Optical writing device, image forming device, maintenance support method, and maintenance support program

Abstract

Facilitates maintenance. [Solution] The optical writing device comprises a polygon mirror (212) that deflects a light beam, an optical sensor (403) arranged at a position where the light beam deflected by the polygon mirror (212) is incident, a storage case (300) that houses the polygon mirror (212) in its internal space, and an adjustment member (401) that adjusts the photoelectric conversion gain for light incident on the optical sensor (403), and the adjustment member (401) is arranged outside the storage case (300).

Description

[Technical Field]

[0001] The present invention relates to an optical writing device, an image forming device, a maintenance support method, and a maintenance support program, and in particular to an optical writing device that emits light deflected in one direction, an image forming device equipped with the optical writing device, a maintenance support method executed in the image forming device, and a maintenance support program that causes a computer to execute the maintenance support method. [Background technology]

[0002] An image forming device, typified by an MFP (Multi Function Peripheral), forms an electrostatic latent image on the image carrier by exposing the charged image carrier to light, and then forms a toner image on the image carrier by developing the electrostatic latent image with toner.

[0003] For example, Japanese Patent Application Laid-Open No. 2018-196942 describes an image forming apparatus including a photosensitive drum, a light source of laser light, a rotating polygonal mirror that scans the laser light on the photosensitive drum, a synchronization sensor that receives the scanned laser light at a predetermined position to generate a synchronization signal in the main scanning direction, a drive circuit that drives the light source, and a control circuit that uses the drive circuit to control the light emission amount of the light source based on the synchronization signal, wherein the control circuit, in an exposure amount adjustment process, identifies the pulse width of the synchronization signal, uses the drive circuit to cause the light source to emit the laser light at an emission amount corresponding to the pulse width, and adjusts the exposure amount of the photosensitive drum by the laser light to a predetermined value.

[0004] Because rotating polygon mirrors rotate, dirt on the rotating polygon mirror often accumulates on a single part of the mirror's reflective surface. It is thought that dust particles are caught in the airflow generated by the rotation of the rotating polygon mirror and adhere to that part of the reflective surface. The light reflectance decreases in areas of the reflective surface where dust has adhered. This creates a problem in that if the light received by the optical sensor is reflected from an area of ​​the reflective surface where dust has adhered, the optical sensor may not be able to detect that light.

[0005] The accuracy of the position at which the exposure unit irradiates the image carrier with light affects the quality of the image formed by the image forming device. The optical path from when light is irradiated inside the exposure unit until it is irradiated onto the image carrier must be kept constant. For this reason, cleaning the reflective surface of the rotating polygon mirror is one option, but disassembling the exposure unit requires advanced skills. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-196942 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide an optical writing device that is easy to maintain.

[0008] Another object of the present invention is to provide an image forming apparatus that is easy to maintain.

[0009] A further object of the present invention is to provide a maintenance support method that facilitates maintenance.

[0010] A further object of the present invention is to provide a maintenance support program that facilitates maintenance. [Means for solving the problem]

[0011] According to one aspect of the present invention, an optical writing device includes a polygon mirror that deflects a light beam, an optical sensor arranged at a position where the light beam deflected by the polygon mirror is incident, a storage case that houses the polygon mirror in its internal space, and an adjustment member that adjusts the photoelectric conversion gain of light incident on the optical sensor, the adjustment member being arranged outside the storage case.

[0012] According to another aspect of the present invention, an image forming apparatus includes the optical writing device described above.

[0013] According to yet another aspect of the present invention, a maintenance support method is a maintenance support method executed by the above-mentioned optical writing device, and includes a resistance value determination step of determining a resistance value of the adjustment member, and a display control step of displaying the resistance value determined in the resistance value determination step.

[0014] According to yet another aspect of the present invention, the maintenance support program is a maintenance support program executed by a computer that controls the above-mentioned optical writing device, and causes the computer to execute a resistance value determination step that determines the resistance value of the adjustment member, and a display control step that displays the resistance value determined in the resistance value determination step. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view showing the appearance of an MFP according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the internal configuration of the MFP. [Figure 3] FIG. 2 is a diagram illustrating an example of the internal configuration of an exposure unit. [Figure 4] FIG. 2 is a plan view showing the inside of the exposure unit. [Figure 5] FIG. 2 is a perspective view of an exposure unit. [Figure 6] FIG. 2 is a plan view of the exposure unit. [Figure 7] FIG. 10 is a diagram showing an example of the tendency of contamination of a polygon mirror. [Figure 8] FIG. 2 is a circuit diagram showing an example of a circuit formed on a base substrate. [Figure 9] FIG. 1 is a first diagram showing an example of an analog output and a digital signal of a base substrate. [Figure 10] FIG. 2 is a second diagram showing an example of an analog output and a digital signal of the base substrate. [Figure 11]FIG. 10 is a third diagram showing an example of an analog output and a digital signal of the base substrate. [Figure 12] FIG. 10 is a diagram illustrating an example of a correspondence table. [Figure 13] 1 is a block diagram showing an outline of the hardware configuration of an MFP according to the present embodiment. [Figure 14] 2 is a block diagram showing an example of functions of a CPU 111 included in the MFP according to the present embodiment. FIG. [Figure 15] 10 is a flowchart illustrating an example of the flow of a maintenance support process. [Figure 16] FIG. 10 is a diagram showing an example of a correspondence table in a first modified example. [Figure 17] FIG. 10 is a diagram showing an example of a correspondence table in a second modified example. [Figure 18] FIG. 13 is a diagram showing an example of a correspondence table in a third modified example. [Figure 19] FIG. 13 is a diagram showing an example of a correspondence table in a fourth modified example. [Figure 20] FIG. 13 is a diagram showing an example of a correspondence table in a fifth modified example. [Figure 21] FIG. 13 is a diagram showing an example of a correspondence table in a sixth modified example. [Figure 22] FIG. 13 is a diagram showing an example of a correspondence table in a seventh modified example. [Figure 23] FIG. 13 is a diagram showing an example of functions of a CPU 111 included in an MFP 100 according to an eighth modified example. [Figure 24] FIG. 13 is a diagram showing an example of a correspondence table in an eighth modified example. [Figure 25] 13 is a flowchart showing an example of the flow of a maintenance support process in an eighth modified example. [Figure 26] FIG. 13 is a diagram showing an example of a correspondence table in a ninth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are designated by the same reference numerals. The names and functions of these components are also the same. Therefore, detailed description thereof will not be repeated.

[0017] Fig. 1 is a perspective view showing the appearance of an MFP in one embodiment of the present invention. Some of the drawings from Fig. 1 onwards are marked with arrows indicating the mutually orthogonal X, Y, and Z directions. The X and Y directions are orthogonal to each other in a horizontal plane, and the Z direction corresponds to the vertical direction. In the following description, the direction in which the arrow points in the X direction will be referred to as the right, and the opposite direction will be referred to as the left. In addition, in the Y direction, the direction in which the arrow points will be referred to as the forward direction, and the opposite direction will be referred to as the backward direction.

[0018] 1, an example of an image forming apparatus is an MFP (Multi Function Peripheral) 100. The MFP 100 includes an automatic document feeder 120, a document reading unit 130, an image forming unit 140, a paper feed unit 150, and an operation panel 160 as a user interface.

[0019] Automatic document feeder 120 automatically transports multiple documents set on a document tray one by one to a document reading position of document reading unit 130, and ejects the documents onto a document output tray after the images formed on the documents have been read by document reading unit 130. Document reading unit 130 optically reads the images formed on the documents and performs photoelectric conversion. Document reading unit 130 outputs image data obtained by photoelectric conversion to image forming unit 140.

[0020] Paper feed unit 150 supplies paper to image forming unit 140. Image forming unit 140 forms an image on paper transported by paper feed unit 150 using a well-known electrophotographic method based on image data. Image forming unit 140 forms an image of the image data on paper transported by paper feed unit 150. The paper on which the image has been formed by image forming unit 140 is discharged to paper discharge tray 39.

[0021] Operation panel 160 is a user interface and is provided on the top of MFP 100. Operation panel 160 includes a display unit and an operation unit.

