, a charging device 5, an exposure device 6, a developing device 7, a transfer device 8, and a spraying device 9.

[0127] The main body housing 2 houses the sheet cassette 3, the photosensitive drum 4, the charging device 5, the exposure device 6, the developing device 7, the transfer device 8, and the spraying device 9.

[0128] The sheet cassette 3 can accommodate a sheet S. The sheet S is, for example, printing paper. The sheet S is conveyed toward the photosensitive drum 4.

[0129] The photosensitive drum 4 can rotate relative to the drum shaft A1. The photosensitive drum 4 extends along the drum shaft A1. The photosensitive drum 4 has a cylindrical shape.

[0130] The charging device 5 charges the surface of the photosensitive drum 4. The charging device 5 is a charging roller. The charging device 5 may also be a grid-controlled corotron charger.

[0131] The exposure device 6 can expose the surface of the photosensitive drum 4. While the surface of the photosensitive drum 4 is charged by the charging device 5, the exposure device 6 exposes the surface of the photosensitive drum 4, thereby forming an electrostatic latent image on the surface of the photosensitive drum 4. Specifically, the exposure device 6 is a laser scanning unit. The exposure device 6 can also be an LED array.

[0132] The developing device 7 supplies toner to the photosensitive drum 4. The developing device 7 can also be detachable from the main body housing 2. The developing device 7 includes a developing housing 71 and a developing roller 72.

[0133] The developing housing 71 can accommodate toner. In other words, the developing device 7 can accommodate toner. The toner contains toner particles and, if necessary, external additives. The toner particles contain a binder resin and, if necessary, a colorant, a pigment dispersant, a release agent, a magnetic body, and a charge control agent. The binder resin is the base of the toner particles. The binder resin binds the components contained in the toner particles. The colorant imparts a desired color to the toner particles. The colorant is dispersed in the binder resin. The pigment dispersant improves the dispersibility of the colorant. The charge control agent imparts an electric charge property to the toner particles. The electric charge property can be either a positive charge property or a negative charge property. The external additives adjust the electric charge property, fluidity, and storage stability of the toner particles.

[0134] The developing roller 72 can supply the toner in the developing housing 71 to the surface of the photosensitive drum 4. The developing roller 72 is in contact with the photosensitive drum 4. The developing roller 72 can also not be in contact with the photosensitive drum 4. The developing roller 72 can rotate relative to the developing axis A2. The developing roller 72 extends along the developing axis A2. The developing roller 72 has a cylindrical shape.

[0135] The transfer device 8 transfers the toner supplied to the photosensitive drum 4 to the sheet S. The transfer device 8 is in contact with the photosensitive drum 4. The transfer device 8 can also not be in contact with the photosensitive drum 4. The transfer device 8 is a transfer roller. The transfer roller can rotate relative to the transfer axis A3. The transfer roller extends along the transfer axis A3. The transfer roller has a cylindrical shape. The transfer device 8 can also be a belt unit equipped with a transfer belt.

[0136] The ejection device 9 ejects a fixing liquid toward the sheet S onto which the toner has been transferred. The fixing liquid fixes the toner to the sheet S. The fixing liquid can soften the binder resin of the toner. The fixing liquid is, for example, an aliphatic monocarboxylic acid ester, an aliphatic dicarboxylic acid ester, a carbonate, or the like.

[0137] The ejection device 9 is an ejection device using an electrostatic spraying method. The ejection device 9 sprays the fixing liquid toward the sheet S by electrostatic spraying, thereby imparting the fixing liquid to the sheet S. The ejection device 9 includes a housing 91, a plurality of nozzles 92, a nozzle electrode 93, and a counter electrode 94.

[0138] The housing 91 can accommodate the fixing liquid.

[0139] A plurality of nozzles 92 extend downward from the housing 91. The plurality of nozzles 92 communicate with the internal space of the housing 91 respectively. The plurality of nozzles 92 eject the fixing liquid in the housing 91 respectively. The plurality of nozzles 92 are located between the nozzle electrode 93 and the counter electrode 94.

[0140] The nozzle electrode 93 is located in the housing 91. A nozzle voltage is applied to the nozzle electrode 93. The nozzle electrode 93 charges the fixing liquid in the housing 91. In other words, the nozzle electrode 93 charges the fixing liquid supplied to the plurality of nozzles 92. The fixing liquid charged by the nozzle electrode 93 is ejected from the plurality of nozzles 92 respectively, and thus the fixing liquid ejected from the plurality of nozzles 92 becomes a mist. That is to say, the ejection device 9 ejects the fixing liquid in a mist. In other words, the ejection device 9 atomizes the fixing liquid.

[0141] The counter electrode 94 faces the plurality of nozzles 92 with a space therebetween. The counter electrode 94 is located on the opposite side of the nozzle electrode 93 with respect to the plurality of nozzles 92. A counter voltage is applied to the counter electrode 94. The counter electrode 94 attracts the fixing liquid atomized from the plurality of nozzles 92 by electrostatic force.

[0142] The sheet S transferred with toner passes between the plurality of nozzles 92 and the counter electrode 94. At this time, the fixing liquid atomized from the plurality of nozzles 92 is imparted to the sheet S. The sheet S imparted with the fixing liquid is discharged to the upper surface of the main body housing 2.

[0143] Next, refer to Figure 2 Details of the image forming apparatus 1 will be described.

[0144] The image forming apparatus 1 further includes a supply device 11, a recovery device 12, and a control device 100.

[0145] The supply device 11 supplies the fixing liquid to the housing 91. The supply device 11 includes a fixing liquid cartridge 111, a first supply pipe 112, a first supply pump 113, a first supply valve 114, a supply tank 115, a stirring member 116, a sensor 117, a second supply pipe 118, a second supply pump 119, and a second supply valve 120. In other words, the image forming apparatus 1 includes a first supply pump 113, a stirring member 116, and a sensor 117.

[0146] The fixing liquid cartridge 111 accommodates the fixing liquid. The fixing liquid cartridge 111 can be mounted on the main body housing 2.

[0147] One end of the first supply pipe 112 is connected to the fixing liquid cartridge 111 in a state where the fixing liquid cartridge 111 is installed in the main body housing 2. The other end of the first supply pipe 112 is connected to the supply tank 115. The fixing liquid in the fixing liquid cartridge 111 is transported to the supply tank 115 through the first supply pipe 112. That is to say, the first supply pipe 112 allows the passage of the fixing liquid in the fixing liquid cartridge 111. The first supply pipe 112 is an example of the supply pipe of the present invention.

[0148] The first supply pump 113 transports the fixing liquid in the first supply pipe 112 towards the supply tank 115. The first supply pump 113 is located between one end of the first supply pipe 112 and the other end of the first supply pipe 112. In a state where the fixing liquid cartridge 111 is installed in the main body housing 2, the first supply pump 113 is located between the fixing liquid cartridge 111 and the supply tank 115. Specifically, the first supply pump 113 is a gear pump. The first supply pump 113 is an example of the supply pump of the present invention.

[0149] The first supply valve 114 suppresses the situation where the fixing liquid in the fixing liquid cartridge 111 is transported to the supply tank 115 through the inside of the first supply pipe 112. The first supply valve 114 is located between one end of the first supply pipe 112 and the other end of the first supply pipe 112. In a state where the fixing liquid cartridge 111 is installed in the main body housing 2, the first supply valve 114 is located between the fixing liquid cartridge 111 and the supply tank 115. In a state where the fixing liquid cartridge 111 is installed in the main body housing 2, the first supply valve 114 is located between the fixing liquid cartridge 111 and the first supply pump 113. When the first supply pump 113 is driven in a state where the first supply valve 114 is open, the fixing liquid in the fixing liquid cartridge 111 passes through the first supply valve 114 and is transported to the supply tank 115. On the other hand, in a state where the first supply valve 114 is closed, the fixing liquid in the fixing liquid cartridge 111 cannot pass through the first supply valve 114. Thus, the first supply valve 114 suppresses the situation where the fixing liquid in the fixing liquid cartridge 111 is transported to the supply tank 115 through the inside of the first supply pipe 112. The first supply valve 114 is, for example, an electromagnetic valve.

[0150] The supply tank 115 is connected to the other end of the first supply pipe 112. The supply tank 115 can accommodate the fixing liquid that has passed through the first supply pipe 112.

[0151] Here, when the supply tank 115 is located above the housing 91, according to the position of the liquid level of the fixing liquid in the supply tank 115, a water pressure is applied to the fixing liquid in the housing 91. That is to say, the pressure in the housing 91 is a positive pressure relative to the pressure in the supply tank 115. Therefore, the second supply pump 119 cannot make the pressure in the housing 91 lower than the positive pressure applied according to the position of the liquid level of the fixing liquid in the supply tank 115. In addition, the second supply pump 119 is an example of the supply pump of the present invention.

[0152] Regarding this point, in the present embodiment, the supply tank 115 is located below the housing 91. By positioning the supply tank 115 below the housing 91, the pressure inside the housing 91 becomes negative relative to the pressure inside the supply tank 115. Therefore, the second supply pump 119 can control the pressure inside the housing 91 to a desired pressure by controlling the amount of the fixing liquid delivered to the housing 91.

[0153] The stirring member 116 is located inside the supply tank 115. The stirring member 116 stirs the fixing liquid inside the supply tank 115.

[0154] The sensor 117 detects the position of the liquid level of the fixing liquid inside the supply tank 115. Preferably, the liquid level of the fixing liquid inside the supply tank 115 is separated from the other end portion of the first supply pipe 112. The sensor 117 is, for example, a photoelectric sensor. The sensor 117 may also be a liquid level sensor such as a float type liquid level sensor.

[0155] One end portion of the second supply pipe 118 is connected to the supply tank 115. The other end portion of the second supply pipe 118 is connected to the housing 91. In other words, the housing 91 is connected to the second supply pipe 118. The fixing liquid inside the supply tank 115 is delivered to the housing 91 through the second supply pipe 118. That is to say, the second supply pipe 118 allows the passage of the fixing liquid inside the supply tank 115. The housing 91 can accommodate the fixing liquid that has passed through the second supply pipe 118. The second supply pipe 118 is an example of the supply pipe of the present invention.

[0156] The second supply pump 119 delivers the fixing liquid inside the second supply pipe 118 toward the housing 91. The second supply pump 119 is located between one end portion and the other end portion of the second supply pipe 118. The second supply pump 119 is located between the supply tank 115 and the housing 91. Specifically, the second supply pump 119 is a gear pump.

[0157] The second supply valve 120 suppresses the case where the fixing liquid inside the supply tank 115 is delivered to the housing 91 through the inside of the second supply pipe 118. The second supply valve 120 is located between one end portion and the other end portion of the second supply pipe 118. The second supply valve 120 is located between the supply tank 115 and the housing 91. The second supply valve 120 is located between the second supply pump 119 and the housing 91. When the second supply pump 119 is driven in a state where the second supply valve 120 is open, the fixing liquid inside the supply tank 115 passes through the second supply valve 120 and is delivered to the housing 91. On the other hand, in a state where the second supply valve 120 is closed, the fixing liquid inside the supply tank 115 cannot pass through the second supply valve 120. Thus, the second supply valve 120 suppresses the case where the fixing liquid inside the supply tank 115 is delivered to the housing 91 through the inside of the second supply pipe 118. The second supply valve 120 is, for example, an electromagnetic valve.

[0158] The recovery device 12 recovers the fixing liquid that has been ejected from the plurality of nozzles 92 and has not adhered to the sheet S. The recovery device 12 includes a recovery tray 121, a recovery pipe 122, a recovery pump 123, and a recovery valve 124.

[0159] The recovery tray 121 can accommodate the fixing liquid that has been ejected from the plurality of nozzles 92 and has not adhered to the sheet S. The recovery tray 121 faces the plurality of nozzles 92 at a spaced interval. The recovery tray 121 is located on the opposite side of the nozzle electrode 93 with respect to the plurality of nozzles 92. The counter electrode 94 is located within the recovery tray 121. Thus, the fixing liquid ejected from the plurality of nozzles 92 can be attracted into the recovery tray 121 by the counter electrode 94. As a result, the fixing liquid that has not adhered to the sheet S can be reliably accommodated within the recovery tray 121.

[0160] One end of the recovery pipe 122 is connected to the recovery tray 121. The other end of the recovery pipe 122 is connected to the supply tank 115. The fixing liquid within the recovery tray 121 is transported to the supply tank 115 through the recovery pipe 122. That is to say, the recovery pipe 122 allows the passage of the fixing liquid within the recovery tray 121. A part of the recovery pipe 122 extends in the vertical direction. The recovery pipe 122 has a filter 125.

[0161] The filter 125 is located between one end of the recovery pipe 122 and the other end of the recovery pipe 122. The filter 125 is located between the recovery tray 121 and the supply tank 115. The filter 125 is located in the part of the recovery pipe 122 that extends in the vertical direction. The filter 125 extends in a direction intersecting the vertical direction. There is a possibility that foreign matters such as toner and paper dust are mixed into the fixing liquid accommodated in the recovery tray 121. The filter 125 allows the passage of the fixing liquid and does not allow the passage of foreign matters mixed into the fixing liquid. The filter 125 removes the foreign matters mixed into the fixing liquid from the fixing liquid.

[0162] The recovery pump 123 transports the fixing liquid within the recovery pipe 122 toward the supply tank 115. As described above, the fixing liquid within the supply tank 115 is transported to the housing 91 through the second supply pipe 118. That is to say, the recovery pump 123 transports the fixing liquid within the recovery pipe 122 to the ejection device 9 via the supply tank 115. In other words, the recovery pump 123 transports the fixing liquid within the recovery pipe 122 toward the housing 91. The recovery pump 123 is located between one end of the recovery pipe 122 and the other end of the recovery pipe 122. The recovery pump 123 is located between the recovery tray 121 and the supply tank 115. The recovery pump 123 is located between the filter 125 and the supply tank 115. Specifically, the recovery pump 123 is a gear pump.

[0163] The recovery valve 124 inhibits the situation where the fixing liquid in the recovery tray 121 is transported to the supply tank 115 through the inside of the recovery pipe 122. The recovery valve 124 is located between one end of the recovery pipe 122 and the other end of the recovery pipe 122. The recovery valve 124 is located between the recovery tray 121 and the supply tank 115. The recovery valve 124 is located between the recovery pump 123 and the supply tank 115. When the recovery pump 123 is driven in a state where the recovery valve 124 is open, the fixing liquid in the recovery tray 121 passes through the recovery valve 124 and is transported to the supply tank 115. On the other hand, in a state where the recovery valve 124 is closed, the fixing liquid in the recovery tray 121 cannot pass through the recovery valve 124. Thus, the recovery valve 124 inhibits the situation where the fixing liquid in the recovery tray 121 is transported to the supply tank 115 through the inside of the recovery pipe 122. The recovery valve 124 is, for example, an electromagnetic valve.

[0164] The control device 100 controls the operations of the first supply pump 113, the second supply pump 119, and the recovery pump 123. The control device 100 controls the opening and closing of the first supply valve 114, the second supply valve 120, and the recovery valve 124. The control device 100 can receive the signals sent by the sensor 117. The control device 100 is electrically connected to the first supply pump 113, the first supply valve 114, the second supply pump 119, the second supply valve 120, the recovery pump 123, the recovery valve 124, and the sensor 117.

[0165] Next, with reference to Figure 2 and Figure 3 , the control of the first supply pump 113 by the control device 100 will be described.

[0166] When the control device 100 acquires a printing job (S1), the control device 100 forms an image on the sheet S according to the printing job. When forming an image on the sheet S, the control device 100 causes the ejection device 9 to spray the fixing liquid (S2).

[0167] Specifically, the control device 100 drives the second supply pump 119 in a state where a nozzle voltage is applied to the nozzle electrode 93 and a counter electrode voltage is applied to the counter electrode 94. After that, the control device 100 opens the second supply valve 120 after the operation of the second supply pump 119 stabilizes. By opening the second supply valve 120, the fixing liquid is supplied to the housing 91. The fixing liquid in the housing 91 is sprayed from the plurality of nozzles 92 respectively.

[0168] Then, when the printing job ends (S3: Yes), the control device 100 stops the spraying of the fixing liquid from the ejection device 9 (S4).

