JP2023084620A - Image forming apparatus - Google Patents

Abstract

To adjust transfer voltage at an appropriate timing, while reducing the amount of recording materials used for forming a chart for adjustment of the transfer voltage.SOLUTION: An image forming apparatus 100 has: an image carrier 44b; transfer means 45b; application means 170; a feeding unit 151; an execution unit 101 that performs control of executing a formation operation to form a chart for adjustment of transfer voltage; recording material remaining amount detection means 61 that can detect the remaining amount of recording materials P held by the feeding unit 151; and operation detection means 71 that can detect an operation to the feeding unit 151. When an operation to the feeding unit 151 is detected by the operation detection means 71 and a change in the remaining amount of recording materials P held by the paper feeding unit 151 is detected by the recording material remaining amount detection means 61, the execution unit 101 can perform control to execute the formation operation.SELECTED DRAWING: Figure 4

Description

The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine using an electrophotographic system or an electrostatic recording system, or a multifunction machine having a plurality of these functions.

Conventionally, for example, in an electrophotographic image forming apparatus, an image is formed on a recording material such as paper by transferring a toner image formed on a photosensitive member or an intermediate transfer member as an image bearing member to the recording material. . In such an image forming apparatus, when the amount of water contained in the recording material (sheet, transfer material, paper), which is generally paper (hereinafter also simply referred to as "moisture content"), changes, the formed image is affected. is known to appear. For example, when the moisture content of the recording material increases, the electrical resistance of the recording material decreases. Therefore, when a predetermined transfer voltage is applied, an excess transfer current occurs, and the toner image is transferred from the image carrier to the recording material. A transfer failure may occur in which the transfer is not properly performed. Conversely, when the moisture content of the recording material decreases, the electrical resistance of the recording material increases, so that when a predetermined transfer voltage is applied, the transfer current becomes insufficient, and a transfer failure may occur.

Therefore, conventionally, a chart is formed by transferring adjustment patches to a recording material used for image formation by a user, the patches on the chart are read by a reading unit, and an appropriate transfer voltage is determined to execute an adjustment operation. It has been proposed (Patent Document 1). In the adjustment operation, a chart in which a plurality of patches are formed on one sheet of recording material is output by switching the transfer voltage for each patch. Then, the density of each patch is read by reading means, and the optimum transfer voltage condition is selected according to the result.

Although the recording material is sometimes referred to as "paper," the recording material is not limited to paper, and may be synthetic paper, OHP sheets, or other materials containing synthetic resin as a main component. Also, conveying the recording material to pass through the image forming unit is also referred to as "passage".

JP 2020-86107 A

Here, for example, when paper is fed from an image forming apparatus that is not equipped with a heater for heating a cassette containing a recording material, or from a manual feed tray that is often used for paper that has been left exposed to the outside air. Improper transfer may occur because the material has absorbed moisture. In particular, when a recording material is added to the cassette, the moisture content of the recording material may differ from the moisture content of the recording material when the previous adjustment operation was performed, so there is a high possibility that a transfer failure will occur.

Further, in order to reduce the burden on the operator involved in the inspection work of the printed matter, there is a demand for an inspection apparatus that automatically performs the inspection work in parallel with the printing operation. For example, in order to reduce the burden on the operator, it is conceivable to adjust the transfer voltage using an in-line sensor provided in the image forming apparatus. However, since the transfer voltage needs to be adjusted when the moisture content of the recording material changes, there is a problem that the amount of wasted paper increases unless the adjustment is performed at an appropriate timing.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to adjust the transfer voltage at an appropriate timing while reducing the amount of recording material used to form a chart for adjusting the transfer voltage.

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention comprises an image carrier for carrying a toner image, transfer means for transferring the toner image from the image carrier to a recording material at a transfer portion, and a transfer voltage for the transfer to the transfer means. a feeding unit for holding the recording material supplied to the transfer unit; and a plurality of test voltages are applied to the transfer unit by the application unit to transfer a plurality of test images onto the recording material to form a chart. an execution unit that controls execution of a forming operation, a recording material remaining amount detecting means capable of detecting the remaining amount of recording material held by the feeding unit, and capable of replenishing the recording material to the feeding unit. and an operation detecting means capable of detecting an operation on the feeding section as The image forming apparatus is characterized in that the image forming apparatus can be controlled to execute the forming operation when a change in the remaining amount of the recording material held by the paper feeding unit is detected.

According to another aspect of the present invention, an image carrier carrying a toner image, transfer means for transferring the toner image from the image carrier to a recording material in a transfer section, and a transfer voltage applied to the transfer means for the transfer. a feeding unit for holding the recording material to be supplied to the transfer unit; and a plurality of test voltages are applied to the transfer unit by the application unit to transfer a plurality of test images onto the recording material, and a chart is obtained. and recording material remaining amount detection means capable of detecting the remaining amount of the recording material held by the feeding unit, wherein the execution unit controls the recording material There is provided an image forming apparatus characterized by being controllable so as to execute the forming operation when an increase in the remaining amount of the recording material held by the paper feeding unit is detected by means for detecting the remaining amount of material. be.