[0022] Fig. 2 is a schematic cross-sectional view showing the internal configuration of the MFP. Referring to Fig. 2, document reading unit 130 exposes an image of a document set on document glass 11 by automatic document feeder 120 using exposure lamp 13 attached to slider 12 that moves below the document. Light reflected from the document is guided to lens 16 by mirror 14 and two reflecting mirrors 15 and 15A, and forms an image on CCD (Charge Coupled Devices) sensor 18.

[0023] The reflected light that forms an image on the CCD sensor 18 is converted into image data as an electrical signal within the CCD sensor 18. The image data is converted into printing data for yellow (Y), magenta (M), cyan (C), and black (K) and output to the image forming unit 140.

[0024] The exposure unit 21 generates light beams corresponding to yellow, magenta, cyan, and black, respectively, in accordance with print data (electrical signals) received from the document reading unit 130.

[0025] The image forming section 140 has developing units 20Y, 20M, 20C, and 20K and corresponding removable toner bottles 41Y, 41M, 41C, and 41K. The toner bottles 41Y, 41M, 41C, and 41K contain yellow, magenta, cyan, and black toner, respectively. Here, "Y," "M," "C," and "K" represent yellow, magenta, cyan, and black, respectively. The toner in the toner bottles 41Y, 41M, 41C, and 41K is supplied to the developing units 20Y, 20M, 20C, and 20K, respectively.

[0026] An image is formed by driving at least one of the developing units 20Y, 20M, 20C, and 20K. A full-color image is formed when all of the developing units 20Y, 20M, 20C, and 20K are driven. Printing data for yellow, magenta, cyan, and black are input to the developing units 20Y, 20M, 20C, and 20K, respectively. The developing units 20Y, 20M, 20C, and 20K differ only in the color of the toner they handle, so here we will explain the developing unit 20Y for forming a yellow image.

[0027] The developing unit 20Y includes a photosensitive drum (image carrier) 23Y, a charging roller 22Y, a developing device 24Y, and a primary transfer roller 25Y.

[0028] The exposure unit 21 emits a light beam corresponding to the photosensitive drum 23Y and scans the surface of the photosensitive drum 23Y in the main scanning direction. The exposure unit 21 irradiates the light beam based on the yellow printing data so that the light beam scans the photosensitive drum 23Y in the main scanning direction. This exposes the photosensitive drum 23Y.

[0029] After being charged by charging roller 22Y, photoconductor drum 23Y is irradiated with a light beam emitted by exposure unit 21. As a result, an electrostatic latent image is formed on photoconductor drum 23Y. Subsequently, developer 24Y applies toner onto the electrostatic latent image, forming a toner image on photoconductor drum 23Y. The toner image formed on photoconductor drum 23Y is transferred onto intermediate transfer belt 30 by primary transfer roller 25Y.

[0030] Meanwhile, the intermediate transfer belt 30 is suspended tightly by a drive roller 33 and a driven roller 34. When the drive roller 33 rotates counterclockwise, the intermediate transfer belt 30 rotates counterclockwise at a predetermined speed. As the intermediate transfer belt 30 rotates, the driven roller 34 rotates counterclockwise.

[0031] As a result, the developing units 20Y, 20M, 20C, and 20K sequentially transfer the toner images onto the intermediate transfer belt 30. The timing at which each of the developing units 20Y, 20M, 20C, and 20K transfers a toner image onto the intermediate transfer belt 30 is adjusted by detecting the reference marks on the intermediate transfer belt 30. As a result, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 30.

[0032] Paper sheets of different sizes are set in paper feed cassettes 35, 35A, and 35B, respectively. The paper sheets stored in paper feed cassettes 35, 35A, and 35B are supplied to conveyance path 40 by take-out rollers 36, 36A, and 36B attached to paper feed cassettes 35, 35A, and 35B, respectively, and are sent to registration roller pair 31 by conveyance roller 37.

[0033] The pair of registration rollers 31 transports the paper transported by the transport roller 37 to a nip portion between the intermediate transfer belt 30 and the secondary transfer roller 26, which is a transfer member.

[0034] The secondary transfer roller 26 generates an electric field at the nip. The toner image formed on the intermediate transfer belt 30 is transferred to the paper being transported by the pair of registration rollers 31 due to the action of the electric field force at this nip. The paper with the transferred toner image is transported to the fixing roller 32, where it is heated and pressed. This melts the toner and fixes it to the paper. The paper is then ejected onto the paper ejection tray 39.

[0035] A belt cleaning blade 28 is provided upstream of the developing unit 20Y on the intermediate transfer belt 30. The belt cleaning blade 28 removes toner remaining on the intermediate transfer belt 30 that has not been transferred to paper.

[0036] Here, an example will be described in which the MFP 100 employs a tandem system equipped with developing units 20Y, 20M, 20C, and 20K that form four color toners on paper. The MFP 100 may also form images using a four-cycle system in which four color toners are transferred sequentially onto paper using a single photosensitive drum.

[0037] FIG. 3 is a diagram showing an example of the internal configuration of an exposure unit. In FIG. 3, exposure unit 21 is shown together with development units 20Y, 20M, 20C, and 20K to illustrate the positional relationship between exposure unit 21 and photoconductor drums 23Y, 23M, 23C, and 23K. Referring to FIG. 3, exposure unit 21 includes a light source unit 210, a polygon unit 211, and a first scanning lens 213. Exposure unit 21 also includes second scanning lenses 217Y, 217M, 217C, and 217K, first mirrors 215Y, 215M, 215C, and 215K, second mirrors 216Y, 216M, 216C, and 216K, and light-transmitting portions 219Y, 219M, 219C, and 219K. Light-transmitting portions 219Y, 219M, 219C, and 219K are provided on the upper surface of a housing 300 of exposure unit 21.

[0038] FIG. 4 is a plan view showing the interior of the exposure unit. Optical components downstream of the first mirrors 215Y, 215M, 215C, and 215K are omitted from FIG. 3 and FIG. 4. Referring to FIGS. 3 and 4, the light source unit 210 emits four light beams corresponding to the photosensitive drums 23Y, 23M, 23C, and 23K, respectively. The light source unit 210 includes a light source, a collimator lens, and a mirror, one for each of the photosensitive drums 23Y, 23M, 23C, and 23K. The light source is, for example, a semiconductor laser equipped with a photodiode. The light beam emitted from the light source is collimated by the collimator lens, reflected by the mirror, and directed to the outside of the light source unit 210. The four mirrors are staggered so as not to block the light beams reflected by the other mirrors. The light beam emitted from the light source unit 210 is reflected by the mirror and directed to the polygon unit 211.

[0039] The polygon unit 211 includes a polygon mirror 212, a polygon motor 212M, and a housing 211A. The housing 211A has a sealed space. The housing 211A accommodates the polygon mirror 212 and the polygon motor 212M in the sealed space. The housing 211A is provided with transmission windows 211B and 211C that transmit the light beam emitted from the light source unit 210.

[0040] The light beam emitted from the light source unit 210 passes through a transmission window 211B and is irradiated onto the polygon mirror 212. The polygon mirror 212 is rotated in one direction by a polygon motor 212M to deflect the light beam in the main scanning direction.

[0041] More specifically, the yellow light beam emitted from light source unit 210 is deflected in the main scanning direction by being reflected by rotating polygon mirror 212 and passes through first scanning lens 213. First scanning lens 213 corrects the traveling direction of the incident light beam so that the light beam is main-scanned at a constant speed on photosensitive drum 23Y. The light beam that passes through first scanning lens 213 has its optical path changed by first mirror 215Y and is guided to second scanning lens 217Y. The light beam that passes through second scanning lens 217Y has its optical path changed by second mirror 216Y and passes through light-transmitting portion 219Y to reach the outer peripheral surface of photosensitive drum 23Y.

