Image forming device

Abstract

The present invention discloses an image forming device, comprising: a scanning component provided with a light source, a polygonal mirror, and a driving component for driving the rotation of the polygonal mirror; a photosensitive member; a developing component; and a detecting component for detecting laser light from the light source. A controller controls the device to perform a light emission operation such that an area including an image forming area of ​​the photosensitive member is irradiated with laser light. The controller controls the device to perform a switching operation in which the rotational speed of the polygonal mirror is switched from a first speed to a second speed different from the first speed. The controller controls the device to perform the light emission operation while the photosensitive member and the developing component are in contact and rotating, and performs the switching operation based on a detection result of the detecting component during the light emission operation.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, for example, an image forming device provided with a rotating polygon mirror through which laser light is scanned on a photosensitive member. Background Art

[0002] Conventionally, in the case of a printing operation with a mixture of several process speeds and resolution levels when printing continuously on various media, it is necessary to switch the rotation speed of the scanner motor. In this case, the printing operation is paused, and then the rotation speed of the scanner motor is switched. It is well known that an image forming apparatus like this has a technology for detecting the rotation speed by forcibly emitting a laser (hereinafter referred to as forced emission) for a certain duration when the scanner motor is started. For example, in Japanese Laid-Open Patent Application 2019-038219, a technology for shortening the first print-out time within the limit of forced laser emission only in a state where the developing part is separated from the photosensitive drum has been disclosed.

[0003] On the other hand, the use of mixed process speeds and resolution levels for printing on all types of media at once is increasing. However, switching the rotational speed of the scanner motor when printing at different process speeds takes time. Japanese Patent 4389495, for example, discloses a technique for addressing this issue. In Japanese Patent 4389495, when printing at different process speeds, the order of the reservations is alternating to minimize the number of speed changes or by printing at the slowest speed among the reservations, thereby minimizing overall productivity reduction.

[0004] However, there is still a problem that it takes time to switch the rotation speed of the scanner motor with forced emission. The switching operation takes time because during the switching of the rotation speed of the scanner motor with forced emission, it is necessary to suspend driving components related to image formation or separate the developing unit from the photosensitive drum. Summary of the Invention

[0005] Under the above circumstances, an object of the present invention is to shorten the time for switching the rotation speed of the scanner motor accompanying forced emission.

[0006] The above object is achieved in an image forming apparatus related to / associated with the present invention. In summary, a representative component of the present disclosure includes an image forming apparatus including: a scanner provided with a light source, a rotating polygonal mirror for deflecting laser light emitted from the light source, and a first drive motor for driving rotation of the rotating polygonal mirror; a photosensitive member on which an electrostatic latent image is formed by laser light emitted from the scanner; a developing member for developing the electrostatic latent image formed on the photosensitive member with toner to form a toner image; a detector for detecting laser light; and a controller for controlling the scanner and the first drive motor, wherein the controller controls the light source to perform a light emitting operation so that an area including an image forming area of ​​the photosensitive member is irradiated with laser light emitted from the light source, wherein the controller controls the first drive motor to perform a switching operation in which a rotational speed of the rotating polygonal mirror is switched from a first rotational speed to a second rotational speed different from the first rotational speed; and wherein the controller controls the light source to perform the light emitting operation in a state in which the photosensitive member and the developing member are in contact with each other and are rotating, and the controller controls to perform the switching operation based on a detection result of the detector in the light emitting operation.

[0007] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a cross-sectional view of a main portion of a cartridge according to Example 1-5.

[0009] Figure 2 It is a cross-sectional view of a main part of the image forming apparatus.

[0010] Figure 3 is an explanatory diagram of the structure of a scanner unit according to Embodiment 1-5.

[0011] Figure 4 is a timing chart indicating a switching operation according to Embodiment 1.

[0012] Figure 5 is a timing chart indicating a conventional switching operation to be compared with Embodiment 1.

[0013] Figure 6 is a cross-sectional view of a main portion of an image forming apparatus according to Embodiment 2.

[0014] Figure 7 is a timing chart indicating a switching operation according to Embodiment 2.

[0015] Figure 8is a timing chart indicating a conventional switching operation to be compared with Embodiment 2.

[0016] Figure 9 is a cross-sectional view of a main portion of an image forming apparatus according to Embodiment 3.

[0017] Figure 10 is a timing chart indicating a switching operation according to Embodiment 3.

[0018] Figure 11 is a timing chart indicating a conventional switching operation to be compared with Embodiment 3.

[0019] Figure 12 is a timing chart indicating a switching operation according to Embodiment 4.

[0020] Figure 13 is a timing chart indicating a switching operation according to Embodiment 5. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the sizes, materials, shapes, and relative positioning of the components described in this embodiment should be appropriately modified depending on the structure and / or various conditions of the device to which the present invention is applied. The present invention is not limited to the following embodiments.

[0022] In Embodiment 1, a multicolor image forming apparatus with intermediate transfer will be described as an example. The multicolor image forming apparatus with intermediate transfer forms a multicolor image by primarily transferring a toner image on a photosensitive drum onto an intermediate transfer belt (intermediate transfer member) (hereinafter referred to as "primary transfer"), and then transferring the image from the intermediate transfer belt to a recording medium (hereinafter referred to as "secondary transfer").

[0023] <Description of the device>

[0024] First, we will use Figure 1 and 2 The image forming process is described in a cross-sectional view in FIG. 1 . A charging roller 102 is in contact with the surface of a photosensitive drum 101 as a photosensitive member.

[0025] The charging roller 102 charges the photosensitive drum 101 to a uniform potential by applying a charging voltage (charging process). The scanner unit 103 forms an electrostatic latent image on the surface of the photosensitive drum 101 charged with the voltage (latent image process). The developing roller 104, which serves as a developing component (developing member), contacts the photosensitive drum 101. By applying a developing voltage, the developing roller 104 develops the electrostatic latent image on the photosensitive drum 101 with toner and forms a toner image (development process). The developing roller 104 is housed in a developing container 105 containing toner. The developing roller 104 and the photosensitive drum 101 are controlled between a first state in which the two components are in contact with each other and a second state in which the two components are separated from each other by a contact and separation structure 130, which serves as a contact and separation component. Furthermore, the developing roller 104 and the photosensitive drum 101 are rotated by a drive motor 120, which serves as a second drive component. The recording material S is fed by a feed roller (not shown in the figure), which serves as a feeding component located on a feeding path (not shown in the figure). The feed roller (not shown) is also driven by the drive motor 120 .

