Image forming apparatus

Abstract

To provide an image forming apparatus capable of suppressing the occurrence of process speed switching after the image forming preparation operation. [Solution] In "life priority mode," the image forming unit does not perform the image forming preparation operation (pre-rotation) until the media sensor has finished detecting the sheet characteristics. The image forming preparation operation is performed only after the process speed is determined by the media sensor's detection. Therefore, the image forming unit does not operate unnecessarily from the time the first sheet is fed to detect the sheet characteristics until the media sensor finishes detecting them. In addition, there is no need to switch the process speed of the image forming unit when transitioning from the image forming preparation operation to the image forming operation. In this way, it is possible to suppress the occurrence of process speed switching after the image forming preparation operation. Since there is no process speed switching time, the image forming unit is not operated unnecessarily.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine.

Background Art

[0002] An image forming apparatus develops an electrostatic latent image formed on a photoreceptor with toner, and transfers and fixes the developed toner image onto a sheet. The sheets are pre-set in a manual feed tray or a paper feed cassette, and are fed one by one from them to a conveyance path as an image forming job starts, and are conveyed by a conveyance unit to an image forming unit that forms an image on the sheets. The sheets may have different sheet characteristics such as thickness and surface property, and the sheet characteristics are set manually by a user from an operation unit or the like, or are detected by a media sensor disposed in the conveyance path. Patent Document 1 proposes an image forming apparatus that sets image forming conditions including the operation speed of an image forming unit (conveniently called a process speed) and the sheet conveyance speed of a conveyance unit based on sheet characteristics detected by a media sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in an image forming job, an image forming preparation operation (so-called, pre-rotation) required for forming an image on a sheet is started, and then an image forming operation for forming an image on the sheet is performed. At this time, if the process speed started in the image forming preparation operation is different from the process speed set by detecting the sheet characteristics by a media sensor, there is a possibility that a process speed switching occurs after the preparation operation.

[0005] This disclosure is made in view of the above-mentioned problems and aims to provide an image forming apparatus capable of suppressing the occurrence of process speed switching after the image forming preparation operation. [Means for solving the problem]

[0006] An image forming apparatus according to one embodiment of the present invention comprises: an image forming unit that forms an image on a recording material; a detection unit disposed upstream of the image forming unit with respect to the transport direction of the recording material and detecting the characteristics of the recording material; and a control unit that controls the process speed, which is the speed at which the image forming unit is driven, based on the characteristics of the recording material detected by the detection unit. The control unit is characterized in that, when the detection unit detects the recording material in a first preparation operation mode, it does not start the preparation operation of the image forming unit before the detection of the recording material by the detection unit is completed, and after the detection of the recording material by the detection unit is completed, it starts the preparation operation of the image forming unit so as to drive the image forming unit at a first process speed corresponding to the characteristics of the recording material detected by the detection unit. [Effects of the Invention]

[0007] According to this disclosure, it is possible to suppress the occurrence of process speed switching after the image formation preparation operation. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram showing the image forming apparatus of this embodiment. [Figure 2] A block diagram showing the control system of an image forming apparatus. [Figure 3] A schematic diagram showing the configuration of a media sensor. [Figure 4] A diagram illustrating the sheet size detection configuration. [Figure 5] (a) A diagram showing the initial media settings screen, (b) A diagram showing the settings selection screen, and (c) A diagram showing the sheet type input screen. [Figure 6] A flowchart illustrating the media setup process. [Figure 7](a) A diagram illustrating job operation in FCOT priority mode, (b) A diagram illustrating job operation in lifespan priority mode. [Figure 8] A flowchart illustrating the image formation process of this embodiment. [Figure 9] (a) Initial screen, (b) Priority mode input screen. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will now be described with reference to the drawings. Figure 1 is a schematic diagram showing the configuration of the image forming apparatus of this embodiment, and Figure 2 is a block diagram showing the control system for controlling the image forming apparatus. In the control system of the image forming apparatus, various other components may be connected to the control unit 300 in addition to those shown in Figure 2, but their illustration and description are omitted here as they are not relevant to the essence of the invention.

[0010] The control unit 300 shown in Figure 2 consists of a CPU (Central Processing Unit) 301, a ROM (Read Only Memory) 302, a RAM (Random Access Memory) 303, and an EEPROM (Electrically Erasable Programmable Read-Only Memory) 304. The CPU 301 controls the entire image forming apparatus 1 to form an image on a sheet by executing programs stored in the ROM 302 and EEPROM 304. In doing so, the CPU 301 can use the RAM 303 as a work area. Various types of sheet-like recording materials can be used as sheets, such as plain paper, cardboard, rough paper, textured paper, coated paper, plastic film, and cloth.

[0011] The image forming apparatus 1 includes an operation unit 330 capable of receiving user input. The operation unit 330 has an input unit 331 into which the user can input various information, such as instructions to start a print operation on a sheet (called an image forming job) and information about the sheet, and a liquid crystal display 332. The liquid crystal display 332 can display various information such as various programs, various data, or various screens, which will be described later. The operation unit 330 may also be a touch panel that accepts information input corresponding to the touch location in response to touch operations by the user on the screen displayed on the liquid crystal display 332. The CPU 301 can control the liquid crystal display 332 to display various screens.