[0042] The magenta light beam emitted from light source unit 210 is deflected in the main scanning direction by being reflected by rotating polygon mirror 212 and passes through first scanning lens 213. First scanning lens 213 corrects the traveling direction of the incident light beam so that it is main-scanned at a constant speed on photosensitive drum 23M. The light beam that passes through first scanning lens 213 has its optical path changed by first mirror 215M and is guided to second scanning lens 217M. The light beam that passes through second scanning lens 217M has its optical path changed by second mirror 216M and passes through light-transmitting portion 219M to reach the outer peripheral surface of photosensitive drum 23Y.

[0043] The cyan light beam emitted from light source unit 210 is deflected in the main scanning direction by being reflected by rotating polygon mirror 212 and passes through first scanning lens 213. First scanning lens 213 corrects the traveling direction of the incident light beam so that it is main-scanned at a constant speed on photoconductor drum 23C. The light beam that passes through first scanning lens 213 has its optical path changed by first mirror 215C and is guided to second scanning lens 217C. The light beam that passes through second scanning lens 217C has its optical path changed by two second mirrors 216C and passes through light-transmitting portion 219C to reach the outer peripheral surface of photoconductor drum 23Y.

[0044] The black light beam emitted from light source unit 210 is deflected in the main scanning direction by being reflected by rotating polygon mirror 212 and passes through first scanning lens 213. First scanning lens 213 corrects the traveling direction of the incident light beam so that it is main-scanned at a constant speed on photosensitive drum 23K. The light beam that passes through first scanning lens 213 is guided to second scanning lens 217K. The optical path of the light beam that passes through second scanning lens 217K is changed by first mirror 215K, and passes through light-transmitting portion 219K to reach the outer peripheral surface of photosensitive drum 23Y.

[0045] Exposure unit 21 and development units 20Y, 20M, 20C, and 20K are fixed to the frame of MFP 100. The relative positions of exposure unit 21 and development units 20Y, 20M, 20C, and 20K are determined by the relative positions of exposure unit 21 and the frame and the relative positions of development units 20Y, 20M, 20C, and 20K and the frame.

[0046] FIG. 5 is a perspective view of the exposure unit. FIG. 6 is a plan view of the exposure unit. Referring to FIGS. 5 and 6, a housing 300 of the exposure unit 21 includes a base 301 with an open top and a lid 303 that covers the top of the base 301. The base 301 includes a bottom, a right side wall 225, a left side wall 226, a front side wall 227, and a rear side wall 228. By attaching the lid 303 to the base 301, an internal space is formed inside the housing 300. The internal space is a sealed space surrounded by the base 301 and the lid 303. Light-transmitting portions 219Y, 219M, 219C, and 219K are provided in the lid 303. The light-transmitting portions 219Y, 219M, 219C, and 219K are arranged on the lid 303 so as to extend in the main scanning direction. The housing 300 accommodates in its internal space a light source unit 210, a polygon unit 211, a first scanning lens 213, second scanning lenses 217Y, 217M, 217C, and 217K, first mirrors 215Y, 215M, 215C, and 215K, and second mirrors 216Y, 216M, 216C, and 216K.

[0047] A substantially cylindrical first protrusion 221 protruding outward from the right side wall 225 is provided on the right side of the base 301 of the exposure unit 21. A substantially cylindrical second protrusion 224 protruding outward from the left side wall 226 is provided on the left side of the base 301 of the exposure unit 21. Two substantially rectangular parallelepiped third protrusions 223 protruding outward from the right side wall 225 are also provided. The two third protrusions 223 are provided at positions sandwiching the first protrusion 221 in the Y direction. When the exposure unit 21 is attached to the main frame, the first protrusion 221 and the two third protrusions 223 each pass through an opening formed in the main frame. When the exposure unit 21 is attached to the main frame, the second protrusion 224 passes through an opening formed in the main frame. This determines the relative positions of the exposure unit 21 and the main frame.

[0048] Returning to FIG. 4 , a base substrate 400B is disposed on the front wall 227 of the housing 300 of the exposure unit 21. The base substrate 400B constitutes a part of the front wall 227. A hole is formed penetrating the front wall 227, and the hole is blocked by the base substrate 400B. As a result, the internal space of the housing 300 is maintained in an airtight state. At least a part of the base substrate 400B constitutes a part of the front wall 227, which is a sealing wall that partitions the internal space of the housing 300. A base substrate 400A is disposed on the rear wall 228 of the housing 300. The base substrate 400A constitutes a part of the rear wall 228. A hole is formed penetrating the rear wall 228, and the hole is blocked by the base substrate 400A. As a result, the internal space of the housing 300 is maintained in an airtight state. At least a part of the base substrate 400A constitutes a part of the rear wall 228, which is a sealing wall that partitions the internal space of the housing 300.

[0049] Since the base substrates 400A and 400B have a symmetrical configuration in the XZ plane, the base substrate 400A will be described here as an example. The base substrate 400A is a printed circuit board. The base substrate 400A has an inner surface facing the internal space of the housing 300 and an outer surface facing away from the internal space. An optical sensor 403 is disposed on the inner surface of the base substrate 400A, and an adjustment member 401 is disposed on the outer surface. In this embodiment, only the adjustment member 401 is disposed on the outer surface of the base substrate 400A. This makes it easy to replace the adjustment member 401.

[0050] The light beam deflected in the main scanning direction by the polygon mirror 212 is guided by the first rear reflecting mirror 411A and the second rear reflecting mirror 412A to the optical sensor 403 arranged on the base substrate 400A. The light beam deflected in the main scanning direction by the polygon mirror 212 is guided by the first front reflecting mirror 411B and the second front reflecting mirror 412B to the optical sensor 403 arranged on the base substrate 400B. The first rear reflecting mirror 411A and the first front reflecting mirror 411B are arranged outside the first mirror 215Y, first mirror 215M, first mirror 215C, and first mirror 215K in the main scanning direction.

[0051] The first rear-reflection mirror 411A is arranged next to the first mirror 215K in the main scanning direction outside the upstream end of the first mirror 215K in the main scanning direction. The first front-reflection mirror 411B is arranged next to the first mirror 215K in the main scanning direction outside the downstream end of the first mirror 215K in the main scanning direction. The first mirror 215K is farthest from the polygon mirror 212 among the first mirrors 215Y, 215M, 215C, and 215K.

[0052] The light beams reflected by the first rear-reflection mirror 411A and the second rear-reflection mirror 412A are incident on the optical sensor 403 arranged on the base substrate 400A. The optical detection signal output by the optical sensor 403 arranged on the base substrate 400A is used as an SOS (Start of Scan) signal for synchronizing the start of main scanning of the light beams deflected in the main scanning direction by the polygon mirror 212.

[0053] The light beam reflected by the first pre-reflection mirror 411B and the second pre-reflection mirror 412B is incident on the optical sensor 403 arranged on the base substrate 400B. The optical detection signal output by the optical sensor 403 arranged on the base substrate 400B is used as an EOS (End of Scan) signal for synchronizing the end of main scanning of the light beam deflected in the main scanning direction by the polygon mirror 212.

[0054] FIG. 7 is a diagram showing an example of how contamination tends to occur on a polygon mirror. The upper part of FIG. 7 shows a plan view of the polygon mirror 212, and the lower part shows a side view of the polygon mirror 212. Referring to FIG. 7, the polygon mirror 212 has a low outer shape, such as a regular hexagonal prism, and has six mirror surfaces that form the side surfaces of the hexagonal prism. Note that the shape of the polygon mirror 212 in plan view is not limited to a regular hexagon and may be any polygonal shape. The mirror surfaces are flat. The polygon mirror 212 rotates around an axis of rotational symmetry. While the polygon mirror 212 rotates, light incident from the light source unit 210 is deflected in the main scanning direction by each of the six mirror surfaces. A light beam deflected by one mirror surface scans one line in the main scanning direction.

[0055] As the polygon mirror 212 rotates, airflow is generated around the polygon mirror 212. Because the polygon mirror 212 has a regular hexagonal prism shape, the airflow generated at different positions varies depending on the direction of rotation of the rotating mirror surface. In particular, while the polygon mirror 212 is rotating, a vortex may be generated at the front end of the mirror in the direction of rotation. This vortex in the airflow may cause dust particles floating around the polygon mirror 212 to adhere to the front end of the mirror surface. For this reason, more dust particles tend to adhere to the front end of the mirror surface than to other parts.