[0026] The primary transfer roller 106, which serves as a primary transfer component (primary transfer member), is pressed against the photosensitive drum 101 via the intermediate transfer belt 107, which serves as a clamping and feeding member. The primary transfer roller 106 transfers the toner image to the intermediate transfer belt 107 (primary transfer process) by applying a primary transfer voltage in a primary transfer voltage applying component (primary transfer voltage applying portion) (not shown). The toner remaining on the photosensitive drum 101 is moved to a drum cleaning blade 108, which serves as an image carrier cleaning component, by the rotation of the photosensitive drum 101 and is removed from the photosensitive drum 101. The drum cleaning blade 108 is accommodated in a waste toner container 109 together with the cleaned toner. In Example 1, the components including: the photosensitive drum 101, the charging roller 102, the developing roller 104, the developing container 105, the drum cleaning blade 108 and the waste toner container 109 are box 100.

[0027] In the case of the above-described image forming process with several colors (for example, four colors), yellow (y), magenta (m), cyan (c), and black (b) are operated in this order, and then a multi-color image is formed on the intermediate transfer belt 107. Figure 2 In FIG, for example, regarding the photosensitive drum 101, each color is shown as 101y, 101m, 101c, and 101b. Figure 1 In the figures, only the main parts of the box 100 are described, so those color codes (y, m, c and k) at the end of each number are not shown. Also hereinafter, the color codes at the end of the numbers will be omitted except when describing a component of a specific color.

[0028] The multicolor image formed as described above is transferred onto the recording material S conveyed along the feeding direction from the paper supply box (not shown) by the secondary intermediate transfer roller 110 as the secondary transfer component (secondary transfer member) (secondary transfer process). A secondary transfer voltage is applied to the secondary transfer roller 110 from the secondary transfer voltage source 140 as the secondary transfer voltage applying component (secondary transfer voltage applying portion). The secondary transfer voltage source 140 can also apply positive and negative voltages. The fixing unit 112 fixes the unfixed colorant image on the recording material S as a permanent image (fixing process). The colorant remaining on the intermediate transfer belt 107 in the secondary transfer process is removed from the intermediate transfer belt 107 by the belt cleaning blade 111 as the cleaning component of the intermediate transfer member. These operations described above are controlled by the control unit 200.

[0029] <Scanner Unit>

[0030] Next, we will use Figure 3 The scanner unit 103 is described below. The scanner unit 103 includes a laser 301, which is a light source for emitting laser light, a rotating polygonal mirror 302, which deflects the laser light, and a scanner motor 303, which is a first driving component for rotating the rotating polygonal mirror 302. The laser 301, the rotating polygonal mirror 302, and the scanner motor 303 function as a scanning component. The rotating polygonal mirror 302 periodically scans the photosensitive drum 101 (the photosensitive member) by reflecting the laser light emitted from the laser 301 and passing it through a reflecting mirror 304.

[0031] The scanner unit 103 is provided with a BD (beam detector) 305 as a detection component. When the laser is emitted to the position of the BD 305, the BD 305 transmits a main scanning synchronization signal 306. The main scanning synchronization signal 306 is used to detect the rotation period of the rotating polygon mirror 302 and serves as a guide for determining the start position of image formation in the main scanning direction. The main scanning direction refers to the direction of laser scanning. In addition, the direction orthogonal to the main scanning direction is called the sub-scanning direction.

[0032] The scanner unit 103 is provided with an ASIC 300 as a control component for controlling the scanner unit 103. The ASIC 300 communicates with a CPU (not shown) included in the control unit 200 and controls the scanner unit 103 according to the instructions from the CPU. The ASIC receives a main scanning synchronization signal 306 as a result of the BD 305 detecting the laser. When the ASIC 300 receives the main scanning synchronization signal 306, the ASIC 300 outputs a scanner motor drive signal 307 for rotating the scanner motor 303 and a laser drive signal 308 for turning on the laser 301. As described above, the ASIC 300 controls the rotation speed based on the detection result of the BD 305.

[0033] When the CPU receives a start print command sent from an external device such as a personal computer, the rotation speed control operation starts. When the rotation speed control starts, the scanner motor 303 starts to drive in an acceleration mode of the required rotation acceleration. After a period of time since the start of the rotation speed control operation, the ASIC 300 causes the laser 301 to continue to emit and counts the number of rotations of the rotating polygon mirror 302 based on the main scanning synchronization signal 306 output by the BD 305. In other words, the ASIC 300 performs a detection operation (hereinafter referred to as forced emission) of detecting the laser in a state where at least a portion of the laser is exposed in the image forming area on the photosensitive drum 101. It is noted that in the present invention, the image forming area is an area along the long side direction of the device in which an image can be formed by exposing the laser to the photosensitive drum 101. The long side direction is the same direction of the rotation axis of the photosensitive drum 101 and is also the main scanning direction.

[0034] When the number of rotations (rotational speed) of the scanner motor 303 reaches the target number of rotations (target rotational speed), the ASIC 300 switches the operation from the rotational speed control operation to the emission control operation in which the laser 301 is emitted outside the image forming area. The emission control operation outside the image forming area controls emission outside the image forming area on the photosensitive drum 101, only in the vicinity of the BD 305 outside the image forming area. The reason why emission is performed in the image forming area (including the image forming area) by forced emission is because the number of rotations of the scanner motor 303 constantly changes during the transition period to reach the target number of rotations, making it difficult to aim only at the outside of the image forming area for emission. Forced emission is necessary not only for the acceleration time when the rotation control operation is started, but also for the acceleration and deceleration time when the scanner motor 303 switches the target number of rotations.