[0169] Specifically, after closing the second supply valve 120, the control device 100 stops the second supply pump 119. After that, the control device 100 stops applying the nozzle voltage to the nozzle electrode 93 and stops applying the opposing voltage to the opposing electrode 94. As a result, the spraying of the fixing liquid from the spraying device 9 stops.

[0170] After that, the control device 100 executes a pump driving process (S6) and a pump stopping process (S8). That is, after the printing operation ends (S3: Yes), the control device 100 executes the pump driving process (S6) and the pump stopping process (S8).

[0171] In the pump driving process (S6), when the liquid level position detected by the sensor 117 is lower than the threshold value (S5: Yes), the control device 100 drives the first supply pump 113 to supply the fixing liquid from the fixing liquid cartridge 111 to the supply tank 115.

[0172] Specifically, when the fixing liquid in the supply tank 115 decreases due to forming an image on the sheet S according to the printing operation, the liquid level of the fixing liquid in the supply tank 115 drops. Then, after the printing operation ends, when the liquid level position detected by the sensor 117 is lower than the threshold value (S5: Yes), the control device 100 opens the first supply valve 114 and drives the first supply pump 113 (S6). Then, the fixing liquid is supplied from the fixing liquid cartridge 111 to the supply tank 115.

[0173] In addition, when the liquid level position detected by the sensor 117 is equal to or higher than the threshold value (S5: No), the control device 100 does not execute the pump driving process (S6).

[0174] Next, the control device 100 executes the pump stopping process (S8) after the pump driving process (S6).

[0175] In the pump stopping process (S8), when the liquid level position detected by the sensor 117 is equal to or higher than the threshold value (S7: Yes), the control device 100 stops driving the first supply pump 113 to stop the supply of the fixing liquid from the fixing liquid cartridge 111 to the supply tank 115.

[0176] Specifically, when the fixing liquid is supplied from the fixing liquid cartridge 111 to the supply tank 115 through the pump driving process (S6), the liquid level of the fixing liquid in the supply tank 115 rises. Then, when the liquid level position detected by the sensor 117 is equal to or higher than the threshold value (S7: Yes), the control device 100 stops driving the first supply pump 113 (S8) and closes the first supply valve 114. As a result, the supply of the fixing liquid from the fixing liquid cartridge 111 to the supply tank 115 stops.

[0177] <Effects of the First Embodiment>

[0178] (1) According to the image forming apparatus 1 according to the first embodiment, as Figure 2 shown, the fixing liquid ejected from the plurality of nozzles 92 and not attached to the sheet S can be accommodated in the recovery tray 121, and is transported to the supply tank 115 through the recovery pipe 122, and then transported from the supply tank 115 to the housing 91.

[0179] Thus, the fixing liquid not attached to the sheet S can be recovered and ejected again from the plurality of nozzles 92.

[0180] As a result, the consumption amount of the fixing liquid can be suppressed.

[0181] (2) According to the image forming apparatus 1 according to the first embodiment, as Figure 2 shown, the counter electrode 94 is located in the recovery tray 121.

[0182] Thus, the fixing liquid ejected from the plurality of nozzles 92 can be attracted into the recovery tray 121 by the counter electrode 94.

[0183] As a result, the fixing liquid not attached to the sheet S can be reliably accommodated in the recovery tray 121.

[0184] (3) According to the image forming apparatus 1 according to the first embodiment, as Figure 2 shown, the fixing liquid in the fixing liquid cartridge 111 can be supplied to the housing 91 via the supply tank 115.

[0185] Therefore, by making the amount of the fixing liquid in the supply tank 115 constant, even if the fixing liquid in the fixing liquid cartridge 111 decreases, the fixing liquid can be stably supplied to the housing 91.

[0186] As a result, the ejection state of the fixing liquid ejected from the plurality of nozzles 92 can be stabilized.

[0187] (4) According to the image forming apparatus 1 according to the first embodiment, as Figure 2 shown, the recovery pipe 122 is connected to the supply tank 115.

[0188] Therefore, the fixing liquid from the recovery tray 121 and the fixing liquid from the fixing liquid cartridge 111 can be accommodated in the supply tank 115 together.

[0189] As a result, while stabilizing the ejection state of the fixing liquid ejected from the plurality of nozzles 92, the fixing liquid from the recovery tray 121 can be reused.

[0190] (5) According to the image forming apparatus 1 according to the first embodiment, as Figure 2 shown, the supply device 11 includes a sensor 117 that detects the liquid level position of the fixing liquid in the supply tank 115. AsFigure 3 As shown, when the liquid level position detected by the sensor 117 is lower than the threshold value (S5: Yes), the control device 100 drives the first supply pump 113 (S6) to supply the fixing liquid from the fixing liquid cartridge 111 to the supply tank 115. After that, when the liquid level position detected by the sensor 117 is equal to or higher than the threshold value (S7: Yes), the control device 100 stops driving the first supply pump 113 (S8) to stop the supply of the fixing liquid from the fixing liquid cartridge 111 to the supply tank 115.

[0191] Thus, the amount of the fixing liquid in the supply tank 115 can be made constant based on the liquid level position detected by the sensor 117.

[0192] As a result, the ejection state of the fixing liquid ejected from the plurality of nozzles 92 can be stabilized.

[0193] (6) According to the image forming apparatus 1 according to the first embodiment, as Figure 2 shown, the recovery pipe 122 has a filter 125.

[0194] Thus, even if foreign matters such as toner and paper dust are mixed in the fixing liquid in the recovery tray 121, the foreign matters can be removed by the filter 125 and the fixing liquid can be reused.

[0195] (7) According to the image forming apparatus 1 according to the first embodiment, as Figure 2 shown, a part of the recovery pipe 122 extends in the vertical direction. The filter 125 extends in a direction crossing the vertical direction.

[0196] Therefore, the fixing liquid is passed through the filter 125 in the vertical direction, whereby the fixing liquid can be brought into contact with the entire surface of the filter 125.

[0197] As a result, it is possible to suppress the situation where only a part of the filter 125 is clogged and reduce the replacement frequency of the filter 125.

[0198] <First Modification of the First Embodiment>

[0199] Next, with reference to Figures 4 - 6 , a modification of the first embodiment will be described. In the modification, the same reference numerals are given to the same components as those in the above-described first embodiment, and the description thereof will be omitted.

[0200] (1) As Figure 4As shown, alternatively, the other end of the recovery pipe 122 is connected to the first supply pipe 112. The other end of the recovery pipe 122 is connected to the first supply pipe 112 between the first supply valve 114 and the first supply pump 113. The first supply pipe 112 allows the fixing liquid that has passed through the recovery pipe 122 to pass through. The fixing liquid that has passed through the recovery pipe 122 is received in the supply tank 115 through the first supply pipe 112.

[0201] In this modified example, the same operational effects as those of the above-described first embodiment can also be obtained.

[0202] (2) As Figure 5 shown, alternatively, the recovery device 12 is independent of the supply device 11. Specifically, the recovery device 12 includes a recovery tank 126 and a second recovery pipe 127. In other words, the image forming apparatus 1 includes a recovery tank 126 and a second recovery pipe 127.

[0203] The recovery tank 126 is connected to the other end of the recovery pipe 122. The recovery tank 126 can receive the fixing liquid that has passed through the recovery pipe 122. The recovery tank 126 is located below the housing 91.

[0204] One end of the second recovery pipe 127 is connected to the recovery tank 126. The other end of the second recovery pipe 127 is connected to the housing 91. In other words, the housing 91 is connected to the other end of the second recovery pipe 127. The fixing liquid in the recovery tank 126 is transported to the housing 91 through the second recovery pipe 127. That is to say, the second recovery pipe 127 allows the fixing liquid in the recovery tank 126 to pass through. The housing 91 can receive the fixing liquid that has passed through the second supply pipe 118 and the fixing liquid that has passed through the second recovery pipe 127.

[0205] In this modified example, the same operational effects as those of the above-described first embodiment can also be obtained.

[0206] (3) As Figure 6 shown, alternatively, the supply device 11 does not include a supply tank 115. Alternatively, the recovery device 12 is independent of the supply device 11 and does not include a recovery tank 126. The housing 91 is connected to the first supply pipe 112 and the recovery pipe 122, and can receive the fixing liquid that has passed through the first supply pipe 112 and the fixing liquid that has passed through the recovery pipe 122.

[0207] In this modified example, the same operational effects as those of the above-described first embodiment can also be obtained.

[0208] (4) Alternatively, the control device 100 executes a pump drive process (S6) and a pump stop process (S8) when forming an image on the sheet S according to a printing job.

[0209] [Second Embodiment]

[0210] Next, while referring to Figures 7 - 15 , the image forming apparatus according to the second embodiment of the present invention will be described in detail.

[0211] In the second embodiment, the same reference numerals are assigned to the same structures as those described in the first embodiment, and the description thereof will be given.

[0212] Referring to Figure 7 , the outline of the image forming apparatus 201 according to the second embodiment will be described.

[0213] The image forming apparatus 201 includes a main body housing 2, a sheet accommodating portion 3, a photosensitive drum 4, a charging device 5, an exposure device 6, a developing device 7, a transfer device 8, and a spraying device 9.

[0214] The main body housing 2 houses the sheet accommodating portion 3, the photosensitive drum 4, the charging device 5, the exposure device 6, the developing device 7, the transfer device 8, and the spraying device 9.

[0215] The sheet accommodating portion 3 can accommodate a sheet S. The sheet S is, for example, printing paper. The sheet S is conveyed toward the transfer device 8. The sheet accommodating portion 3 may be a sheet cassette that can be mounted on the main body housing 2.

[0216] The photosensitive drum 4 extends in the first direction. The photosensitive drum 4 can rotate relative to the drum shaft. The drum shaft extends in the first direction.

[0217] The charging device 5 charges the surface of the photosensitive drum 4. In the present embodiment, the charging device 5 is a charging roller. The charging device 5 may also be a grid-controlled corona charger.

[0218] The exposure device 6 can expose the surface of the photosensitive drum 4 charged by the charging device 5. Specifically, the exposure device 6 is a laser scanning unit. The exposure device 6 may also be an LED array.

[0219] The developing device 7 supplies toner to the photosensitive drum 4. Alternatively, the developing device 7 can be attached to and detached from the main body housing 2. The developing device 7 includes a developing housing 71 and a developing roller 72.

[0220] The developing housing 71 can accommodate toner. In other words, the developing device 7 can accommodate toner. The toner contains toner particles and, as needed, external additives. The toner particles contain a binder resin and, as needed, a colorant, a pigment dispersant, a release agent, a magnetic body, and a charge control agent. The binder resin is the base of the toner particles. The binder resin binds the components contained in the toner particles. The colorant imparts the desired color to the toner particles. The colorant is dispersed in the binder resin. The pigment dispersant improves the dispersibility of the colorant. The charge control agent imparts chargeability to the toner particles. The chargeability can be either positive chargeability or negative chargeability. The external additives adjust the chargeability, fluidity, and storage stability of the toner particles.

[0221] The developing roller 72 can supply the toner in the developing housing 71 to the surface of the photosensitive drum 4. The developing roller 72 is in contact with the photosensitive drum 4. The developing roller 72 may not be in contact with the photosensitive drum 4. The developing roller 72 extends in a first direction. The developing roller 72 can rotate relative to the developing shaft. The developing shaft extends in the first direction.

[0222] The transfer device 8 transfers the toner on the photosensitive drum 4 to the sheet S. In the present embodiment, the transfer device 8 has a transfer roller 81. The transfer roller 81 is in contact with the photosensitive drum 4. The transfer roller 81 may not be in contact with the photosensitive drum 4. The transfer roller 81 extends in a first direction. The transfer roller 81 can rotate relative to the transfer shaft. The transfer shaft extends in the first direction. The transfer device 8 may also include a transfer belt.

[0223] The spraying device 9 sprays a fixing liquid onto the sheet S onto which toner has been transferred. The fixing liquid fixes the toner to the sheet S. The fixing liquid can soften the binder resin of the toner. The fixing liquid is, for example, an aliphatic monocarboxylic acid ester, an aliphatic dicarboxylic acid ester, a carbonate ester, or the like.

[0224] The spraying device 9 is an electrostatic spraying method. The spraying device 9 sprays the fixing liquid toward the sheet S by electrostatic spraying. The spraying device 9 includes a housing 91, a plurality of nozzles 92, a nozzle electrode 93, and a counter electrode 94.

[0225] The housing 91 can accommodate the fixing liquid.

[0226] The plurality of nozzles 92 extend downward from the housing 91. The plurality of nozzles 92 communicate with the internal space of the housing 91 respectively. The plurality of nozzles 92 spray the fixing liquid in the housing 91 respectively. The plurality of nozzles 92 are located between the nozzle electrode 93 and the counter electrode 94.

[0227] The nozzle electrode 93 is located inside the housing 91. A voltage is applied to the nozzle electrode 93. The nozzle electrode 93 charges the fixing liquid in the housing 91. In other words, the nozzle electrode 93 charges the fixing liquid supplied to the plurality of nozzles 92.

[0228] The counter electrode 94 faces the plurality of nozzles 92 with a clearance therebetween. The counter electrode 94 is located on the opposite side of the nozzle electrode 93 with respect to the plurality of nozzles 92. A voltage having a polarity opposite to that of the voltage applied to the nozzle electrode 93 is applied to the counter electrode 94. In the present embodiment, a positive voltage is applied to the nozzle electrode 93, and a negative voltage is applied to the counter electrode 94. As a result, a potential difference (electric field) is generated between the nozzle 92 and the counter electrode 94, and the counter electrode 94 attracts the fixing liquid sprayed from the plurality of nozzles 92 by electrostatic force.

[0229] The sheet S on which toner is transferred passes between the plurality of nozzles 92 and the counter electrode 94. At this time, the fixing liquid is sprayed from the plurality of nozzles 92 onto the sheet S respectively. The sheet S sprayed with the fixing liquid is discharged to the upper surface of the main body housing 2.

[0230] Next, with reference to Figure 8 , details of the image forming apparatus 201 according to the second embodiment will be described.

[0231] The image forming apparatus 201 includes a supply device 11, a recovery device 12, and a control device 200.

[0232] The supply device 11 can supply the fixing liquid to the housing 91 of the spraying device 9. The supply device 11 includes a supply tank 115, a sensor 117, a supply pipe 118, a supply pump 119, a supply valve 120, a fixing liquid cartridge 111, a replenishment pipe 112, a replenishment pump 113, and a replenishment valve 114.

[0233] The supply tank 115 can store the fixing liquid supplied to the housing 91 of the spraying device 9.

[0234] The sensor 117 detects whether the amount of the fixing liquid in the supply tank 115 is less than a specified amount. In the present embodiment, the specified amount is an amount less than the maximum amount of the fixing liquid that the supply tank 115 can store, and is an amount such that the supply tank 115 will not become empty even when printing the maximum number of sheets S that the sheet storage section 3 can store. The sensor 117 sends a signal when it detects that the amount of the fixing liquid in the supply tank 115 is equal to or more than the specified amount. When the sensor 117 sends a signal, the sensor 117 is in an on state. On the other hand, the sensor 117 does not send a signal when it detects that the amount of the fixing liquid in the supply tank 115 is less than the specified amount. When the sensor 117 does not send a signal, the sensor 117 is in an off state.

[0235] Specifically, the sensor 117 detects whether the amount of the fixing liquid in the supply tank 115 is less than the specified amount by detecting the liquid level position of the fixing liquid in the supply tank 115. The sensor 117 is, for example, a photoelectric sensor. The sensor 117 may also be a liquid level sensor such as a float type liquid level sensor.

[0236] One end of the supply pipe 118 is connected to the supply tank 115. The other end of the supply pipe 118 is connected to the housing 91. The supply pipe 118 allows the fixing liquid to pass from the supply tank 115 to the housing 91. Thus, the fixing liquid in the supply tank 115 enters the housing 91 through the supply pipe 118.

[0237] The supply pump 119 conveys the fixing liquid in the supply pipe 118 toward the housing 91. The supply pump 119 is located between one end of the supply pipe 118 and the other end of the supply pipe 118. The supply pump 119 is located between the supply tank 115 and the housing 91. The supply pump 119 is, for example, a gear pump.