[0056] The dirt on the mirror surface decreases the reflectivity of the light beam as it accumulates over time on the polygon mirror 212. As mentioned above, dirt on the mirror surface progresses faster on the front end than on other parts, so the degree of decrease in reflectivity is greater on the front end than on other parts.

[0057] If the reflectance of the front end portion of the mirror surface of the polygon mirror 212 decreases excessively, the amount of light received by the optical sensor 403 disposed on the base substrate 400A decreases, and an SOS signal cannot be obtained. If an SOS signal is not obtained, the start of the main scanning of the light beam cannot be synchronized. On the other hand, the reflectance of the mirror surface of the polygon mirror 212 other than the front end portion is higher than that of the front end portion. Therefore, the amount of light beam output by the exposure unit 21 to the development units 20Y, 20M, 20C, and 20K may be sufficient. In this embodiment, the exposure unit 21 is able to output an SOS signal by increasing the sensitivity of the optical sensor 403 when the front end portion of the mirror surface of the polygon mirror 212 becomes dirty.

[0058] FIG. 8 is a circuit diagram showing an example of a circuit formed on a base substrate. Referring to FIG. 8, the circuit formed on a base substrate 400A includes an adjustment member 401, an optical sensor 403, an amplifier 405, and a comparator 407. The optical sensor 403 is a photoelectric conversion element. The optical sensor 403 is, for example, a photodiode or a charge-coupled device (CCD). The optical sensor 403 may be a phototransistor. Here, an example will be described in which a photodiode is used as the optical sensor 403. The amplifier 405 is an amplifier that amplifies current. The adjustment member 401 adjusts the photoelectric conversion gain of the optical sensor 403. In this embodiment, the adjustment member 401 is a resistor that converts a current generated by the optical sensor 403 upon receiving light into a voltage. The resistance value of the adjustment member 401 is predetermined.

[0059] An amplifier 405 and an adjustment member 401 are connected in series to the optical sensor 403. When a light beam is incident on the optical sensor 403, the optical sensor 403 generates a current proportional to the amount of light of the incident light beam. The current generated by the optical sensor 403 is input to the amplifier 405. The amplifier 405 amplifies the current. The current amplified by the amplifier 405 flows to the adjustment member 401. The adjustment member 401 converts the current output from the amplifier 405 into a voltage.

[0060] The comparator 407 is a comparator. A reference voltage Vref, which serves as a reference for comparison, and a voltage converted from a current by the adjustment member 401 are input to the comparator 407. The comparator 407 compares the input voltage converted from a current by the adjustment member 401 with the reference voltage Vref and outputs a digital signal. The comparator 407 outputs a digital signal H indicating a high level when the input voltage is equal to or greater than the reference voltage Vref, and outputs a digital signal L indicating a low level when the input voltage is smaller than the reference voltage Vref. The input voltage converted from a current by the adjustment member 401 is also output as an analog signal.

[0061] Here, the resistance value of the adjustment member 401 is R, the current flowing through the adjustment member 401 is Igain, and the voltage converted from the current by the adjustment member 401 is Vgain. Vgain = Igain × R …(1) The above formula (1) holds. Vgain corresponds to the analog output of the base substrate 400A. Hereinafter, the resistance value of the adjustment member 401 will be referred to as a gain resistance value R.

[0062] 9 to 11 are diagrams showing examples of analog output and digital signals of the base substrate. Fig. 9 is a diagram showing examples of analog output and digital signals in an initial state where polygon mirror 212 is not contaminated. Referring to Fig. 9, in the analog output, the difference between the voltage when no light beam is incident on optical sensor 403 and the voltage when a light beam is incident on optical sensor 403 is 2.0 V. In the digital signal, the period during which the digital signal becomes a high level H is 480 ns.

[0063] 10 is a diagram showing an example of the analog output and digital signal when the polygon mirror 212 is moderately dirty. Referring to Fig. 10, in the analog output, the difference between the voltage when no light beam is incident on the optical sensor 403 and the voltage when the light beam is incident on the optical sensor 403 is 1.6 V. In the digital signal, the period during which the digital signal remains at high level H is 270 ns.

[0064] Fig. 11 shows an example of the analog output and digital signal when the degree of contamination on polygon mirror 212 is large. Referring to Fig. 11, in the analog output, the difference between the voltage when no light beam is incident on optical sensor 403 and the voltage when a light beam is incident on optical sensor 403 is 1.0 V. In the digital signal, the period during which the signal remains at a high level is 190 ns.

[0065] The peak value of the analog output decreases as the degree of contamination on the polygon mirror 212 increases. The degree of contamination on the polygon mirror 212 can be detected from the peak value. Furthermore, the pulse width of the digital signal decreases as the degree of contamination on the polygon mirror 212 increases. The degree of contamination on the polygon mirror 212 can be detected from the pulse width of the digital signal.

[0066] When the contamination of the polygon mirror 212 becomes extremely large, the peak value of the analog output further decreases. In this case, the analog output does not exceed the reference voltage Vref, and the digital signal does not become a high-level digital signal H. As shown in the above formula (1), the analog output is determined by Igain and the gain resistance value R of the adjustment member 401. Therefore, Vgain can be increased by increasing the gain resistance value R of the adjustment member 401. This allows the analog output to be made larger than the reference voltage Vref.

[0067] FIG. 12 is a diagram showing an example of a correspondence table. The correspondence table associates the analog output Vgain of the base substrate 400A with the gain resistance value R required for the adjustment member 401. The gain resistance value R required for the adjustment member 401 indicates the resistance value of the adjustment member 401 that should replace the adjustment member 401 currently attached to the base substrate 400A. The analog output Vgain indicates the analog output corresponding to the gain resistance value R of the adjustment member 401 in the initial state. The gain resistance value R is associated with an analog output Vgain of 0 to 0.2 (V). This indicates that if the analog output Vgain is 0 to 0.2 (V) for the gain resistance value R in the initial state, the polygon mirror 212 needs to be replaced. The gain resistance value R required for the adjustment member 401 is determined in increments of 0.2 V within the range of the analog output Vgain of the base substrate 400A from 0.2 V to less than 3.0 V. For example, when the analog output Vgain of the base substrate 400A is equal to or greater than 0.2 and less than 0.4 V, the gain resistance value R required for the adjustment member 401 is 10.0 kΩ.

[0068] Fig. 13 is a block diagram showing an outline of the hardware configuration of the MFP in this embodiment. Referring to Fig. 4, MFP 100 includes a main circuit 110, a document reading unit 130, an automatic document feeder 120, an image forming unit 140, a paper feeding unit 150, and an operation panel 160. Operation panel 160 is a user interface.

[0069] Main circuit 110 includes CPU 111, communication interface (I / F) unit 112, ROM 113, RAM 114, HDD 115, facsimile unit 116, and external storage device 117. HDD 115 is a large-capacity storage device. A solid-state drive (SSD) may be used instead of HDD 115. CPU 111 is connected to automatic document feeder 120, document reading unit 130, image forming unit 140, paper feed unit 150, and operation panel 160, and controls the entire MFP 100. HDD 115 stores the correspondence table shown in FIG. 12.

[0070] Facsimile unit 116 is connected to the public switched telephone network (PSTN) and transmits facsimile data to the PSTN. Facsimile unit 116 also receives facsimile data from the PSTN. Facsimile unit 116 stores the received facsimile data in HDD 115, converts it into print data that can be printed by image forming unit 140, and outputs it to image forming unit 140. As a result, image forming unit 140 forms an image on paper based on the facsimile data received by facsimile unit 116. Facsimile unit 116 also converts the data stored in HDD 115 into facsimile data and transmits it to a facsimile device connected to the PSTN.

[0071] The communication I / F unit 112 is an interface for connecting the MFP 100 to a network. The communication I / F unit 112 communicates with the PC 200 connected to the network using a communication protocol such as TCP (Transmission Control Protocol) or FTP (File Transfer Protocol).

