JP2009122518A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To downsize, reduce cost, to provide an effect of suppressing radiated noise and to evade a risk of a line getting stuck which poses a safety problem. <P>SOLUTION: A registration detection sensor, a patch detection sensor or a photosensor are directly implemented on a control substrate and the substrate is arranged so as to directly reading an object for the sensors (paper path). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus employing an electrophotographic system, an electrostatic recording system, or the like, and more particularly to a configuration of an electric substrate.

  In recent years, following the rapid shift of inkjet printers to color printers, electrophotographic image forming apparatuses (copiers and printers) have also shifted from monochrome machines to color machines.

  In a color image forming apparatus, electrophotographic recording methods are roughly classified into 1-drum type and tandem type. The one-drum type includes a plurality of color developing devices around one image carrier, and a toner is attached to these developing devices to form a composite toner image on the image carrier, and the toner image is transferred. In this method, a color image is recorded on a recording medium. On the other hand, the tandem type is a system in which single color toner images are formed on a plurality of image carriers provided side by side, and these single color toner images are sequentially transferred to record a composite color image on a recording medium.

  Comparing the one-drum type and the tandem type image forming apparatus, the one-drum type has one image carrier, so that the image forming unit can be downsized and the cost can be reduced compared to the tandem type. However, since a color image is formed by repeating image formation a plurality of times using one image carrier, it is not suitable for speeding up image formation. In contrast, the tandem type is inferior to the one-drum type in terms of downsizing and cost, but can perform image formation independently for each color (image formation in one pass), and is suitable for high speed. Therefore, in the color image forming apparatus, a tandem type capable of obtaining a monochrome-like speed from the viewpoint of image forming speed has attracted much attention in recent years.

  In the tandem type color image forming apparatus, image forming means for developing the electrostatic latent image formed on the photosensitive drum by the electrophotographic process and transferring the toner image of each color onto the transfer paper or the intermediate transfer belt is provided. A plurality of toner images of each color are multiplex-transferred on the transfer paper while the transfer paper is sequentially conveyed to each image forming unit by the transfer material conveyance belt, or after each toner image of each color is multiplex-transferred on the intermediate transfer belt, There has been proposed an image forming apparatus capable of forming a color image by a method such as batch transfer of a multicolor toner image primarily transferred to an intermediate transfer belt onto a transfer sheet.

  In this type of image forming apparatus, the substrates that control various motors and control high voltage are arranged on the back, side, and bottom of the apparatus, and signal lines from there to the drive parts such as sensors and motors are wired. There are many things that are configured to do.

In order to reduce the wiring as described above, a plurality of detection means and a control means for controlling the printing operation based on the detection signal of the detection means are mounted on the same substrate and arranged on the inner surface of the apparatus. An invention has been proposed (see Patent Document 1).
JP 2002-123048 A

  However, in the case of the conventional configuration (Patent Document 1), there is a problem that a complicated link mechanism is required for the detection means because the substrate is arranged perpendicularly to the paper transport path.

  When the substrate is arranged on the side surface, a patch detection sensor for detecting the density of the toner patch formed on the intermediate transfer belt or the photosensitive drum, and a color shift detection sensor for detecting the position (color shift) of the toner patch are provided. It cannot be arranged on the same substrate, and wiring from the substrate to the sensor is still necessary.

  Accordingly, an object of the present invention is to provide an image forming apparatus that can further reduce the wiring between the sensor and the substrate.

An image carrier on which an electrostatic latent image is formed on the surface;
Exposure means for exposing the image carrier in accordance with an image signal or a control signal;
Image forming means for developing an electrostatic latent image on the image carrier with a plurality of colors of toner to form a toner image on the image carrier;
A light emitting unit for irradiating the toner image with light, and an image information detecting unit having a light receiving unit for obtaining image information by receiving reflected light from the light emitting unit irradiated from the light emitting unit;
An intermediate transfer belt to which an image formed by the image forming unit is transferred; and transfer means for transferring the transferred toner image to a recording medium;
Fixing means for fixing the toner image transferred to the recording medium;
A plurality of detection means for detecting the passage timing of the recording medium or detecting the presence or absence of the recording medium;
Control means for controlling the printing operation based on signals detected by the plurality of detection means;
An image formation comprising: the image information detection unit; a plurality of the detection units; and the control unit mounted on the same substrate and disposed along the recording medium conveyance path. apparatus.

  The image information detecting means is arranged in the vicinity of the secondary transfer roller.

  The control board is a material whose shape can be freely changed.