According to the present invention, it is possible to adjust the transfer voltage at appropriate timing while reducing the amount of recording material used to form a chart for adjusting the transfer voltage.

1 is a schematic cross-sectional view of an image forming apparatus; FIG. 1 is a schematic external view of an image forming apparatus; FIG. 2 is a schematic block diagram for explaining a control mode of the image forming apparatus; FIG. FIG. 10 is a flow chart of control for determining the execution timing of the adjustment operation of the secondary transfer voltage; FIG. 7 is a schematic diagram of an example of a screen for inputting whether or not to execute the adjustment operation of the secondary transfer voltage. FIG. 10 is a flow chart of an adjustment operation of the secondary transfer voltage; FIG. 4 is a schematic diagram of an example of a chart for adjusting the secondary transfer voltage;

Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[Example 1]
1. 1. Configuration and Operation of Image Forming Apparatus FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 of this embodiment. In this embodiment, the image forming apparatus 100 is a tandem-type full-color printer that employs an intermediate transfer method and is capable of forming a full-color image using an electrophotographic method.

The image forming apparatus 100 includes an apparatus main body 10, a paper feed section 150, an image forming section 140, a discharge section 180, a control section 110, an operation section 120 (FIG. 2), and a document reading section 130 (FIG. 2). and have The image forming apparatus 100 prints an image on the recording material P according to an image signal from the document reading unit 130, or an image signal from a host device such as a personal computer, or an external device 200 (FIG. 3) such as a digital camera or a smartphone. can be formed. The recording material (sheet, transfer material, paper) P is a material on which a toner image is formed. There are sheets, etc. In this embodiment, the recording material P will be described as plain paper.

The image forming unit 140 can form an image on the recording material P fed from the paper feeding unit 150 based on image information created by the image processing unit 105, which will be described later. The image forming section 140 has four image forming units 50y, 50m, 50c, and 50k that form yellow (y), magenta (m), cyan (c), and black (k) images, respectively, as a plurality of image forming units. have Elements having the same or corresponding functions or configurations in these four image forming units 50y, 50m, 50c, and 50k have the suffixes y, m, c, and k indicating that they are elements for one of the colors. may be omitted for a comprehensive explanation. In addition to the image forming unit, the image forming section 140 has an intermediate transfer unit 44, a secondary transfer device 45, a fixing device 46, an in-line image sensor 90, and the like.

The image forming unit 50 has a photosensitive drum 51 that is a drum-shaped (cylindrical) photosensitive member (electrophotographic photosensitive member) as a first image carrier. In addition, the image forming unit 50 has a charging roller 52 which is a roller-type charging member as charging means. Further, the image forming unit 50 has an exposure device 42 as exposure means. Further, the image forming unit 50 has a developing device 20 as developing means. The image forming unit 50 also has a primary transfer roller 47 which is a roller type primary transfer member as a primary transfer means. Further, the image forming unit 50 has a pre-exposure device 54 as a static eliminating means. Further, the image forming unit 50 has a cleaning blade 55 which is a cleaning member as a photoreceptor cleaning means. The image forming unit 50 also has a toner bottle 41 as a replenishment developer container. The image forming unit 50 then forms a toner image on an intermediate transfer belt 44b, which will be described later.

The photosensitive drum 51 is movable (rotatable) while carrying an electrostatic image (electrostatic latent image) or a toner image. When the image forming operation is started, the photosensitive drum 51 is rotationally driven counterclockwise in FIG. 1 at a predetermined process speed (peripheral speed) by a motor (not shown) as driving means.

The surface of the rotating photosensitive drum 51 is uniformly charged to a predetermined potential with a predetermined polarity (negative polarity in this embodiment) by the charging roller 52 . In this embodiment, the charging roller 52 is a rubber roller that contacts the surface of the photosensitive drum 51 and is driven to rotate as the photosensitive drum 51 rotates.

The charged surface of the photosensitive drum 51 is scanned and exposed by the exposure device 42 based on image information, and an electrostatic image is formed on the photosensitive drum 51 . In this embodiment, the exposure device 42 is composed of a laser scanner. The exposure device 42 emits a laser beam in accordance with the separated color image information output from the control unit 110 to scan and expose the surface (outer peripheral surface) of the photosensitive drum 51 .

The electrostatic image formed on the photosensitive drum 51 is developed (visualized) by supplying toner as a developer from the developing device 20 to form a toner image on the photosensitive drum 51 . Toner is supplied from a toner bottle 41 to the developing device 20 . The developing device 20 has a developing sleeve 24 as a developer carrier (developing member). Inside the developing sleeve 24, a magnet roller, which is a roller-shaped magnet, is fixed to the main body (developing container) of the developing device 20 so as not to rotate. The developing sleeve 24 carries developer and conveys it to a developing area facing the photosensitive drum 51 . In this embodiment, the exposure portion (image portion) on the photosensitive drum 51, in which the absolute value of the potential is lowered by being exposed after being uniformly charged, is provided with the same polarity as the charging polarity of the photosensitive drum 51 (this embodiment). Negatively charged toner adheres (reversal development method). In this embodiment, the normal charge polarity of the toner, which is the main charge polarity of the toner during development, is negative.