[0072] ROM 113 stores programs executed by CPU 111 or data required to execute the programs. RAM 114 is used as a work area when CPU 111 executes the programs. RAM 114 also temporarily stores scanned images continuously sent from document scanning unit 130.

[0073] Operation panel 160 is provided on the top surface of MFP 100. Operation panel 160 includes display unit 161 and operation unit 163. Display unit 161 is, for example, a liquid crystal display (LCD), and displays an instruction menu for the user, information related to acquired image data, etc. Note that instead of an LCD, for example, an organic EL display may be used as long as it is a device that displays images.

[0074] The operation unit 163 includes a touch panel 165 and a hard key unit 167. The touch panel 165 is of a capacitance type. Note that the touch panel 165 is not limited to a capacitance type, and other types such as a resistive film type, a surface acoustic wave type, an infrared type, or an electromagnetic induction type can be used. The hard key unit 167 includes a plurality of hard keys. The hard keys are, for example, contact switches.

[0075] External storage device 117 is controlled by CPU 111, and has CD-ROM 118 attached thereto. In this embodiment, an example will be described in which CPU 111 executes a program stored in ROM 113. Note that CPU 111 may control external storage device 117 to read a program to be executed by CPU 111 from CD-ROM 118, store the read program in RAM 114, and execute it.

[0076] Fig. 14 is a block diagram showing an example of functions of CPU 111 included in the MFP according to the present embodiment. The functions shown in Fig. 14 are realized by CPU 111 included in MFP 100 by causing CPU 111 to execute a program stored in ROM 113, HDD 115, or CD-ROM 118. The functions shown in Fig. 14 may also be realized by hardware included in MFP 100.

[0077] 14, the CPU 111 included in the MFP 100 includes a resistance value determination unit 51 and a resistance value display unit 53. The resistance value determination unit 51 controls the base substrates 400A and 400B and acquires the digital signals and analog outputs output by the base substrates 400A and 400B. The resistance value determination unit 51 determines a gain resistance value based on the analog output of the base substrate 400A. Specifically, the resistance value determination unit 51 refers to a correspondence table stored in the HDD 115 to determine a gain resistance value corresponding to the analog output of the base substrate 400A. The resistance value determination unit 51 outputs the gain resistance value to the resistance value display unit 53.

[0078] The resistance value display unit 53 notifies the user of the gain resistance value. For example, the resistance value display unit 53 displays the gain resistance value on the display unit 161. The user can look at the gain resistance value displayed on the display unit 161 and replace the adjustment member 401 arranged on the base substrate 400A with a resistor of the gain resistance value. Because the adjustment member 401 is arranged outside the housing 300, there is no need to remove the cover 303 from the base 301 of the housing 300. This makes it easy to replace the adjustment member 401. Furthermore, because there is no need to disassemble the exposure unit 21, it is possible to prevent the positions of the optical members in the internal space of the exposure unit 21 from changing.

[0079] 15 is a flowchart showing an example of the flow of maintenance support processing. The maintenance support processing is processing carried out by CPU 111 included in MFP 100 as CPU 111 executes a maintenance support program stored in ROM 113, HDD 115, or CD-ROM 118. Referring to FIG. 15, CPU 111 included in MFP 100 acquires the voltage to be applied to adjustment member 401 (step S01), and proceeds to step S02. CPU 111 determines the voltage to be applied to adjustment member 401 based on the analog output output from base substrate 400A.

[0080] In step S02, the voltage is compared with a threshold value Th1. The peak voltage of the analog output is compared with the threshold value Th1. The threshold value Th1 is a predetermined value stored in the HDD 115. If the peak voltage is equal to or less than the threshold value Th1, the CPU 111 proceeds to step S03; otherwise, the CPU 111 returns to step S01.

[0081] In step S03, the gain resistance value R is determined, and the process proceeds to step S04. CPU 111 determines the gain resistance value R corresponding to the peak voltage by referring to a correspondence table stored in HDD 115. In step S04, the gain resistance value R is displayed, and the process ends. CPU 111 displays the gain resistance value R on display unit 161.

[0082] <First Modification> 12 defines the relationship between the analog output Vgain of the base substrate 400A and the gain resistance value R required for the adjustment member 401. The correspondence table may associate the analog output Vgain of the base substrate 400A with a magnification for the resistance value of the currently attached adjustment member 401.

[0083] FIG. 16 is a diagram showing an example of a correspondence table in the first modified example. The correspondence table in the first modified example associates the analog output Vgain of the base substrate 400A with a magnification for the resistance value of the currently attached adjustment member 401. The analog output Vgain indicates the analog output for the gain resistance value R of the currently attached adjustment member 401. The magnification for the current resistance value is "unacceptable" when the analog output Vgain is 0 to 0.2 (V). This indicates that the polygon mirror 212 needs to be replaced. The magnification for the resistance value of the currently attached adjustment member 401 is determined in 0.2V increments within the range of the analog output Vgain of the base substrate 400A from 0.2V to less than 3.0V. For example, when the analog output Vgain of the base substrate 400A is 0.2V to less than 0.4V, a magnification of 10.0 is associated with the resistance value of the currently attached adjustment member 401. The user can calculate the resistance value at which the adjustment member 401 should be replaced from the resistance value of the adjustment member 401 currently attached to the base substrate 400A and the magnification. By using the correspondence table in the first modified example, the adjustment member 401 can be replaced multiple times.

[0084] <Second Modification> The correspondence table may associate the pulse width of the digital signal of the base substrate 400A with the gain resistance value. FIG. 17 is a diagram showing an example of the correspondence table in the second modified example. The correspondence table associates the pulse width of the digital signal of the base substrate 400A with the gain resistance value R required for the adjustment member 401. The pulse width of the digital signal of the base substrate 400A is indicated by the pulse width of the digital signal for the gain resistance value R in the initial state. The gain resistance value R is associated with a pulse width of 0 to 0.2 (μs) of the digital signal of the base substrate 400A as "unacceptable." This indicates that if the pulse width of the digital signal is 0 to 0.2 (μs) for the gain resistance value R in the initial state, the polygon mirror 212 needs to be replaced. The gain resistance value R after replacement is determined in increments of 0.2 μs within a range of the pulse width of the digital signal of the base substrate 400A from 0.2 μs to less than 2.0 μs. For example, when the pulse width of the digital signal of the base substrate 400A is equal to or greater than 0.2 μs and less than 0.4 μs, it is indicated that the gain resistance value R is replaced with a resistor having a value of 4.7 kΩ.

[0085] <Third Modification> 17 defines the relationship between the pulse width of the digital signal of the base substrate 400A and the gain resistance value R required for the adjustment member 401. The correspondence table in the third modification associates the pulse width of the digital signal of the base substrate 400A with a magnification factor for the resistance value of the currently attached adjustment member 401.

[0086] FIG. 18 is a diagram showing an example of a correspondence table in the third modified example. The correspondence table in the third modified example associates the pulse width of the digital signal of the base substrate 400A with a multiplication factor for the resistance value of the currently attached adjustment member 401. The pulse width of the digital signal of the base substrate 400A indicates the pulse width of the digital signal for the gain resistance value R of the currently attached adjustment member 401. A multiplication factor of "unacceptable" for the current resistance value corresponds to a pulse width of 0 to 0.2 (μs) of the digital signal of the base substrate 400A. This indicates that replacement of the polygon mirror 212 is necessary. The multiplication factor for the resistance value of the currently attached adjustment member 401 is determined in 0.2 μs increments within the range of the pulse width of the digital signal of the base substrate 400A from 0.2 μs to less than 3.0 μs. For example, when the pulse width of the digital signal of the base substrate 400A is from 0.2 μs to less than 0.4 μs, a multiplication factor of 4.7 corresponds to the resistance value of the currently attached adjustment member 401. The user can calculate the resistance value at which the adjustment member 401 should be replaced from the resistance value of the adjustment member 401 currently attached to the base substrate 400A and the magnification. By using the correspondence table in the third modified example, the adjustment member 401 can be replaced multiple times.