[0012] The CPU 301 is capable of executing image forming jobs and starts printing operations in response to input of an input instruction to start an image forming job from an external device (not shown) or from the operation unit 330. The CPU 301 can drive and control the pre-fusing transport motor 145, the fuser motor 173, the post-fusing transport motor 146, the manual feed transport motor 147, the paper discharge transport motor 148, and the paper discharge transport motor 2 149, which are connected via the input / output interface (I / O) 307. In addition, the CPU 301 can detect input signals from the sheet transport sensor 171, the pre-cash register transport sensor 160, and the paper feed pickup sensor 152 via the input / output interface (I / O) 307.

[0013] Furthermore, the CPU 301 can detect input signals from the media sensor 280, sheet presence detection sensor 214, sheet width volume sensor 217, sheet sub-scan length detection sensor 1 218, and sheet sub-scan length detection sensor 2 219 via the input / output interface (I / O) 307. In addition, the CPU 301 can accept the start of image forming jobs input from the network interface (I / F) 314 and the fax interface (I / F) 315.

[0014] The CPU 301 has an image processing unit 316 that processes an image corresponding to an image formation job input from an external device (not shown) or an operation unit 330, etc., and performs image processing such as image expansion and rotation. Also, the CPU 301 is configured to be able to control the image forming unit 320. The image forming unit 320 includes the process unit 120, transfer belt 130, secondary transfer unit 140, and laser scanner unit 110 shown in FIG. 1. Also, the CPU 301 can control the temperature of a heater (not shown) of the fixing unit 170 shown in FIG. 1. The scanner unit 101 can read an original when performing copying.

[0015] Next, the basic operation of forming an image on a sheet will be described using FIGS. 1 and 2. When an image formation job is started from the operation unit 330, the CPU 301 analyzes a print signal and starts a print operation. When the CPU 301 receives an instruction to convey a sheet from the paper feed cassette 150 where sheets can be loaded, it drives the pre-fixing conveyance motor 145 via the input / output interface (I / O) 307. As a result, the paper feed pickup roller 151 rotates, and the sheets loaded in the paper feed cassette 150 are conveyed one by one to the common conveyance path 400 via the first conveyance path 410. Then, the CPU 301 monitors whether the paper feed operation of the sheets from the paper feed cassette 150 is performed normally using the paper feed pickup sensor 152.

[0016] When the CPU 301 continuously conveys sheets from the paper feed cassette 150, in order to improve the sheet conveyance efficiency without causing paper jams, it changes the paper feed timing from the paper feed cassette 150 according to the sheet length of the sheet size (for example, A4, B4, etc.) included in the start instruction of the image formation job. The sheet length refers to the length of the sheet in the conveyance direction.

[0017] Similarly, when the CPU 301 receives an instruction to convey a sheet from the manual tray 210 on which sheets can be loaded, it drives the manual conveyance motor 147 via the input / output interface (I / O) 307. As a result, the manual pickup roller 211 rotates, and the sheets loaded on the manual tray 210 serving as the loading unit are conveyed one by one to the common conveyance path 400 via the second conveyance path 420. Then, the CPU 301 monitors whether or not the sheet feeding operation from the manual tray 210 is normally performed, using the pre-registration conveyance sensor 160.

[0018] The CPU 301 determines the sheet length before starting the sheet feeding operation based on the detection results of the sheet presence / absence detection sensor 214, the sheet width volume sensor 217, the sheet sub-scanning length detection 1 sensor 218, and the sheet sub-scanning length detection 2 sensor 219 provided on the manual tray 210. The CPU 301 can change the sheet feeding timing from the manual tray 210 according to the determined sheet length.

[0019] In the case of this embodiment, for the sheet conveyed from the manual tray 210, the sheet characteristics such as the thickness and surface property of the sheet are detected by the media sensor 280. The media sensor 280 is disposed upstream of the image forming unit 320 with respect to the sheet conveyance direction, here, in the middle of the second conveyance path 420, specifically, between the manual pickup roller 211 and the confluence of the second conveyance path 420 and the first conveyance path 410 in the common conveyance path 400. The media sensor 280 can detect the sheet characteristics while stopping the sheet conveyed from the manual tray 210 at the stop position for a predetermined detection time in the second conveyance path 420.

[0020] The CPU 301 can change the image forming conditions such as the process speed, the sheet conveyance speed, the fixing temperature, and the transfer voltage based on the sheet characteristics detected by the media sensor 280. The process speed is the speed at which the image forming unit 320 forms an image on the sheet, and includes, for example, the peripheral speed of the photosensitive drum and the rotation speed of the transfer belt 130.

[0021] The CPU 301 starts the process unit 120 in accordance with the timing of the sheet's arrival at the secondary transfer unit 140. The process unit 120 consists of a photosensitive drum, a developer, a charging roller, a photosensitive drum cleaner, and the like. In the process unit 120, after the surface of the photosensitive drum is charged, an electrostatic latent image is formed on the photosensitive drum by a laser irradiated from the laser scanner unit 110. The electrostatic latent image formed on the photosensitive drum is then developed on the photosensitive drum by toner in the developer. Subsequently, the toner image developed on the photosensitive drum is subjected to a primary transfer voltage in the primary transfer unit 121 and transferred to the transfer belt 130. The toner image transferred to the transfer belt 130 is then moved to the secondary transfer unit 140 by the rotation of the transfer belt 130.

[0022] Furthermore, the CPU 301 detects the position of the sheets transported by the transport rollers A153, B154, and C155 by monitoring the pre-cash register transport sensor 160. Transport roller C155, as an example of a transport unit, transports sheets that are to be transported to the common transport path 400 where the first transport path 410 and the second transport path 420 merge, to the image forming unit 320.