An intermediate transfer unit 44 is arranged to face the four photosensitive drums 51y, 51m, 51c, and 51k. The intermediate transfer unit 44 has an intermediate transfer belt 44b, which is an intermediate transfer member formed of an endless belt as a second image bearing member. The intermediate transfer belt 44b is stretched over a plurality of tension rollers (support rollers) such as a driving roller 44a, a tension roller 44d, and a secondary transfer inner roller 45a, and is stretched with a predetermined tension. The intermediate transfer belt 44b carries a toner image and is movable (rotatable). The driving roller 44a is rotationally driven by a motor (not shown) as driving means to rotate (rotate) the intermediate transfer belt 44b. The tension roller 44d controls the tension of the intermediate transfer belt 44b to be constant. The tension roller 44d is applied with a force that pushes the intermediate transfer belt 44b toward the outer peripheral surface side by the biasing force of a spring (not shown) as a biasing means. A tension of about 2 to 5 kg is applied. The inner secondary transfer roller 45a constitutes a secondary transfer device 45 as described later. A driving force is transmitted to the intermediate transfer belt 44b by the drive roller 44a, and the intermediate transfer belt 44b is rotationally driven clockwise in FIG. Further, the intermediate transfer unit 44 has a belt cleaning device 30 as intermediate transfer member cleaning means on the outer peripheral surface side of the intermediate transfer belt 44b. Further, the intermediate transfer unit 44 is a primary transfer member which is a roller-type primary transfer member serving as a primary transfer means and arranged corresponding to each of the photosensitive drums 51y, 51m, 51c, and 51k on the inner circumferential surface side of the intermediate transfer belt 44b. It has transfer rollers 47y, 47m, 47c and 47k. In this embodiment, the primary transfer roller 47 and the photosensitive drum 51 sandwich the intermediate transfer belt 44b. As a result, the intermediate transfer belt 44b contacts the photosensitive drum 51 to form a primary transfer portion (primary transfer nip portion) T1 with the photosensitive drum 51. As shown in FIG. The tension rollers other than the drive roller 44a and the primary transfer rollers 47 are rotated following the rotation of the intermediate transfer belt 44b.

The toner image formed on the photosensitive drum 51 is primarily transferred onto the rotating intermediate transfer belt 44b by the action of the primary transfer roller 47 in the primary transfer portion T1. That is, in this embodiment, a primary transfer voltage (primary transfer bias) having a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment) is applied to the primary transfer roller 47 . As a result, the toner image formed with the negative toner on the photosensitive drum 51 is primarily transferred onto the intermediate transfer belt 44b. For example, when forming a full-color image, yellow, magenta, cyan, and black toner images formed on the photosensitive drums 51y, 51m, 51c, and 51k are sequentially superimposed on the intermediate transfer belt 44b. It is multiple transcribed. A primary transfer power supply 160 (FIG. 3) as a primary transfer voltage applying means (primary transfer voltage applying section) is connected to the primary transfer roller 47 . The primary transfer power supply 160 applies a DC voltage having a polarity opposite to the normal charge polarity of the toner (positive polarity in this embodiment) as a primary transfer voltage to the primary transfer roller 47 during the primary transfer process. The primary transfer power source 160 is connected to a voltage detection sensor 160a as a voltage detection section for detecting output voltage and a current detection sensor 160b as a current detection section for detecting output current (FIG. 3). In this embodiment, the primary transfer power sources 160y, 160m, 160c and 160k are provided independently for the primary transfer rollers 47y, 47m, 47c and 47k. Thereby, the primary transfer voltages applied to the primary transfer rollers 47y, 47m, 47c, and 47k can be individually controlled.

A secondary transfer outer roller 45b, which constitutes a secondary transfer device 45 together with a secondary transfer inner roller 45a, is arranged on the outer peripheral surface side of the intermediate transfer belt 44b. The secondary transfer outer roller 45b contacts the intermediate transfer belt 44b to form a secondary transfer portion (secondary transfer nip portion) T2 with the intermediate transfer belt 44b. The toner image formed on the intermediate transfer belt 44b is sandwiched and conveyed between the intermediate transfer belt 44b and the secondary transfer outer roller 45b by the action of the secondary transfer device 45 at the secondary transfer portion T2. Secondarily transferred onto the material P. In this embodiment, a secondary transfer voltage (secondary transfer bias) having a polarity opposite to the normal charge polarity of the toner (positive polarity in this embodiment) is applied to the secondary transfer outer roller 45b, thereby performing intermediate transfer. A toner image formed of negative toner on the belt 44b is secondarily transferred onto the recording material P. As shown in FIG. The recording material P is fed from the paper feeding unit 150 in parallel with the above-described toner image forming operation. Then, the recording material P is conveyed to the secondary transfer portion T2 in timing with the toner image on the intermediate transfer belt 44b by a registration roller 80 provided in the conveyance path of the recording material P.