  As described above, according to the present invention, a sensor that detects the arrival of a sheet, a patch detection sensor that detects the density of a patch pattern formed on an intermediate transfer belt or a photosensitive drum, and a color shift detection that detects color shift. By mounting the sensor on the same substrate and arranging the substrate along the paper conveyance path, wiring from the substrate to the sensor can be reduced. This leads to downsizing of the device, cost reduction, and prevention of contact failure during assembly, and the number of antennas that radiate noise generated on the substrate is reduced, so that radiation noise can be suppressed. can get.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  As an example of the image forming apparatus according to the present invention, an embodiment when applied to a tandem type color image output apparatus in which a plurality of image forming units are arranged in parallel will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional explanatory view showing a configuration of an image forming apparatus according to the present invention, FIG. 2 is a schematic explanatory view showing a state where an image shift detection pattern on a belt member is read by an optical sensor, and FIG. 4 is a diagram showing the arrangement of the control board, FIG. 4 is a diagram showing the arrangement of the sensors on the electric board according to the present invention, FIG. 5 is a block diagram of the control system, FIG. 6 is a diagram showing the detection signal of the photo sensor, FIG. FIG. 8 is a diagram showing a state in which a sheet metal is disposed on the upper part of the substrate, and FIG. 8 is a diagram in which the shape of the substrate is made flexible and disposed along the paper path.

  In FIG. 1, an image forming apparatus 1 is an electrophotographic system and is configured as a so-called tandem type color image output apparatus in which a plurality of image forming units are arranged in parallel.

  A color image forming apparatus 1 shown in FIG. 1 includes an image reading unit 1a and an image output unit 1b. The image reading unit 1a is placed on a platen glass 1c or conveyed by an automatic document feeder (not shown). An original image of the original is optically read, converted into an electrical signal, and sent to the image output unit 1b.

  The image output unit 1b is broadly divided into image forming means 10 having four stations a, b, c, and d having the same configuration as image forming means, feeding cassettes 21a, 21b, and manual feed. The feeding unit 20 that feeds the transfer material P accommodated in the tray 27, and the toner image primarily transferred to the intermediate transfer belt 31 that is a belt member and is an intermediate transfer member at the stations a, b, c, and d. An intermediate transfer unit 30 for secondary transfer to the transfer material P, a fixing unit 40 for fixing the toner image secondarily transferred to the transfer material P, a cleaning unit 50 for cleaning residual toner on the intermediate transfer belt 31, and the like. A control unit 60 for comprehensively controlling the unit is included.

  In the image forming unit 10, photosensitive drums 11a, 11b, 11c, and 11d as image carriers are pivotally supported at the centers and are driven to rotate in the direction of the arrow in FIG. Opposing to the outer peripheral surfaces of the photosensitive drums 11a to 11d, primary chargers 12a, 12b, 12c, and 12d, optical systems 13a, 13b, 13c, and 13d, folding mirrors 16a, 16b, 16c, and 16d, and developing in the rotation direction. Devices 14a, 14b, 14c, 14d are arranged.

  First, a uniform charge amount is applied to the surfaces of the photosensitive drums 11a to 11d by the primary chargers 12a to 12d, and then a light beam such as a laser beam modulated according to the recording image signal by the optical systems 13a to 13d. Is exposed on the photoconductive drums 11a to 11d to form an electrostatic latent image thereon.

  Further, the toner of each color is supplied by developing devices 14a to 14d each containing developer of four colors of yellow, cyan, magenta, and black (hereinafter referred to as “toner”) to develop the electrostatic latent image. Image.

  On the downstream side of the primary transfer areas Ta, Tb, Tc, and Td where the visualized visible image is transferred to the intermediate transfer belt 31 as an intermediate transfer member, the transfer material P is transferred to the transfer material P by the cleaning devices 15a, 15b, 15c, and 15d. Residual toner remaining on the photosensitive drums 11a to 11d without being transferred is scraped off to clean the surfaces of the photosensitive drums 11a to 11d. Image formation with each color toner is sequentially performed by the image forming process described above.

  The feeding unit 20 includes feeding cassettes 21a and 21b and a manual feed tray 27 for storing the transfer material P, and pickup rollers 22a for feeding the transfer material P one by one from the feeding cassettes 21a and 21b or the manual feeding tray 27. , 22b, 26, a feeding roller pair 23 and a feeding guide 24 for conveying the transfer material P fed from the pickup rollers 22a, 22b, 26 to the registration roller pair 25, and image formation of the image forming unit 10 A registration roller pair 25 for feeding the transfer material P to the secondary transfer region Te in accordance with the timing is configured.