[0087] <Fourth Modification> The correspondence table may associate the cumulative number of printed pages with the gain resistance value. FIG. 19 is a diagram showing an example of the correspondence table in the fourth modified example. The correspondence table associates the cumulative number of printed pages with the gain resistance value R required for the adjustment member 401. The gain resistance value R "no replacement required" is associated with the number of printed pages between 0 and 50 (k pages). This indicates that the adjustment member 401 does not need to be replaced when the cumulative number of printed pages is between 0 and 50 (k pages). The gain resistance value R "not required" is associated with the number of printed pages between 450 and 500 (k pages). This indicates that the polygon mirror 212 needs to be replaced when the cumulative number of printed pages is between 450 and 500 (k pages). The gain resistance value after replacement is determined in increments of 50k pages within the range of the cumulative number of printed pages between 50k and 500k pages. For example, when the cumulative number of printed sheets is equal to or greater than 50,000 sheets but less than 100,000 sheets, it is indicated that the gain resistance value should be replaced with a resistor having a 1.0 kΩ resistance.

[0088] <Fifth Modification> 19 defines the relationship between the cumulative number of printed pages and the gain resistance value R required for the adjustment member 401. The correspondence table in the fifth modification associates the cumulative number of printed pages with a magnification factor for the resistance value of the currently installed adjustment member 401.

[0089] FIG. 20 is a diagram showing an example of a correspondence table in the fifth modified example. The correspondence table in the fifth modified example associates the cumulative number of printed sheets with a magnification factor for the resistance value of the currently installed adjustment member 401. A magnification factor of "no replacement required" for the current resistance value is associated with a number of printed sheets between 0 and 50 (k sheets). This indicates that the adjustment member 401 does not need to be replaced when the cumulative number of printed sheets is between 0 and 50 (k sheets). A magnification factor of "not required" for the current resistance value is associated with a number of printed sheets between 450 and 500 (k sheets). This indicates that the polygon mirror 212 needs to be replaced. When the cumulative number of printed sheets is between 50k and 450k sheets, the magnification factor for the resistance value of the currently installed adjustment member 401 is determined in increments of 50k sheets. For example, when the cumulative number of printed sheets is between 50k and 100k sheets, a magnification factor of 1.1 is associated with the resistance value of the currently installed adjustment member 401. The user can calculate the resistance value at which the adjustment member 401 should be replaced from the resistance value of the adjustment member 401 currently attached to the base substrate 400A and the magnification. By using the correspondence table in the fifth modified example, the adjustment member 401 can be replaced multiple times.

[0090] <Sixth Modification> The correspondence table may associate the cumulative operation time of the polygon mirror with the gain resistance value. FIG. 21 is a diagram showing an example of the correspondence table in the sixth modified example. The correspondence table in the sixth modified example associates the cumulative operation time of the polygon mirror 212 with the gain resistance value R required for the adjustment member 401. The gain resistance value R "no replacement required" is associated with an accumulated operation time of 0 to 500 (hours). This indicates that the adjustment member 401 does not need to be replaced when the accumulated operation time is 0 hour or more and less than 500 hours. The gain resistance value R "not required" is associated with an accumulated operation time of 4500 to 5000 (hours). This indicates that the polygon mirror 212 needs to be replaced when the accumulated operation time is 4500 hours or more and less than 5000 hours. The gain resistance value after replacement is determined in increments of 500 hours within the range of the accumulated operation time of 500 hours or more and less than 5000 hours. For example, if the cumulative operating time is 500 hours or more but less than 1000 hours, it is recommended to replace the resistor with one having a gain resistance of 1.0 kΩ.

[0091] <Seventh Modification> 20 defines the relationship between the accumulated operating time and the gain resistance value R required for the adjustment member 401. The correspondence table in the seventh modification associates the accumulated operating time with a magnification factor for the resistance value of the currently attached adjustment member 401.

[0092] FIG. 22 is a diagram showing an example of a correspondence table in the seventh modification. The correspondence table in the seventh modification associates accumulated operating time with a magnification factor for the resistance value of the currently installed adjustment member 401. A magnification factor of "no replacement required" for the current resistance value is associated with accumulated operating time of 0 to 500 (hours). This indicates that the adjustment member 401 does not need to be replaced when the accumulated operating time is 0 to 500 (hours). A magnification factor of "not required" for the current resistance value is associated with accumulated operating time of 4500 to 5000 (hours). This indicates that the polygon mirror 212 needs to be replaced. Within a range of accumulated operating time of 500 hours or more and less than 4500 hours, the magnification factor for the resistance value of the currently installed adjustment member 401 is determined in increments of 500 hours. For example, when the accumulated operating time is 500 hours or more and less than 1000 hours, a magnification factor of 1.1 is associated with the resistance value of the currently installed adjustment member 401. The user can calculate the resistance value at which the adjustment member 401 should be replaced from the resistance value of the adjustment member 401 currently attached to the base substrate 400A and the magnification. By using the correspondence table in the seventh modification, the adjustment member 401 can be replaced multiple times.

[0093] <Eighth Modification> In the above-described embodiment, CPU 111 included in MFP 100 determines the resistance value of adjustment member 401 arranged on base substrate 400A based on the analog output of base substrate 400A. CPU 111 included in MFP 100 in the eighth modification determines the resistance value of adjustment member 401 arranged on base substrate 400A based on the density difference of the toner image formed by image forming unit 140.

[0094] 23 is a diagram showing an example of functions of CPU 111 included in MFP 100 in the eighth modification. Referring to Fig. 23, MFP 100 in the eighth modification includes two concentration sensors 421 and 423. CPU 111 has resistance value determination unit 51A, resistance value display unit 53, and concentration detection unit 55.

[0095] The two density sensors 421 and 423 detect the density of the toner image formed by the developing unit 20Y at both ends in the main scanning direction. For example, the two density sensors 421 and 423 are disposed near the photosensitive drum 23Y and detect the toner density of the toner image formed on the photosensitive drum 23Y at both ends in the main scanning direction. The two density sensors 421 and 423 may be disposed near any of the photosensitive drums 23Y, 23M, 23C, and 23K. In other words, the two density sensors 421 and 423 may detect the density of the toner image formed on any of the photosensitive drums 23Y, 23M, 23C, and 23K. The two density sensors 421 and 423 may also detect the density of the image formed on the paper at both ends in the main scanning direction. Here, an example will be described in which the density sensor 421 detects the density on the upstream side in the main scanning direction, and the density sensor 423 detects the density on the downstream side in the main scanning direction.

[0096] The density detection unit 55 controls the density sensors 421 and 423 to obtain the densities detected by each. The density detection unit 55 calculates the difference between the two densities and outputs the density difference to the resistance value determination unit 51A. The density is a value within the range of 0 to 255. The density in a portion where no toner is carried on the photosensitive drum 23Y is 0, and the density in a portion where the maximum amount of toner is carried on the photosensitive drum 23Y is 255.

[0097] The resistance value determination unit 51A determines the gain resistance value R based on the concentration difference. Specifically, the resistance value determination unit 51A determines the gain resistance value R of the adjustment member 401 arranged on the base substrate 400A by referring to the correspondence table in the eighth modification example stored in the HDD 115. The resistance value determination unit 51A outputs the gain resistance value to the resistance value display unit 53.

[0098] Resistance value display unit 53 notifies the user of the gain resistance value R. The user can look at the gain resistance value displayed on display unit 161 and replace adjustment member 401 arranged on base substrate 400A with a resistor having gain resistance value R. Because adjustment member 401 is arranged outside housing 300, there is no need to remove lid 303 from base 301 of housing 300. This makes it easy to replace adjustment member 401. Furthermore, because there is no need to disassemble exposure unit 21, it is possible to prevent the positions of optical members in the internal space of exposure unit 21 from changing.

[0099] FIG. 24 is a diagram showing an example of a correspondence table in the eighth modification. The correspondence table in the eighth modification associates density differences with gain resistance values ​​R required for the adjustment member 401. Density differences of 0 to 31 are associated with a gain resistance value R that indicates no replacement is required. This indicates that when the cumulative operating time is 0 to 31, the adjustment member 401 does not need to be replaced. Within a density difference range of 32 to 255, the gain resistance value after replacement is determined in increments of 32. For example, when the density difference is 32 to 63, it indicates that the gain resistance value should be replaced with a resistor having a 1.0 kΩ value.