In this manner, the secondary transfer device 45 has a secondary transfer inner roller 45a as a facing member and a secondary transfer outer roller 45b as a roller type secondary transfer member as a secondary transfer means. Configured. The inner secondary transfer roller 45a is arranged to face the outer secondary transfer roller 45b via the intermediate transfer belt 44b. A secondary transfer power supply 170 (FIG. 3) as a secondary transfer voltage applying means (secondary transfer voltage applying section) is connected to the secondary transfer outer roller 45b. During the secondary transfer process, the secondary transfer power source 170 applies a DC voltage having a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment) as a secondary transfer voltage to the secondary transfer outer roller 45b. do. A voltage detection sensor 170a as a voltage detection section for detecting output voltage and a current detection sensor 170b as a current detection section for detecting output current are connected to the secondary transfer power source 170 (FIG. 3). The core metal of the secondary transfer inner roller 45a is connected to the ground potential. Then, when the recording material P is supplied to the secondary transfer portion T2, a constant voltage-controlled secondary transfer voltage having a polarity opposite to the normal charge polarity of the toner is applied to the secondary transfer outer roller 45b. . In this embodiment, a secondary transfer voltage of, for example, 1 to 7 kV is applied, and a current of 40 to 120 μA is applied to secondarily transfer the toner image on the intermediate transfer belt 44b onto the recording material P. FIG. In this embodiment, the inner secondary transfer roller 45a is connected to the ground potential and the voltage is applied to the outer secondary transfer roller 45b from the secondary transfer power supply 170, but the present invention is limited to such an aspect. not a thing A voltage may be applied from the secondary transfer power source 170 to the secondary transfer inner roller 45a, and the secondary transfer outer roller 45b may be connected to the ground potential. In this case, a DC voltage having the same polarity as the normal charging polarity of the toner is applied to the secondary transfer inner roller 45a.

The recording material P onto which the toner image has been transferred is conveyed to a fixing device 46 as fixing means. The fixing device 46 has a fixing roller 46a and a pressure roller 46b. The fixing roller 46a incorporates a heater as a heating means. The fixing device 46 heats and presses the recording material P bearing an unfixed toner image by sandwiching and conveying the recording material P between a fixing roller 46a and a pressure roller 46b. As a result, the toner image is fixed (melted, fixed) on the recording material P. As shown in FIG. The temperature (fixing temperature) of the fixing roller 46a is detected and controlled by a fixing temperature sensor (not shown).

The recording material P on which the toner image has been fixed is conveyed through an ejection path in an ejection section 180, ejected (output) from an ejection port, and stacked on an ejection tray 181 provided outside the apparatus main body .

On the other hand, the surface of the photosensitive drum 51 after the primary transfer is neutralized by the pre-exposure device 54 . Toner remaining on the photosensitive drum 51 without being transferred to the intermediate transfer belt 44b during the primary transfer process (primary transfer residual toner) is removed from the surface of the photosensitive drum 51 by a cleaning blade 55 and collected in a collection container (not shown). ). The cleaning blade 55 is a plate-like member that abuts against the photosensitive drum 51 with a predetermined pressing force. The cleaning blade 55 is in contact with the surface of the photosensitive drum 51 in the counter direction in which the tip of the free end side faces the upstream side in the rotational direction of the photosensitive drum 51 . Toner remaining on the intermediate transfer belt 44b without being transferred to the recording material P during the secondary transfer process (secondary transfer residual toner) and adherents such as paper dust are removed by the belt cleaning device 30 from the intermediate transfer belt 44b. Removed from the surface and recovered.

Note that the image forming apparatus 100 can also use a desired single or some of the four image forming units 50 to form a monochromatic image such as a monochromatic black image or a multicolor image. is.

In each image forming unit 50, the photosensitive drum 51 and at least one of the charging roller 52 acting thereon, the developing device 20 and the cleaning blade 55 are integrated into a cartridge to form a process cartridge. good. The process cartridge is detachable from the apparatus main body 10 .

Further, in this embodiment, the image forming apparatus 100 has an in-line image sensor as reading means for reading an image on the recording material P, which is located downstream of the fixing device 46 in the conveying direction of the recording material P in the apparatus main body 10 . It has a sensor 90 . In this embodiment, the in-line image sensor 90 reads a chart formed by the adjustment operation of the secondary transfer voltage, which will be described later, and the setting voltage of the secondary transfer voltage is adjusted by the control unit 110 based on the result. . The image sensor 90 is configured to be able to read the image on the recording material P, particularly the image density of the patches on the chart, at 1200 dpi (that is, convert the optically acquired information into an electrical signal). . In this embodiment, the image sensor 90 reads the toner image formed and fixed on the recording material P when the recording material P is discharged from the apparatus main body 10 .