[0023] Then, taking into account the timing when the leading edge of the sheet reaches the pre-cash register transport sensor 160, the transport of the sheet is controlled so that the leading edge of the sheet and the leading edge of the toner image on the transfer belt 130 coincide at the secondary transfer unit 140. For example, if the sheet arrives earlier than the toner image, the CPU 301 stops the sheet for a predetermined time using the pre-cash register transport roller 161 before resuming transport. In this way, the CPU 301 applies a secondary transfer voltage to the secondary transfer unit 140 to the sheet and toner image that have reached the secondary transfer unit 140, thereby transferring the toner image to the sheet.

[0024] After secondary transfer, the sheet is transported to the transport belt 190 and then to the fuser 170. In the fuser 170, the toner image on the sheet is heat-fixed to the sheet. The appropriate operating speed of the fuser 170 varies depending on the characteristics of the sheet being transported. The image forming unit 320 operates at a process speed that is preset to be approximately the same as the operating speed of the fuser 170. In this embodiment, the image forming unit 320 is capable of operating at a "normal speed" that ensures fixation on general sheets and a "thick paper speed" that ensures fixation on thick sheets. The "thick paper speed" is slower than the "normal speed". Note that the process speed is not limited to "normal speed" and "thick paper speed" and may be further subdivided.

[0025] Subsequently, when the leading edge of the fixed sheet, which has been transported downstream in the sheet transport direction, reaches the sheet transport sensor 171, the CPU 301 performs the following operation. Specifically, according to the content of the image forming job, the CPU 301 determines which transport path—sheet transport path A230, sheet transport path B231, or sheet transport path C234—to which the sheet being transported along the common transport path 400 should be transported by the transport roller 162, and switches the destination of the sheet by switching the transport flapper A172 and the transport flapper B182 according to the determination.

[0026] Specifically, when the image forming job is a double-sided print job, or when the printed side is to be ejected to the output tray A200 with the printed side facing downwards, the CPU 301 switches the transport flapper A172 to transport the sheet to the sheet transport path A230. Also, when the image forming job is a single-sided print job, or when the sheet is to be ejected to the output tray B196 or output tray C199 during double-sided printing, the CPU 301 switches the transport flapper B182 to transport the sheet to the sheet transport path B231. Finally, when the sheet is to be ejected to the output tray A200, the CPU 301 switches between the transport flappers A172 and B182 to transport the sheet to the sheet transport path C234.

[0027] The sheets transported to sheet transport path B231 are further transported downstream in the transport direction by transport roller E232. Subsequently, the sheets are transported to sheet transport path D181 and then to output tray B196 and output tray C199. The sheets transported to sheet transport path D181 are transported by output rollers F241, G242, and H243, which are driven by output transport motor 148. When CPU 301 wants to output a sheet to output tray B196, it switches flapper 183 to transport the sheet to transport path 193 and outputs the sheet to output tray B196. When CPU 301 wants to output a sheet to output tray C199, it switches flapper 183 to transport path 184. Next, the CPU 301 uses the paper output rollers I244, J245, and K246, driven by the paper output transport motor 149, to transport the sheets to the transport path 184 and eject them into the paper output tray C199.

[0028] When printing on one side and ejecting the printed side downwards to the output tray A200, the sheet moves along the sheet transport path A230, and when the trailing edge of the sheet passes the reversal roller 163, the CPU 301 reverses its drive towards the output roller 180 and ejects the sheet to the output tray A200.

[0029] During double-sided printing, the sheet proceeds to the sheet transport path A230 and is then transported to the double-sided reversal transport path D233 by double-sided transport rollers A164, B165, C166, D179, and E168. Next, when the trailing edge of the sheet passes double-sided transport roller D179, the double-sided reversal flapper 178 is switched to the side of double-sided transport roller F169, and the drive is reversed. Subsequently, the sheet is transported by double-sided transport rollers F169, G175, H176, and I177 and handed over to transport roller C155. When all image forming jobs are completed, the CPU 301 displays completion to the operation unit 330.

[0030] An image forming job is a series of operations for forming an image on a sheet based on a print signal. It refers to the entire process from the start of the preparatory operations necessary for image forming (so-called pre-rotation), through the image forming operations that create the image on the sheet, to the completion of the preliminary operations necessary to finish image forming (so-called post-rotation).

[0031] <Media Sensor> Next, the media sensor 280, which acts as a detection unit for detecting sheet characteristics such as sheet thickness and surface properties, will be explained using Figure 3. As shown in Figure 3, the media sensor 280 has a media sensor main unit 54 and an external LED (light-emitting diode) 55b. The media sensor main unit 54 has an LED 55a as a light source, a phototransistor 56a, and a phototransistor 56b within the unit.