[0238] The supply valve 120 is located between one end of the supply pipe 118 and the other end of the supply pipe 118. The supply valve 120 is located between the supply tank 115 and the housing 91. The supply valve 120 is located between the supply pump 119 and the housing 91.

[0239] When the supply pump 119 is driven in a state where the supply valve 120 is open, the fixing liquid in the supply pipe 118 passes through the supply valve 120. On the other hand, in a state where the supply valve 120 is closed, the fixing liquid in the supply pipe 118 cannot pass through the supply valve 120. Thus, the supply valve 120 suppresses the situation where the fixing liquid passes through the supply pipe 118. The supply valve 120 is, for example, an electromagnetic valve.

[0240] The fixing liquid cartridge 111 can accommodate the fixing liquid replenished to the supply tank 115. The fixing liquid cartridge 111 can be installed on the main body housing 2. The fixing liquid cartridge 111 installed on the main body housing 2 can be removed from the main body housing 2.

[0241] In a state where the fixing liquid cartridge 111 is installed on the main body housing 2, one end of the replenishing pipe 112 is connected to the fixing liquid cartridge 111. The other end of the replenishing pipe 112 is connected to the supply tank 115. The replenishing pipe 112 allows the fixing liquid to pass from the fixing liquid cartridge 111 to the supply tank 115. Thus, the fixing liquid in the fixing liquid cartridge 111 enters the supply tank 115 through the replenishing pipe 112.

[0242] The replenishing pump 113 conveys the fixing liquid in the replenishing pipe 112 toward the supply tank 115. The replenishing pump 113 is located between one end of the replenishing pipe 112 and the other end of the replenishing pipe 112. In a state where the fixing liquid cartridge 111 is installed on the main body housing 2, the replenishing pump 113 is located between the fixing liquid cartridge 111 and the supply tank 115. The replenishing pump 113 is, for example, a gear pump.

[0243] The supply valve 114 is located between one end portion and the other end portion of the supply pipe 112. In a state where the fixing liquid cartridge 111 is installed in the main body housing 2, the supply valve 114 is located between the fixing liquid cartridge 111 and the supply tank 115. In a state where the fixing liquid cartridge 111 is installed in the main body housing 2, the supply valve 114 is located between the fixing liquid cartridge 111 and the supply pump 113.

[0244] When the supply pump 113 is driven with the supply valve 114 open, the fixing liquid in the supply pipe 112 passes through the supply valve 114. On the other hand, in a state where the supply valve 114 is closed, the fixing liquid in the supply pipe 112 cannot pass through the supply valve 114. Thus, the supply valve 114 suppresses the situation where the fixing liquid in the fixing liquid cartridge 111 passes through the supply pipe 112. The supply valve 114 is, for example, an electromagnetic valve.

[0245] The recovery device 12 can recover the fixing liquid that is sprayed from the spraying device 9 and not attached to the sheet S. The recovery device 12 includes a recovery tray 121, a recovery pipe 122, a recovery pump 123, and a recovery valve 124.

[0246] The recovery tray 121 can accommodate the fixing liquid that is not attached to the sheet S. The recovery tray 121 faces the plurality of nozzles 92 with a space therebetween. The recovery tray 121 is located on the opposite side of the nozzle electrode 93 with respect to the plurality of nozzles 92. The counter electrode 94 is located within the recovery tray 121. Thus, the fixing liquid sprayed from the plurality of nozzles 92 can be attracted into the recovery tray 121 by the counter electrode 94. As a result, the fixing liquid that is not attached to the sheet S can be reliably accommodated in the recovery tray 121.

[0247] One end portion of the recovery pipe 122 is connected to the recovery tray 121. The other end portion of the recovery pipe 122 is connected to the supply tank 115. The other end portion of the recovery pipe 122 may also be connected to the fixing liquid cartridge 111. The recovery pipe 122 allows the passage of the fixing liquid from the recovery tray 121 to the supply tank 115. Thus, the fixing liquid in the recovery tray 121 enters the supply tank 115 through the recovery pipe 122. A part of the recovery pipe 122 extends in the vertical direction. The recovery pipe 122 has a filter 125.

[0248] The filter 125 is located between one end portion and the other end portion of the recovery pipe 122. The filter 125 is located between the recovery tray 121 and the supply tank 115. The filter 125 is located in the part of the recovery pipe 122 that extends in the vertical direction. The filter 125 extends in a direction intersecting the vertical direction. There is a possibility that foreign matters such as colored powder and paper dust are mixed into the fixing liquid accommodated in the recovery tray 121. The filter 125 allows the passage of the fixing liquid and does not allow the passage of the foreign matters mixed into the fixing liquid. The filter 125 removes the foreign matters mixed into the fixing liquid from the fixing liquid.

[0249] The recovery pump 123 conveys the fixing liquid in the recovery pipe 122 toward the supply tank 115. Thus, the recovery pump 123 conveys the fixing liquid accommodated in the recovery tray 121 toward the supply device 11. The recovery pump 123 is located between one end portion and the other end portion of the recovery pipe 122. The recovery pump 123 is located between the recovery tray 121 and the supply tank 115. The recovery pump 123 is located between the filter 125 and the supply tank 115. Specifically, the recovery pump 123 is a gear pump.

[0250] The recovery valve 124 is located between one end portion and the other end portion of the recovery pipe 122. The recovery valve 124 is located between the recovery tray 121 and the supply tank 115. The recovery valve 124 is located between the recovery pump 123 and the supply tank 115.

[0251] When the recovery pump 123 is driven in a state where the recovery valve 124 is open, the fixing liquid in the recovery pipe 122 passes through the recovery valve 124. On the other hand, in a state where the recovery valve 124 is closed, the fixing liquid in the recovery pipe 122 cannot pass through the recovery valve 124. Thus, the recovery valve 124 suppresses the situation where the fixing liquid passes through the recovery pipe 122. The recovery valve 124 is, for example, an electromagnetic valve.

[0252] The control device 200 controls the operations of the supply pump 119, the recovery pump 123, and the replenishment pump 113. The control device 200 controls the opening and closing of the supply valve 120, the recovery valve 124, and the replenishment valve 114. The control device 200 can receive the signals sent by the sensor 117. The control device 200 is electrically connected to the supply pump 119, the supply valve 120, the recovery pump 123, the recovery valve 124, the replenishment pump 113, the replenishment valve 114, and the sensor 117.

[0253] The control device 200 stores a first set value P1, a second set value P2, and a third set value P3. Specifically, the control device 200 includes a processor and a non-volatile memory. The non-volatile memory stores the first set value P1, the second set value P2, and the third set value P3.

[0254] The first set value P1 is the number of pages that can be printed continuously until the supply tank 115 becomes empty. The first set value P1 is set based on the capacity of the supply tank 115. The first set value P1 is, for example, the number of pages when the supply tank 115 assumed to be full becomes empty. In addition, the state where the supply tank 115 is full means the state where the supply tank 115 holds the fixing liquid at the water level at which the sensor 117 changes from the closed state to the open state. In other words, the state where the supply tank 115 is full means the state where a specified amount of fixing liquid is accommodated in the supply tank 115. That is to say, the first set value P1 is the number of pages that can be printed continuously with the specified amount of fixing liquid in the supply tank 115. The first set value P1 is set based on the standard fixing liquid amount used in each page of printing determined in advance through experiments, simulations, etc. and the fixing liquid amount in the supply tank 115 in the full state determined in advance according to the capacity of the supply tank 115. In the present embodiment, the first set value P1 is set to the same value as the maximum number of sheets S that can be accommodated in the sheet accommodating section 3.

[0255] The second set value P2 is set based on the capacity of the recovery tray 121. The second set value P2 is, for example, the number of pages that can be printed assuming that the amount of fixing liquid in the recovery tray 121 reaches 80% of the capacity of the recovery tray 121 from the empty state. In addition, the amount of fixing liquid recovered into the recovery tray 121 in each page of printing is a value determined in advance through experiments, simulations, etc., and the second set value P2 is set based on this value and the capacity of the recovery tray 121. In the present embodiment, the second set value P2 is smaller than the first set value P1.

[0256] The third set value P3 is the number of pages assuming that the sensor 117 in the open state becomes the closed state. The third set value P3 is a value determined in advance through experiments and simulations based on the capacity of the supply tank 115, and is set by converting the amount of fixing liquid in the supply tank 115 consumed from the full state of the supply tank 115 until the sensor 117 changes to the open state into the number of pages. In the present embodiment, the third set value P3 is smaller than the first set value P1 and smaller than the second set value P2.

[0257] Next, with reference to Figures 9 - 15 , the control of the control device 200 will be described.

[0258] As Figure 9 shown, when a print job is acquired (S201), the control device 200 prints an image on the sheet S according to the print job. The print job includes a print instruction command, and includes print data to be printed on the sheet S, the number of pages, etc. When printing an image on the sheet S, the control device 200 causes the spray device 9 to spray the fixing liquid (S202).

[0259] Specifically, the control device 200 drives the supply pump 119 in a state where a voltage is applied to the nozzle electrode 93 and a voltage is applied to the counter electrode 94. After that, after the operation of the supply pump 119 stabilizes, the control device 200 opens the supply valve 120. Then, the fixing liquid is supplied to the housing 91. The fixing liquid in the housing 91 is sprayed from the plurality of nozzles 92 respectively.

[0260] The control device 200 counts the accumulation of printed pages. The accumulation of printed pages is defined as the first accumulated page number C1.

[0261] Then, when the first accumulated page number C1 is less than the first set value P1 (S203: Yes) and the execution of the printing operation is completed (S204: Yes), the control device 200 stops the spraying of the fixing liquid from the spraying device 9 (S205).

[0262] Specifically, the control device 200 stops the supply pump 119 after closing the supply valve 120. After that, the control device 200 stops applying a voltage to the nozzle electrode 93 and stops applying a voltage to the counter electrode 94. Then, the spraying of the fixing liquid from the spraying device 9 stops.

[0263] Next, as Figure 10 shown, the control device 200 starts the recovery process (S206), that is, the control device 200 executes the recovery process (S206) when the execution of the printing operation is completed (S204: Yes).

[0264] In the recovery process, the control device 200 drives the recovery pump 123 to transport the fixing liquid in the recovery tray 121 to the supply tank 115 of the supply device 11. Additionally, in the recovery process, the control device 200 may transport the fixing liquid in the recovery tray 121 to the fixing liquid cartridge 111 of the supply device 11.

[0265] Specifically, the control device 200 drives the recovery pump 123. After the operation of the recovery pump 123 stabilizes, the recovery valve 124 is opened. Then, the fixing liquid in the recovery tray 121 is transported to the supply tank 115.

[0266] Here, the more the first accumulated page number C1 is, the more the amount of the fixing liquid in the recovery tray 121 is. Also, the less the first accumulated page number C1 is, the less the amount of the fixing liquid in the supply tank 115 is. Therefore, the more the first accumulated page number C1 is, the longer the control device 200 extends the driving time of the recovery pump 123 during the recovery process. In other words, the more the first accumulated page number C1 is, the longer the control device 200 extends the time of the recovery process.

[0267] Next, when the control device 200 does not receive a new printing job during the recycling process (S207: No), the recycling process ends (S208). A new printing job is defined as an embedded job.

[0268] Specifically, after closing the recycling valve 124, the control device 200 stops the recycling pump 123. Then, the fixing liquid from the recycling tray 121 to the supply tank 115 stops. Thereby, the recycling process ends.

[0269] Next, when the control device 200 has completed the recycling process (S208), it resets the first cumulative page count C1 (S209). That is, the next first cumulative page count C1 is the cumulative count of the pages printed after the current first cumulative page count C1 is reset. In other words, the first cumulative page count C1 is the cumulative count of the pages printed after the previous recycling process.

[0270] In addition, as Figure 11 shown, when the control device 200 receives an embedded job during the recycling process (S207: Yes, refer to Figure 10 ), and when the first cumulative page count C1 is less than the second set value P2 (S221: Yes), after executing the embedded job, the recycling process is executed (S226).

[0271] Specifically, the control device 200 interrupts the recycling process in order to print an image on the sheet S according to the embedded job, and sprays the fixing liquid from the spraying device 9 (S222).

[0272] Next, after the control device 200 has completed the embedded job (S223: Yes), it stops the spraying of the fixing liquid from the spraying device 9 (S224).

[0273] Next, the control device 200 executes the recycling process (S226).

[0274] Here, the control device 200 adds the number of pages N printed in the embedded job to the first cumulative page count C1 (S225).

[0275] Moreover, in the recycling process after the embedded job (S226), based on the first cumulative page count C1 after adding the number of pages N printed in the embedded job, the more the first cumulative page count C1 is, the longer the control device 200 extends the driving time of the recycling pump 123 during the recycling process.

[0276] Next, after the control device 200 has completed the recycling process (S227), it resets the first cumulative page count C1 (S209, refer to Figure 10 ).

[0277] On the other hand, when the control device 200 receives an embedded job during the recycling process (S207: Yes, refer toFigure 10 ) and when the first cumulative page count C1 is equal to or greater than the second set value P2 (S221: No), after the recycling process (S228), the embedding operation is executed (S202, refer to Figure 9 ).

[0278] Specifically, the control device 200 continues the recycling process without executing the embedding operation, and ends the recycling process (S228).

[0279] Next, the control device 200 resets the first cumulative page count C1 (S229), and executes the embedding operation (S202, refer to Figure 9 ).

[0280] In addition, as Figure 12 shown, when the first cumulative page count C1 is equal to or greater than the first set value P1 during the execution of the printing operation (S203: No, refer to Figure 9 ), the printing operation is interrupted (S231), and the recycling process is executed (S233).

[0281] Specifically, when the first cumulative page count C1 is equal to or greater than the first set value P1 during the execution of the printing operation (S203: No, refer to Figure 9 ), the spraying of the fixing liquid from the spraying device 9 is stopped (S231).

[0282] Next, when the sensor 117 is in the off state (S232: No), the control device 200 starts the recycling process (S233). The greater the first cumulative page count C1, the longer the driving time of the recycling pump 123 during the recycling process by the control device 200.

[0283] Next, after the control device 200 has completed the recycling process (S234), the first cumulative page count C1 is reset (S235).

[0284] Figure 13 It is a flowchart showing the recovery process of the image forming apparatus 201 when an error such as the sheet S being jammed in the image forming apparatus 201 occurs and the jammed sheet S is removed by the user or the like, thereby eliminating the error.

[0285] As Figure 13 shown, the control device 200 executes the recycling process (S243) after nozzle cleaning (S242) during the recovery process.

[0286] Specifically, when the sensor 117 is in the off state (S241: No), the control device 200 executes nozzle cleaning (S242). During nozzle cleaning (S242), the control device 200 cleans the nozzle 92 by spraying the fixing liquid from the nozzle 92.

[0287] In addition, when the sensor 117 is in the ON state (S241: Yes) and the second cumulative page count C2 is less than the third set value P3 (S248: No), the control device 200 also performs nozzle cleaning (S242). The second cumulative page count C2 is the accumulation of the pages printed after the last replenishment process. The replenishment process will be described later.

[0288] Next, the control device 200 starts the recovery process (S243). The more the first cumulative page count C1 is, the longer the control device 200 makes the driving time of the recovery pump 123 in the recovery process.

[0289] Next, after the control device 200 has completed the recovery process (S244), it resets the first cumulative page count C1 (S245).

[0290] As Figure 10 , Figure 12 , Figure 13 shown, when the sensor 117 is in the OFF state after the recovery process (S210: No, S236: No, S246: No), the control device 200 performs the replenishment process (S211, S237, S247). In other words, the control device 200 performs the replenishment process when the sensor 117 detects that the amount of the fixing liquid in the supply tank 115 is less than the specified amount after the recovery process.

[0291] In addition, when the sensor 117 is in the ON state (S210: Yes, S236: Yes, S246: Yes) and the second cumulative page count C2 is less than the third set value P3 (S212: No, S248: No, S254: No), the control device 200 does not perform the replenishment process (S211, S237, S247).

[0292] In addition, as Figure 14 shown, when the sensor 117 is in the OFF state during the warm-up process of the image forming apparatus 201 (S251), the control device 200 performs the replenishment process (S253). In other words, the control device 200 performs the replenishment process when the sensor 117 detects that the amount of the fixing liquid in the supply tank 115 is less than the specified amount during the warm-up process of the image forming apparatus 201. The warm-up process means the process required until the image forming apparatus 201 becomes capable of performing printing after the power of the image forming apparatus 201 is turned on.