FIG. 2 is a schematic external view of the image forming apparatus 100 of this embodiment. In this embodiment, the image forming apparatus 100 has a paper feeding section 150 arranged below the image forming section 140 . In this embodiment, the paper feeding unit 150 is provided with four cassettes (paper feeding cassettes) 151, 152, 153, and 154 as feeding units capable of holding 500 sheets of the recording material P each. Hereinafter, these four cassettes 151 to 154 are also simply referred to as "cassette 1," "cassette 2," "cassette 3," and "cassette 4." Recording material remaining amount sensors 61, 62, 63, and 64 as recording material remaining amount detecting means for detecting the remaining amount of the recording material P contained in each cassette 1 to 4 are attached to each of the cassettes 1 to 4. . As the recording material remaining amount sensors 61 to 64, for example, available ones can be appropriately selected and used from known ones. For example, a device that mechanically or optically detects the position (height) of the upper surface of the stacked recording material P, a device that detects the weight of the stacked recording material P, and the like. Further, opening/closing sensors 71, 72, 73, and 74 as opening/closing detecting means for detecting opening/closing of the cassettes 1-4 are attached to the respective cassettes 1-4. As the open/close sensors 71 to 74, for example, available ones can be appropriately selected and used from known ones. For example, one that detects at least one of the open state and the closed state by turning on/off a microswitch or by transmitting or blocking detection light can be used. Detecting opening and closing typically means detecting opening and closing, but only one of these may be detected. The paper feed unit 150 further includes a paper feed roller 155 for feeding the recording material P from each of the cassettes 1 to 4, and a transport roller 155 for transporting the recording material P fed from each of the cassettes 1 to 4 to the registration roller 80 by the paper feed roller 155. Rollers 156 and the like are provided.

2. Control Mode FIG. 3 is a schematic block diagram for explaining the control mode of the image forming apparatus 100 of this embodiment. Each component of the control unit 110 is connected to the image bus 107 . The image bus 107 is composed of a general-purpose bus such as a PCI bus, IEEE1394, and PCIEx. System software for controlling the operation of each unit of the image forming apparatus 100 of this embodiment is stored in the ROM 102 or the storage memory 106 and executed by the CPU 101 . The CPU 101 is connected to the operation unit 120, the document reading unit 130, the image forming unit 140, and the paper feeding unit 150 via the input/output IF 104, exchanges signals with these units, and controls the operations of these units. The paper feed section 150 feeds the recording material P to the image forming section 140 during image formation. Further, the paper feed unit 150 is provided with remaining recording material sensors 61 to 64 and open/close sensors 71 to 74 . The control unit 110 can detect the remaining amount of the recording material P in each of the cassettes 1-4 based on the signals from the recording material remaining amount sensors 61-64. Further, the control unit 110 can detect opening/closing of each of the cassettes 1-4 based on the signals from the opening/closing sensors 71-74.

The ROM 102 stores a system boot program, an image formation control sequence for forming an image on the recording material P, and the like. A RAM 103 is a system work memory area for the CPU 101 to execute software, and is also an image memory for temporary storage when processing image data. The image processing unit 105 includes a plurality of ASICs that perform image processing such as resolution conversion, compression/expansion, and binary multi-value conversion on input and output image data. Storage memory 106 is used as an internal storage, and includes an HDD (hard disk), SSD (Solid State Drive), and the like. Storage memory 106 stores data read from document reading unit 130, data read from image sensor 90, image data, information on various operation settings, information on detection results of various sensors, system software, and the like.

A primary transfer power source 160 and a secondary transfer power source 170 are connected to the control unit 110 and controlled by signals from the control unit 110 . A voltage detection sensor 160a and a current detection sensor 160b of the primary transfer power source 160 and a voltage detection sensor 170a and a current detection sensor 170b of the secondary transfer power source 170 are connected to the controller 110 . A signal detected by each sensor is input to the control unit 110 .

The operation unit 120 has operation buttons as input means, and a display unit 120a configured by a liquid crystal panel or the like as display means. In this embodiment, the display unit 120a is configured as a touch panel and also has a function as an input means. An operator such as a user or a service person can execute a print job by operating the operation unit 120 . The control unit 110 receives signals from the operation unit 120 and operates various devices of the image forming apparatus 100 . The image forming apparatus 100 can also execute a print job based on an image forming signal (image data, control command) from an external device 200 such as a personal computer.