[0032] <Sheet surface texture detection> First, the method for detecting the surface properties of the sheet using the media sensor 280 will be explained. Light emitted from the LED (light-emitting element) 55a passes through the slit 57a and the upper window provided in the sheet transport guide 40, and irradiates the surface of the sheet P being transported while being guided by the sheet transport guide 40. The reflected light from the sheet P passes through the slits 57b and 57c and is received by the phototransistors 56a and 56b (light-receiving elements). Phototransistor 56a receives a portion of the diffusely reflected light emitted from the LED 55a and reflected from the surface of the sheet P, and outputs a diffuse reflection output value. Phototransistor 56b receives the specularly reflected light emitted from the LED 55a and reflected from the surface of the sheet P, and outputs a specular reflection output value. The surface property value x is calculated by Equation 1 shown below. Surface quality value x = Specular reflection output value / Diffuse reflection output value ... (Equation 1)

[0033] Equation 1 utilizes the characteristic that the smoother and finer the surface of sheet P, the easier it is to specularly reflect light. A calculation device (not shown) located on the media sensor 280 quantifies the surface properties of sheet P using Equation 1 and sends the calculated surface property value x to the CPU 301. The CPU 301 uses the received surface property value x and a threshold value for determining surface properties to determine the surface properties of sheet P. If the surface property value x is greater than the threshold value, the CPU 301 determines that the surface properties of sheet P are smooth and fine. If the surface property value x is less than or equal to the threshold value, the CPU 301 determines that the surface properties of sheet P are rough and coarse. Here, one threshold value is used to detect two types of sheet surface properties, but multiple threshold values ​​may be used to further subdivide and detect them.

[0034] <Sheet thickness detection> Next, the method for detecting the sheet thickness using the media sensor 280 will be described. The sheet transport guide 40 is provided with a lower window for irradiating light from the back side of the sheet P. Light emitted from the external LED (light-emitting element) 55b passes through the light-gathering guide 57d and the lower window to irradiate the back side of the sheet P. The transmitted light from the sheet P passes through the upper window and the slit 57b to be received by the phototransistor 56a. The phototransistor 56a receives the positively transmitted light emitted from the external LED 55b and transmitted through the sheet P and outputs a positively transmitted output value. The positively transmitted output value detected by the phototransistor 56a is sent to the CPU 301.

[0035] The CPU 301 determines the thickness of sheet P using the transmitted positive transmission output value and a threshold value for determining thickness. In this embodiment, thresholds A and B are used to make three types of distinctions: "thick," "normal," and "thin" (threshold A < threshold B). If the positive transmission output value is less than or equal to threshold A, the CPU 301 determines that the thickness of sheet P is "thin." If the positive transmission output value is greater than threshold A and less than or equal to threshold B, the CPU 301 determines that the thickness of sheet P is "normal." If the positive transmission output value is greater than threshold B, the CPU 301 determines that the thickness of sheet P is "thick." In this embodiment, the operating speed of the fuser 170 and the process speed of the image forming unit 320 are set to "normal speed" for sheet P determined to be "thin" and "normal," and to "cardboard speed" for sheet P determined to be "thick."

[0036] In this embodiment, two thresholds are used, but one threshold may be used, or three or more thresholds may be used to determine a more finely subdivided thickness. Also, in this embodiment, an optical sensor is used for the media sensor 280, but it is not limited to this, and other types of sensors such as ultrasonic sensors may be used as long as they can detect surface properties or thickness.

[0037] <Sheet size detection> Next, the sheet size detection configuration for sheets set in the manual feed tray 210 will be explained using Figure 4. Note that the same detection configuration may be used for the paper feed cassette 150, so the explanation will be omitted here. As shown in Figure 4, the manual feed tray 210 is equipped with a manual feed pickup roller 211 and sheet side regulating guides 212 and 213. Sheets set in the manual feed tray 210 are held in place by the sheet side regulating guides 212 and 213, preventing the sheets from being transported at an angle when they are separated and transported by the manual feed pickup roller 211. The sheet side regulating guides 212 and 213 are slidable in the direction of arrows 215 and 216 in the figure, so that even if sheets of different widths are set, the sheets can be prevented from becoming skewed.

[0038] The manual feed tray 210 is also equipped with a sheet presence detection sensor 214, a sheet width volume sensor 217, a sheet sub-scan length detection sensor 1 218, and a sheet sub-scan length detection sensor 219. The sheet presence detection sensor 214 is provided to detect whether or not a sheet is loaded in the manual feed tray 210. When a sheet is set on the manual feed tray 210, the sheet presence detection sensor 214 turns on, and an on signal is input to the CPU 301 from the sheet presence detection sensor 214, causing the CPU 301 to determine that there is a sheet in the manual feed tray 210. When no sheet is set on the manual feed tray 210, the sheet presence detection sensor 214 turns off, and an off signal is input to the CPU 301 from the sheet presence detection sensor 214, causing the CPU 301 to determine that there is no sheet in the manual feed tray 210.

[0039] The sheet width volume sensor 217 is connected to the sheet side regulating guides 212 and 213 via a link member (not shown). Therefore, the sheet width volume sensor 217 outputs a signal (AD value) to the CPU 301 corresponding to the position of the sheet side regulating guides 212 and 213 in conjunction with the operation of the sheet side regulating guides 212 and 213. The CPU 301 detects the sheet width based on the signal (AD value) output from the sheet width volume sensor 217. Here, the sheet width is the length in the width direction intersecting the sheet transport direction (main scan length). In contrast, the sheet sub-scan length detection sensor 1 218 and the sheet sub-scan length detection sensor 2 219 have, for example, a flag-type configuration and detect the transport direction length (sub-scan length) of the sheet set on the manual feed tray 210. In this way, the manual feed tray 210 is configured to automatically detect the sheet size, including the main scan length and sub-scan length, for the sheet that is set on it.