[0035] The image forming apparatus in Example 1 operates at a second process speed of 200 mm / s when feeding lightweight paper such as plain paper. On the other hand, the image forming apparatus in Example 1 operates at a first process speed of 140 mm / s, which is slower than the second process speed, when feeding heavy paper such as thick paper. The rotational speed of the scanner motor 303 operating at the second process speed is 35433 rpm, which is the second rotational speed. On the other hand, the rotational speed of the scanner motor 303 operating at the first process speed is 24803 rpm, which is the first rotational speed and different from the second rotational speed. It should be noted that the effects of the present invention are not limited to the two rotational speeds of the scanner motor 303. The same effects are provided when at least two rotational speeds of the scanner motor 303 are included. The ASIC 300 and the control unit 200 are capable of communicating with each other. The ASIC 300 performs emission control operations of the laser 301 and rotational speed control operations of the scanner motor 303 through commands from the control unit 200.

[0036] <Operation of Example 1>

[0037] Will use Figure 4 The diagram in describes the switching operation of the processing speed in Example 1.

[0038] An operation of switching the number of rotations of the scanner motor 303 accompanied by forced emission without separation between the photosensitive drum 101 and the developing roller 104 and / or pause of the drive motor 120 during continuous printing from thick paper to plain paper will be described as an example. Figure 4 (i) shows the above-mentioned image forming process such as Y latent image process. Y, M, C, and K indicate the process of each color. Figure 4 (ii) shows the rotation speed (such as 24803 rpm) and the state (such as acceleration, forced emission) of the scanner motor 303 in the scanner unit 103 for each color. Figure 4 (iii) shows a primary transfer voltage (such as +560V), and Figure 4 (iv) shows the secondary transfer voltage (such as +700 V). Figure 4 (v) shows the processing speed (such as 140 mm / s) and the state (such as the switching speed) of the driving motor 120 . Figure 4 (vi) shows the state of the contact / separation structure 130 (such as the state of the development contact). The horizontal axis shows time.

[0039] exist Figure 4 The operation timing of the image forming process for explanation is shown above the time line in the diagram of The first half shows the image forming process on thick paper and the second half shows the image forming process on plain paper.

[0040] As described above, the image forming process operates in the order of charging process, latent process, developing process, primary transfer process, secondary transfer process, and fixing process. Figure 4 The charging process and the developing process are omitted in the diagram.

[0041] Each image forming process will be described. The Y latent image process in the diagram indicates the time period during which laser light is exposed to form an image on the yellow photosensitive drum 101y. The Y primary transfer process in the diagram indicates the time period during which toner is transferred to the intermediate transfer belt 107y on the yellow photosensitive drum 101y. The same is true for magenta, cyan, and black. The secondary transfer process in the diagram indicates the time period during which the multi-color toner image formed on the intermediate transfer belt 107 is transferred to the recording material S. The fixing process in the diagram indicates the time period during which the toner image transferred to the recording material S is fixed. The faster the processing speed, the shorter the time it takes to complete each process, making the image forming process on plain paper shorter than the image forming process on thick paper.

[0042] The operating status of each component is indicated below the timeline in the chart. The scanner unit 103 for each color indicates the time period during which the scanner motor 303 is operating for forced firing and the number of revolutions of the scanner motor 303. The primary transfer voltage and secondary transfer voltage indicate the applied voltage and the applied time period. The drive motor 120 indicates the drive process speed and the switching speed time period. The contact / separation mechanism 130 indicates the state of separation between the developing roller 104 and the photosensitive drum 101.

[0043] <Switching Processing Speed>

[0044] The operation of switching the processing speed begins at timing 401, when the latent image processing for yellow ends. First, at timing 401, when the latent image processing for yellow ends, the rotational speed of the scanner motor 303y is accelerated from 24803 rpm to 35433 rpm, and the switching operation is performed. At timing 402, after time T401 has elapsed since the acceleration began at timing 401, the laser 301 begins forced emission. Time T401 is assumed to be the time from the start of acceleration until the rotational speed of the scanner motor 303 reaches, for example, -10% of the target rotational speed (even under the slowest speed conditions), and is determined experimentally. After timing 402, when forced emission begins, the scanner motor 303 reaches the target rotational speed of 35433 rpm after time T402 has elapsed, and forced emission ends at timing 403. The same operation is then performed in the order of magenta, cyan, and black. At timing 404 when the fixing process for the thick paper is completed, the drive motor 120 starts accelerating to switch the process speed from 140 mm / s to 200 mm / s (switching speed).

[0045] On the other hand, the developing roller 104 and the photosensitive drum 101 are in contact with each other, so that a toner image is formed on the photosensitive drum 101y by forced emission at timing 402, which starts from the forced emission of the scanner motor 103y. During this time, a primary transfer voltage (e.g., +560V) of the same polarity as the voltage applied to form an image on thick paper is applied to the primary transfer roller 106. Thus, the formed toner image is transferred to the intermediate transfer belt 107 and reaches the secondary transfer belt 110 at timing 405, after a time T403 has elapsed since the forced emission started at timing 402. Note that the applied voltage is not limited to the value in Example 1, and any voltage sufficient to transfer the toner image to the intermediate transfer belt 107 is acceptable.

[0046] If the voltage of the same polarity as the voltage for forming the image (for example, +700 V) is kept applied when the toner image reaches the secondary transfer roller, the toner is placed on the secondary transfer roller.

[0047] The toner deposited on the secondary transfer roller will become backside dirt on the plain paper to be printed next. Here, backside dirt means a phenomenon in which the recording material S puts contamination on the backside of the surface on which the toner image is formed.

[0048] To avoid the above situation, from the timing 405 when the yellow toner image reaches the secondary transfer roller 110, a voltage of opposite polarity (e.g., negative polarity) to the voltage (e.g., positive polarity) applied to form the image is applied (e.g., -500V). By applying the opposite voltage, the toner deposition on the secondary transfer roller 110 is prevented. From the timing 406 when the forced emission of black ends to the timing 407 when the time T404 has passed, the toner image keeps moving to reach the secondary transfer roller 110. Therefore, between the timing 405 and the timing 407, it is necessary to keep applying the voltage of opposite polarity. In other words, while the toner image on the intermediate transfer belt 107 (on the intermediate transfer member) passes through the secondary transfer roller 110, it is necessary to keep the voltage of opposite polarity applied to the secondary transfer roller 110. After passing through the secondary transfer roller 110, the toner on the intermediate transfer belt 107 is removed by the belt cleaning blade 111. Note that as a means of avoiding toner deposition on the secondary transfer roller 110, the mechanism described below is possible: a contact / separation structure is additionally provided between the secondary transfer roller 110 and the intermediate transfer belt 107, and the contact / separation structure operates the temporary separation of the secondary transfer roller 110 from the intermediate transfer belt 107.