[0100] Fig. 25 is a flowchart showing an example of the flow of the maintenance support process in the eighth modified example. Referring to Fig. 25, the difference from the maintenance support process shown in Fig. 15 is that steps S01 and S02 are changed to steps S01A and S02A, respectively. The other processes are the same as the processes shown in Fig. 15, and therefore description thereof will not be repeated here.

[0101] CPU 111 included in MFP 100 acquires the density (step S01A) and proceeds to step S02. CPU 111 acquires the density output from each of density sensors 421 and 423. In step S02A, the density difference is compared with threshold value Th2. The density difference output from each of density sensors 421 and 423 is compared with threshold value Th2. Threshold value Th2 is a predetermined value and is stored in HDD 115. If the density difference is equal to or less than threshold value Th2, CPU 111 proceeds to step S03; otherwise, CPU 111 returns to step S01A.

[0102] <Ninth Variation> 24 defines the relationship between the density difference and the gain resistance value R required for the adjustment member 401. The correspondence table in the ninth modification associates the density difference with a magnification for the resistance value of the currently attached adjustment member 401.

[0103] FIG. 26 is a diagram showing an example of a correspondence table in the ninth modification. The correspondence table in the ninth modification associates density differences with magnifications for the resistance value of the currently attached adjustment member 401. Density differences of 0 to 31 are associated with a magnification for the current resistance value indicating no replacement is required. This indicates that a density difference of 0 to 31 indicates that the adjustment member 401 does not need to be replaced. The magnification for the resistance value of the currently attached adjustment member 401 is determined in increments of 32 within a density difference range of 32 to 255. For example, a density difference of 32 to 63 is associated with a magnification of 1.1 for the resistance value of the currently attached adjustment member 401. The user can calculate the resistance value at which the adjustment member 401 should be replaced based on the resistance value of the adjustment member 401 currently attached to the base substrate 400A and the magnification. Using the correspondence table in the ninth modification, the adjustment member 401 can be replaced multiple times.

[0104] <Other variations> (1) The adjustment member 401 may have a dip shape. The dip shape has a main body and a connection terminal, and the connection terminal extends in one direction from the main body. Therefore, by moving the adjustment member 401 in one direction, the adjustment member 401 can be attached to and detached from the base substrate 400A, making attachment and detachment easy.

[0105] (2) The adjustment member 401 may be a variable resistor whose resistance value is changeable. Because the resistance value of the adjustment member 401 is changeable, there is no need to replace the adjustment member 401, and the work of changing the resistance value of the adjustment member 401 is easy.

[0106] (3) The adjustment member 401 may include a plurality of resistors with different resistance values ​​and a switching unit that switches between any of the plurality of resistors. The switching unit switches between any of the plurality of resistors. This allows the user to select any of the plurality of resistors by operating the switching unit, making it easy to switch between resistance values.

[0107] (4) In this embodiment, only the adjustment member 401 is arranged on the outer surface of the base substrate 400A. In addition to the adjustment member 401, other members may be arranged on the outer surface of the base substrate 400A. In this case, it is preferable that the size of the adjustment member 401 is larger than the other members. In this case, it becomes easy to identify the adjustment member 401 from among the multiple members arranged on the outer surface of the base substrate 400A.

[0108] <Summary of implementation form> (Item 1) A polygon mirror that deflects a light beam; an optical sensor disposed at a position where the light beam deflected by the polygon mirror is incident; a housing case that houses the polygon mirror in an internal space; an adjustment member for adjusting a photoelectric conversion gain for the light incident on the optical sensor, The optical writing device, wherein the adjustment member is disposed outside the accommodating case.

[0109] According to this aspect, an adjustment member that adjusts the photoelectric conversion gain of the incident light to the optical sensor disposed at the position where the light beam deflected by the polygon mirror is incident is disposed outside the housing case that houses the polygon mirror in its internal space. Therefore, the photoelectric conversion gain of the adjustment member can be adjusted with the polygon mirror housed in the internal space of the housing case. As a result, an optical writing device that is easy to maintain can be provided.

[0110] (Item 2) The optical writing device according to item 1, wherein the storage case seals the internal space.

[0111] According to this aspect, the internal space is sealed by the accommodating case, so that the photoelectric conversion gain can be adjusted without opening the internal space of the accommodating case to the outside.

[0112] (Item 3) Further provided with a base member on which the adjustment member is disposed, 5. The optical writing device according to any one of items 1 to 4, wherein at least a part of the base member forms a part of a sealing wall that partitions the internal space of the casing.

[0113] According to this aspect, at least a portion of the base member on which the adjustment member is arranged constitutes a part of the sealing wall of the storage case, so that the adjustment member can be arranged outside the storage case while sealing the case member.

[0114] (Item 4) The base member has an inner surface facing the internal space of the storage case and an outer surface facing away from the internal space, the optical sensor is disposed on the inner surface; Item 4. The optical writing device according to item 3, wherein the adjustment member is disposed on the outer surface.

[0115] According to this aspect, the optical sensor is disposed on the inner surface and the adjustment member is disposed on the outer surface, so that the photoelectric conversion gain of the optical sensor can be adjusted with the case member sealed.

[0116] (Item 5) The optical writing device according to item 4, wherein only the adjustment member is attached to the outer surface.

[0117] According to this aspect, the outer surface does not have any other member attached to it apart from the adjustment member, so the user can easily access the adjustment member.

[0118] (Item 6) The optical writing device according to item 4, wherein the adjustment member is larger in size than another member attached to the outer surface.

[0119] According to this aspect, the adjustment member is larger in size than the other members attached to the outer surface, so that the user can easily distinguish the adjustment member from the other members.

[0120] (Item 7) The optical writing device according to any one of Items 3 to 6, wherein the adjustment member is detachably attached to the base member.

[0121] According to this aspect, the adjustment member is detachable from the base member, so that the adjustment member can be easily replaced.

[0122] (Item 8) The storage case has the internal space, the optical sensor; a motor that drives the polygon mirror; A light source and Lenses and 8. The optical writing device according to any one of items 2 to 7, further comprising a mirror.

[0123] According to this aspect, the optical sensor, the motor, the light source, the lens, and the mirror are housed in the internal space of the storage case. Since the photoelectric conversion gain can be adjusted without disassembling the storage case, changes in the optical path due to disassembly of the storage case can be suppressed.

[0124] (Item 9) The optical writing device according to any one of items 2 to 8, wherein the storage case is provided with a light projecting section that transmits light.

[0125] According to this aspect, the light projecting section is provided in the storage case, so that light can be output to the outside.

[0126] (Item 10) The optical writing device according to any one of items 1 to 9, wherein the adjustment member is a resistor.

[0127] According to this aspect, since the adjusting member is a resistor, the photoelectric conversion gain can be easily adjusted.

[0128] (Item 11) The optical writing device according to item 10, wherein the adjustment member is a variable resistor.

[0129] According to this aspect, since the adjusting member is a variable resistor, the photoelectric conversion gain can be adjusted without replacing the adjusting member.

[0130] (Item 12) The optical writing device according to any one of Items 1 to 11, wherein the adjustment member has a dip shape.

[0131] According to this aspect, since the adjusting member has a dip shape, it is easy to replace the adjusting member.

[0132] (Item 13) The adjusting member includes a plurality of resistors having different resistance values, 13. The optical writing device according to any one of items 1 to 12, further comprising: a switching unit that switches one of the plurality of resistors.

[0133] According to this aspect, since it is possible to switch to one of a plurality of resistors having different resistance values, it is easy to adjust the photoelectric conversion gain.

[0134] (Item 14) The optical writing device according to any one of items 1 to 13, wherein the optical sensor is a plurality of sensors.

[0135] According to this aspect, since there are a plurality of optical sensors, it is possible to detect the light beams deflected at a plurality of positions on the polygon mirror.