[0040] <Initial media settings screen> In this embodiment, when a sheet is detected in the manual feed tray 210 as described above, the "Media Setup Initial Screen" is displayed on the liquid crystal display 332. Figure 5(a) shows the "Media Setup Initial Screen". The "Media Setup Initial Screen" is displayed to allow the user to set whether or not to perform automatic detection of sheet characteristics by the media sensor 280.

[0041] As shown in Figure 5(a), the "Media Settings Initial Screen" displays the sheet detection size 503 of the sheet set in the manual feed tray 210. The sheet detection size 503 is displayed based on the main scan length, which is determined by the detection result of the sheet width volume sensor 217, and the sub-scan length, which is determined by the detection results of the sheet sub-scan length detection sensor 1 218 and the sheet sub-scan length detection sensor 2 219. For example, if the main scan length is "210 mm" and the sub-scan length is "297 mm", "A4 Portrait" will be displayed in the sheet detection size 503, and if the main scan length is "257 mm" and the sub-scan length is "182 mm", "B5 Landscape" will be displayed in the sheet detection size 503. Although not explained here, the user can also manually input the size of the sheet set in the manual feed tray 210.

[0042] Furthermore, the "Initial Media Settings Screen" displays a "Change Sheet Type" button 501 and an "OK" button 550. When the "Change Sheet Type" button 501 is pressed, the "Settings Selection Screen" is displayed on the LCD display 332. Figure 5(b) shows the "Settings Selection Screen". As shown in Figure 5(b), the "Settings Selection Screen" displays a "Automatically Detect During Printing" button 511 and a "Select from List" button 512. The "Automatically Detect During Printing" button 511 is used by the user to set the automatic detection of sheet characteristics by the media sensor 280.

[0043] The "Select from List" button 512 is a button for the user to manually input the sheet type. When the "Select from List" button 512 is pressed, the "Sheet Type Input Screen" is displayed on the liquid crystal display 332. Figure 5(c) shows the "Sheet Type Input Screen". The "Sheet Type Input Screen" is a screen for inputting information about multiple sheet types, and as shown in Figure 5(c), the sheet types are displayed in a list to prompt the user to input the sheet type. Here, the sheet types (thin paper 1, plain paper 1, etc.) are displayed along with their basis weight. The control unit 300 stores the sheet type selected by the user from the list in the RAM 303.

[0044] <Media setup process> Figure 6 is a flowchart of the "media setup process" using the "initial media setup screen" described above. The "media setup process" is started by the control unit 300 (specifically the CPU 301) when the power of the image forming apparatus 1 is turned on. As shown in Figure 6, the control unit 300 determines whether or not a sheet is set in the manual feed tray 210 based on the detection result (on signal or off signal) sent from the sheet presence detection sensor 214 (S1). If no sheet is set in the manual feed tray 210 (NO in S1), the control unit 300 repeatedly executes the process in step S1. If a sheet is set in the manual feed tray 210 (YES in S1), the control unit 300 displays the "initial media setup screen" (see Figure 5(a)) on the liquid crystal display 332 (S2).

[0045] Then, the control unit 300 determines whether the user has pressed the "Change Sheet Type" button 501 on the "Initial Media Settings Screen" (S3). If the "Change Sheet Type" button 501 has not been pressed (NO in S3), the control unit 300 determines whether the user has pressed the "OK" button 550 on the "Initial Media Settings Screen" (S4). If the "OK" button 550 has not been pressed (NO in S4), the control unit 300 returns to the process in step S3. If the "OK" button 550 has been pressed (YES in S4), the control unit 300 terminates the "Media Settings Process".

[0046] If the "Change Sheet Type" button 501 on the "Initial Media Settings Screen" is operated (YES in S3), the control unit 300 displays the "Setting Selection Screen" (see Figure 5(b)) on the liquid crystal display 332 (S5). After the "Setting Selection Screen" is displayed, the control unit 300 determines whether the "Automatically Detect During Printing" button 511 on the "Setting Selection Screen" has been operated by the user (S6). If the "Automatically Detect During Printing" button 511 has been operated by the user (YES in S6), the control unit 300 proceeds to step S9. If the "Automatically Detect During Printing" button 511 has been operated by the user, the control unit 300 automatically detects the sheet characteristics of the first sheet transported from the manual feed tray 210 using the media sensor 280.

[0047] If the "Automatically detect during printing" button 511 on the "Settings Selection Screen" is not pressed by the user (NO in S6), the control unit 300 determines whether the "Select from list" button 512 on the "Settings Selection Screen" has been pressed by the user (S7). If the "Select from list" button 512 has not been pressed by the user (NO in S7), that is, if the "OK" button 551 on the "Settings Selection Screen" has been pressed, the control unit 300 returns to the process in step S6. On the other hand, if the "Select from list" button 512 has been pressed by the user (YES in S7), the control unit 300 displays the "Sheet type input screen" (see Figure 5(c)) on the liquid crystal display 332 (S8).

[0048] The control unit 300 determines whether the user has pressed the "OK" button 551 on the "Settings Selection Screen" or the "OK" button 553 on the "Sheet Type Input Screen" (S9). If the user has pressed the "OK" button 552 on the "Settings Selection Screen" or the "OK" button 553 on the "Sheet Type Input Screen" (YES in S9), the control unit 300 returns to the process in step S2 and redisplays the "Media Settings Initial Screen" (see Figure 5(a)) on the liquid crystal display 332 (S2).