[0049] The image forming process of ordinary paper starts at the timing 408 when the switching operation of the drive motor 120 is completed. The primary transfer voltage is switched to the voltage applied to the ordinary paper (for example, +800V) at the same timing 408. The image forming process of ordinary paper is the same as the image forming process of thick paper, except that the rotation speed of the scanner motor is 35433rpm, the processing speed is 200mm / s, the primary transfer voltage is +800V and the secondary transfer voltage is +1000V. The time between the timing 404 when the fixing process is completed before switching the rotation speed of the scanner motor 303 and the timing 408 when the latent image process starts after switching the speed is defined as the switching time Tc. In Example 1, the switching time Tc is 0.9 seconds.

[0050] <Effects of Example 1>

[0051] The effects of the embodiment 1 will be described. For comparison, the conventional switching operation of the processing speed is shown. Figure 5 The diagrams in are used for description. Figure 5 (i) to (vi) in the diagram in Figure 4(i) to (vi) in the diagram in correspond to each other. The switching operation of the processing speed starts at the timing 1101 at which the primary transfer processing of black is completed as the starting point. First, the developing separation operation starts at the timing 1101 at which the primary transfer processing of black is completed, and ends at the timing 1102 at which the time T1101 has passed. During this time, the primary transfer voltage and the secondary transfer voltage are operated to pause toward the timing 1103 at which the secondary transfer processing is completed. The driving motor 120 is operated to pause toward the timing 1104 at which the fixing processing is completed. On the other hand, the developing contact operation starts at the timing 1102 at which the developing separation operation ends, and ends at the timing 1105 at which the time T1102 has passed since the timing 1102.

[0052] In preparation for image formation on plain paper, the scanner motor 303 starts driving in advance at timing 1106 so that forced emission is completed (to achieve the target rotation speed) by timing 1105 when the development contact operation is completed. Furthermore, at timing 1108, the drive motor 120 starts driving so that the required speed is reached by timing 1107 when forced emission is started (starting operation).

[0053] The image formation process for plain paper begins at timing 1105, when the developer contact operation is completed. The primary transfer voltage begins to be applied at timing 1109 in advance so that the voltage required for the start of the yellow primary transfer process (e.g., +800 V) is reached. Furthermore, the secondary transfer voltage begins to be applied at timing 1110 in advance so that the rotation speed required for the start of the secondary transfer process (e.g., +1000 V) is reached. Therefore, the switching time Tc for conventional operation from timing 1104 to timing 1105 is 3.2 seconds (>0.9 seconds).

[0054] As described above, by switching the number of rotations of the scanner motor 303 while the developing roller 104 is in contact, the switching time Tc can be shortened from 3.2 seconds to 0.9 seconds. Therefore, when it is necessary to switch the process speed during continuous printing (even on recording materials S of different weights), it is not necessary to pause the driving motor 120 and / or operate the contact / separation development. Therefore, the reduction in productivity is minimized.

[0055] <Edit 1>

[0056] In Example 1, the switching operation in which the target rotation number increases is described. However, the effects of the present invention are not limited to the case where the rotation number increases. For example, the same effects can be obtained in the switching operation in which the target rotation number decreases. The above content is similarly applied to other embodiments as in Example 1.

[0057] <Edit 2>

[0058] In Example 1, the cleaning part of the intermediate transfer member was described using an example in which a cleaning scraper is provided as a structure. However, the shortening of the switching operation time as an effect of the present invention can be obtained in a structure other than a cleaning scraper. For example, a structure in which the toner image is transferred to the photosensitive drum in the primary transfer member after a charging brush in contact with the intermediate transfer belt removes the charge from the toner image, and then the image carrier cleaning part removes the toner can obtain the same effect. The image carrier cleaning part may be the structure of the cleaning scraper in Example 1, or a cleaner-free structure in which a developing roller collects toner. The above content is applied to other embodiments similarly to Example 1.

[0059] <Edit 3>

[0060] In Example 1, an example in which a separating member is provided between the developing roller 104 and the photosensitive drum 101 was described. However, regardless of whether a separating member is provided or not, the effect of the present invention, that is, shortening the switching operation time, can be achieved. This is because the separating member does not operate during the switching operation and does not affect the switching operation, even if a separating member is provided or not. Even if the present invention is applied to an image forming apparatus that does not include a separating member, the effect of shortening the switching operation can be achieved because pausing and restarting are omitted. The above content applies to other embodiments similarly to Example 1.

[0061] As described above, according to Embodiment 1, the duration of the operation of switching the number of rotations of the scanner motor accompanying forced emission can be shortened.

[0062] In Embodiment 2, a tandem type direct transfer multi-color image forming apparatus will be described in which a multi-color image is formed on a recording material S fed by an electrostatic bearing belt by directly transferring a toner image on a photosensitive drum 101 .

[0063] <Description of the device>

[0064] The structure and operation of the box 100 and the scanner unit 103 in the embodiment 2 are the same as those in the embodiment 1. Figure 6A structure and operation different from those of Example 1 are described. In Example 2, the toner image formed on the photosensitive drum 101 is directly transferred to the recording material S, which is one of the clamping and feeding members, to which the feeding belt 507, which is a feeding bearing member, is adhered and carried by the feeding belt 507, which is one of the clamping and feeding members, by a transfer voltage applied to the transfer roller 506, which is a transfer member. What is different from Example 1 is that a secondary transfer roller is not provided in the structure because the toner image is directly transferred to the recording material S in the primary transfer. The direct transfer process operates in order of each color and forms a multi-color image on the recording material S. The recording material S on which the multi-color image is formed is separated from the feeding belt 507 and sent to the fixing container 112. Thus, the multi-color image is fixed on the recording material S as a permanent image. Note that, on the feeding belt 507, a belt cleaning blade 511, which is a first cleaning member, is provided to remove the toner placed on the feeding belt 507 (bearing and feeding member).