  Next, the configuration of the intermediate transfer unit 30 will be described in detail. The intermediate transfer belt 31 serving as a belt member is made of, for example, PET (polyethylene terephthalate), PVdF (polyvinylidene fluoride), and the like. A tension roller 33 that applies an appropriate tension to the intermediate transfer belt 31 by the force, and a driven roller 34 that is opposed to the secondary transfer region Te across the intermediate transfer belt 31 are wound and stretched.

  In the intermediate transfer belt 31, a primary transfer plane A is formed between the driving roller 32 and the tension roller 33.

  The drive roller 32 is coated with rubber (for example, urethane rubber or chloroprene rubber) having a thickness of several millimeters on the surface of the metal roller to prevent slippage with the intermediate transfer belt 31. The drive roller 32 is driven to rotate by a pulse motor (not shown).

  Primary transfer chargers 35a, 35b, 35c, and 35d are disposed on the back surface side of the intermediate transfer belt 31 in the primary transfer regions Ta to Td where the photosensitive drums 11a to 11d and the intermediate transfer belt 31 face each other. Yes.

  A secondary transfer roller 36 is disposed opposite the driven roller 34 with the intermediate transfer belt 31 interposed therebetween, and a secondary transfer region Te is formed by a nip portion with the intermediate transfer belt 31.

  The secondary transfer roller 36 is a belt member, and is pressed with an appropriate pressure against the intermediate transfer belt 31 serving as an intermediate transfer member. A cleaning unit 50 for cleaning the image forming surface on the intermediate transfer belt 31 is provided on the intermediate transfer belt 31 downstream of the secondary transfer region Te in the rotation direction of the intermediate transfer belt 31.

  The cleaning unit 50 includes a cleaning blade 51 that contacts the surface of the intermediate transfer belt 31 and a waste toner box 52 that stores residual toner scraped by the cleaning blade 51.

  The fixing unit 40 includes a fixing roller 41a having a heat source such as a halogen heater inside, and a pressure roller 41b that is pressed against the fixing roller 41a (the pressure roller 41b may also have a heat source). And a conveyance guide 43 for guiding the transfer material P to the nip portion of the roller pair 41a, 41b, a fixing heat insulating cover 46, 47 for confining the heat of the fixing unit 40 inside, and the roller pair 41a, 41b. It further includes an inner discharge roller pair 44 and an outer discharge roller pair 45 for guiding the discharged transfer material P to the outside of the image forming apparatus 1, a discharge tray 48 for loading the transfer material P discharged outside the apparatus, and the like. Configured.

  As shown in detail in FIG. 5, the control unit 60 includes a CPU (Central Processing Unit) 61, a RAM (Random Access Memory) 62, and a ROM (Read Only Memory) 63 for controlling the operation of the mechanism in each unit. And a motor driver unit 64, an image forming unit 65, an I / O unit 66, and the like.

  Next, the image forming operation of the image forming apparatus 1 will be described in detail. When an image forming operation start signal is issued from the CPU 61 shown in FIG. 5, the feeding operation is started from the feeding means selected according to the paper size or the like of the selected transfer material P.

  For example, the case where the sheet is fed from the upper feeding unit shown in FIG. 1 will be described. First, the transfer material P is fed one by one from the feeding cassette 21a by the pickup roller 22a. The transfer material P is guided between the feed guides 24 by the feed roller pair 23 and conveyed to the registration roller pair 25.

  At that time, the registration roller pair 25 is stopped, and the leading edge of the transfer material P abuts against the nip portion of the registration roller pair 25. Thereafter, the registration roller pair 25 starts rotating in accordance with the timing at which the image forming unit 10 starts to form an image.

  The rotation timing of the registration roller pair 25 is set so that the toner image primarily transferred onto the intermediate transfer belt 31 by the image forming unit 10 and the transfer material P exactly coincide with each other in the secondary transfer region Te. ing.

  On the other hand, in the image forming unit 10, when an image forming operation start signal is issued, the toner image formed on the photosensitive drum 11d on the most upstream side in the rotation direction of the intermediate transfer belt 31 by the image forming process described above is high. Primary transfer is performed on the intermediate transfer belt 31 in the primary transfer region Td by the primary transfer charger 35d to which a voltage is applied.

  The primarily transferred toner image is conveyed to the next primary transfer region Tc. In this case, image formation is delayed by a time during which the toner image is conveyed between the image forming units 10, and the next toner image is transferred with the resist aligned on the previous toner image. The same process is repeated thereafter, and eventually, the four color toner images are sequentially primary-transferred onto the intermediate transfer belt 31.