[0049] On the other hand, if the user has not pressed the "OK" button 551 on the "Settings Selection Screen" or the "OK" button 553 on the "Sheet Type Input Screen" (NO in S9), the control unit 300 returns to the process in step S6. In this case, even if the user has pressed the "Automatically detect during printing" button 511 on the "Settings Selection Screen," the control unit 300 will not perform automatic detection of sheet characteristics by the media sensor 280 during the image forming job. Also, even if the user has selected any of the sheet types from the list displayed on the "Sheet Type Input Screen," the user-selected sheet type will not be stored in the RAM 303.

[0050] <Operation of the image formation job> Next, the operation of the image forming job in this embodiment will be explained using Figures 1 and 2, and Figures 7(a) and 7(b). Figure 7(a) is a diagram illustrating the job operation when "FCOT priority mode" is executed, and Figure 7(b) is a diagram illustrating the job operation when "life priority mode" is executed. In Figures 7(a) and 7(b), the upper section shows the operation of the manual feed pickup roller 211 that feeds sheets from the manual feed tray 210 to the second transport path 420, and the lower section shows the operation of the image forming unit and the process speed.

[0051] In the following explanation, we will use an image forming job as an example, in which the media sensor 280 automatically detects the sheet characteristics of the first sheet transported from the manual feed tray 210, and then performs image forming on the second and subsequent sheets transported from the manual feed tray 210.

[0052] As shown in FIGS. 7(a) and 7(b), the manual pickup roller 211 feeds the first sheet from the manual tray 210 to the second conveyance path 420 in response to the start of an image forming job, and temporarily stops the fed sheet at the media detection position (stop position) of the media sensor 280. This is because it takes a predetermined detection time (e.g., 1000 ms) for the media sensor 280 to detect the sheet characteristics, and if the sheet to be detected is not temporarily stopped, the media sensor 280 cannot appropriately detect the sheet characteristics. In the example shown here, it takes "1000 ms" (conveyance time) to convey the sheet from the manual tray 210 to the media detection position. After the detection by the media sensor 280 is completed, the manual pickup roller 211 resumes sheet conveyance and conveys the detected sheet from the second conveyance path 420 to the common conveyance path 400. The sheet conveyed to the common conveyance path 400 is conveyed to the image forming unit 320 by the conveyance roller C155.

[0053] <FCOT Priority Mode> In the case of the "FCOT Priority Mode" (second preparation operation mode) shown in FIG. 7(a), the image forming unit 320 starts an image forming preparation operation (pre-rotation) in response to the start of an image forming job. The image forming unit 320 operates at a process speed of a predetermined default speed during the image forming preparation operation. Here, the default speed (second process speed) is set as the "thick paper speed", and it is assumed that it takes "1300 ms" for the process speed of the image forming unit 320 to reach the "thick paper speed" from the start of the image forming job.

[0054] As described above, the manual feed pickup roller 211 feeds the first sheet from the manual feed tray 210 in response to the start of the image forming job and detects the sheet characteristics using the media sensor 280. At this time, it takes "2000 (1000 + 1000) ms" from the feeding of the first sheet until the detection by the media sensor 280 is completed. In other words, when the process speed of the image forming unit 320 reaches the predetermined speed (1300 ms), the detection by the media sensor 280 has not yet been completed. Therefore, the image forming unit 320 does not transition from the image forming preparation operation to the image forming operation to form an image on the sheet, but waits until the detection by the media sensor 280 is completed. This waiting time is the media detection waiting time and is "700 (2000 - 1300) ms". In "FCOT priority mode", the machine operates at "thick paper speed" before the media sensor 280 starts detecting the sheet characteristics, and also operates at "thick paper speed" during the media detection waiting time.

[0055] After the media sensor 280 finishes detection, the image forming unit 320 transitions from image forming preparation to image forming. Here, as an example, let's assume that the process speed of the image forming unit 320 is set to "normal speed" based on the sheet characteristics detection result. In this case, the image forming unit 320 transitions from image forming preparation to image forming while switching the process speed from "thick paper speed" to "normal speed". The switching time required to switch the process speed from "thick paper speed" to "normal speed" is "1500 ms". Once the process speed switch is complete, the image forming unit 320 operates at "normal speed" and begins image forming on the second and subsequent sheets that are fed sequentially from the manual feed tray 210. Here, image forming on the second and subsequent sheets begins "3500 (1300 + 700 + 1500) ms" after the start of the image forming job.

[0056] The aforementioned waiting time of "700ms" and switching time of "1500ms" are due to detection by the media sensor 280. During this time, the image forming unit 320 cannot start image formation but operates at "cardboard speed". Therefore, this can accelerate the wear of the process unit 120, transfer belt 130, secondary transfer unit 140, etc. in the image forming unit 320. While the operation of this image forming job is the same as in conventional operations, in this embodiment, it is made possible for the user to selectively execute it as an "FCOT priority mode".

[0057] This is because, compared to the "life priority mode" described later, the "FCOT (First Copy Output Time)" is sometimes faster. In other words, if the process speed based on the detection result of the sheet characteristics matches the process speed "thick paper speed" (default speed) during the image formation preparation operation, the image forming unit 320 starts image formation without switching the process speed. In this case, since there is no switching time, the "FCOT (First Copy Output Time)" becomes faster. Here, image formation for the second and subsequent sheets starts 2000 (1300 + 700) ms after the start of the image formation job. In this embodiment, "FCOT" refers to the time from when the media sensor 280 finishes detecting the first sheet until the second sheet is fed from the manual feed tray 210 and ejected to the output tray A200.