[0293] In addition, when the sensor 117 is in the ON state (S252: Yes), the control device 200 does not perform the replenishment process (S253).

[0294] In the replenishment process, the control device 200 drives the replenishment pump 113 to transport the fixing liquid contained in the fixing liquid cartridge 111 to the supply tank 115.

[0295] Specifically, the control device 200 drives the replenishment pump 113. After that, after the operation of the replenishment pump 113 stabilizes, the replenishment valve 114 is opened. Then, the fixing liquid in the fixing liquid cartridge 111 is transported to the supply tank 115.

[0296] Thus, as Figure 15 shown, the replenishment of the fixing liquid from the fixing liquid cartridge 111 to the supply tank 115 starts (S261).

[0297] Next, when the sensor 117 is in the on state before the elapse of the specified time (S262: Yes), the control device 200 ends the replenishment of the fixing liquid from the fixing liquid cartridge 111 to the supply tank 115 (S263). In addition, the control device 200 can also change the specified time according to the first cumulative number of pages C1. Specifically, it can be that the more the first cumulative number of pages, the longer the control device 200 extends the specified time.

[0298] Specifically, after closing the replenishment valve 114, the replenishment pump 113 is stopped. Then, the supply of the fixing liquid from the fixing liquid cartridge 111 to the supply tank 115 stops. Thus, the replenishment process ends.

[0299] On the other hand, when the sensor 117 is not in the on state even after the elapse of the specified time (S262: No, S264: Yes), the control device 200 displays the content that the fixing liquid cartridge 111 is empty (S265).

[0300] The control device 200 performs an error display process when suspecting a failure of the sensor 117. In the present embodiment, although it is assumed that the sensor 117 is in the off state, the error display process is also performed when the sensor 117 is in the on state.

[0301] Specifically, as Figure 10 , Figure 13 , Figure 14 shown, when the sensor 117 is in the on state (S210: Yes, S241: Yes, S252: Yes), and the second cumulative number of pages C2 is equal to or more than the third set value P3 (S212: Yes, S248: Yes, S254: Yes), the error display process (S213, S249, S255) is performed. In other words, when the second cumulative number of pages C2 is equal to or more than the third set value P3 and the sensor 117 does not detect that the amount of the fixing liquid in the supply tank 115 is less than the specified amount, the control device 200 performs the error display process.

[0302] More specifically, as Figure 10As shown, after the control device 200 finishes executing the printing job (S204: Yes, refer to Figure 9 ), when the sensor 117 is in the on state (S210: Yes) and the second cumulative page count C2 is equal to or greater than the third set value P3 (S212: Yes), the control device 200 executes an error display process (S213). In other words, after the control device 200 finishes executing the printing job, when the second cumulative page count C2 is equal to or greater than the third set value P3 and the sensor 117 does not detect that the amount of fixing liquid in the supply tank 115 is less than the specified amount, the control device 200 executes an error display process.

[0303] In addition, as Figure 13 shown, in the recovery process, when the sensor 117 is in the on state (S241: Yes) and the second cumulative page count C2 is equal to or greater than the third set value P3 (S248: Yes), the control device 200 executes an error display process (S249). In other words, in the recovery process after the sheet S jammed in the image forming apparatus 201 is removed, when the second cumulative page count C2 is equal to or greater than the third set value P3 and the sensor 117 does not detect that the amount of fixing liquid in the supply tank 115 is less than the specified amount, the control device 200 executes an error display process.

[0304] In addition, as Figure 14 shown, in the preheating process of the image forming apparatus 201, when the sensor 117 is in the on state (S252: Yes) and the second cumulative page count C2 is equal to or greater than the third set value P3 (S254: Yes), the control device 200 executes an error display process (S255). In other words, in the preheating process of the image forming apparatus 201, when the second cumulative page count C2 is equal to or greater than the third set value P3 and the sensor 117 does not detect that the amount of fixing liquid in the supply tank 115 is less than the specified amount, the control device 200 executes an error display process.

[0305] In addition, as Figure 12 shown, during the execution of the printing job by the control device 200, when the first cumulative page count C1 is equal to or greater than the first set value P1 (S203: No, refer to Figure 9 ) and the sensor 117 is in the on state (S232: Yes), the control device 200 executes an error display process (S238).

[0306] In the error display process, the control device 200 causes an error indicating the possibility of a failure of the sensor 117 to be displayed on a display device 21 (refer to Figure 7 ) provided on the outer surface of the main body housing 2, for example.

[0307] In addition, the display device is not limited. For example, the display device may be an LED, and an error indicating the possibility of a failure of the sensor 117 is displayed by the lighting and extinguishing pattern of the LED. Additionally, the display device may also be a display of a personal computer connected to the image forming apparatus 201 via a local area network or the like, and an error message indicating the possibility of a failure of the sensor 117 is displayed.

[0308] <Effects of the Second Embodiment>

[0309] (1) According to the image forming apparatus 201 according to the second embodiment, as Figure 9 and Figure 10 shown, when the execution of the printing operation is completed (S204: Yes), the fixing liquid in the recovery tray 121 can be transported to the supply tank 115 (S206).

[0310] Therefore, it is possible to suppress the enlargement of the recovery tray 121 and recover the fixing liquid not attached to the sheet S.

[0311] In addition, the following has also been studied: regardless of whether the execution of the printing operation is completed, the recovery process is executed when the amount of the fixing liquid in the recovery tray 121 reaches a specified amount.

[0312] However, in the present embodiment, the fixing liquid in the housing 91 is positively charged by the nozzle electrode 93 to which a positive voltage is applied. In this case, the fixing liquid in the supply tank 115 connected to the housing 91 is also positively charged. On the other hand, the fixing liquid in the recovery tray 121 is negatively charged by the counter electrode 94 to which a negative voltage is applied.

[0313] Therefore, when the recovery process is executed in a state where the fixing liquid is being sprayed from the spraying device 9, the negatively charged fixing liquid in the recovery tray 121 is recovered into the supply tank 115 that houses the positively charged fixing liquid.

[0314] As a result, in the supply tank 115, electrical interference (a phenomenon like a short circuit) between the negatively charged fixing liquid and the positively charged fixing liquid occurs, and there is a possibility that the spraying state becomes unstable.

[0315] Therefore, when the recovery process is performed during the execution of the printing operation, it is necessary to interrupt the execution of the printing operation and then execute the recovery process.

[0316] If the execution of the printing operation is interrupted and then the recovery process is executed, the printing speed is reduced.

[0317] Regarding this point, according to the image forming apparatus 201 according to the second embodiment, after the execution of the printing job is completed (S204: Yes), the recovery process (S206) is executed. Therefore, it is possible to suppress the recovery process during the execution of the printing job and suppress the reduction of the printing speed.

[0318] (2) According to the image forming apparatus 201 according to the second embodiment, the more the first cumulative number of pages C1 is, the longer the control device 200 extends the driving time of the recovery pump 123 in the recovery process (S206).

[0319] Therefore, when the first cumulative number of pages C1 is small and the fixing liquid in the recovery tray 121 is small, it is possible to shorten the time of the recovery process (S206) and shorten the printing waiting time.

[0320] In addition, when the first cumulative number of pages C1 is large and the fixing liquid in the recovery tray 121 is large, it is possible to extend the time of the recovery process (S206) and reliably transport the fixing liquid in the recovery tray 121 to the supply tank 115.

[0321] (3) According to the image forming apparatus 201 according to the second embodiment, as Figure 11 shown, when the first cumulative number of pages C1 is less than the first set value P1 (S203: Yes, refer to Figure 9 ) and an embedded job is received during the recovery process (S207: Yes, refer to Figure 10 ), and when the first cumulative number of pages C1 is equal to or more than the second set value P2 (S221: No), after the recovery process (S228), the embedded job (S202, refer to Figure 9 ) is executed.

[0322] When the first cumulative number of pages C1 is equal to or more than the second set value P2, the possibility of the recovery tray 121 overflowing is high.

[0323] In this regard, by giving priority to the recovery process over the embedded job, it is possible to suppress the situation where the recovery tray 121 overflows.

[0324] On the other hand, when the first cumulative number of pages C1 is less than the first set value P1 (S203: Yes, refer to Figure 9 ) and an embedded job is received during the recovery process (S207: Yes, refer to Figure 10 ), and when the first cumulative number of pages C1 is less than the second set value P2 (S221: Yes), after the embedded job (S223: Yes), the recovery process (S226) is executed.

[0325] When the first cumulative number of pages C1 is less than the second set value P2, the possibility of the recovery tray 121 overflowing is low.

[0326] Therefore, by giving priority to the embedding operation over the recovery process, the printing waiting time can be shortened.

[0327] (4) According to the image forming apparatus 201 according to the second embodiment, in the recovery process (S226) after the embedding operation, based on the first cumulative number of pages C1 plus the number of pages printed in the embedding operation, the more the first cumulative number of pages C1 is, the longer the control device 200 extends the driving time of the recovery pump 123 in the recovery process (S226).

[0328] Therefore, in the case of giving priority to the embedding operation over the recovery process, the time of the recovery process can be extended by the amount of the number of pages printed in the embedding operation.

[0329] Therefore, in the case of giving priority to the embedding operation over the recovery process, the fixing liquid in the recovery tray 121 can also be reliably transported to the supply tank 115.

[0330] (5) According to the image forming apparatus 201 according to the second embodiment, as Figure 12 shown, when the first cumulative number of pages C1 is equal to or more than the first set value P1 during the execution of the printing operation (S203: No, refer to Figure 9 ), the control device 200 interrupts the printing operation (S231) and executes the recovery process (S233).

[0331] Thereby, it is possible to suppress the following situation: continuing the printing operation in a state where the fixing liquid in the supply tank 115 has run out, resulting in air entering the nozzle 92.

[0332] (6) According to the image forming apparatus 201 according to the second embodiment, as Figure 10 、 Figure 12 、 Figure 13 shown, when the sensor 117 detects that the amount of the fixing liquid in the supply tank 115 is less than the specified amount after the recovery process (S208, S234, S244) (S210: No, S236: No, S246: No), the control device 200 executes the replenishment process (S211, S237, S247).

[0333] Here, if the recovery process is executed after the replenishment process, there is a possibility that the supply tank 115 overflows when the supply tank 115 is filled by the replenishment process and then the fixing liquid is transported from the recovery tray 121 to the supply tank 115 by the recovery process.

[0334] Regarding this point, according to such a structure, the replenishment process is executed after the recovery process, so it is possible to prevent the supply tank 115 from overflowing due to the recovery process.

[0335] (7)According to the image forming apparatus 201 according to the second embodiment, as shown in Figure 10 , Figure 13 , Figure 14 , when the second cumulative page count C2 is equal to or greater than the third set value P3 (S212: Yes, S248: Yes, S254: Yes) and the sensor 117 does not detect that the amount of the fixing liquid in the supply tank 115 is less than the specified amount (S210: Yes, S241: Yes, S252: Yes), the control device 200 executes an error display process (S213, S249, S255).

[0336] Therefore, in a case where the sensor 117 does not detect a decrease in the amount of the fixing liquid in the supply tank 115 although it is assumed that the amount of the fixing liquid in the supply tank 115 is decreasing, the display device 21 (see Figure 7 ) can display a malfunction of the sensor 117.

[0337] [Third Embodiment]

[0338] Next, while referring to Figures 16 - 21 , the image forming apparatus according to the third embodiment of the present invention will be described in detail.

[0339] In an image forming apparatus including a fixing device that sprays a fixing liquid stored in a storage unit onto a sheet for fixing and a recovery tray that recovers the fixing liquid not attached to the sheet, when the image forming apparatus is moved or transported, there is a possibility that the fixing liquid remaining inside the storage unit or the recovery tray leaks due to vibration, shock, or inclination of the image forming apparatus. The third embodiment solves this problem.

[0340] In the following description, the directions will be described with reference to the directions shown in Figure 16 . That is, in Figure 16 , the right side facing the paper surface is defined as the "front side", the left side facing the paper surface is defined as the "rear side", the inside facing the paper surface is defined as the "right side", and the near front side facing the paper surface is defined as the "left side". In addition, the vertical direction facing the paper surface is defined as the "vertical direction".

[0341] Figure 16 is a diagram showing the structure of a laser printer 301 which is an example of the image forming apparatus according to the third embodiment of the present invention. As shown in Figure 16 , the laser printer 301 includes a main body housing 32, a paper feeding unit 33 for feeding a sheet P which is an example of a recording sheet, and an image forming unit 34 for forming an image on the sheet P.

[0342] The sheet feeding unit 33 includes: a paper supply tray 331 that is detachably attached to the lower part of the main body casing 32; and a paper supply mechanism 332 that supplies the sheet P in the paper supply tray 331 to the image forming unit 34. The paper supply mechanism 332 includes a paper supply roller 332A, a separation roller 332B, a separation pad 332C, a paper dust removal roller 332D, and a registration roller 332E. The registration roller 332E is a roller that aligns the top position of the sheet P and is appropriately switched between stop / rotation by a control unit 300 described later.

[0343] The image forming unit 34 is housed in the main body casing 32 and mainly includes a scanner unit 35, a process cartridge 36, a transfer roller TR, and a fixing device 37.

[0344] The scanning unit 35 is provided in the upper part of the main body casing 32 and includes a laser emitting unit, a polygon mirror, a lens, a mirror, etc. not shown. In this scanning unit 35, a laser beam is irradiated onto the surface of a photosensitive drum 361 described later at a high speed.

[0345] The process cartridge 36 is detachable from the main body casing 32. The process cartridge 36 includes a photosensitive drum 361 that forms an electrostatic latent image, a charger not shown, a toner storage unit 362 that stores toner, a supply roller 363 that supplies the toner in the toner storage unit 362 to the photosensitive drum 361, and a developing roller 364.

[0346] In this process cartridge 36, a charger not shown uniformly charges the surface of the rotating photosensitive drum 361. The scanning unit 35 emits a laser beam onto the surface of the photosensitive drum 361 to expose the surface of the photosensitive drum 361, thereby forming an electrostatic latent image based on image data on the surface of the photosensitive drum 361.

[0347] Next, the driven rotating developing roller 364 supplies toner to the electrostatic latent image of the photosensitive drum 361, thereby forming a toner image on the surface of the photosensitive drum 361. After that, when the sheet P is conveyed between the photosensitive drum 361 and the transfer roller TR, the toner image carried on the surface of the photosensitive drum 361 is attracted by the transfer roller TR and transferred onto the sheet P.

[0348] The fixing device 37 is a device that supplies a charged fixing liquid L to the toner image on the sheet P by electrostatic spraying, thereby fixing the toner image onto the sheet P. In addition, the structure of the fixing device 37 will be described in detail later.

[0349] A pair of downstream conveying rollers Rd are provided on the downstream side of the fixing device 37 for clamping the sheet P discharged from the fixing device 37 and conveying it downstream. The sheet P conveyed by the downstream conveying rollers Rd is conveyed to the paper discharge roller R and discharged from the paper discharge roller R onto the paper discharge tray 321. Next, the structure of the fixing device 37 will be described in detail.

[0350] Figure 17 It is a diagram showing the specific structure of the fixing device 37. As Figure 17 shown, the fixing device 37 includes a spray unit 371, a supply unit 372, a recovery unit 373, and a control unit 300. In addition, the fixing device 37 further includes an air supply unit 379, a first power supply 378A, and a second power supply 378B.

[0351] The spray unit 371 is an example of the spray device in the present invention. The supply unit 372 is an example of the supply device in the present invention. The recovery unit 373 is an example of the recovery device in the present invention. The control unit 300 is an example of the control device in the present invention.

[0352] The spray unit 371 sprays the fixing liquid L for fixing the toner transferred onto the sheet P onto the sheet P. The spray unit 371 has: a housing 371A that can accommodate the fixing liquid L; a nozzle electrode 371B that charges the fixing liquid L in the housing 371A; a counter electrode 371C that is located at a position spaced apart from the nozzle electrode 371B; and a nozzle 371D that sprays the fixing liquid L in the housing 371A onto the sheet P having the transferred toner when the potential difference between the nozzle electrode 371B and the counter electrode 371C is equal to or greater than a specified spray potential difference (specified value).