[0136] (Item 15) An optical writing device according to any one of items 1 to 14, a resistance value determining unit that determines a resistance value of the adjusting member; a display control unit that displays the resistance value determined by the resistance value determination unit.

[0137] According to this aspect, the resistance value of the adjusting member is determined and displayed, so that an image forming apparatus that allows for easy maintenance can be provided.

[0138] (Item 16) The image forming apparatus according to Item 15, wherein the resistance value determining unit determines the resistance value of the adjusting member based on an output voltage value or an output voltage width of the optical sensor.

[0139] According to this aspect, the resistance value of the adjusting member is determined based on the output voltage value or output voltage width of the optical sensor, so that the resistance value can be determined according to the degree of contamination on the polygon mirror.

[0140] (Item 17) An image forming unit that forms an image on a recording medium is further provided, Item 17. The image forming apparatus according to item 15 or 16, wherein the resistance value determining unit determines the resistance value of the adjusting member based on a cumulative number of recording media on which images have been formed by the image forming unit.

[0141] According to this aspect, the resistance value of the adjusting member is determined based on the cumulative number of recording media on which images have been formed, so that the resistance value according to the degree of contamination on the polygon mirror can be easily determined.

[0142] (Item 18) The image forming apparatus according to any one of Items 15 to 17, wherein the resistance value determining unit determines the resistance value of the adjusting member based on an accumulated operating time of the polygon mirror.

[0143] According to this aspect, the resistance value of the adjustment member is determined based on the accumulated operating time of the polygon mirror, so that the resistance value according to the degree of contamination on the polygon mirror can be easily determined.

[0144] (Item 19) An image forming unit that forms an image on a recording medium; a density detection unit that detects the density of an image formed by the image forming unit, 19. The image forming apparatus according to any one of items 15 to 18, wherein the resistance value determining section determines the resistance value of the adjusting member based on the density detected by the density detecting section.

[0145] According to this aspect, the resistance value of the adjusting member is determined based on the density of the image formed on the recording medium, so that the resistance value according to the degree of contamination on the polygon mirror can be easily determined.

[0146] (Item 20) A maintenance support method executed by the optical writing device according to any one of items 1 to 14, a resistance value determining step of determining a resistance value of the adjusting member; a display control step of displaying the resistance value determined in the resistance value determination step.

[0147] According to this aspect, it is possible to provide a maintenance support method that makes maintenance easier.

[0148] (Item 21) A maintenance support program executed by a computer that controls the optical writing device according to any one of items 1 to 14, a resistance value determining step of determining a resistance value of the adjusting member; a display control step of displaying the resistance value determined in the resistance value determination step.

[0149] According to this aspect, it is possible to provide a maintenance support program that makes maintenance easier. (Item 22) An optical writing device according to any one of claims 1 to 14, wherein the position at which the optical sensor is arranged is a position where the optical beam at the upstream end in the main scanning direction is irradiated among the optical beams deflected in the main scanning direction by the polygon mirror.

[0150] According to this aspect, the optical sensor is disposed at a position where the optical beam deflected in the main scanning direction by the polygon mirror is irradiated by the optical beam at the upstream end in the main scanning direction. The amount of dust adhering to the mirror surface of the polygon mirror is greater at the upstream end in the main scanning direction than at other portions. Therefore, the amount of light beam deflected in the portion of the polygon mirror where the dirt is relatively large can be detected.

[0151] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0152] 100 MFP, 110 main circuit, 111 CPU, 112 communication I / F unit, 113 ROM, 114 RAM, 115 HDD, 116 facsimile unit, 117 external storage device, 118 CD-ROM, 120 automatic document feeder, 130 document reading unit, 140 image forming unit, 150 paper feeding unit, 160 operation panel, 161 display unit, 163 operation unit, 165 touch panel, 167 hard key unit, 20Y, 20M, 20C, 20K development unit, 23Y, 23M, 23C, 23K photosensitive drum, 51, 51A resistance value determination unit, 53 resistance value display unit, 55 density detection unit, 210 light source unit, 211 polygon unit, 211A housing, 211B, 211C transmission window, 212 Polygon mirror, 212M polygon motor, 213 first scanning lens, 215Y, 215M, 215C, 215K first mirror, 216Y, 216M, 216C, 216K second mirror, 217Y, 217M, 217C, 217KY second scanning lens, 219C light-transmitting portion, 219K light-transmitting portion, 219M light-transmitting portion, 219Y light-transmitting portion, 221 first protrusion, 223 third protrusion, 224 second protrusion, 225 right side, 226 left side, 227 front side, 228 rear side, 300 housing, 301 base, 303 lid, 400A, 400B base substrate, 400B base substrate, 401 adjustment member, 403 optical sensor, 405 amplifier, 407 Comparator, 421 concentration sensor, 423 concentration sensor, H high level, R gain resistance value, Vgain analog output, Vref reference voltage.

Claims

1. a polygon mirror that deflects the light beam; an optical sensor disposed at a position where the light beam deflected by the polygon mirror is incident; a housing case that houses the polygon mirror in an internal space; an adjustment member for adjusting a photoelectric conversion gain for the light incident on the optical sensor, The optical writing device, wherein the adjustment member is disposed outside the accommodating case.

2. The optical writing device according to claim 1 , wherein the storage case seals the internal space.

3. a base member on which the adjustment member is disposed, The optical writing device according to claim 2 , wherein at least a portion of the base member constitutes a part of a sealing wall that partitions the internal space of the accommodating case.

4. the base member has an inner surface facing the interior space of the storage case and an outer surface facing away from the interior space; the optical sensor is disposed on the inner surface; The optical writing device of claim 3 , wherein the adjustment member is disposed on the outer surface.

5. The optical writing device according to claim 4 , wherein only the adjustment member is attached to the outer surface.

6. The optical writing device according to claim 4 , wherein the adjustment member is larger in size than another member attached to the outer surface.

7. The optical writing device according to claim 3 , wherein the adjustment member is detachably attached to the base member.

8. The storage case has the following in the internal space: the optical sensor; a motor that drives the polygon mirror; A light source and Lenses and The optical writing device of claim 2 further comprising a mirror.

9. The optical writing device according to claim 2 , wherein the storage case is provided with a light-transmitting portion that transmits light.

10. The optical writing device according to claim 1 , wherein the adjustment member is a resistor.

11. The optical writing device according to claim 10 , wherein the adjustment member is a variable resistor.

12. The optical writing device according to claim 1 , wherein the adjustment member has a dip shape.

13. The adjusting member includes a plurality of resistors having different resistance values, The optical writing device according to claim 1 , further comprising: a switching unit that switches one of the plurality of resistors.

14. The optical writing device according to claim 1 , wherein the optical sensor is a plurality of optical sensors.

15. An optical writing device according to any one of claims 1 to 14; a resistance value determining unit that determines a resistance value of the adjusting member; a display control unit that displays the resistance value determined by the resistance value determination unit.

16. The image forming apparatus according to claim 15 , wherein the resistance value determining section determines the resistance value of the adjusting member based on an output voltage value or an output voltage width of the optical sensor.

17. further comprising an image forming unit that forms an image on a recording medium; 16. The image forming apparatus according to claim 15, wherein the resistance value determining section determines the resistance value of the adjusting member based on a cumulative number of recording media on which images have been formed by the image forming section.

18. The image forming apparatus according to claim 15 , wherein the resistance value determining unit determines the resistance value of the adjusting member based on an accumulated operating time of the polygon mirror.

19. an image forming unit that forms an image on a recording medium; a density detection unit that detects the density of an image formed by the image forming unit, The image forming apparatus according to claim 15 , wherein the resistance value determining section determines the resistance value of the adjusting member based on the density detected by the density detecting section.

20. A maintenance support method executed by the optical writing device according to any one of claims 1 to 14, comprising: a resistance value determining step of determining a resistance value of the adjusting member; a display control step of displaying the resistance value determined in the resistance value determination step.

21. A maintenance support program executed by a computer that controls the optical writing device according to any one of claims 1 to 14, a resistance value determining step of determining a resistance value of the adjusting member; a display control step of displaying the resistance value determined in the resistance value determination step.

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