The image forming apparatus 100 executes a print job (print operation), which is a series of operations for forming and outputting an image on a single or a plurality of recording materials P, which is started by one start instruction. A print job generally includes an image forming process, a pre-rotation process, an inter-paper process when forming images on a plurality of recording materials P, and a post-rotation process. The image forming process is a period in which electrostatic image formation of an image to be actually formed and output on recording material P, formation of a toner image, primary transfer of the toner image, secondary transfer of the toner image, and fixing of the toner image are performed. , and the time of image formation (image formation period) refers to this period. More specifically, the timing of image formation differs depending on the position where each step of forming an electrostatic image, forming a toner image, primary transfer of the toner image, secondary transfer of the toner image, and fixing of the toner image is performed. . The pre-rotation process is a period from when the start instruction is input to when the image formation is actually started, during which preparatory operations are performed before the image forming process. The paper interval process is a period corresponding to the interval between recording materials P when image formation is continuously performed on a plurality of recording materials P (continuous image formation). The post-rotation process is a period during which an arrangement operation (preparation operation) is performed after the image forming process. The non-image forming period (non-image forming period) is a period other than the image forming period, and includes the pre-rotation process, the inter-paper process, the post-rotation process, and further, when the power of the image forming apparatus 100 is turned on or from the sleep state. It includes a pre-multi-rotation step, etc., which is a preparatory operation at the time of return.

The information about the recording material P includes attributes based on general characteristics such as plain paper, thick paper, and thin paper (so-called paper type category), numerical values and numerical ranges such as basis weight, thickness, and rigidity, or brand ( (including manufacturer, product name, product number, etc.). It can be considered that each type of recording material P is configured for each recording material P that is distinguished by information about the recording material P. FIG.

3. Adjustment Operation FIG. 4 is a flow chart of control for determining the execution timing of the adjustment operation of the secondary transfer voltage in this embodiment. Starting conditions for adjusting the secondary transfer voltage in this embodiment will be described with reference to FIG. 4 is stored in the ROM 102, read out to the RAM 103 and executed by the CPU 101. FIG. Further, the control of the flowchart of FIG. 4 is executed periodically (for example, each time an image is formed on one sheet of recording material P) during execution of a print job, for example.

First, the CPU 101 acquires the remaining amounts N1 to N4 of the recording materials P in the respective cassettes 1 to 4 from the recording material remaining amount sensors 61 to 64, and stores them in the RAM 103 or the storage memory 106 (S101). Next, the CPU 101 acquires signal values indicating the open/close states of the cassettes 1 to 4 from the open/close sensors 71 to 74 (S102).

Next, the CPU 101 determines whether any one of the cassettes 1 to 4 has been opened or closed based on the signal value acquired in S102 (S103). Then, if the CPU 101 does not detect the opening/closing in S103, the process ends. On the other hand, when the CPU 101 detects that the cassette 1 has been opened/closed in S103 (here, it is assumed that the cassette 1 has been opened/closed), the information specifying the opened/closed cassette 1 and the information corresponding to the cassette 1 The registered (stored in the storage memory 106 in advance) information on the type and size of the recording material P is stored in the RAM 103 or the storage memory 106 (S104). Next, the CPU 101 acquires the remaining amount N1' of the recording material P of the cassette 1 whose opening/closing has been detected, and stores it in the RAM 103 or storage memory 106 (S105). Next, the CPU 101 determines whether or not the remaining amount of the recording material P in the cassette 1 whose opening/closing has been detected has changed (S106). The CPU 101 compares N1 (before opening/closing) and N1' (after opening/closing), which are the values of the remaining amount of the recording material P in the cassette 1 stored in the RAM 103 or storage memory 106, and if they are not equal, the recording material It is determined that the remaining amount of P has changed. Note that it may be determined that the remaining amount of the recording material P has changed when the change in the remaining amount exceeds a predetermined value. Typically, a change in the remaining amount of the recording material P means an increase in the remaining amount of the recording material P due to the addition of the recording material P to the cassette 1 . However, even if the remaining amount of the recording material P after the opening and closing of the cassette 1 is less than the remaining amount of the recording material P before opening and closing the cassette 1, the moisture content of the newly replenished (added) recording material P is may be different from the recording material P accommodated before the opening and closing of the . Therefore, in this embodiment, it is determined whether or not the remaining amount of the recording material P has changed (increased or decreased). However, the adjusting operation may be executed when the recording material remaining amount sensor 61 detects an increase in the remaining amount of the recording material P. FIG. In this case, the adjustment operation may be performed based on the detection result of the recording material remaining amount sensor 61 instead of the detection result of the open/close sensor 71 .

When the CPU 101 determines in S106 that the remaining amount of the recording material P has not changed, the process ends. On the other hand, when the CPU 101 determines in S106 that the remaining amount of the recording material P has changed, it inputs to the display section 120a of the operation section 120 whether or not to execute the adjustment operation of the secondary transfer voltage shown in FIG. A screen (here, also referred to as an "execution screen") 500 to be displayed (S107). Next, when the CPU 101 detects that the OK button 501 on the execution screen 500 has been operated by the operator (S108), the CPU 101 executes the adjustment operation of the secondary transfer voltage (S109). When the CPU 101 detects that the cancel button 502 of the execution screen 500 has been operated by the operator (S108), the process ends.