[0353] In order to perform electrostatic spraying well and perform fixing, the fixing liquid L can be a solution in which a solute dissolving the toner is dispersed in a solvent having a high dielectric constant. As the solvent having a high dielectric constant, safe water can be used. That is, in the present embodiment, the toner is dissolved in a type in which a solute dissolving the toner is dispersed in water, a so-called water-in-oil droplet type emulsion. That is, a fixing liquid in which a solute that is insoluble or hardly soluble in water as a solvent is dispersed in water is used. In addition, a surfactant may be added in order to form an emulsion well.

[0354] The supply unit 372 supplies the fixing liquid L to the spray unit 371. The supply unit 372 has: a tank 372A that can accommodate the fixing liquid L; and a supply pipe 372B that is connected to the tank 372A and allows the fixing liquid L accommodated in the tank 372A to pass through. The tank 372A is an example of the supply tank in the present invention.

[0355] The supply pipe 372B has a second liquid feeding section 375 for controlling the supply of the fixing liquid L. Specifically, in the supply pipe 372B, a second pump 375B and a second valve 375A are sequentially provided as the second liquid feeding section 375 starting from the side of the tank 372A. The second pump 375B has a function of pressurizing the fixing liquid L by feeding the fixing liquid L from the tank 372A into the housing 371A, and is controlled by a motor. The second valve 375A has a function of regulating the flow rate of the fixing liquid L supplied from the tank 372A to the housing 371A by using an electromagnetic valve. However, the second liquid feeding section 375 does not necessarily have to include the second valve 375A, and may only include the second pump 375B. The second pump 375B is an example of the supply pump in the present invention.

[0356] In addition, the supply unit 372 further has: a cartridge 372C that houses the fixing liquid L; and a cartridge supply pipe 372D that is connected to the cartridge 372C and allows the fixing liquid L housed in the cartridge 372C to pass through. The cartridge 372C is an example of the fixing liquid cartridge in the present invention. The cartridge supply pipe 372D is an example of the replenishment pipe in the present invention.

[0357] The cartridge supply pipe 372D has a fourth liquid feeding section 377 for controlling the supply of the fixing liquid L. Specifically, in the cartridge supply pipe 372D, a fourth valve 377A and a fourth pump 377B are sequentially provided as the fourth liquid feeding section 377 starting from the side of the cartridge 372C. The fourth valve 377A has a function of regulating the flow rate of the fixing liquid L supplied from the cartridge 372C to the tank 372A by using an electromagnetic valve. The fourth pump 377B has a function of pressurizing the fixing liquid L by feeding the fixing liquid L from the cartridge 372C into the tank 372A, and is controlled by a motor. However, the fourth liquid feeding section 377 does not necessarily have to include the fourth valve 377A, and may only include the fourth pump 377B. The fourth pump 377B is an example of the replenishment pump in the present invention.

[0358] The recovery unit 373 recovers the fixing liquid L that is sprayed from the nozzle 371D and not attached to the sheet P. The recovery unit 373 has: a recovery tray 373A that can house the fixing liquid L; and a recovery pipe 373B that is connected to the recovery tray 373A and allows the fixing liquid L in the recovery tray 373A to pass through.

[0359] In the spraying unit 371, the housing 371A, the nozzle electrode 371B, and the nozzle 371D are arranged above the recovery tray 373A. In particular, the nozzle 371D is arranged to spray the fixing liquid L downward. On the other hand, the counter electrode 371C is arranged in the recovery tray 373A. The counter electrode 371C has a plurality of protrusions extending toward the nozzle 371D.

[0360] The recovery pipe 373B has a first liquid delivery section 374 that delivers the fixing liquid L to the tank 372A. Specifically, in the recovery pipe 373B, a first pump 374B and a first valve 374A, which serve as the first liquid delivery section 374, are provided starting from the recovery tray 373A side. The first pump 374B has the function of pressurizing the fixing liquid L by sending the fixing liquid L from the recovery tray 373A to the tank 372A, and is controlled by a motor. The first valve 374A has the function of regulating the flow rate of the fixing liquid L that circulates from the recovery tray 373A to the tank 372A using an electromagnetic valve. However, the first liquid delivery section 374 does not necessarily have to include the first valve 374A, and may only include the first pump 374B. Additionally, a filter F that removes impurities from the fixing liquid L is provided between the recovery tray 373A of the recovery pipe 373B and the first liquid delivery section 374. The first valve 374A is an example of the recovery valve in the present invention. The first pump 374B is an example of the recovery pump in the present invention.

[0361] The first power supply 378A is a constant current source that applies a voltage by inputting current to the nozzle electrode 371B. The second power supply 378B is a constant voltage source that applies a constant voltage to the counter electrode 371C.

[0362] The air supply section 379 supplies air to the housing 371A. In the present embodiment, the air supply section 379 has the function of regulating the flow rate of the air flowing into the housing 371A using an electromagnetic valve. In a state where the air supply section 379 is closed, air is not supplied to the housing 371A. Therefore, except when a voltage is applied to the nozzle electrode 371B and the counter electrode 371C, the fixing liquid L inside the housing 371A does not flow out from the nozzle 371D to the outside. In a state where the air supply section 379 is open, air is supplied to the housing 371A. Therefore, atmospheric pressure is applied to the fixing liquid L inside the housing 371A, and the fixing liquid L is extruded and drops from the nozzle 371D.

[0363] The fixing device 37 further includes a first sensor Se1 that can detect the accommodation state of the fixing liquid L inside the housing 371A and a second sensor Se2 that can detect the accommodation state of the fixing liquid L inside the housing 372A. The first sensor Se1 is, for example, a pressure sensor that outputs a signal corresponding to the pressure generated by the fixing liquid L to the control unit 300. Additionally, the second sensor Se2 is, for example, a photoelectric sensor that outputs a signal corresponding to the amount of received light.

[0364] Figure 18 It is a diagram showing a method for detecting the accommodation state of the fixing liquid L in the tank 372A when the second sensor Se2 is a photoelectric sensor. In Figure 18In the figure, symbol 3001 indicates a state where the amount of the fixing solution L stored in the tank 372A is less than a specified amount. Additionally, symbol 3002 indicates a state where the amount of the fixing solution L stored in the tank 372A is equal to or greater than the specified amount.

[0365] A float 381, a rotating shaft 382, a light-shielding portion 383, and a light-projecting portion 384 are provided in the tank 372A. The float 381 is formed of a material that floats on the fixing solution L. The shape of the float 381 is spherical, but it is not limited thereto. The light-shielding portion 383 is formed of a material that does not transmit light. The shape of the light-shielding portion 383 is plate-like, but it is not limited thereto.

[0366] The float 381 and the light-shielding portion 383 are connected to the rotating shaft 382 at a constant relative angle. Therefore, as shown by symbols 3001 and 3002 in Figure 18 , the positions of the float 381 and the light-shielding portion 383 change according to the amount of the fixing solution L stored in the tank 372A.

[0367] The light-projecting portion 384 and the second sensor Se2 are provided on the side wall of the tank 372A so as to face each other. The light-projecting portion 384 emits light toward the second sensor Se2, and the light-projecting portion 384 is a light-emitting diode, an infrared light oscillator, etc. As shown by symbol 3002 in Figure 18 , the second sensor Se2 is provided at a position where the light from the light-projecting portion 384 is blocked by the light-shielding portion 383 when the amount of the fixing solution L stored in the tank 372A is equal to or greater than the specified amount. Therefore, when the amount of the fixing solution L stored in the tank 372A is equal to or greater than the specified amount, the signal output from the second sensor Se2 becomes smaller.

[0368] In addition, the laser printer 301 further includes an instruction receiving unit 310. The instruction receiving unit 310 receives instructions from the user for the laser printer 301. The instruction receiving unit 310 includes a power-off instruction receiving unit 311 and a moving mode switching instruction receiving unit 312. The power-off instruction receiving unit 311 receives an instruction to turn off the power of the laser printer 301. The power-off instruction receiving unit 311 is a soft switch that generates a power-off signal when it receives an instruction to turn off the power. The moving mode switching instruction receiving unit 312 receives instructions to turn off and on the moving mode. The moving mode switching instruction receiving unit 312 is an example of the cancellation instruction receiving unit in the present invention.

[0369] The control unit 300 controls the first liquid supply unit 374. Additionally, the control unit 300 also controls the fourth liquid supply unit 377 and the air supply unit 379. Further, in the laser printer 301, the control unit 300 comprehensively controls the operations of the laser printer 301.

[0370] [Operations of the Laser Printer 301]

[0371] Figure 19 This is a flowchart showing an example of the processing in the fixing device 37. When the power of the laser printer 301 is turned on, first, the control unit 300 performs a preparation process (SA). The details of the preparation process will be described later. Next, the control unit 300 determines whether a print command for the sheet P has been received (S301). If a print command for the sheet P has been received (Yes in S301), the control unit 300 outputs a signal for driving the second liquid feeding unit 375 and the first liquid feeding unit 374 (S302). In this state, the control unit 300 performs printing (image formation) on the sheet P (S303). At this time, the control unit 300 outputs a signal to the first power supply 378A and the second power supply 378B to generate a potential difference between the nozzle electrode 371B and the counter electrode 371C required for spraying the fixing liquid L, and sprays the fixing liquid L from the nozzle 371D onto the toner image on the sheet P. In addition, the control unit 300 outputs a signal for driving the fourth liquid feeding unit 377 as needed, and supplies the fixing liquid L from the cartridge 372C to the tank 372A.

[0372] After starting the printing on the sheet P, the control unit 300 determines whether the printing has ended (S304). If the printing process has not ended (No in S304), the control unit 300 continues to spray the fixing liquid L. If the printing process has ended (Yes in S304), the control unit 300 stops the second liquid feeding unit 375 and the first liquid feeding unit 374 (S305). After that, the control unit 300 repeats the process from S301.

[0373] If a print command for the sheet P has not been received (No in S301), the control unit 300 determines whether the power-off instruction receiving unit 311 has received an instruction to turn off the power (S306). If the power-off instruction receiving unit 311 has not received an instruction to turn off the power (No in S306), the control unit 300 repeats the process from S301.

[0374] When the disconnection instruction receiving unit 311 receives an instruction to disconnect the power supply (Yes in S306), the control unit 300 determines whether the mode of the fixing device 37 is set to the moving mode (S307). When the mode of the fixing device 37 is set to the moving mode (Yes in S307), the control unit 300 drives the first liquid supply unit 374 and outputs a signal to open the air supply unit 379 (S308), and stands by for a certain period of time in this state (S309). After that, the control unit 300 stops the first liquid supply unit 374, outputs a signal to close the air supply unit 379 (S310), and disconnects the power supply of the laser printer 301 (S311). On the other hand, when the mode of the fixing device 37 is not set to the moving mode (No in S307), the control unit 300 disconnects the power supply of the laser printer 301 (S311) without executing S308 to S310.

[0375] Figure 20 It represents Figure 19 The flowchart showing the content of "preparation process" in the flowchart shown. In the following description, for the case where the signal indicating the detection result of the first sensor Se1 or the second sensor Se2 shows that the fixing liquid L is stored in the housing 371A or the tank 372A in a specified amount, it is sometimes expressed as "fully filled".

[0376] In the preparation process, first, the control unit 300 determines whether the fixing device 37 is set to the moving mode (SA31). When the fixing device 37 is set to the moving mode (Yes in SA31), the control unit 300 determines whether the fixing liquid L is fully filled in the tank 372A (SA32). When the fixing liquid L is fully filled in the tank 372A (Yes in SA32), the control unit 300 outputs a signal to drive the second liquid supply unit 375 (SA33). Thereby, the fixing liquid L is filled in the housing 371A. When the fixing liquid L is not fully filled in the tank 372A (No in SA32), the control unit 300 outputs a signal to drive the fourth liquid supply unit 377 (SA34). Thereby, the fixing liquid L is filled in the tank 372A. In this state, the control unit 300 executes SA33.

[0377] When the fixing device 37 is not set to the transfer mode (No in SA31), the control unit 300 determines whether the fixing liquid L is sufficiently filled in the housing 371A (SA35). When the fixing liquid L is not sufficiently filled in the housing 371A (No in step SA35), the control unit 300 executes the processes of SA32 to SA34 in the same manner as when the fixing device 37 is set to the transfer mode. When the fixing liquid L is sufficiently filled in the housing 371A (Yes in SA35), the control unit 300 ends the preparation process.

[0378] As described above, when the disconnection instruction receiving unit 311 receives an instruction to turn off the power, that is, when the disconnection signal generated by the disconnection instruction receiving unit 311 is detected, the control unit 300 executes the following liquid feeding process. In the liquid feeding process, the control unit 300 outputs a signal to the air supply unit 379 to spray the fixing liquid L in the housing 371A from the nozzle 371D, and outputs a signal to the first pump 374B to convey the fixing liquid L collected by the recovery unit 373 to the tank 372A. In addition, when the first liquid feeding unit 374 includes the first valve 374A, the control unit 300 also outputs a signal to the first valve 374A to convey the fixing liquid L to the tank 372A. The liquid feeding process corresponds to Figure 19 the S308 to S310 shown in the flowchart. Thereby, it is possible to suppress the following situation: when the power of the laser printer 301 is turned off, the fixing liquid L remaining inside the housing 371A or the recovery unit 373 leaks out. After that, in S311, the power of the laser printer 301 is turned off.

[0379] The air supply unit 379 may further include a pump for sending air into the housing 371A from the outside. In this case, the control unit 300 only needs to drive the pump corresponding to the opening of the air supply unit 379 and output a signal to stop the pump corresponding to the closing of the air supply unit 379.

[0380] In addition, when the laser printer 301 is started, when the control unit 300 indicates that a predetermined amount of the fixing liquid L is not accommodated in the housing 371A according to the signal indicating the detection result of the first sensor Se1, the control unit 300 outputs a signal to the second pump 375B to supply the fixing liquid L from the tank 372A to the housing 371A. In addition, when the second liquid feeding unit 375 includes the second valve 375A, the control unit 300 also outputs a signal to the second valve 375A to supply the fixing liquid L from the tank 372A to the housing 371A. This process corresponds to Figure 20SA33 of the flowchart shown. Thus, when the laser printer 301 is started and a predetermined amount of fixing liquid L is not contained in the housing 371A, the control unit 300 supplies fixing liquid L from the tank 372A to the housing 371A. Therefore, the laser printer 301 can print on the sheet P.

[0381] Furthermore, when the laser printer 301 is started, the control unit 300, when the signal indicating the detection result of the second sensor Se2 indicates that the tank 372A does not contain a predetermined amount of the fixing liquid L, executes the supply of the fixing liquid L from the cartridge 372C to the tank 372A by the fourth pump 377B. Furthermore, when the fourth liquid supply unit 377 includes a fourth valve 377A, the control unit 300 also outputs a signal to the fourth valve 377A to supply the fixing liquid L to the tank 372A. This process corresponds to Figure 20 SA34 of the flowchart shown. Thus, when the laser printer 301 is started and a predetermined amount of fixing liquid L is not contained in the tank 372A, the control unit 300 supplies the fixing liquid L from the cartridge 372C to the tank 372A. Therefore, the fixing liquid L can be supplied from the tank 372A to the housing 371A, and further, printing can be performed on the sheet P by the laser printer 301.

[0382] When the transport mode switching instruction receiving unit 312 receives an instruction to turn off the transport mode, the control unit 300 does not execute the liquid supply process of S308 to S310 until the transport mode switching instruction receiving unit 312 receives an instruction to turn on the transport mode.

[0383] Thus, the transport mode refers to the following mode: when the power of the laser printer 301 is turned off in preparation for the movement of the laser printer 301 due to transport or the like, the process of feeding the fixing liquid L in the housing 371A and the like to the tank 372A is performed. In the third embodiment, the transport mode of the laser printer 301 is set to be turned on in the initial state. When the power of the laser printer 301 is turned off in the state where the transport mode is turned off, the liquid feeding process is not performed. That is, the instruction of turning off the transport mode can be expressed as an instruction to cancel the liquid feeding process. In addition, when the power of the laser printer 301 is turned off in the state where the transport mode is turned on from off, the liquid feeding process that has been canceled in the state where the transport mode is turned off is performed again. That is, the instruction of turning on the transport mode can be expressed as an instruction to cancel the liquid feeding process.