[0065] <Operation of Example 2>

[0066] Will use Figure 7 The diagram in describes the switching operation of the processing speed in Example 2.

[0067] An operation of switching the number of rotations of the scanner motor accompanied by forced emission without a separation operation between the photosensitive drum 101 and the developing roller 104 and / or a pause of the drive motor 120 during continuous printing from thick paper to plain paper will be described exemplarily. All operations in Example 2 are the same as those described in Example 1, except that the secondary transfer process is omitted and the primary transfer process is replaced by a transfer process of directly transferring the toner image onto the recording material S.

[0068] The operation of switching the processing speed begins at the timing 601 when the latent image processing of yellow is completed. First, at the timing 601 when the latent image processing of yellow is completed, the rotation speed of the scanner motor 303y is accelerated from 24803rpm to 35433rpm. At the timing 602 when the time T601 has passed since the acceleration started at the timing 601, forced emission begins. At the timing 603 when the time T602 has passed since the timing 602 when forced emission started, the scanner motor 303 reaches the target rotation speed of 35433rpm and forced emission ends. The same operation is then performed in the order of magenta, cyan and black. The drive motor 120 starts to accelerate at the timing 604 when the fixing process for thick paper is completed to switch the processing speed to 200mm / s (switching speed).

[0069] On the other hand, the developing roller 104 and the photosensitive drum 101 are in contact with each other, so that a toner image is formed on the photosensitive drum 101y by forced emission at timing 602 starting from the forced emission of the scanner motor 103y. During this time, a primary transfer voltage (e.g., +630v) of the same polarity as the voltage applied to form an image on thick paper is applied to the primary transfer roller 506. Thus, the formed toner image is transferred to the feeding belt 507. The transferred toner image is removed by the belt cleaning scraper 511. The image forming process of ordinary paper starts at timing 605 when the drive motor 120 completes the switching speed. In Example 2, the switching time Tc is 0.9 seconds. It is noted that the transfer voltage in the transfer process of ordinary paper is +900v.

[0070] <Effects of Example 2>

[0071] The effects of the embodiment 1 will be described. For comparison, the conventional switching operation of the processing speed is shown. Figure 8 All operations are the same as the conventional operations described in Embodiment 1, except that the secondary transfer process is omitted and the primary transfer process is replaced by a transfer process in which the toner image is directly transferred onto the recording material S.

[0072] The process speed switching operation starts at the timing 1201 when the transfer process of black is completed. The development separation operation starts at the timing 1201 when the transfer process of black is completed, and ends at the timing 1202 when the time T1201 has elapsed. The transfer voltage is operated to pause toward the timing 1201 when the transfer process is completed. The drive motor 120 is operated to pause toward the timing 1203 when the fixing process is completed.

[0073] On the other hand, the development contact operation starts at timing 1202 when the development separation operation ends, and ends at timing 1204 when time T1202 has elapsed. In preparation for image formation on plain paper, the scanner motor 303 starts driving (accelerating) in advance at timing 1205 so that forced emission is completed by timing 1204 when the development contact operation is completed. Furthermore, at timing 1207, the drive motor 120 starts driving so that the required speed (200 mm / s) is reached by timing 1206 when forced emission starts (starting operation). Note that the transfer voltage in the transfer process for thick paper is +630 V.

[0074] The image forming process for plain paper begins at timing 1204 when the developer contact operation is completed. The transfer voltage is applied in advance at timing 1208 so that the voltage required for the start of the yellow transfer process (e.g., +900 V) is reached. The switching time Tc of the conventional operation is 3.2 seconds (>0.9 seconds).

[0075] As described above, by switching the number of rotations of the scanner motor 303 while the developing roller 104 is in contact, the switching time Tc can be shortened from 3.2 seconds to 0.9 seconds. Therefore, when it is necessary to switch the process speed during continuous printing (even on recording materials S of different weights), it is not necessary to pause the driving motor 120 and / or operate the contact / separation development. Therefore, the reduction in productivity is minimized.

[0076] <Edit>

[0077] In Example 2, a structure in which the feed belt cleaning member serves as a cleaning blade was described. However, the shortened switching operation, which is an effect of the present invention, can be achieved with a structure other than a cleaning blade. For example, a structure in which toner is removed by applying a cleaning voltage to a collection brush in contact with the feed belt is possible.

[0078] As described above, according to Embodiment 2, the duration of the operation of switching the number of rotations of the scanner motor 303 accompanying forced emission can be shortened more.

[0079] In Embodiment 3, an example will be described in which the present invention is applied to a monochrome image forming apparatus that provides a contact development method in which a toner image formed on the photosensitive drum 101 is directly transferred onto a recording material S to form a monochrome image. As a feature of Embodiment 3, an operation is performed so as not to transfer the toner image on the photosensitive drum 101 to the next processing member.

[0080] <Description of the device>

[0081] The structure and operation of the box 100 and the scanner unit 103 in embodiment 3 are the same as those in embodiments 1 and 2. Figure 9 The structure and operation different from those of Embodiments 1 and 2 are described. In Embodiment 3, the toner image formed on the photosensitive drum 101 is directly transferred to the recording material S, which is one of the clamping and feeding members, by applying a transfer voltage to the transfer roller 706, which is a transfer member (transfer member). The recording material S on which the monochrome image is formed is sent to the fixing container 112. Thus, the monochrome image is fixed as a permanent image. A transfer voltage is applied to the transfer roller 706 from a transfer voltage source 150, which is a voltage applying member. Note that the transfer voltage source 150 is capable of applying both a positive polarity voltage and a negative polarity voltage.

[0082] <Operation of Example 3>

[0083] Will use Figure 10The diagram in FIG. 1 illustrates the process speed switching operation in Embodiment 3. The operation of switching the number of rotations of the scanner motor 303 with forced emission without a separation operation between the photosensitive drum 101 and the developing roller 104 and / or a pause of the drive motor 120 during continuous printing from thick paper to plain paper will be exemplarily described. All operations in Embodiment 3 are the same as those described in Embodiment 2, except that the multi-color transfer process is omitted.

