JPH11272073A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a change in a gap between an image carrier and a developer carrier and hence a degradation in the quality of an image to be formed, in an image forming device which forms a latent image on the image carrier and develops the latent image with developer held on the developer carrier of a developing means. SOLUTION: In the image forming device having the image carrier 105 on which a latent image is formed and the developing means 109 which develops a latent image with developer held on the developer carrier 109A, a gap between the image carrier 105 and the developer carrier 109A is detected by a gap detection means 152, and according to the result of the detection by the gap detection means 152, the moving means of the developing means 109 is controlled by a control means 1004, thereby correcting the gap between the image carrier 105 and developer carrier 109A so as to bring into a specific value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive drum as an image carrier and an image forming apparatus such as a copying machine, a printer, a facsimile, etc., having a developing device for developing a latent image formed on the photosensitive drum. Things.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus in which an electrostatic latent image is formed on a photosensitive drum by electrophotography and the latent image is developed by a developing device using a developer, a photosensitive drum and It is necessary to maintain a predetermined gap between the developing roller and the sleeve roller of the developing device, but correction control of the gap has not been performed.

Under a developing process condition that requires a predetermined gap between the photosensitive drum and a sleeve roller in the developing device, a conventional developing device has a structure in which a predetermined gap is secured on the developing device side facing the drum surface. A predetermined gap was secured by providing a roller on the side and abutting the roller against the drum surface.

[0004]

However, in the above-mentioned conventional example, the gap between the photosensitive drum and the sleeve roller of the developing device is a micron-order gap. There is a possibility that the reproducibility may become unstable.

Further, under a developing process condition requiring a predetermined gap between the photosensitive drum and the sleeve in the developing device, conventionally, a configuration in which a predetermined gap is secured on the developing device side opposite to the drum surface is provided on the developing device side. In a configuration in which a roller is provided and a gap is secured by abutting the drum surface, the photosensitive drum and the sleeve roller in the developing device may be affected by uneven rotation and vibration.

The present invention has been made in view of the above circumstances, and has a light emitting element and a light receiving element. The distance between the photosensitive drum as an image carrier and the sleeve roller as a developer carrier is defined by the distance. It is an object of the present invention to provide an image forming apparatus which has a detecting means for detecting, and manages and corrects a gap between a photosensitive drum and a sleeve roller of a developing device to improve the reproducibility of a stable image. I do.

[0007]

In order to achieve the above-mentioned object, a means of the present invention is to develop a latent image with an image carrier on which a latent image is formed and a developer carried on the developer carrier. In an image forming apparatus having a developing unit, a gap detecting unit that detects a gap between the image carrier and the developer carrier, and the image carrier and the developer carrier according to a detection result by the gap detecting unit. And a correcting means for correcting the gap to a predetermined value.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view showing an embodiment of the image forming apparatus of the present invention.

In FIG. 2, reference numeral 100 denotes an image forming apparatus.
An example of a copying apparatus main body, 200 is a circulating automatic document feeder or feeder (hereinafter referred to as RDF) for automatically feeding a document, and 250 is a sorter or sorter. It can be used freely.

In FIG. 2, reference numeral 101 denotes a document table glass as a document table. Reference numeral 102 denotes an optical system as an image reading unit, and a document illumination lamp (exposure lamp)
103, a scanning mirror, a lens 143, and a motor 10
The original is illuminated by an exposure lamp 103 while being scanned by a motor 104, and reflected light from the original is irradiated on a photosensitive drum 105 as an image carrier by a scanning mirror and a lens.

Around the photosensitive drum 105, a primary charger 106, a blank exposure unit 107, a potential sensor 108, a developing device 109 as a developing means,
A charger 110 as a transfer unit, a charger 111 as a separation unit, and a cleaning device 112 are provided, and an image forming unit is configured by the photosensitive drum 105 and the like.

The photosensitive drum 105 includes a main motor 113
2 rotates in the direction of the arrow shown in FIG. 2 and is corona-charged by the primary charging device 106.
Irradiates the document with reflected light, an electrostatic latent image is formed by electrophotography. This electrostatic latent image is developed
Is developed using a developer, and is visualized as a toner image.

On the other hand, a sheet such as transfer paper sent from the upper cassette 114 or the lower cassette 115 to the main body 100 by the paper feed rollers 118 and 119 via the pickup rollers 116 and 117 is transferred to the front end of the toner image by the registration roller 120. After the timing is set so that the image and the leading edge of the transfer paper coincide with each other, the sheet is fed to the photosensitive drum 105, and the transfer charger 110 transfers the toner image. After the transfer, the transfer paper is separated from the photosensitive drum 106 by a separation charger 111, guided to a fixing unit 122 as a fixing unit by a conveyor belt 121, and fixed by pressure and heat. It is discharged out of 100. The photosensitive drum 105 is cleaned by the cleaning device 112 to remove residual toner on the surface thereof after the transfer.