FIG. 6 is a flow chart of the adjustment operation (adjustment process, adjustment mode) of the secondary transfer voltage executed in S109 of FIG. 4 in this embodiment. The adjustment operation of the secondary transfer voltage in this embodiment will be described with reference to FIG. 6 is stored in the ROM 102, read out to the RAM 103 and executed by the CPU 101. FIG.

First, the CPU 101 reads the type and size of the recording material P stored in the RAM 103 or storage memory 106 in S104 of FIG. 4 (S201). Next, the CPU 101 instructs the image forming section 140 to output the image of the secondary transfer voltage adjustment chart created by the image processing section 105 (S202). For example, as shown in FIG. 7, a plurality of patches (test images) are applied to a sheet of recording material P having the read type and size along the conveying direction of the recording material P, and different secondary transfer images are applied. It is formed by secondary transfer at a set voltage. Note that the chart is not limited to being formed on one sheet of recording material P, and depending on the type and size of the recording material P read out above, a plurality of patches may be formed on a plurality of sheets of recording material P. A set of charts may be formed. Next, the CPU 101 instructs the inline image sensor 90 provided in the apparatus main body 10 to read the image of the chart formed on the recording material P (S203). Next, the CPU 101 determines the optimum set voltage for the secondary transfer voltage based on the density information of each patch on the chart read by the image sensor 90 (S204). In S<b>204 , the CPU 101 acquires image density information of each patch obtained by cutting out each patch of the image of the chart read by the image processing unit 105 . Then, the CPU 101 determines the optimum secondary transfer voltage based on the relationship between the set voltage of the secondary transfer voltage corresponding to each patch and the image density of each patch (change in image density due to change in secondary transfer voltage). Determine the voltage setting voltage. In S204, the CPU 101 causes the storage memory 106 to store the final set voltage of the secondary transfer voltage, and ends the process.

Here, the secondary transfer voltage generally includes a transfer partial voltage corresponding to the electrical resistance of the secondary transfer portion T2 detected during a pre-rotation process before image formation, and a preset type of recording material P. can be determined on the basis of the recording material allotted voltage corresponding to . Thereby, the secondary transfer voltage can be set according to the environmental change, the usage history of the transfer member, the type of the recording material P, and the like. However, since there are various types of recording materials P used for image formation, and it is difficult to accurately determine in advance the state of the recording materials P to be replenished in the image forming apparatus 100, a preset default , the transfer voltage may be excessive or insufficient. Therefore, it is effective to perform an adjustment operation for adjusting the set voltage of the secondary transfer voltage according to the recording material P actually used for image formation. In the adjustment operation, a chart in which a plurality of patches are formed on one sheet of recording material P is output by switching the secondary transfer voltage for each patch. At this time, a plurality of patches are transferred to the recording material P by switching between a plurality of settings for the voltage corresponding to the recording material allotted voltage. Then, the density of each patch is detected, and an optimum setting voltage for the secondary transfer voltage is selected according to the detection result. The optimal setting voltage of the secondary transfer voltage can be determined, for example, based on the setting voltage of the secondary transfer voltage when the patch having the lowest brightness (highest density) among the plurality of patches is secondary-transferred. can. However, the process itself for determining the setting of the transfer voltage in the adjustment operation is not limited, and for example, a known process that can be used can be appropriately selected and used.

Note that the paper feed unit 150 may be configured to feed the recording material P held in the manual feed tray. In this case, a recording material remaining amount sensor for detecting the remaining amount of the recording material P held in the manual feed tray and an open/close sensor for detecting opening/closing of the manual feed tray can be provided. Then, the same control as in the above embodiment can be performed. Further, the adjustment operation may be executed when the recording material remaining amount sensor detects an increase in the remaining amount of the recording material P held in the manual feed tray.

In addition, in the adjustment operation, the display unit 120a displays information about the set voltage determined by the control unit 101, and the displayed setting is confirmed according to the result of observation of the output chart by the operator. It may be possible to change it.

Further, by adjusting the transfer voltage using the in-line image sensor 90, the burden on the operator can be reduced. good too.