[0084] The operation of switching the processing speed begins at timing 801, when latent image processing is completed. First, at timing 801, when latent image processing is completed, the rotation speed of the scanner motor 303 begins to accelerate from 24803 rpm to 35433 rpm. At timing 802, after time T801 has elapsed since the acceleration began at timing 801, forced firing begins. At timing 803, after time T802 has elapsed since the forced firing began at timing 802, the scanner motor 303 reaches the target rotation speed of 35433 rpm, and forced firing ends. At timing 804, when the fixing process for thick paper is completed, the drive motor 120 begins accelerating to switch the processing speed to 200 mm / s (switching speed).

[0085] Meanwhile, the developing roller 104 and the photosensitive drum 101 are in contact with each other, forming a toner image on the photosensitive drum 101 through forced emission. At timing 805, after time T801 has elapsed since timing 802, when forced emission began, the toner image reaches the transfer roller 706. If a voltage of the same polarity as the voltage used to form the image continues to be applied, toner will be deposited on the transfer roller 706, the next processing element, and will become contaminant on the back surface of the plain paper to be printed. To avoid this, at timing 805, when the toner image reaches the transfer roller 706, a voltage of opposite polarity to the voltage applied to form the image is applied. By applying the opposite voltage, toner deposition on the secondary transfer roller 110 is prevented. The applied voltage is not limited to the value in Example 3; it can be within a value that prevents the toner image from being transferred to the transfer roller 706. From timing 803, when forced emission ends, to timing 806, after time T804 has elapsed, the toner image continues to move until it reaches the transfer roller 706. Therefore, it is necessary to maintain application of voltages of opposite polarity between timing 805 and timing 806. In other words, it is necessary to maintain application of voltages of opposite polarity while the toner image on the photosensitive drum passes through transfer roller 706. The toner image that passes through transfer roller 706 is collected by drum cleaning blade 108, which serves as the second cleaning component. The image formation process for plain paper begins at timing 807, when the switching operation of drive motor 120 is completed. Image formation then proceeds through the latent image processing, transfer process, and fixing process. In Example 3, the switching time Tc is 0.9 seconds.

[0086] <Effects of Example 3>

[0087] The effects of the embodiment 3 will be described. For comparison, the conventional switching operation of the processing speed is shown. Figure 11 The diagram in is used for description. All operations are the same as the conventional operations described in Example 2, except that the multi-color transfer process is omitted. The switching operation of the process speed starts at the timing 1301 when the transfer process is completed as the starting point. The development separation operation starts at the timing 1301 when the transfer process is completed, and ends at the timing 1302 when the time T1301 has passed. The transfer voltage is operated to pause toward the timing 1301 when the transfer process is completed. The drive motor 120 is operated to pause toward the timing 1303 when the fixing process is completed. On the other hand, the development contact operation starts at the timing 1302 when the development separation operation ends, and ends at the timing 1304 when the time T1302 has passed. In order to prepare for image formation on ordinary paper, at timing 1305, the scanner motor 303 starts driving (accelerating) in advance so as to complete the forced emission by the timing 1204 when the development contact operation is completed. Moreover, at timing 1307, the drive motor 120 starts driving so as to reach the required speed (for example, 200 mm / s) by the timing 1306 when the forced emission starts (starting operation).

[0088] The image forming process for plain paper starts at timing 1304 when the development contact operation is completed. The transfer voltage starts to be applied in advance at timing 1308 so as to reach the required voltage (+900V) before the transfer process starts. The switching time Tc of the conventional operation is 3.2 seconds (>0.9 seconds).

[0089] As described above, by switching the number of rotations of the scanner motor 303 while the developing unit is in contact, the switching time Tc can be shortened from 3.2 seconds to 0.9 seconds. Therefore, when it is necessary to switch the process speed during continuous printing (even on recording materials S of different weights), it is not necessary to pause the driving motor 120 and / or operate the contact / separation developing. Therefore, the reduction in productivity is minimized.

[0090] <Edit 1>

[0091] In Embodiment 3, an operation in which a toner image is not transferred from the photosensitive drum 101 to the transfer roller 706 as the next process member accompanied by forced emission is performed in a monochrome image forming apparatus is exemplified. The operation in which a toner image is not transferred to the next process member is performed can be applied to any of the multi-color image forming apparatuses in Embodiments 1 or 2.

[0092] <Edit 2>

[0093] In Example 3, an example in which the image carrier cleaning member is configured as a cleaning blade was described. However, the shortened switching operation, which is an effect of the present invention, can be achieved using a structure other than a cleaning blade. For example, a structure in which the developing roller 104 collects the toner after the toner is removed by the charging roller 102 in contact with the photosensitive drum 101 is possible. The above description applies to other embodiments similarly to Example 3.

[0094] As described above, according to Embodiment 3, the duration of the operation of switching the number of rotations of the scanner motor accompanying forced emission can be shortened more.

[0095] A monochrome image forming apparatus to which the present invention is applied will be described. This monochrome image forming apparatus operates using a contact development method that forms a monochrome image by directly transferring a toner image formed on a photosensitive drum 101 onto a recording material S. Embodiment 4 is characterized in that it is implemented to suppress toner development caused by forced emission.

[0096] <Description of the device>

[0097] All structures and operations in Example 4 are the same as those in Figure 9 The structure and operation described in Example 3 are the same as those in Example 3, except that the charging voltage is operated to remove the static charge from the image bearing member using a weak charging voltage as a means for removing the static charge. The description of the same structure and operation is omitted. Figure 9 As shown in FIG, the charging roller 102 as a charging member (charging member) is applied with a charging voltage from a charging voltage source 160 as a charging voltage applying member (charging voltage applying portion). Furthermore, the developing roller 104 as a developing member is applied with a developing voltage from a developing voltage source 170 as a developing voltage applying member (developing voltage applying portion). Note that the developing voltage source 170 is capable of applying both a positive polarity voltage and a negative polarity voltage.