  Thereafter, when the transfer material P enters the secondary transfer region Te and contacts the intermediate transfer belt 31, a high voltage is applied to the secondary transfer roller 36 in accordance with the passing timing of the transfer material P.

  Then, the four color toner images formed on the intermediate transfer belt 31 by the above-described image forming process are transferred onto the surface of the transfer material P. Thereafter, the transfer material P is accurately guided by the conveyance guide 43 to the nip portion between the fixing roller 41a and the pressure roller 41b.

  The toner image is fixed on the surface of the transfer material P by the heat of these roller pairs 41a and 41b and the pressure of the nip. Thereafter, the transfer material P is conveyed by the pair of inner and outer discharge rollers 44 and 45 and discharged outside the apparatus, and is stacked on the discharge tray 48.

  Hereinafter, the arrangement of the electric control board will be described with reference to FIG.

  A photo sensor 70 for detecting whether or not there is a transfer material P in the cassette, photo sensors 71 and 72 for detecting the arrival of the transfer material P, and a patch for detecting the density of a toner patch formed on the intermediate transfer belt 31 Detection sensor 2c, color misregistration detection sensors 2a and 2b for detecting the color misregistration of each color of the toner patch formed on the intermediate transfer belt 31, and the transfer material P between the secondary transfer roller 36 and the fixing rollers 41a and 41b. An electric control board 74 directly mounted with a photo sensor such as a loop detection sensor 73 for detecting the loop amount is arranged along the transfer material P conveyance path as shown in FIG. In this embodiment, there are two sensors that detect the arrival of the transfer material P. However, when the signal of the photo sensor 71 is detected, the CPU 61 starts a jam timer to detect the jam and detect the signal of the photo sensor 72. When this happens, the CPU 61 performs a control to stop the paper feed motor with a timer for stopping the paper feed motor. Here, since the photosensor has a reflection type configuration as shown in FIG. 2, when the transfer material P is conveyed as shown in FIG. In this configuration, the output of the photo sensor changes to determine the presence or absence of the transfer material P. The reflective object 75 needs to have a light reflectance different from that of the transfer material P.

  Also, a photo sensor 70 that detects whether or not the transfer material P is in the cassette, photo sensors 71 and 72 that detect the arrival of the transfer material P, and the transfer material P between the secondary transfer roller 36 and the fixing rollers 41a and 41b. Regarding the loop detection sensor 73 for detecting the loop amount, a light-emitting element and a light-receiving element are incorporated in one unit in parallel, and a transmissive photointerrupter that detects whether or not there is a light shielding plate between these elements. I do not care. In this case, it is necessary to arrange a light shielding plate, but since it can be arranged immediately above or just below the photosensor, a complicated link mechanism is not required.

  On the other hand, a patch detection sensor 2c for detecting the density of the toner patch formed on the intermediate transfer belt 31, and a color shift detection sensor for detecting the color shift of each color of the toner patch formed on the intermediate transfer belt 31. 2a and 2b need to be disposed opposite to the intermediate transfer belt 31, and therefore are disposed in the vicinity of the secondary transfer roller 36.

  Here, the arrangement of sensors and control units on the electric control board 74 will be described with reference to FIG.

  The patch detection sensor 2c for detecting the density of the toner patch formed on the intermediate transfer belt 31 is disposed substantially at the center with respect to the direction orthogonal to the conveyance direction of the transfer material P. The color misregistration detection sensors 2a and 2b for detecting the color misregistration of each color of the toner patch formed on the toner patch are disposed at both ends with respect to the direction orthogonal to the transfer direction of the transfer material P. Further, the CPU 61, the motor driver unit 64, the image control unit 65, and the I / O unit 66 are also arranged and mounted on the same substrate. Detection signals from the sensors are input to the I / O unit 66 and processed by the CPU 61, or commanded from the CPU 61 to the image control unit 65 and the motor driver unit 64 at the timing of the sensor signal. Note that the function of the patch detection sensor 2c can be added to the color misregistration detection sensors 2a and 2b described above.

  Next, a second embodiment will be described with reference to FIG.

  When the electric control board 74 is arranged along the transfer material P conveyance system path, dust such as paper dust and toner may be accumulated on the sensor surface on the electric control board 74. In order to solve such a problem, it is effective to adopt a configuration in which the upper part of the electric control board 74 is covered with a sheet metal as shown in FIG. In order to prevent the influence of dust from the sensor small window 77, it is more effective to close the small window with a shutter when not in use and open the shutter when the sensor is used. .

  Next, a third embodiment will be described with reference to FIG.