The main body 100 is provided with a deck 124 capable of storing, for example, 4000 transfer papers.
The lifter 125 of the deck 124 rises according to the amount of the transfer paper so that the transfer paper always contacts the paper feed roller 126. In FIG. 2, reference numeral 127 denotes a discharge flapper, which is a double-side recording side or a multiple recording side and a discharge side (sorter 25).
Switch the route of 0). The transfer paper sent from the discharge roller 123 is switched to the double-sided recording side or the multiple recording side by the discharge flapper 127. Also, 128
A lower conveyance path guides the transfer sheet sent out from the discharge roller 123 to the re-feed tray 130 with the transfer sheet turned over via the reversing path 129.

Reference numeral 131 designates a multiplex flapper for switching the path between double-sided recording and multiplex recording. When the flapper is tilted to the left, the transfer paper is led directly to the lower transport path 128 without passing through the reverse path 129. Reference numeral 132 denotes a paper feed roller for feeding the transfer paper to the photosensitive drum 105 through the path 133.
Reference numeral 134 denotes a discharge roller that is disposed near the discharge flapper 127 and discharges the transfer sheet switched to the discharge side by the discharge flapper 127 to the outside of the apparatus.

At the time of double-sided recording (double-sided copying) or multiple recording (multiplexed copying), the discharge flapper 127 is raised upward, and the copied transfer paper is turned over via the conveyance paths 128 and 129 to re-feed the tray. 130. At this time, the multiplex flapper 131 is tilted to the right during double-sided recording, and the multiplex flapper 131 is tilted to the left during multiplex recording.

At the time of the next backside recording or multiplex recording, the transfer paper stored in the re-feeding tray 130 is changed from the bottom by one.
Each sheet is guided to the registration roller 120 of the main body by the sheet feeding roller 132 via the path 133. When the transfer paper is inverted and discharged from the main body, the discharge flapper 127 is raised upward, the flapper 131 is tilted rightward, and the copied transfer paper is transported to the transport path 129 side. After passing through one feed roller 140, the transfer paper is conveyed to the second feed roller side by the reversing roller 142, and the transfer paper is turned over by the discharge roller 134 and discharged outside the machine.

The transfer paper transport path includes a plurality of transfer paper detection sensors (not shown), and each of the sensors detects that the transfer paper has not reached by a predetermined timing (delay jam detection). ), Paper jam detection (jam detection) such as detection that the transfer paper does not fall out of the sensor by a predetermined timing (retention jam detection) is performed, and if a paper jam is detected, the apparatus is operated after a predetermined operation. The operation is stopped, and a predetermined paper jam display (jam display) is performed.

FIG. 3 shows an example of the arrangement of an operation unit 600 provided in the apparatus main body 100 described above.

In FIG. 3, reference numeral 601 denotes a reset key.
Used to set the copy mode to the standard mode. 602
Is a stop key used to stop copying. 6
A start key 03 is used to start copying. A numeric keypad 604 is used for setting the number of copies and for inputting a numerical value from the numeric keypad. A clear key 605 is used to set the number of copies to 1 and to clear numerical input from the numeric keypad. Reference numeral 606 denotes a password key used when setting a password mode. A preheating key 607 is used when setting / releasing the preheating mode. When the preheating mode is set, the power consumption can be reduced by lowering the temperature of the fixing device. An interrupt key 608 is used for interrupt copying. A user mode key 609 is used when setting / releasing a user mode such as specification setting and timer setting. A guide key 610 is used to display a mode description.

Reference numeral 700 denotes a message display.
0 * 240 dot transmissive LCD (liquid crystal) unit 70
1 and a backlight 702 made of a cold cathode tube. A 15 * 20 key matrix touch panel 703 is arranged on the surface, and various setting mode displays, various status displays, and keys corresponding to key inputs of the touch panel are provided. Display etc. are performed.

FIG. 4 shows an example of the display of the message display 700 and the key arrangement. Reference numeral 710 denotes a display unit for displaying a magnification, a selected paper feed cassette, the number of copies, and the like. 711 is reduced /
The enlargement key is used when reducing / enlarging the fixed magnification. 71
Reference numeral 2 denotes an equal-magnification key, which is used to return the magnification to equal-magnification (100%). A paper selection key 713 is used to select the automatic paper selection, the upper paper lifter 119, the lower paper lifter 115, the paper deck 124, and the multi manual feed 150. A zoom key 714 is used for setting a zoom mode. A slightly smaller key 715 is used when a document image is slightly reduced (93%) and copied. 7
A copy density key 16 is used to manually adjust the copy density. An AE key 717 is used to set / cancel the AE mode (automatic density adjustment). A sorter key 718 is used when a sort mode, a staple sort mode, or a group mode is selected. A double-sided key 719 is used to set / cancel the double-sided mode. An application mode key 720 is used to select an application mode that is not displayed on the basic screen.