[0058] <Lifespan Priority Mode> On the other hand, in the "life priority mode" (first preparation operation mode) shown in Figure 7(b), the image forming unit 320 does not start the image forming preparation operation (pre-rotation) in response to the start of the image forming job, but starts the image forming preparation operation after the media sensor 280 has finished detecting. At this time, the image forming unit 320 operates at a process speed (first process speed) corresponding to the detection result of the sheet characteristics. Here, as an example, let's assume that the process speed of the image forming unit 320 is set to "normal speed" based on the detection result of the sheet characteristics. In this case, the image forming unit 320 starts the image forming preparation operation and operates at "normal speed" after "2000 (1000 + 1000) ms" has elapsed from the start of the image forming job. Since the process speed based on the detection result of the sheet characteristics is "normal speed", the image forming unit 320 transitions from the image forming preparation operation to the image forming operation at "normal speed" without switching the process speed.

[0059] Thus, in "life priority mode," the image forming unit 320 does not perform image forming preparation operations until the media sensor 280 has finished detecting the image. The image forming preparation operations are performed only after the process speed is determined by the detection of the media sensor 280. In other words, the image forming unit 320 is not operated unnecessarily for "2000 ms" from the feeding of the first sheet (first recording material) until the media sensor 280 finishes detecting the image. Then, image forming for the second and subsequent sheets (second recording material) begins after "3300 (1000 + 1000 + 1300) ms" has elapsed from the start of the image forming job. This is faster than the "FCOT priority mode" (3500 ms) shown in Figure 7(a), and the image forming unit 320 is not operated unnecessarily. Therefore, wear and tear on the image forming unit 320, which was previously operated unnecessarily, can be suppressed.

[0060] <Image Formation Processing> Next, the "image forming process" of this embodiment, which realizes the operation of the image forming job described above, will be explained using Figures 8 to 10(b) with reference to Figures 2, 7(a), and 7(b). The "image forming process" shown in Figure 8 is executed by the control unit 300 (specifically the CPU 301) in response to the input of an instruction to start the image forming job when the "Automatic detection during printing" button 511 (see Figure 5(b)) is operated by the user.

[0061] As shown in Figure 8, the control unit 300 determines whether the image formation preparation mode is "FCOT priority mode" (S11). In this embodiment, before the start of the image formation job, the user can selectively input either "FCOT priority mode" or "life priority mode" according to the screen displayed on the liquid crystal display 332. The screens displayed on the liquid crystal display 332 are the "initial screen" shown in Figure 9(a) and the "priority mode input screen" shown in Figure 9(b).

[0062] <Initial screen and priority mode input screen> As shown in Figure 9(a), the "Initial Screen" displays the "Priority Mode Input" button 800. When the user operates the "Priority Mode Input" button 800, the screen displayed on the liquid crystal display 332 transitions from the "Initial Screen" to the "Priority Mode Input Screen".

[0063] As shown in Figure 9(b), the "Priority Mode Input Screen" displays the "FCOT Priority Mode" button 801, the "Lifespan Priority Mode" button 802, and the "OK" button 803. When the user selects the "FCOT Priority Mode" button 801 and operates the "OK" button 803, "FCOT Priority Mode" is set and stored in RAM 303 (see Figure 2). When the user selects the "Lifespan Priority Mode" button 802 and operates the "OK" button 803, "Lifespan Priority Mode" is set and stored in RAM 303 (see Figure 2). In this way, the image formation preparation mode is set when either the "FCOT Priority Mode" button 801 or the "Lifespan Priority Mode" button 802 is selected and the "OK" button 803 is operated.

[0064] Returning to the explanation of Figure 8, if the image formation preparation mode is "FCOT priority mode" (YES in S11), the control unit 300 starts the image formation unit 320 at the default process speed (e.g., cardboard speed) as an image formation preparation operation (S18). At the same time as the start of the image formation preparation operation, the control unit 300 feeds the first sheet from the manual feed tray 210 and transports it to the media detection position of the media sensor 280 (S19). When the sheet reaches the media detection position, the control unit 300 temporarily stops the transport and starts detecting the sheet characteristics with the media sensor 280 (S20). The control unit 300 then determines whether the detection of the sheet characteristics by the media sensor 280 has finished (S21). This completion determination can be made by determining whether a predetermined detection time (e.g., 1000 ms) has elapsed since the sheet temporarily stopped. The control unit 300 waits until the detection of the sheet characteristics is finished (NO in S21).

[0065] When sheet characteristic detection is complete (YES in S21), the control unit 300 switches the process speed of the image forming unit 320 according to the sheet characteristic detection result (S22). As described above, for example, if the process speed based on the sheet characteristic detection result is "normal speed", the control unit 300 switches the process speed from the default speed "thick paper speed" to "normal speed". Then, after the process speed switching time (e.g., 1500ms) has elapsed, the control unit 300 starts the image forming operation (S17). That is, the control unit 300 sequentially feeds the second and subsequent sheets from the manual feed tray 210 and causes the image forming unit 320, which is operating at the switched "normal speed", to form an image. Note that if the process speed based on the sheet characteristic detection result is "thick paper speed", the control unit 300 starts the image forming operation without switching the process speed.