[0384] In the laser printer 301, the liquid feeding process can be omitted according to the user's choice. Therefore, when the liquid feeding process is not required, (i) the liquid feeding process when the power of the laser printer 301 is turned off, i.e., Figure 19The time required for the execution of S308 to S310 in the flowchart shown, and the time that can be reduced for (ii) supplying the fixing liquid L to the housing 371A, etc. when the laser printer 301 is started, that is Figure 20 The time required for SA31 to SA35 in the flowchart shown. However, regarding the start-up of the laser printer 301, when the power of the laser printer 301 is turned off just before starting and the fixing liquid L is not sufficiently filled in the housing 371A, the time for supplying the fixing liquid L to the housing 371A is required.

[0385] [Modification Example of the Third Embodiment]

[0386] Hereinafter, a modification example of the third embodiment will be described. In addition, for the sake of convenience of explanation, components having the same functions as those described in the above third embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0387] Figure 21 It is a diagram showing the structure of the fixing device 37A according to the modification example. As Figure 21 shown, the fixing device 37A is different from the fixing device 37 in that it includes a second recovery unit 390 instead of the recovery unit 373. The second recovery unit 390 has a recovery tray 390A, a second recovery tank 390B, and a second recovery pipe 390C.

[0388] The recovery tray 390A has the same structure as the recovery tray 373A. The second recovery tank 390B houses the fixing liquid housed in the recovery tray 390A. The second recovery pipe 390C is connected to the recovery tray 390A and the second recovery tank 390B, and allows the fixing liquid L in the recovery tray 390A to pass through. Since the fixing liquid L transported to the second recovery tank 390B is not directly reused, a filter is not provided in the second recovery pipe 390C.

[0389] In addition, the second recovery pipe 390C has a third liquid supply unit 376 that controls the recovery of the fixing liquid L. Specifically, in the second recovery pipe 390C, a third valve 376A and a third pump 376B are provided starting from the recovery tray 390A side. The third valve 376A has a function of adjusting the flow rate of the fixing liquid L recovered from the recovery tray 390A to the second recovery tank 390B using an electromagnetic valve. The third pump 376B has a function of pressurizing the fixing liquid L by sending the fixing liquid L from the recovery tray 390A to the second recovery tank 390B, and is controlled by a motor (not shown), for example. However, the third liquid supply unit 376 does not necessarily have to include the third valve 376A, and may only include the third pump 376B.

[0390] In the fixing device 37A, when the disconnection instruction receiving unit 311 receives an instruction to disconnect the power supply, the control unit 300A performs the following liquid feeding process. In the liquid feeding process, the control unit 300A sprays the fixing liquid L in the housing 371A from the nozzle 371D, and outputs a signal to the third pump 376B to convey the fixing liquid L collected by the recovery tray 390A from the recovery tray 390A to the second recovery tank 390B. Additionally, when the third liquid feeding unit 376 includes the third valve 376A, the control unit 300A also outputs a signal to the third valve 376A to convey the fixing liquid L collected by the recovery tray 390A to the second recovery tank 390B. With such a fixing device 37A, it is also possible to suppress the following situation: when the power supply of the laser printer 301 is in the disconnected state, the fixing liquid L remaining inside the housing 371A or in the recovery tray 390A leaks out.

[0391] The specific process performed by the control unit 300A is substantially the same as that performed by the control unit 300 Figure 19 and Figure 20 shown. However, the control unit 300A outputs a signal to drive or stop the third liquid feeding unit 376 instead of a signal to drive the first liquid feeding unit 374 in steps S302, S305, S308, and S310 shown in Figure 19 .

[0392] [Software-based implementation example]

[0393] The control blocks of the laser printer 301 and the fixing device 37 (particularly the control units 300 and 300A) can be implemented by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or can be implemented by software.

[0394] In the latter case, the laser printer 301 and the fixing device 37 include a computer that executes commands of a program that is software for implementing each function. The computer includes, for example, one or more processors and a computer-readable recording medium storing the above program. Further, in the above computer, the processor reads and executes the above program from the recording medium, thereby achieving the object of the present invention. As the above processor, for example, a CPU (Central Processing Unit) can be used. As the above recording medium, a "non-transitory tangible medium" can be used. For example, in addition to being able to use a ROM (Read Only Memory), etc., a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, etc. can also be used. Additionally, a RAM (Random Access Memory) etc. for expanding the above program may be further included. Further, the above program can be provided to the above computer via any transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. In addition, one aspect of the present invention can also be implemented in the form of a data signal embedded in a carrier wave in which the above program is embodied by electronic transmission.

[0395] [Fourth Embodiment]

[0396] Next, while referring to Figures 22 - 29 , the image forming apparatus according to the fourth embodiment of the present invention will be described in detail.

[0397] In an image forming apparatus including a fixing device that sprays a fixing liquid stored in a storage unit onto a sheet for fixing and a recovery tray that recovers the fixing liquid not attached to the sheet, there is a problem that it is difficult to appropriately control the spraying amount of the fixing liquid. The fourth embodiment solves this problem.

[0398] In the following description, directions will be described in the directions shown in Figure 22 . That is, in Figure 22 , the right side facing the paper surface is taken as the "front side", the left side facing the paper surface is taken as the "rear side", the inner side facing the paper surface is taken as the "right side", and the near front side facing the paper surface is taken as the "left side". In addition, the up and down directions facing the paper surface are taken as the "up and down directions".

[0399] Figure 22 is a diagram showing a laser printer 401 which is an example of the image forming apparatus according to the fourth embodiment in the present invention. As shown in Figure 22 , the laser printer 401 includes a main body case 42, a paper feeding unit 43 that supplies a sheet P which is an example of a sheet, and an image forming unit 44 that forms an image on the sheet P.

[0400] The paper feeding unit 43 includes: a paper supply tray 431 detachably attached to the lower part of the main body housing 42; and a paper feeding mechanism 432 that feeds the sheet P in the paper supply tray 431 toward the image forming unit 44. The paper feeding mechanism 432 includes a paper feed roller 432A, a separation roller 432B, a separation pad 432C, a paper dust removal roller 432D, and a registration roller 432E. The registration roller 432E is a roller that aligns the top position of the sheet P and is appropriately switched between stop / rotation by a control unit 400 described later.

[0401] The image forming unit 44 is housed in the main body housing 42 and mainly includes a scanning unit 45, a processing cartridge 46, a transfer roller TR, and a fixing device 47.

[0402] The scanning unit 45 is provided in the upper part of the main body housing 42 and includes a laser emitting unit, a polygon mirror, a lens, a mirror, etc., which are not shown. In this scanning unit 45, a laser beam is irradiated onto the surface of a photosensitive drum 461 described later at a high speed.

[0403] The processing cartridge 46 is detachable from the main body housing 42. The processing cartridge 46 includes a photosensitive drum 461 that forms an electrostatic latent image, a charger (not shown), a toner storage section 462 that stores toner as an example of a developer, a supply roller 463 that supplies the toner in the toner storage section 462 to the photosensitive drum 461, and a developing roller 464.

[0404] In this processing cartridge 46, a charger (not shown) uniformly charges the surface of the rotating photosensitive drum 461. The scanning unit 45 emits a laser beam onto the surface of the photosensitive drum 461 to expose the surface of the photosensitive drum 461, thereby forming an electrostatic latent image based on image data on the surface of the photosensitive drum 461.

[0405] Next, the driven rotating developing roller 464 supplies toner to the electrostatic latent image on the photosensitive drum 461, thereby forming a toner image on the surface of the photosensitive drum 461. After that, when the sheet P is conveyed between the photosensitive drum 461 and the transfer roller TR, the toner image carried on the surface of the photosensitive drum 461 is attracted by the transfer roller TR and transferred onto the sheet P.

[0406] The fixing device 47 sprays a fixing liquid L onto the sheet P on which the toner image is formed. Specifically, the fixing device 47 is a device that supplies the charged fixing liquid L to the toner image on the sheet P by electrostatic spraying, thereby fixing the toner image on the sheet P. In addition, the structure of the fixing device 47 will be described in detail later.

[0407] A pair of downstream conveyance rollers Rd are provided on the downstream side of the fixing device 47 to hold the sheet P discharged from the fixing device 47 and convey it downstream. The sheet P conveyed by the downstream conveyance rollers Rd is conveyed to the paper discharge roller R and discharged from the paper discharge roller R onto the paper discharge tray 421. Next, the structure of the fixing device 47 will be described in detail.

[0408] Figure 23 FIG. is a diagram showing the specific structure of the fixing device 47. As Figure 23 shown, the fixing device 47 includes a spray unit 471, a supply unit 472, a recovery unit 473, a first voltage generation circuit 475, a second voltage generation circuit 476, and a control unit 400.

[0409] The spray unit 471 is an example of the spray device in the present invention. The supply unit 472 is an example of the supply device in the present invention. The recovery unit 473 is an example of the recovery device in the present invention.

[0410] The spray unit 471 sprays a fixing liquid L for fixing the toner transferred onto the sheet P onto the sheet P. The spray unit 471 has: a housing 471A that can accommodate the fixing liquid L; a nozzle electrode 471B that charges the fixing liquid L in the housing 471A; a counter electrode 471C that is located at a position spaced apart from the nozzle electrode 471B; and a nozzle 471D that sprays the fixing liquid L in the housing 471A onto the sheet P onto which toner is transferred when the potential difference between the nozzle electrode 471B and the counter electrode 471C is equal to or greater than a specified spray potential difference (specified value).

[0411] In order to perform electrostatic spraying well and perform fixing, the fixing liquid L can be a solution in which a solute in which toner is dissolved is dispersed in a solvent having a high dielectric constant. As the solvent having a high dielectric constant, safe water can be used. That is, in the present embodiment, a so-called oil-in-water droplet type emulsion in which a solute in which toner is dissolved is dispersed in water is used for dissolving the toner. That is, a fixing liquid in which a solute that is insoluble or hardly soluble in water as a solvent is dispersed in water is used. In addition, a surfactant may be added in order to form an emulsion well.

[0412] The supply unit 472 supplies the fixing liquid L to the spray unit 471. The supply unit 472 has: a tank 472A that can accommodate the fixing liquid L; a supply pipe 472B that is connected to the tank 472A and allows the fixing liquid L accommodated in the tank 472A to pass through; a cartridge 472C; and a supply pipe 472D.

[0413] The can 472A is an example of the supply can in the present invention. The cartridge 472C is an example of the fixing liquid cartridge in the present invention.

[0414] The supply pipe 472B has a first liquid feeding part 451 for controlling the supply of the fixing liquid L. Specifically, in the supply pipe 472B, a first pump 451B and a first valve 451A are sequentially arranged from the can 472A side as the first liquid feeding part 451. The first pump 451B has a function of pressurizing the fixing liquid L by feeding the fixing liquid L from the can 472A into the housing 471A, and is controlled by a motor. The first valve 451A has a function of regulating the flow rate of the fixing liquid L supplied from the can 472A to the housing 471A by using an electromagnetic valve. The first pump 451B is an example of the supply pump in the present invention.

[0415] The recovery unit 473 recovers the fixing liquid L that is sprayed from the nozzle 471D and not attached to the sheet P. The recovery unit 473 has: a recovery tray 473A that can accommodate the fixing liquid L; and a recovery pipe 473B that is connected to the recovery tray 473A and allows the fixing liquid L in the recovery tray 473A to pass through.

[0416] In the spraying unit 471, the housing 471A, the nozzle electrode 471B, and the nozzle 471D are arranged above the recovery tray 473A. In particular, the nozzle 471D is arranged to spray the fixing liquid L downward. On the other hand, the counter electrode 471C is arranged in the recovery tray 473A. The counter electrode 471C has a plurality of protrusions extending toward the nozzle 471D.

[0417] The recovery pipe 473B has a second liquid feeding part 452 for conveying the fixing liquid L to the can 472A. Specifically, in the recovery pipe 473B, a second pump 452B and a second valve 452A are arranged as the second liquid feeding part 452 from the recovery tray 473A side. The second pump 452B has a function of pressurizing the fixing liquid L by feeding the fixing liquid L from the recovery tray 473A into the can 472A, and is controlled by a motor. The second valve 452A has a function of regulating the flow rate of the fixing liquid L circulated from the recovery tray 473A to the can 472A by using an electromagnetic valve. In addition, a filter F for removing impurities from the fixing liquid L is provided between the recovery tray 473A and the second liquid feeding part 452 in the recovery pipe 473B. The second valve 452A is an example of the recovery valve in the present invention. The second pump 452B is an example of the recovery pump in the present invention.

[0418] The cartridge 472C is a can for accommodating the fixing liquid L, and is installed on the main body housing 2 in a detachable manner. The supply pipe 472D is connected to the cartridge 472C and allows the fixing liquid L accommodated in the cartridge 472C to pass through.

[0419] The supply pipe 472D has a third liquid supply section 453 that controls the supply of the fixing liquid L. Specifically, in the supply pipe 472D, a third valve 453A and a third pump 453B are sequentially provided as the third liquid supply section 453 starting from the cartridge 472C side. The third valve 453A has a function of regulating the flow rate of the fixing liquid L supplied from the cartridge 472C to the tank 472A using an electromagnetic valve. The third pump 453B has a function of pressurizing the fixing liquid L by feeding the fixing liquid L from the cartridge 472C to the tank 472A and is controlled by a motor. The third pump 453B is an example of the replenishing pump in the present invention. The supply pipe 472D is an example of the replenishing pipe in the present invention.

[0420] The first voltage generation circuit 475 is connected to the nozzle electrode 471B and generates a first voltage applied to the nozzle electrode 471B. In the fourth embodiment, the first voltage generation circuit 475 is a constant current source that applies a first voltage V1 by outputting a constant first current I1 to the nozzle electrode 471B. In addition, the first voltage generation circuit 475 can also output a constant first voltage V1.

[0421] The second voltage generation circuit 476 is connected to the counter electrode 471C and generates a second voltage applied to the counter electrode 471C. In the present embodiment, the second voltage generation circuit 476 is a constant voltage source that applies a constant second voltage V2 to the counter electrode 471C. At this time, a second current I2 flows from the counter electrode 471C to the second voltage generation circuit 476.

[0422] In Figure 23 In the example shown, the fixing device 47 has a voltage generation circuit 478, and the voltage generation circuit 478 has the first voltage generation circuit 475 and the second voltage generation circuit 476. That is, the first voltage generation circuit 475 and the second voltage generation circuit 476 are formed on a single voltage generation circuit board. Therefore, the number of parts of the laser printer 401 can be reduced.

[0423] The control unit 400 controls the first voltage generation circuit 475 and the second voltage generation circuit 476. In the fourth embodiment, a case where the control unit 400 performs PWM (Pulse Width Modulation) control on the first voltage generation circuit 475 and the second voltage generation circuit 476 will be described. However, the control unit 400 can also control the first voltage generation circuit 475 and the second voltage generation circuit 476 by a control method other than PWM control. The control unit 400 is an example of the control device in the present invention.

[0424] Figure 23The fixing device 47 shown is an image forming apparatus having a recovery tube 473B. The recovery tube 473B returns the fixing liquid L recovered in the recovery tray 473A to the tank 472A that houses the fixing liquid L in order to reuse the fixing liquid L recovered by the recovery unit 473. In the fixing device 47, there is a case where the fixing liquid L in the recovery tube 473B and the fixing liquid L in the tank 472A are connected via the fixing liquid L adhering to the inner wall surface near the inlet of the tank 472A. In this case, in the laser printer 401, a leakage current flows through a detour circuit formed via the nozzle electrode 471B, the supply tube 472B, the tank 472A, the recovery tube 473B, and the counter electrode 471C.

[0425] In the fourth embodiment, the control unit 400 calculates the resistance value (circulation resistance value Rcir) of the detour circuit based on the value of the first current I1 or the second current I2 when the fixing liquid L is not sprayed by the nozzle 471D. Hereinafter, a case where the control unit 400 calculates the resistance value of the detour circuit based on the first current I1 will be described.