[0098] <Operation of Example 4>

[0099] Will use Figure 12 The diagram in exemplarily describes the operation of switching the number of rotations of the scanner motor 303 with forced emission without a separation operation between the photosensitive drum 101 and the developing roller 104 and / or a pause of the drive motor 120 during continuous printing from thick paper to plain paper. Figure 12 In the graphs in , the charging process and the developing process omitted in Examples 1 to 3 are added. The charging process is shown in (iii) and the developing process is shown in (iv).

[0100] The operation of switching the processing speed starts at timing 901 when the latent image processing is completed. First, at timing 901 when the latent image processing is completed, the rotation speed of the scanner motor 303 starts to accelerate from 24803 rpm to 35433 rpm. At timing 902 when time T901 has passed since the acceleration started at timing 901, forced emission starts. At timing 903 when time T902 has passed since the timing 902 when forced emission started, the scanner motor 303 reaches the target rotation speed of 35433 rpm and forced emission ends. The drive motor 120 starts to accelerate (switching speed) to 200 mm / s at timing 904 when the fixing process for thick paper is completed. At timing 902 when the scanner motor 303 starts forced emission, the forced emitted laser is exposed on the photosensitive drum.

[0101] At timing 905 when the charging process is completed, the charging voltage is switched to a weak charging voltage (e.g., -500V) below the discharge threshold. Therefore, the surface of the photosensitive drum 101 becomes in a state of removing static charge until it is almost 0V. On the other hand, at timing 906 when the development process is completed, the development voltage is switched to a voltage (+200V) of the opposite polarity to the voltage (-300V) during image formation. Therefore, the toner development from the developing roller 104 to the photosensitive drum 101 is suppressed. Through both the charging process and the development process, it is possible to suppress the toner deposition on the photosensitive drum caused by forced emission. Therefore, without applying a voltage of the opposite polarity to the voltage applied during image formation to the transfer roller 706, the contamination on the back side caused by toner deposition is suppressed. Note that the charging voltage and the development voltage are examples. The weak charging voltage can be within a value that can maintain the electrical removal state, and the development voltage can be within a value that can suppress toner development.

[0102] At timing 907, when the speed of the drive motor 120 is switched, latent image processing for plain paper begins. Towards timing 908, when charging processing for plain paper begins, the charging voltage is switched to the voltage (-1200 V) applied during image formation. Therefore, during the period between the completion of charging for thick paper image formation and the start of charging for plain paper image formation, the charging voltage source 160 applies a voltage to the charging roller 102 that is below the threshold for causing discharge between the charging roller 102 and the photosensitive drum 101.

[0103] Furthermore, towards the start of the development process at timing 909, the development voltage is switched to the voltage applied during image formation. Therefore, between the time the charging operation for thick paper image formation is completed and the time the charging operation for plain paper image formation begins, the development voltage source 170 applies a voltage of opposite polarity to the voltage applied during image formation to the development roller 104. In Example 4, the switching time Tc is 0.9 seconds. Note that the charging voltage during the thick paper charging process is -1000 V.

[0104] <Effects of Example 4>

[0105] The effects of Example 4 will be described. The conventional operation to be compared with Figure 11 The switching operation time Tc is 3.2 seconds. The switching operation time Tc in the fourth embodiment is 0.9 seconds, so that the switching operation time can also be shortened by the operation in the fourth embodiment.

[0106] When Embodiment 4 is applied, by suppressing the development of toner onto the photosensitive drum 101 even in the case of forced emission, the effect of shortening the switching operation as an effect of the present invention can be obtained.

[0107] As described above, by switching the number of rotations of the scanner motor while the developing unit is in contact, the switching time Tc can be shortened from 3.2 seconds to 0.9 seconds. Therefore, when switching the process speed during continuous printing (even on recording materials S of different weights), it is unnecessary to pause the drive motor 120 and / or operate the contact / separation development. Therefore, the reduction in productivity is minimized.

[0108] <Edit 1>

[0109] In Embodiment 4, the operation of suppressing the development of toner due to forced emission in a monochrome image forming apparatus is exemplarily described. However, the operation of suppressing the development of toner due to forced emission in a monochrome image forming apparatus can be similarly applied to the multi-color image forming apparatus shown in Embodiment 1 or 2.

[0110] <Edit 2>

[0111] In Example 4, a structure using a weak charging voltage as a charge removal means for removing static charge from an image carrier was described as an example. However, the operation of suppressing toner development can be similarly applied, and is not limited to the means described in Example 4. For example, a structure provided with charge removal light or a charge removal brush and / or using transfer means for charge removal is possible. The above content applies similarly to Example 4 to other embodiments.

[0112] As described above, according to Embodiment 4, the duration of the operation of switching the number of rotations of the scanner motor accompanying forced emission can be shortened more.

[0113] In Embodiment 5, an example will be described in which the present invention is applied to an image forming apparatus that provides a contact development method in which a toner image formed on a photosensitive drum 101 is directly transferred onto a recording material S to form a monochrome image. As a feature of Embodiment 5, the number of rotations of the scanner motor 303 is controlled not by switching the process speed but by switching the resolution.

[0114] <Description of the device>

[0115] The structure and operation of the cartridge 100 and scanner unit 103 in Example 5 are the same as those in Example 3. The image forming apparatus operates in two modes: a high-quality mode operating at a second resolution of 400 dpi and a normal-quality mode operating at a first resolution of 300 dpi. The scanner motor 303 rotates at 33,070 rpm in the high-quality mode and 24,803 rpm in the normal-resolution mode. Note that both modes operate at a processing speed of 140 mm / sec.

[0116] <Operation of Example 5>

[0117] Will use Figure 12 The diagram in describes the operation of switching resolution in Embodiment 5. An operation of switching the number of rotations of the scanner motor 303 accompanied by forced emission without a separation operation between the photosensitive drum 101 and the developing roller 104 and / or a pause of the drive motor 120 during continuous printing from the normal quality mode to the high quality mode will be exemplarily described.