As described above, in this embodiment, the image forming apparatus 100 includes the image carrier 44b that carries a toner image, the transfer means 45b that transfers the toner image from the image carrier 44b to the recording material P at the transfer portion T2, A plurality of test voltages are applied to the transfer means 45b by the application means 170 for applying a transfer voltage for transfer to the means 45b, the feeding portion 151 for holding the recording material P to be supplied to the transfer portion T2, and the application means 170. An execution unit (in the present embodiment, the CPU 101 has the function of the execution unit) that performs control for executing the forming operation of transferring a plurality of test images onto the recording material P to form a chart, and the feeding unit 151 hold Recording material remaining amount detecting means (recording material remaining amount sensor) 61 capable of detecting the remaining amount of the recording material P, and operation of the feeding unit 151 capable of replenishing the recording material P to the feeding unit 151 can be detected. The execution unit 101 detects an operation to the feeding unit 151 by the operation detecting unit 71, and the recording material remaining amount detecting unit 61 detects the operation of the feeding unit 151. When a change in the remaining amount of the recording material P is detected, control can be performed so as to execute the above-described forming operation. When the image forming apparatus 100 has the recording material remaining amount detection unit 61 , the execution unit 101 detects the remaining amount of the recording material P held by the paper feeding unit 151 using the recording material remaining amount detection unit 61 . It may be controllable to perform the forming operation when an increase is detected. Further, in this embodiment, the image forming apparatus 100 includes reading means (image sensor) 90 for reading the test image of the chart, and an adjustment part (this embodiment In the example, the CPU 101 has the function of the adjustment unit). Further, in this embodiment, the reading means 90 reads the test image when the recording material P on which the chart is formed is ejected from the image forming apparatus 100 . In this embodiment, the image forming apparatus 100 has a display unit 120a for displaying information and an input unit 120 for inputting information. The means 120a displays information prompting an input as to whether or not to execute the forming operation, and when the information instructing execution of the forming operation is input from the input means 120, the forming operation is executed.

As described above, according to this embodiment, when the recording material P is added to the image forming apparatus 100, it is possible to suppress transfer failure on the recording material P whose moisture content may have changed. In addition, since the conditions for adjusting the secondary transfer voltage are determined and the adjustment is automatically performed, it is possible to reduce the burden on the operator without increasing waste paper. That is, when there is a possibility that the moisture content of the recording material P has changed, such as when the recording material P is newly replenished, it is desirable to execute the adjustment operation of the secondary transfer voltage in order to suppress the transfer failure. be However, if you don't make adjustments at the right time, you'll end up with more wasted paper. In this embodiment, it is determined that the moisture content of the recording material P may have changed based on the fact that the recording material P is newly added to the cassettes 1 to 4, and the adjustment operation of the secondary transfer voltage is executed. do. As a result, poor transfer to the recording material P that is newly replenished can be suppressed. In addition, it is possible to reduce the burden on the operator without increasing waste paper.

[others]
Although the present invention has been described with reference to specific examples, the present invention is not limited to the above-described examples.

The image forming apparatus is not limited to a tandem type image forming apparatus, and may be an image forming apparatus of another type. Further, the image forming apparatus is not limited to a color image forming apparatus capable of forming a full-color image, and may be a monochrome image forming apparatus that forms a monochrome (black-and-white or mono-color) image. Further, the image forming apparatus may be image forming apparatuses for various purposes such as printers, various printing machines, copiers, facsimiles, and multi-function machines.

61, 62, 63, 64 remaining recording material sensor 71, 72, 73, 74 open/close sensor 90 image sensor 100 image forming apparatus 110 control unit 120 operation unit 140 image forming unit 151, 152, 153, 154 cassette

Claims (5)

an image carrier that carries a toner image;
transfer means for transferring the toner image from the image carrier to a recording material at a transfer portion;
an applying means for applying a transfer voltage for the transfer to the transfer means;
a feeding unit that holds the recording material to be supplied to the transfer unit;
an execution unit that performs control for executing a forming operation of applying a plurality of test voltages to the transfer unit by the applying unit and transferring a plurality of test images onto a recording material to form a chart;
recording material remaining amount detection means capable of detecting the remaining amount of the recording material held by the feeding unit;
an operation detection means capable of detecting an operation on the feeding unit that enables replenishment of the recording material to the feeding unit;
has
When the operation detection means detects an operation on the feeding section and the recording material remaining amount detection means detects a change in the remaining amount of the recording material held by the paper feeding section, the execution section detects the An image forming apparatus, characterized in that it is controllable to perform a forming operation. an image carrier that carries a toner image;
transfer means for transferring the toner image from the image carrier to a recording material at a transfer portion;
an applying means for applying a transfer voltage for the transfer to the transfer means;
a feeding unit that holds the recording material to be supplied to the transfer unit;
an execution unit that performs control for executing a forming operation of applying a plurality of test voltages to the transfer unit by the applying unit and transferring a plurality of test images onto a recording material to form a chart;
recording material remaining amount detection means capable of detecting the remaining amount of the recording material held by the feeding unit;
has
The execution unit is capable of performing control to execute the forming operation when the recording material remaining amount detecting means detects an increase in the remaining amount of the recording material held by the paper feeding unit. image forming device. reading means for reading said test image of said chart;
an adjustment unit that adjusts the set value of the transfer voltage based on the reading result of the reading unit;
3. The image forming apparatus according to claim 1, comprising: 4. The image forming apparatus according to claim 3, wherein the reading means reads the test image when the recording material on which the chart is formed is discharged from the image forming apparatus. display means for displaying information;
input means for inputting information;
has
When executing the forming operation, the execution unit displays information prompting an input of whether or not to execute the forming operation on the display unit, and receives information instructing execution of the forming operation from the input unit. 5. The image forming apparatus according to any one of claims 1 to 4, wherein the image forming operation is performed when a

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