[0426] Figure 24 It is a diagram showing the detour circuit in the fixing device 47. In the fixing device 47, the detour circuit refers to the following circuit: as Figure 24 indicated by the arrow in, it goes from the nozzle electrode 471B through the supply tube 472B, the tank 472A, the recovery tube 473B, and the recovery tray 473A to reach the counter electrode 471C. In a normal state, the fixing liquid L in the recovery tube 473B and the fixing liquid L in the tank 472A are isolated from each other. Therefore, these fixing liquids L are insulated from each other and no current flows in the detour circuit. However, if the fixing liquid L adheres to the inner wall of the tank 472A or the like and the fixing liquid L in the recovery tube 473B and the fixing liquid L in the tank 472A are in a conductive state, the current Icirleak will flow in the detour circuit.

[0427] Figure 25 It is a circuit diagram showing the schematic structure of the first voltage generation circuit 475 and the second voltage generation circuit 476 controlled by the control unit 400. In Figure 25 it, the equivalent circuit between the nozzle electrode 471B and the counter electrode 471C is also shown.

[0428] In the equivalent circuit, there is a circulation resistance Rcir having the above-mentioned circulation resistance value Rcir between the nozzle electrode 471B and the counter electrode 471C. The current flowing through the circulation resistance Rcir is the current Icirleak.

[0429] In addition, when spraying the fixing liquid L using the nozzle 471D, a current In associated with the spraying of the fixing liquid L flows between the nozzle electrode 471B and the counter electrode 471C. In the equivalent circuit, the current In associated with the spraying is represented as the current flowing through a resistor Rs connected in parallel with the loop resistor Rcir. The current In associated with the spraying is a current corresponding to the spraying amount of the fixing liquid L per unit time. Therefore, in order to obtain a desired spraying state, the laser printer 401 performs control so that the current In associated with the spraying is within a specified target current range.

[0430] The first voltage generation circuit 475 is the following DC-DC converter: It chops the DC voltage VCC1 connected to the primary side of the transformer T1 through the switching element Q1, and outputs DC power after voltage conversion through the rectifying and smoothing circuit connected to the secondary side of the transformer T1. The first voltage generation circuit 475 can apply a positive voltage to the nozzle electrode 471B.

[0431] The switching element Q1 is controlled to be turned on / off by a switching control signal Ss1 generated by the control unit 400. The first voltage V1, which is the output voltage of the first voltage generation circuit 475, is proportionally divided by the resistor Rs_Bl1 and the shunt resistor Rs_FBv1 to become the first voltage signal Sv1. The first voltage V1 is monitored by the control unit 400 based on the first voltage signal Sv1 corresponding to the magnitude of the first voltage V1.

[0432] In addition, the first current I1, which is the output current from the first voltage generation circuit 475, is monitored by the control unit 400 based on a first current signal Si1 based on the voltage applied to the shunt resistor Rs_FBi1 through the first current I1. That is, the shunt resistor Rs_FBi1 constitutes a current detection circuit for generating the first current signal Si1.

[0433] Similarly, the second voltage generation circuit 476 is the following DC-DC converter: It chops the DC voltage VCC1 connected to the primary side of the transformer T2 through the switching element Q2, and outputs DC power after voltage conversion through the rectifying and smoothing circuit connected to the secondary side of the transformer T2. The second voltage generation circuit 476 can apply a negative voltage to the counter electrode 471C.

[0434] The switching element Q2 is controlled to be turned on / off by a switching control signal Ss2 generated by the control unit 400. The second voltage V2, which is the output voltage of the second voltage generation circuit 476, is proportionally divided by the resistor Rc_Bl2 and the resistor Rc_FBv2 to become the second voltage signal Sv2. The second voltage V2 is monitored by the control unit 400 based on the second voltage signal Sv2 corresponding to the magnitude of the second voltage V2.

[0435] In addition, a second current I2, which is the output current from the second voltage generation circuit 476, is monitored by the control unit 400 based on a second current signal Si2 based on the voltage applied to the shunt resistor Rc_FBi2. That is, the shunt resistor Rc_FBi2 constitutes a current detection circuit that generates the second current signal Si2.

[0436] The control unit 400 adjusts the switch control signal Ss1 with reference to the magnitude of the first voltage V1 monitored in this way, so that the first voltage generation circuit 475 outputs the first voltage V1 of a required magnitude. Alternatively, the control unit 400 adjusts the switch control signal Ss1 with reference to the magnitude of the first current I1 or the second current I2, so that the first voltage generation circuit 475 outputs the first current I1 of a required current value.

[0437] In addition, the control unit 400 adjusts the switch control signal Ss2 with reference to the magnitude of the second voltage V2 monitored in this way, so that the second voltage generation circuit 476 outputs the second voltage V2 of a required magnitude.

[0438] Before spraying the fixing liquid L using the nozzle 471D, the control unit 400 controls the first voltage generation circuit 475 and the second voltage generation circuit 476 so that the potential difference between the nozzle electrode 471B and the counter electrode 471C is less than the spraying potential difference. Then, the control unit 400 calculates the resistance value of the bypass circuit based on the current value detected by the current detection circuit and the potential difference between the nozzle electrode 471B and the counter electrode 471C.

[0439] In the fourth embodiment, before spraying the fixing liquid L using the nozzle 471D, the control unit 400 controls the second voltage generation circuit 476 to apply a negative voltage to the counter electrode 471C and not to cause the first voltage generation circuit 475 to apply a voltage to the nozzle electrode 471B so that the potential difference between the nozzle electrode 471B and the counter electrode 471C is less than the spraying potential difference. The voltage applied by the control unit 400 to the counter electrode 471C using the second voltage generation circuit 476 is, for example, set to -2 kV. By controlling the first voltage generation circuit 475 and the second voltage generation circuit 476 in this way, the control unit 400 can generate a potential difference between the nozzle electrode 471B and the counter electrode 471C without spraying the fixing liquid L using the nozzle 471D, and calculate the resistance value of the bypass circuit.

[0440] Alternatively, it can also be that before spraying the fixing liquid L using the nozzle 471D, the control unit 400 applies a positive voltage to the nozzle electrode 471B using the first voltage generation circuit 475 and does not apply a voltage to the counter electrode 471C using the second voltage generation circuit 476, and controls the first voltage generation circuit 475 so that the potential difference between the nozzle electrode 471B and the counter electrode 471C is less than the spraying potential difference. In this case, the voltage applied by the control unit 400 to the nozzle electrode 471B using the first voltage generation circuit 475 is set to, for example, 2 kV. By controlling the first voltage generation circuit 475 and the second voltage generation circuit 476 in this way, the control unit 400 can also generate a potential difference between the nozzle electrode 471B and the counter electrode 471C without spraying the fixing liquid using the nozzle 471D, and calculate the resistance value of the bypass circuit.

[0441] When spraying the fixing liquid L using the nozzle 471D, the control unit 400 controls the first voltage generation circuit 475 and the second voltage generation circuit 476 so that the potential difference between the nozzle electrode 471B and the counter electrode 471C becomes equal to or greater than the spraying potential difference, thereby spraying the fixing liquid L using the nozzle 471D. At this time, the control unit 400 sets a target current range for the current value detected by the current detection circuit based on a preset target current value for spraying an appropriate amount of the fixing liquid L.

[0442] In addition, the control unit 400 calculates a correction current value Ifix based on the potential difference between the nozzle electrode 471B and the counter electrode 471C and the resistance value of the bypass circuit. The control unit 400 determines whether the current obtained by correcting the current value detected by the current detection circuit with the correction current value Ifix is within the target current range. If the corrected current is outside the target current range, the control unit 400 controls the first voltage generation circuit 475 and the second voltage generation circuit 476 so that the corrected current is within the target current range.

[0443] Specifically, the control unit 400 calculates the corrected current value by subtracting the correction current value Ifix from the current value detected by the current detection circuit. The corrected current value is the net current value flowing between the nozzle electrode 471B and the counter electrode 471C after subtracting the current value flowing in the bypass circuit from the current value detected by the current detection circuit. Therefore, by controlling the first voltage generation circuit 475 and the second voltage generation circuit 476 by the control unit 400 so that the corrected current value is within the target current range, the net current value flowing between the nozzle electrode 471B and the counter electrode 471C can be set to be within the target current range, and an appropriate amount of the fixing liquid L can be sprayed.

[0444] Hereinafter, the control of the laser printer 401 by the control unit 400 will be described. In the following description, the control unit 400 controls the laser printer 401 using the first current I1 monitored with the shunt resistor Rs_FBi1 as the current detection circuit. However, the control unit 400 may also control the laser printer 401 using the second current I2 monitored with the shunt resistor Rc_FBi2 as the current detection circuit.

[0445] Figure 26 FIG. 4 is a flowchart showing the processing of the control unit 400 when the laser printer 401 forms (prints) an image on the sheet P. First, the control unit 400 acquires the loop resistance value Rcir (SA). The content of the process for acquiring the loop resistance value Rcir will be described later.

[0446] The control unit 400 sets a target current range (S41) that is the target for the current when spraying the fixing liquid L. The target current range is in the range of Is - α or more and Is + α or less with respect to the target current value Is. The target current value Is is a predetermined value stored in a storage unit (not shown). The value of α is a value appropriately determined according to printing conditions or the like, and is set to 50 mA, for example.

[0447] Next, the control unit 400 outputs signals (S42) for driving the first liquid feeding unit 451, the second liquid feeding unit 452, and the third liquid feeding unit 453. In addition, the control unit 400 outputs a PWM signal (S43) that operates the first voltage generation circuit 475 and the second voltage generation circuit 476 at the duty ratio for the first voltage generation circuit 475 and the second voltage generation circuit 476 to output the initial voltage. For example, the control unit 400 operates the first voltage generation circuit 475 and the second voltage generation circuit 476 so as to generate a potential difference of 5 kV between the nozzle electrode 471B and the counter electrode 471C. In this state, the control unit 400 performs spray high-voltage constant current control (SB) for spraying an appropriate amount of the fixing liquid L. The content of the spray high-voltage constant current control will be described later. In addition, the control unit 400 performs processing operations such as charging the photosensitive drum 461, developing the photosensitive drum 461 by the developing roller 464, and transferring the toner from the photosensitive drum 461 to the sheet P together with the step SB.

[0448] The control unit 400 determines whether printing is completed (S44). Before printing is completed (in S44, "No"), the process continues with step SB. When printing is completed (in S44, "Yes"), the control unit 400 outputs signals (S45) to stop the first liquid feeding unit 451, the second liquid feeding unit 452, and the third liquid feeding unit 453. In addition, the control unit 400 outputs signals (S46) to stop the first voltage generation circuit 475 and the second voltage generation circuit 476.

[0449] Figure 27 This is a flowchart showing the process in which the control unit 400 calculates the loop resistance value Rcir. The control unit 400 outputs a PWM signal (SA41) that operates the second voltage generation circuit 476 with a duty ratio such that the output voltage of the second voltage generation circuit 476 is -2 kV. At this time, the first voltage generation circuit 475 does not apply a voltage to the nozzle electrode 471B. In this state, the control unit 400 stands by for a certain period of time (SA42). The certain period of time refers to a sufficiently long time required for at least the output current of the second voltage generation circuit 476 to reach a steady state, for example, set to 3 seconds.

[0450] After the end of step SA42, the control unit 400 obtains the actual first voltage V1 of the nozzle electrode 471B from the first voltage generation circuit 475 (SA43), and obtains the actual second voltage V2 of the counter electrode 471C from the second voltage generation circuit 476 (SA44). In addition, the control unit 400 obtains the first current I1 from the current detection circuit (SA45). The order of steps SA43 to SA45 is arbitrary. Further, the control unit 400 calculates the loop resistance value Rcir through the following formula (1) (SA46).

[0451] Rcir = (V1 - V2) / I1 (1)

[0452] The first current I1 here is equal to the current Icirleak flowing in the bypass circuit.

[0453] Figure 28 This is a flowchart showing the process in which the control unit 400 controls the first voltage generation circuit 475 and the second voltage generation circuit 476 for spraying the fixing liquid L in the fourth embodiment. First, the control unit 400 obtains the first voltage V1 from the first voltage generation circuit 475 (SB411), and obtains the second voltage V2 from the second voltage generation circuit 476 (SB412). Further, the control unit 400 obtains the first current I1 from the current detection circuit (SB413). The order of steps SB411 to SB413 is arbitrary. In addition, the control unit 400 may execute two or more of steps SB411 to SB413 in parallel.

[0454] The control unit 400 uses the first voltage V1, the second voltage V2, and the loop resistance value Rcir calculated in step SA, and calculates the correction current value Ifix through the following formula (2) (SB414).

[0455] Ifix = (V1 - V2) / Rcir (2)

[0456] Step SB414 may be executed prior to step SB413.

[0457] Furthermore, the control unit 400 uses the first current I1 and the current value Ifix for correction, and calculates the corrected current value I1fix (SB415) by the following formula (3).

[0458] I1fix = I1 - Ifix (3)

[0459] The control unit 400 determines whether the corrected current value I1fix is within the target current range (SB416). When the corrected current value I1fix is not within the target current range (No in SB416), the control unit 400 outputs a PWM signal that causes the first voltage generation circuit 475 and the second voltage generation circuit 476 to operate at a duty ratio at which the corrected current value I1fix converges within the target current range (SB417). When the corrected current value I1fix is within the target current range (Yes in SB416), the control unit 400 ends the process without executing step SB417.

[0460] As described above, in the laser printer 401 according to the fourth embodiment, there is a case where a bypass circuit is formed using a flow path for recovering and reusing the fixing liquid L not attached to the sheet P. In the fourth embodiment, the control unit 400 calculates the current value Ifix for correction, which is the current flowing through the bypass circuit during spraying, using the loop resistance value Rcir calculated before spraying the fixing liquid L. Further, the control unit 400 controls the first voltage generation circuit 475 and the second voltage generation circuit 476 so that the corrected current value I1fix obtained by correcting the first current I1 with the current value Ifix for correction is within the target current range. Therefore, an image forming apparatus can be realized that can reuse the recovered fixing liquid and appropriately adjust the spraying amount of the fixing liquid.

[0461] [Modification Example of the Fourth Embodiment]

[0462] Hereinafter, a modification example of the fourth embodiment will be described. The laser printer 401 according to the modification example is different from the laser printer 401 according to the above-described fourth embodiment only in the processing (spraying high-voltage constant current control processing) in the control unit 400 when spraying the fixing liquid using the nozzle. For ease of explanation, components having the same functions as those described in the above fourth embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0463] In the modified example, the control unit 400 determines whether the current value detected by the current detection circuit is within the target current range after being corrected by the correction current value. When the current value detected by the current detection circuit is outside the corrected target current range, the control unit 400 controls the first voltage generation circuit 475 and the second voltage generation circuit 476 so that the current value detected by the current detection circuit is within the corrected target current range. Through such control, the control unit 400 can also set the net current value flowing between the nozzle electrode 471B and the counter electrode 471C to be within the target current range and spray an appropriate amount of fixing liquid L.

[0464] Figure 29 It is a flowchart showing the process in which the control unit 400 controls the first voltage generation circuit 475 and the second voltage generation circuit 476 for spraying the fixing liquid L in the modified example. The control unit 400 executes steps SB411 to SB414 in the same manner as in the fourth embodiment. Then, the control unit 400 uses the target current value Is and the correction current value Ifix, and calculates the corrected target current value Isfix (SB425) by the following formula (4).

[0465] Isfix = Is + Ifix (4)

[0466] The control unit 400 sets the corrected target current range based on the corrected target current value Isfix (SB426). The method of setting the corrected target current range is the same as the method of setting the target current range in step S1 above, except that the corrected target current value Isfix is used instead of the target current value Is.

[0467] The control unit 400 determines whether the first current I1 is within the corrected target current range (SB427). When the first current I1 is not within the corrected target current range (in SB427, "No"), the control unit 400 outputs a PWM signal that causes the first voltage generation circuit 475 and the second voltage generation circuit 476 to operate at a duty ratio that converges the first current I1 within the corrected target current range (SB428). When the first current I1 is within the corrected target current range (in SB427, "Yes"), the control unit 400 ends the process without changing the duty ratio.

[0468] As described above, in the modification example, the control unit 400 controls the first voltage generation circuit 475 and the second voltage generation circuit 476 so that the first current I1 is within the range of the corrected target current corrected by the current value Ifix for correction. Therefore, it is possible to realize the following image forming apparatus: the recycled fixing liquid can be reused, and the spraying amount of the fixing liquid can be appropriately adjusted.