  FIG. 8 shows a photosensor 70 for detecting whether or not the transfer material P is in the cassette on the electric control board 74 whose shape can be changed flexibly, photosensors 71 and 72 for detecting the arrival of the transfer material P, and the middle. Patch detection sensor 2c for detecting the density of the toner patch formed on the transfer belt 31, and color shift detection sensors 2a, 2b for detecting the color shift of each color of the toner patch formed on the intermediate transfer belt 31. Photo sensors such as a loop detection sensor 73 for detecting the loop amount of the transfer material P between the secondary transfer roller 36 and the fixing rollers 41a and 41b, and a paper discharge sensor 78 for detecting the transfer material P being discharged are directly mounted. The transfer material P is disposed along the conveyance path.

  Since the shape of the electrical control board 74 can be changed, even if there is no space due to the restrictions of the parts that make up the main body of the image forming apparatus, there is no need to make significant changes to the machine configuration, and the shape of the electrical control board 74 is absorbed can do.

  The electric control board 74 is the same even when a flexible cable is used.

1 is an explanatory cross-sectional view illustrating a configuration of an image forming apparatus according to the present invention. FIG. 6 is a schematic explanatory diagram illustrating a state where a toner patch on a belt member is read by an optical sensor. It is a figure which shows arrangement | positioning of the electric board | substrate which concerns on this invention. It is a figure which shows arrangement | positioning of the sensor on the electric board | substrate which concerns on this invention. It is a block diagram which shows the structure of a control system. It is a figure which shows the detection signal of a sensor. It is a figure which shows the state which has arrange | positioned the sheet metal on the board | substrate upper part. The figure which made the board | substrate flexible and arrange | positioned along the paper path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1a Image reading part 1b Image output part 1c Platen glass 2a, 2b, 2c Photosensor 3 Image shift detection pattern 4a LED
4b Phototransistor 5-8 Resistor 9 Operational amplifier
10 Image forming unit
11a to 11d Photosensitive drum
12a-12d Primary charger
13a-13d optical system
14a-14d Development device
15a-15d Cleaning device
16a to 16d Folding mirror
17 Receiver circuit
18 Variable resistor
19 Comparator
20 Feeding unit
21a, 21b Feed cassette
22a, 22b Pickup roller
23 Feed roller pair
24 Feeding guide
25 Registration roller pair
26 Pickup roller
27 Bypass tray
28 Pattern detection output
29 Pattern width shaping section
30 Intermediate transfer unit
31 Intermediate transfer belt
32 Drive roller
33 Tension roller
34 Followed roller
35a-35d Charger for primary transfer
36 Secondary transfer roller
37 Pattern width, position storage (register)
40 Fusing unit
41a Fixing roller
41b Pressure roller
43 Transport guide
44 Inner discharge roller pair
45 Outer discharge roller pair
46, 47 Fixing insulation cover
48 Output tray
50 Cleaning unit
51 Cleaning blade
52 Waste toner box
60 Control unit
61 CPU (Central Processing Unit)
62 RAM (Random Access Memory)
63 ROM (Read Only Memory)
64 Motor driver
65 Image forming section
66 I / O section
70-73, 78 Photo interrupter
74 Electric control board
75 Reflective object
76 Sheet metal
77 Small windows for sensors a to d Station A Primary transfer plane P Transfer material Ta to Td Primary transfer area Te Secondary transfer area

Claims (3)

An image carrier on which an electrostatic latent image is formed on the surface;
Exposure means for exposing the image carrier in accordance with an image signal or a control signal;
Image forming means for developing an electrostatic latent image on the image carrier with a plurality of colors of toner to form a toner image on the image carrier;
A light emitting unit for irradiating the toner image with light, and an image information detecting unit having a light receiving unit for obtaining image information by receiving reflected light from the light emitting unit irradiated from the light emitting unit;
An intermediate transfer belt to which an image formed in the image forming unit is transferred;
Transfer means for transferring the transferred toner image to a recording medium;
Fixing means for fixing the toner image transferred to the recording medium;
A plurality of detection means for detecting the passage timing of the recording medium or detecting the presence or absence of the recording medium;
Control means for controlling the printing operation based on signals detected by the plurality of detection means;
An image formation comprising: the image information detection unit; a plurality of the detection units; and the control unit mounted on the same substrate and disposed along the recording medium conveyance path. apparatus.   2. The image forming apparatus according to claim 1, wherein the image information detection unit is disposed in the vicinity of a secondary transfer roller.   2. The image forming apparatus according to claim 1, wherein the control board is a material whose shape can be freely changed.

Images