FIG. 1 shows a control system 1 of the image forming apparatus of the present invention.
It is a block diagram showing an example.

In the figure, reference numeral 1004 denotes a control circuit (controller) which includes a CPU 1004a, a ROM 1004b,
A copy sequence is controlled based on a program stored in the ROM 1004b.

The thermistor 302 detects the surface temperature of the fixing roller 144, and the A / D converted value at 301 is input to the controller 1004. Controller 1004
Is determined by the detection value of the thermistor 302,
4 is controlled so that the surface temperature becomes a predetermined value.

The A / D 301 has S-
A gap detection sensor 152 between D is connected, an input value from each sensor is A / D converted, and the control circuit 10
04 is input.

The high voltage controller 303 includes a primary charger 106,
The control of the charging system such as the transfer charger 110 and the high-voltage unit 304 for applying a predetermined potential to the developing device 109 and the like are performed.

The motor control unit 305 controls driving of a motor 306 such as various stepping motors and a main drive motor. In addition, the driving of the SD control motor 3061 is also controlled.

The DC load control unit 307 controls driving of a solenoid for the pickup roller 116, a clutch for the registration roller 120, and a fan.

Reference numeral 308 denotes sensors for detecting a paper jam of the transfer paper, which are input to the controller 1004.

The AC driver 1000 includes an AC load 310 such as the document illumination lamp 103 and a fixing heater 311.
Control the AC power supply to the Document illumination lamp 1
03: An abnormality of the fixing heater 311 or the like is detected, and the main switch 1001 with the shut-off function is turned off.

The power supply 1100 supplies DC power to the controller 1004 and the like, and commercial power is input to the power supply 1100 from the input power plug 311 via the main switch 1001 and the door switch 1007.

The paper deck 124 is a paper feeding device for increasing the number of sheets of transfer paper, the feeder 200 is an automatic document feeder for automatically setting a plurality of documents, and the sorter 250 is a transfer device for discharging. This is a sorting device for sorting paper.

The operation unit 600 includes the touch panel 703, the LCD 701, the backlight 702, and the like as described above, and is connected to the control unit 1004.

FIG. 5 is a block diagram showing an SD gap detecting sensor according to the present invention. The toner, which is magnetically attached to a sleeve roller 109A provided in a developing unit 109, is applied to a photosensitive drum 105. A latent image is formed on the drum surface by performing jumping development on the surface.

At the time of this jumping development, the gap or distance (hereinafter SD) between the drum 105 as the image carrier and the sleeve roller as the developer carrier in the developing device is set.
The gap is called 200 μm in the image forming apparatus of the present embodiment. However, a change in the SD gap causes image defects such as image unevenness and image density. Therefore, a distance between the drum surface and the sleeve roller is detected by a sensor 152, which is a gap detecting unit, which will be described later, and is attached to the developing unit. Is moved in the direction indicated by the thick arrow in the drawing to obtain a stable latent image.

In the figure, an SD gap detecting sensor 1 is shown.
Regarding 52, in the present embodiment, the gap between the SD is detected by detecting the distance between the PSD and the surface of the drum using a light reflection type PSD (semiconductor position detecting element).

In the figure, the LE driven by the LED driving circuit 2003 in response to the signal of the control circuit 1004 is shown.
The light beam emitted from D2002 is
Is reflected by the photosensitive drum 105 through the
004 is input to the PSD 2005. PSD2
For the light beam input to the 005, the center of gravity of the spot light is calculated / sampled and held by the PSD drive / signal processing circuit 2006, A / D converted by the A / D 301, and input to the CPU 1004a of the control circuit 1004. Here, when the SD gap is 200 μm, which is the predetermined value of the present embodiment, the light beam from the LED 2002 is input to the PSD 2005 along the path shown by the solid line. In the case of 400 microns when opened, the data is input to the PSD 2005 along the dotted line path, and P
The gap between S and D is detected based on the difference in the position of the center of gravity of the spot light input to SD2005.

FIG. 7 is an explanatory diagram of the relationship between the distance between the drum and the sleeve roller and the output of the gap detection sensor 152 between the SD and the gap between the drum and the sleeve roller. The output O of the sensor 152 is shown.