[0469] [Software-based implementation example]

[0470] The control block (particularly the control unit 400) of the laser printer 401 can be implemented by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or can be implemented by software.

[0471] In the latter case, the laser printer 401 includes a computer that executes commands of a program that is software for realizing each function. The computer includes, for example, one or more processors, and includes a computer-readable recording medium storing the above program. Further, in the above computer, the above processor reads and executes the above program from the above recording medium, thereby achieving the object of the present invention. As the above processor, for example, a CPU (Central Processing Unit) can be used. As the above recording medium, a "non-transitory tangible medium" can be used. For example, in addition to being able to use a ROM (Read Only Memory) or the like, a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, etc. can also be used. In addition, a RAM (Random Access Memory) or the like for expanding the above program may also be provided. Further, the above program can be provided to the above computer via any transmission medium (communication network, radio wave, etc.) capable of transmitting the program. In addition, one aspect of the present invention can also be implemented in the form of a data signal embedded in a carrier wave in which the above program is embodied by electronic transmission.

[0472] Any structure and process in the first to fourth embodiments and their modification examples can also be combined with the structures and processes of different embodiments.

[0473] Description of reference numerals

[0474] 1, 201 Image forming apparatus

[0475] 301, 401 Laser printer (image forming apparatus)

[0476] 4, 361, 461 Photosensitive drum

[0477] 7 Developing device

[0478] 64 Developing roller

[0479] 8 Transfer device

[0480] TR Transfer roller

[0481] 9 Spraying device (spraying device)

[0482] 371, 471 Spraying unit (spraying device)

[0483] 91, 371A, 471A Housing

[0484] 12 Recovery device

[0485] 373, 473 Recovery unit (recovery device)

[0486] 121, 373A, 473A Recovery tray

[0487] 122, 373B, 473B Recovery pipe

[0488] 123 Recovery pump

[0489] 374B, 452B Second pump (recovery pump)

[0490] 100, 200 Control device

[0491] 300, 300A, 400 Control section (control device)

Claims

1. An image forming apparatus, characterized in that, Comprising: A photosensitive drum; A developing device that supplies toner to the photosensitive drum; A transfer device that transfers the toner supplied to the photosensitive drum to a sheet; A spraying device that sprays a fixing liquid for fixing the toner to the sheet onto the sheet onto which the toner is transferred, and includes a housing capable of accommodating the fixing liquid and a nozzle for spraying the fixing liquid in the housing; A recovery device that recovers the fixing liquid sprayed from the nozzle and not attached to the sheet, and has a recovery tray capable of accommodating the fixing liquid, a recovery pipe connected to the recovery tray and allowing the fixing liquid in the recovery tray to pass through, and a recovery pump that conveys the fixing liquid in the recovery pipe toward the housing; A main body housing; And A supply device that supplies the fixing liquid to the housing, The supply device comprises: A fixing liquid cartridge that accommodates the fixing liquid and can be installed on the main body housing; A supply pipe that is connected to the fixing liquid cartridge in a state where the fixing liquid cartridge is installed on the main body housing and allows the fixing liquid in the fixing liquid cartridge to pass through; A supply tank that is connected to the supply pipe and can accommodate the fixing liquid that has passed through the supply pipe; and A supply pipe that is connected to the supply tank and allows the fixing liquid in the supply tank to pass through, The housing is connected to the supply pipe and can accommodate the fixing liquid that has passed through the supply pipe, The recovery pipe is connected to the supply tank, The recovery pump conveys the fixing liquid in the recovery pipe to the housing via the supply tank.

2. The image forming apparatus according to claim 1, wherein The spraying device further has: A nozzle electrode that charges the fixing liquid in the housing; and An opposing electrode that is located at a position spaced apart from the nozzle electrode, The nozzle is located between the nozzle electrode and the opposing electrode.

3. The image forming apparatus according to claim 2, wherein The opposing electrode is located in the recovery tray.

4. The image forming apparatus according to any one of claims 1 to 3, wherein The recovery pump is a gear pump.

5. The image forming apparatus according to any one of claims 1 to 3, wherein A supply pump is provided that conveys the fixing liquid in the supply pipe toward the supply tank.

6. The image forming apparatus according to claim 5, wherein The supply pump is a gear pump.

7. The image forming apparatus according to claim 5, wherein Comprising: A sensor that detects the liquid level position of the fixing liquid in the supply tank; and A control device, The control device is capable of performing: A pump driving process of driving the supply pump to supply the fixing liquid from the fixing liquid cartridge to the supply tank when the liquid level position detected by the sensor is lower than a threshold value; and Pump stop processing: When the liquid level position detected by the sensor is above the threshold, the driving of the replenishment pump is stopped to stop the replenishment of the fixing liquid from the fixing liquid cartridge to the supply tank.

8. The image forming apparatus according to claim 7, characterized in that: The control device executes the pump driving process after the printing operation ends.

9. The image forming apparatus according to any one of claims 1 to 3, characterized in that: It further includes a stirring member that stirs the fixing liquid in the supply tank.

10. The image forming apparatus according to any one of claims 1 to 3, characterized in that: The recovery device has a recovery valve that suppresses the case where the fixing liquid in the recovery tray is transported to the supply tank through the inside of the recovery pipe.

11. The image forming apparatus according to any one of claims 1 to 3, characterized in that: The recovery pipe has a filter.

12. The image forming apparatus according to claim 11, characterized in that: At least a part of the recovery pipe extends in the vertical direction, The filter extends in a direction intersecting the vertical direction.

13. The image forming apparatus according to any one of claims 1 to 3, characterized in that: The recovery pipe is connected to the supply pipe, The supply pipe allows the fixing liquid that has passed through the recovery pipe to pass through.

14. The image forming apparatus according to any one of claims 1 to 3, characterized in that, It includes: A recovery tank connected to the recovery pipe and capable of accommodating the fixing liquid that has passed through the inside of the recovery pipe; and A second recovery pipe connected to the recovery tank and allowing the fixing liquid in the recovery tank to pass through, The housing is connected to the second recovery pipe and can accommodate the fixing liquid that has passed through the second recovery pipe.

15. The image forming apparatus according to claim 1, wherein The housing is connected to the supply pipe and the recovery pipe and can accommodate the fixing liquid that has passed through the supply pipe and the fixing liquid that has passed through the recovery pipe.

16. The image forming apparatus according to claim 1, characterized in that: It further includes a control device, The control device can execute a recovery process when the execution of the printing operation is completed. In this recovery process, the recovery pump is driven to transport the fixing liquid in the recovery tray toward the housing.

17. The image forming apparatus according to claim 16, characterized in that: The control device counts the first cumulative number of pages, which is the cumulative number of pages printed after the previous recovery process.

18. The image forming apparatus according to claim 17, characterized in that: The more the first cumulative number of pages, the longer the control device extends the driving time of the recovery pump in the recovery process.

19. The image forming apparatus according to claim 17, characterized in that: The supply device has: A supply tank that accommodates the fixing liquid supplied to the spraying device; and A sensor that detects whether the amount of the fixing liquid in the supply tank is less than a specified amount. The control device stores a first set value and a second set value. The first set value is the number of pages that can be continuously printed using the specified amount of the fixing liquid, and the second set value is a value set based on the capacity of the recovery tray. When the first accumulated number of pages is less than the first set value and the control device receives a new printing job during the recovery process, if the first accumulated number of pages is equal to or greater than the second set value, the control device executes the new printing job after the recovery process. if the first accumulated number of pages is less than the second set value, the control device executes the recovery process after executing the new printing job.

20. The image forming apparatus according to claim 19, wherein when the first accumulated number of pages is less than the first set value and the control device receives a new printing job during the recovery process and the first accumulated number of pages is less than the second set value, in the recovery process after the new printing job, based on the first accumulated number of pages after adding the number of pages printed in the new printing job, the more the first accumulated number of pages, the longer the control device extends the driving time of the recovery pump during the recovery process.

21. The image forming apparatus according to claim 19, wherein when the first accumulated number of pages becomes equal to or greater than the first set value during the execution of the printing job, the control device interrupts the execution of the printing job and executes the recovery process.

22. The image forming apparatus according to any one of claims 17 to 21, wherein the control device resets the first accumulated number of pages when the recovery process is completed.

23. The image forming apparatus according to any one of claims 16 to 21, wherein the supply device includes: a supply tank that houses the fixing liquid supplied to the spraying device; a fixing liquid cartridge that can house the fixing liquid replenished to the supply tank; a supply pipe that allows the fixing liquid to pass from the fixing liquid cartridge to the supply tank; a supply pump that transports the fixing liquid in the supply pipe toward the supply tank; and a sensor that detects whether the amount of the fixing liquid in the supply tank is less than a specified amount.

24. The image forming apparatus according to claim 23, wherein after the recovery process, when the sensor detects that the amount of the fixing liquid in the supply tank is less than the specified amount, the control device executes a replenishment process in which the supply pump is driven to transport the fixing liquid housed in the fixing liquid cartridge to the supply tank.

25. The image forming apparatus according to claim 23, wherein During the preheating process of the image forming apparatus, when the sensor detects that the amount of the fixing liquid in the supply tank is less than the specified amount, the control device performs a replenishment process in which the replenishment pump is driven to transport the fixing liquid stored in the fixing liquid cartridge to the supply tank.

26. The image forming apparatus according to claim 24 or 25, wherein it further includes a display device, when the second cumulative page number, which is the cumulative number of pages printed after the last replenishment process, is equal to or greater than a third set value and the sensor does not detect that the amount of the fixing liquid in the supply tank is less than the specified amount, the control device performs an error display process for causing the display device to display an error.

27. The image forming apparatus according to claim 26, wherein after the control device has completed the execution of a printing job, when the second cumulative page number is equal to or greater than a third set value and the sensor does not detect that the amount of the fixing liquid in the supply tank is less than the specified amount, the control device performs the error display process.

28. The image forming apparatus according to claim 26, wherein during the preheating process of the image forming apparatus, when the second cumulative page number is equal to or greater than a third set value and the sensor does not detect that the amount of the fixing liquid in the supply tank is less than the specified amount, the control device performs the error display process.

29. The image forming apparatus according to claim 26, wherein during the recovery process after the sheet jammed in the image forming apparatus has been removed, when the second cumulative page number is equal to or greater than a third set value and the sensor does not detect that the amount of the fixing liquid in the supply tank is less than the specified amount, the control device performs the error display process.

30. The image forming apparatus according to claim 1, wherein It further includes: a disconnection instruction receiving unit that receives an instruction to disconnect the power supply; and a control device, when the disconnection instruction receiving unit receives an instruction to disconnect the power supply, the control device sprays the fixing liquid in the housing from the nozzle and performs a recovery process in which the recovery pump is driven to transport the fixing liquid in the recovery tray toward the housing.

31. The image forming apparatus according to claim 30, wherein the supply device further has: a supply pump that causes the fixing liquid in the supply tank to pass through the supply pipe and supply the fixing liquid toward the housing; and a first sensor that can detect the storage state of the fixing liquid in the housing, when the image forming apparatus is started, if the detection result of the first sensor indicates that the specified amount of the fixing liquid is not stored in the housing, the control device performs the supply of the fixing liquid from the supply tank to the housing by the supply pump.

32. The image forming apparatus according to claim 31, wherein it further includes a second sensor that can detect the storage state of the fixing liquid in the supply tank, The supply device further includes a replenishing pump that causes the fixing liquid in the fixing liquid cartridge to be replenished to the supply tank through the replenishing pipe. When the image forming apparatus is started and the detection result of the second sensor indicates that the supply tank does not contain a predetermined amount of the fixing liquid, the control device performs replenishment of the fixing liquid from the fixing liquid cartridge to the supply tank by the replenishing pump.

33. The image forming apparatus according to any one of claims 30 to 32, characterized in that it further includes a cancellation instruction receiving unit that receives an instruction to cancel the recovery process and an instruction to cancel the cancellation of the recovery process. When the cancellation instruction receiving unit receives an instruction to cancel the recovery process, the control device does not perform the recovery process until the cancellation instruction receiving unit next receives an instruction to cancel the cancellation of the recovery process.

34. The image forming apparatus according to claim 1, characterized in that the spraying device further includes: a nozzle electrode that charges the fixing liquid in the housing; and a counter electrode that is located at a position spaced apart from the nozzle electrode, and a potential difference is formed between the counter electrode and the nozzle electrode. The image forming apparatus further includes: a supply device that supplies the fixing liquid to the spraying device; a first voltage generation circuit that is connected to the nozzle electrode and generates a first voltage applied to the nozzle electrode; a second voltage generation circuit that is connected to the counter electrode and generates a second voltage applied to the counter electrode; a current detection circuit that detects a current flowing between the first voltage generation circuit and the nozzle electrode or between the second voltage generation circuit and the counter electrode; and a control device. Before spraying the fixing liquid using the nozzle, the control device controls the first voltage generation circuit and the second voltage generation circuit so that the potential difference is less than a predetermined value, and calculates a resistance value of a bypass circuit from the nozzle electrode through the supply device and the recovery device to the counter electrode based on the current value detected by the current detection circuit and the potential difference less than the predetermined value. When spraying the fixing liquid using the nozzle, the control device calculates a correction current value based on the potential difference above the predetermined value and the resistance value. The control device sprays the fixing liquid using the nozzle by controlling the first voltage generation circuit and the second voltage generation circuit so that the potential difference is above the predetermined value. The control device determines whether the corrected current obtained by correcting the current value detected by the current detection circuit with the current value for correction is within the target current range. When the corrected current is outside the target current range, the control device controls the first voltage generation circuit and the second voltage generation circuit so that the corrected current is within the target current range.

35. The image forming apparatus according to claim 1, wherein the spraying device further has: a nozzle electrode that charges the fixing liquid in the housing; and a counter electrode that is located at a position spaced apart from the nozzle electrode, and a potential difference is formed between the counter electrode and the nozzle electrode. The image forming apparatus further includes: a supply device that supplies the fixing liquid to the spraying device; a first voltage generation circuit that is connected to the nozzle electrode and generates a first voltage applied to the nozzle electrode; a second voltage generation circuit that is connected to the counter electrode and generates a second voltage applied to the counter electrode; a current detection circuit that detects the current flowing between the first voltage generation circuit and the nozzle electrode or between the second voltage generation circuit and the counter electrode; and a control device. Before spraying the fixing liquid using the nozzle, the control device controls the first voltage generation circuit and the second voltage generation circuit so that the potential difference is less than a specified value, and calculates the resistance value of the detour circuit from the nozzle electrode through the supply device and the recovery device to the counter electrode based on the current value detected by the current detection circuit and the potential difference less than the specified value. When spraying the fixing liquid using the nozzle, the control device calculates the current value for correction based on the potential difference equal to or greater than the specified value and the resistance value. The control device controls the first voltage generation circuit and the second voltage generation circuit so that the potential difference is equal to or greater than the specified value, thereby spraying the fixing liquid using the nozzle. The control device determines whether the current value detected by the current detection circuit is within the corrected target current range obtained by correcting the target current range with the current value for correction. When the current is outside the corrected target current range, the control device controls the first voltage generation circuit and the second voltage generation circuit so that the current is within the corrected target current range.

36. The image forming apparatus according to claim 34 or 35, wherein Before spraying the fixing liquid using the nozzle, the control device applies a negative voltage to the counter electrode using the second voltage generation circuit, and controls the second voltage generation circuit without causing the first voltage generation circuit to apply a voltage to the nozzle electrode so that the potential difference is less than the specified value.

37. The image forming apparatus according to claim 34 or 35, wherein: Before spraying the fixing liquid using the nozzle, the control device applies a positive voltage to the nozzle electrode using the first voltage generation circuit, and controls the first voltage generation circuit without causing the second voltage generation circuit to apply a voltage to the counter electrode so that the potential difference is less than the specified value.

38. The image forming apparatus according to claim 34 or 35, wherein: It further includes a voltage generation circuit having the first voltage generation circuit and the second voltage generation circuit.

39. The image forming apparatus according to claim 34 or 35, wherein: The supply device further has a supply pipe that allows the fixing liquid stored in the supply tank to pass through.

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