[0066] On the other hand, if the image formation preparation mode is not "FCOT priority mode," that is, if it is "life priority mode" (NO in S11), the control unit 300 does not start the image formation preparation operation, but instead feeds the first sheet from the manual feed tray 210 and transports it to the media detection position of the media sensor 280 (S12). Once the sheet reaches the media detection position, the control unit 300 temporarily stops the transport and starts detecting the sheet characteristics using the media sensor 280 (S13).

[0067] The control unit 300 then determines whether the detection of sheet characteristics by the media sensor 280 has finished (S14). This completion determination can be made by determining whether a predetermined detection time has elapsed since the sheet stopped, as described above. The control unit 300 waits until the detection of sheet characteristics is finished (NO in S14). If the detection of sheet characteristics is finished (YES in S14), the control unit 300 starts the image forming unit 320 to operate at a process speed (e.g., normal speed) corresponding to the sheet characteristic detection result as an image forming preparation operation (S15). That is, the start of the image forming preparation operation of the image forming unit 320 is suspended for the time it takes from the feeding of the first sheet to the completion of detection by the media sensor 280 (i.e., transport time + detection time).

[0068] The control unit 300 then determines whether a predetermined time has elapsed since the start of the image formation preparation operation (S16). The control unit 300 waits until the predetermined time has elapsed (NO in S16). This predetermined time is the time required for the process speed of the image forming unit 320 to reach a speed corresponding to the detection result of the sheet characteristics (for example, 1300 ms). If the predetermined time has elapsed (YES in S16), the control unit 300 starts the image formation operation (S17). That is, the control unit 300 sequentially feeds the second and subsequent sheets from the manual feed tray 210 and causes the image forming unit 320 to form an image. At this time, the control unit 300 starts the image formation operation without switching the process speed of the image forming unit 320, which was operated at "normal speed" during the image formation preparation operation.

[0069] As described above, in this embodiment, in "life priority mode," the image forming unit 320 does not perform image forming preparation operations until the media sensor 280 has finished detecting the sheet characteristics. The image forming preparation operations are performed only after the process speed is determined by the detection by the media sensor 280. This prevents the image forming unit 320 from operating unnecessarily from the time the first sheet is fed until the media sensor 280 finishes detecting the sheet characteristics. Furthermore, there is no need to switch the process speed of the image forming unit 320 when transitioning from the image forming preparation operation to the image forming operation. Since there is no process speed switching time, the image forming unit 320 is not operated unnecessarily. Therefore, wear and tear on the image forming unit 320 can be suppressed.

[0070] In the embodiment described above, the media sensor 280 was described as being located on the second transport path 420 through which sheets from the manual feed tray 210 are transported, but the invention is not limited to this. For example, the media sensor 280 may be located on the first transport path 410 through which sheets from the paper feed cassette 150 are transported. Alternatively, the media sensor 280 may be located on the common transport path 400 through which sheets from both the paper feed cassette 150 and the manual feed tray 210 are transported. [Explanation of symbols]

[0071] 1…Image forming apparatus, 155(211)…Transportation unit (transport roller C, manual feed pickup roller), 210…Loading unit (manual feed tray), 280…Detection unit (media sensor), 300…Control unit, 320…Image forming unit, 331…Input unit, P…Recording material (sheet)

Claims

1. An image forming unit that forms an image on the recording material, A detection unit is positioned upstream of the image forming unit in the direction of transport of the recording material and detects the characteristics of the recording material. The system includes a control unit that controls the process speed, which is the speed at which the image forming unit is driven, based on the characteristics of the recording material detected by the detection unit, When the control unit detects the recording material using the detection unit in the first preparation operation mode, Before the detection of the recording material by the detection unit is completed, the preparation operation of the image forming unit is not started. After the detection of the recording material by the detection unit is completed, the preparatory operation of the image forming unit is started so that the image forming unit is driven at a first process speed corresponding to the characteristics of the recording material detected by the detection unit. An image forming apparatus characterized by the following features.

2. A loading section for loading recording materials, The system includes a transport unit that transports the recording material loaded in the loading unit to the image forming unit, The detection unit detects the characteristics of the recording material while the recording material being transported by the transport unit is stopped at the stop position. The image forming apparatus according to feature 1.

3. When the first preparation operation mode is executed, the control unit starts the preparation operation of the image forming unit after the transport time required for transporting the recording material from the loading unit to the detection position of the detection unit and the detection time required for the detection unit to detect the characteristics of the recording material have elapsed. The image forming apparatus according to feature 2.

4. When the control unit detects the recording material using the detection unit in the second preparation operation mode, Before the detection of the recording material by the detection unit begins, the preparatory operation of the image forming unit is started so that the image forming unit is driven at a predetermined second process speed. After the detection of the recording material by the detection unit is completed, the second process speed is switched to a first process speed corresponding to the characteristics of the recording material detected by the detection unit. The image forming apparatus according to feature 1.

5. It includes an input unit that allows the user to input either the first preparation operation mode or the second preparation operation mode, The control unit executes either the first preparation operation mode or the second preparation operation mode according to the input from the input unit. The image forming apparatus according to feature 4.

6. When the first preparation operation mode is executed, the transport unit feeds a first recording material from the loading unit to allow the detection unit to detect the characteristics of the recording material before the preparation operation of the image forming unit begins, and feeds a second recording material from the loading unit to allow the image forming unit to form an image after a predetermined time has elapsed since the start of the preparation operation. The image forming apparatus according to feature 2.

7. The aforementioned loading section is a manual feed tray. The image forming apparatus according to feature 2.

Images