[0118] In Example 3, the point where the processing speed does not change before and after the switching operation is the same as in Example 3. Figure 10 . In Example 3, after switching the number of revolutions of the scanner motor 303, the latent image processing begins (timing 807) after waiting until the switching process speed is completed. However, the timing 1001 at which the latent image processing begins after switching the number of revolutions of the scanner motor 303 requires waiting until the forced emission ends, even if the process speed does not change. Therefore, the duration Tc between the timing 1002 at which the fixing process ends before switching the number of revolutions of the scanner motor 303 and the timing 1001 at which the latent image processing begins is rate-determined by the switching speed of the scanner motor 303. The switching time Tc in Example 5 is 0.7 seconds.

[0119] <Effects of Example 5>

[0120] The effect of Embodiment 5 is the shortening of the switching time, which is the same as that of the other embodiments. The switching time Tc in the conventional operation to be compared is 3.2 seconds, which is the same as the switching time Tc in the conventional operation described in Embodiment 3. As in the operation of Embodiment 5, even a switching operation in which only the number of rotations of the scanner motor 303 is switched without changing the processing speed can achieve the effect of shortening the switching time, which is an effect of the present invention.

[0121] As described above, by switching the number of revolutions of the scanner motor 303 while the developing roller 104 is in contact, the switching time Tc can be shortened from 3.2 seconds to 0.9 seconds. Therefore, even when the resolution needs to be switched during continuous printing, it is not necessary to pause the motor drive and / or operate the contact / separation development. Consequently, a decrease in productivity is minimized.

[0122] As described above, according to Embodiment 5, the duration of the operation of switching the number of rotations of the scanner motor accompanying forced emission can be shortened more.

[0123] According to the present invention, the duration of the operation of switching the number of rotations of the scanner motor accompanying forced emission can be more shortened.

[0124] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An image forming apparatus, comprising: a scanning section provided with a light source, a rotating polygonal mirror for deflecting laser light emitted from the light source, and a first driving section for driving the rotation of the rotating polygonal mirror; a photosensitive member on which an electrostatic latent image is formed by the laser light emitted from the scanning part; a developing unit for developing the electrostatic latent image formed on the photosensitive member with a toner to form a toner image; A detection component, used for detecting laser; an intermediate transfer member onto which the toner image formed on the photosensitive member by the developing unit is transferred; a primary transfer unit for transferring the toner image to the intermediate transfer member; a secondary transfer unit for transferring the toner image on the intermediate transfer member to a recording material; a secondary transfer voltage applying member for applying a voltage to the secondary transfer member; as well as a control component for controlling the scanning component, the first driving component, and the secondary transfer voltage applying component, wherein the control section controls the light source to perform a light emitting operation so that an area including an image forming area of ​​the photosensitive member is irradiated with laser light emitted from the light source, wherein the control section controls the first driving section to perform a switching operation in which the rotational speed of the rotating polygonal mirror is switched from a first rotational speed to a second rotational speed different from the first rotational speed; wherein the control means controls the light source to perform the light emitting operation in a state where the photosensitive member and the developing means are in contact with each other and are rotating, and the control means controls to perform the switching operation based on a detection result of the detecting means in the light emitting operation, and The control component further controls the secondary transfer voltage applying component to apply a voltage having a polarity opposite to the polarity of the voltage applied by the secondary transfer voltage applying component in the image forming operation to the secondary transfer component during a period in which the colorant image on the intermediate transfer member formed when the light emission operation is performed passes through the secondary transfer component.

2. The image forming apparatus according to claim 1, The photosensitive member and the developing device assume a first state of being in contact with each other and a second state of being separated from each other.

3. The image forming apparatus according to claim 1 , further comprising: a charging member for charging the surface of the photosensitive member; a charging voltage applying component for applying a charging voltage to the charging component; as well as a developing voltage applying member for applying a developing voltage to the developing member, wherein the control means further controls the charging voltage applying means to apply a charging voltage having a value equal to or lower than a threshold value at which discharge occurs between the photosensitive member and the charging voltage applying means during a period from completion of a discharge operation of the charging means when the image forming operation is performed at the first rotational speed to start of the discharge operation after switching to the second rotational speed, to the charging means, and The control component further controls the developing voltage applying component to apply a developing voltage having a polarity opposite to that of the developing voltage applied by the developing voltage applying component in the image forming operation to the developing component during a period from when the discharging operation of the charging component is completed when the image forming operation is performed at the first rotational speed to when the developing operation starts after switching to the second rotational speed.

4. The image forming apparatus according to claim 1 , further comprising: an intermediate transfer member onto which the toner image formed on the photosensitive member by the developing unit is transferred; a primary transfer unit for transferring the toner image to the intermediate transfer member; a primary transfer voltage applying member for applying a voltage to the primary transfer member; and a secondary transfer unit for transferring the toner image on the intermediate transfer member to a recording material, The control component also controls the primary transfer voltage applying component to apply a voltage having a polarity opposite to the polarity of the voltage applied by the primary transfer voltage applying component in the image forming operation to the primary transfer component during a period in which the colorant image on the photosensitive member formed when the light emission operation is performed passes through the primary transfer component.

5. The image forming apparatus according to claim 1 , further comprising: a carrying and feeding member for carrying a recording material of a toner image formed on a photosensitive member by the developing device; a transfer member for transferring the toner image to a recording material; as well as A first cleaning means for cleaning a toner image on the carrying and feeding member formed when the light emitting operation is performed.

6. The image forming apparatus according to claim 1 , further comprising: a transfer unit for transferring the toner image formed on the photosensitive member by the developing unit to a recording material; as well as a transfer voltage applying member for applying a voltage to the transfer member, The control component further controls the transfer voltage applying component to apply a voltage having a polarity opposite to the polarity of the voltage applied by the transfer voltage applying component in the image forming operation to the secondary transfer component during a period in which the colorant image on the photosensitive member formed when the light emission operation is performed passes through the transfer component.

7. The image forming apparatus according to any one of claims 1 to 3, further comprising: a second driving member for driving the photosensitive member and the developing member, When the processing speed is switched from a first processing speed to a second processing speed different from the first processing speed by the second driving component, the control component controls the first driving component to switch the first rotation speed to the second rotation speed. 8 . The image forming apparatus according to claim 1 , wherein when a resolution is switched from a first resolution to a second resolution different from the first resolution, the control section controls the first driving section to switch the first rotation speed to the second rotation speed.

Images