In this embodiment, the predetermined distance between the drum and the sleeve roller is set in advance in the ROM 1004 of the control circuit 1004.
b, the CPU 1004a compares the detection value of the SD gap detection sensor 152 with the stored predetermined distance, and determines whether the difference between the detection value and the predetermined distance falls within a predetermined range. That is, the motor 3061 which is a moving means of the developing device is controlled so that the output O becomes the predetermined value O1. The motor moves the developing device in the direction of the thick arrow in FIG. 6 so that the gap between SD becomes a predetermined value. Thus, the SD gap can be set to a predetermined value.

As the motor for moving the developing device, a DC motor, an AC motor, a stepping motor or the like can be used. As the gap sensor, a known one other than the light reflection type can be used. Conversely, it can be arranged on the image carrier side, and the adjustment of the gap can be performed by moving the developer carrier without moving the entire developing means.

FIG. 9 is an example of a flowchart of a display process of the controller 1004 of the image forming apparatus according to the present invention.

It is determined whether or not the copy button is pressed. (9-1) When the press of the copy button is detected, it is determined whether or not the gap Lx between the drum and the sleeve roller of the developing device is a predetermined value L. (9-2) If the value is the predetermined value L, copying is started (9-8). If the value is not the predetermined value, the magnitude is compared with the predetermined value. If the value is smaller than the predetermined value (9-4), the SD gap control motor 3
According to 061, the developing device is moved in the Ss (closer to the drum) direction (9-6), and it is determined whether a predetermined gap has been reached (9-3). When the value is larger than the predetermined value, (9-
5) The developing device is moved in the Sl (closer to the drum) direction by the SD gap control motor (9-7), and it is determined whether a predetermined gap has been reached (9-3). If readjustment is necessary, the magnitude is compared with a predetermined value, and steps (9-4), (9-5), and (9-7) are repeated to control the gap to a predetermined value. Then, when a predetermined value is reached, the copy operation is started.

As described above, in this embodiment, the gap between the photosensitive drum and the sleeve roller is detected by the SD gap sensor, and the SD gap control motor 3061 is input by the control circuit 1004 to which the detection result is input. As a result, the developing device can be moved, and the gap between the photosensitive drum and the sleeve roller can be automatically controlled to a predetermined value. Therefore, good development can be always performed, and good image formation can be performed. Further, the gap sensor is a non-contact type, and can detect a gap with high accuracy without damaging the photosensitive drum and without receiving vibration of the photosensitive drum.

[0046]

As described above, according to the present invention,
The moving means of the developer carrier is controlled based on the detection result of the detecting means for detecting the gap between the image carrier and the developer carrier, and the developer carrier is moved by the moving means to set the gap to a predetermined value. Thus, the gap can be automatically managed and corrected, and the image density can be stabilized and the image reproducibility can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a control system of an image forming apparatus according to the present invention.

FIG. 2 is a cross-sectional configuration diagram illustrating an embodiment of the image forming apparatus of the present invention.

FIG. 3 is an arrangement configuration diagram of an operation unit provided in the image forming apparatus main body of FIG. 2;

FIG. 4 is a view showing a display and key arrangement of a message display unit in FIG. 2;

FIG. 5 is a configuration diagram showing a gap between a photosensitive drum and a developing sleeve of a developing device and a gap detection sensor according to the present invention.

FIG. 6 is a flowchart for correcting a gap between a photosensitive drum and a developing sleeve of a developing device according to the present invention.

FIG. 7 is an explanatory diagram showing a relationship between an SD gap and an output of an SD gap sensor.

[Explanation of symbols]

 105 photoconductor drum 109 developing device 109A sleeve roller 305 motor control unit 302 thermistor 152 SD gap sensor 1004 control circuit (controller) 1004a CPU 1004b ROM 1004c RAM 2006 PSD sensor 3061 ... SD gap control motor

Claims (6)

[Claims] 1. An image forming apparatus comprising: an image carrier on which a latent image is formed; and developing means for developing the latent image with a developer carried on the developer carrier. An image, comprising: gap detection means for detecting a gap with a body; and correction means for correcting a gap between the image carrier and the developer carrier to a predetermined value according to a detection result by the gap detection means. Forming equipment. 2. An image forming apparatus according to claim 1, wherein said gap detecting means is a light reflection type detecting means having a light emitting element and a light receiving element. 3. The moving means according to claim 1, wherein said correcting means moves said developer carrier in a direction close to and away from said image carrier, and said moving means moves said gap to a predetermined value. An image forming apparatus comprising a control unit for controlling the image forming apparatus. 4. The method according to claim 3, wherein
An image forming apparatus comprising one of a C motor, an AC motor, and a stepping motor. 5. An image forming apparatus according to claim 1, wherein said gap detecting means is provided on said developing means side. 6. An image forming apparatus according to claim 1, wherein said gap detecting means is provided on said image carrier side.