JP4995564B2 - Light source abnormality detection method, optical scanning device - Google Patents

Description

  The present invention belongs to the technical field of image forming apparatuses, and particularly relates to a laser irradiation technique for performing exposure by irradiating a surface of a photosensitive drum with a laser.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a laser irradiated from a laser irradiation unit is reflected by each reflecting surface of a rotary polygon mirror to expose the surface of the photosensitive drum, and electrostatic latent image is formed on the surface of the photosensitive drum. Optical scanning devices that form images are widely known. In addition, in this type of scanning apparatus, there is one that employs a method of exposing the photosensitive member with a plurality of lasers, as disclosed in, for example, Patent Document 1 below.

The following Patent Document 1 has a plurality of laser diodes that are substantially the same in the main scanning direction and separated by a predetermined distance in the sub-scanning direction, and the light beam from each laser diode is scanned in the main scanning direction on the photosensitive member surface by a polygon mirror. In the multi-beam writing apparatus that exposes the surface of the photosensitive drum, the beam light is detected by a sensor installed in the laser beam path on the main scanning start point outside the main scanning writing area on the photosensitive drum surface, and based on the beam light detection signal. A technique for determining a writing start position in the main scanning direction is disclosed. Further, in Patent Document 1 below, in order to detect an abnormality in which the light source does not turn on due to destruction of the light source or the like, each light source is turned on individually, and a synchronization detection signal generated based on the beam light detection signal is generated for a certain period of time. There is disclosed a technique for detecting by detecting that it is not generated even after elapse.
JP 2000-89145 A

  However, in the light source abnormality detection method in Patent Document 1, each light source is individually turned on to detect an abnormality, so that there is a problem that it takes a lot of time to check for the presence or absence of abnormality for all light sources. is there.

  The present invention has been made to solve the above-described problems, and provides a light source abnormality detection method and an optical scanning device capable of shortening the time required for light source abnormality detection as compared with the prior art. Objective.

According to the first aspect of the present invention, the light receiving unit that outputs an electrical signal corresponding to the intensity of the received light is different from the position in the first direction and the position in the second direction orthogonal to the first direction. A plurality of light sources that respectively output light toward each target position; and a scanning unit that scans output light of each light source in the first direction on the light receiving surface of the light receiving unit and on the surface of the photosensitive member; A light source abnormality detection method for detecting the presence or absence of abnormality of the light source in an optical scanning device comprising: a light source abnormality detection unit that operates the scanning unit after outputting a lighting instruction to each light source. A second step of comparing the signal level of the output signal of the light receiving unit obtained in the first step with a predetermined threshold value and generating a rectangular wave signal according to the comparison result; In the second step It is determined whether or not the number of generated rectangular wave signals matches the number of light sources, and when it is determined that they match, it is determined that each of the light sources is normal, and the number of rectangular wave signals is equal to the number of light sources. If there is a discrepancy between the plurality of light sources, a third step for determining that there is a possibility that there is a light source in which the abnormality has occurred among the plurality of light sources, and an abnormality among the plurality of light sources in the third step. If it is determined that there is a possibility that there is a light source in which the light is generated, the light sources are grouped into two sets of light sources that output light adjacent to the target position, and belong to the set in units of sets. A fourth step of operating the scanning unit after outputting lighting instructions to two light sources, a signal level of the output signal of the light receiving unit in each set obtained by the fourth step, and a predetermined threshold value Compare large and small, according to the comparison result The fifth step of generating the waveform signal is compared with the rectangular wave signal generated in the fifth step and the first rectangular wave signal that is set in advance and stored in the storage unit for the rectangular wave signal. If the two rectangular wave signals coincide with each other, it is determined that the two light sources of the set corresponding to the target rectangular wave signal compared with the first rectangular wave signal are normal, and both the rectangular wave signals are And a sixth step of determining that there is a possibility that a light source having an abnormality exists in a set corresponding to the target rectangular wave signal compared with the first rectangular wave signal. Is.

  When a light beam is output from the light source for a certain period of time, the output signal of the light receiving unit reaches a maximum signal level from approximately 0 (maximum amount of change in signal level) and from the maximum signal level to approximately 0. It takes a certain amount of time for each to occur, and the waveform of the output signal of the light receiving unit has a rising edge and a falling edge.

  Each light source is configured to output light toward each target position having a position in the first direction and a position in the second direction orthogonal to the first direction, respectively. The target position of the output light of each light source on the light-receiving surface of the light-receiving unit is obtained from the light-receiving unit for the first and second light rays that should be adjacent to each other in a standard environmental condition such as when shipped from the factory. This is a position where the waveform of each output signal has a relationship such that the rising edge and the falling edge intersect.

  In such a configuration, according to the present invention, after the lighting instruction is output to each light source by the light source abnormality detection unit, the operation by the scanning unit (on the light receiving surface of the light receiving unit and the surface of the photosensitive member). The operation of scanning the output light of the light source in the first direction) is performed, the magnitude of the obtained signal level of the output signal of the light receiving unit and a predetermined threshold value are compared, and according to the comparison result A rectangular wave signal is generated.

  For example, in the aspect in which the waveform of the output signal obtained from the light receiving unit for each of the first and second light beams that should be adjacent to each other in the target position overlaps with each other at the maximum signal level, the first and second light beams On the other hand, in a mode in which one rectangular wave signal is generated at the rising edge and the falling edge, a signal level temporarily different from the maximum signal level is included in the waveform of the output signal of the light receiving unit. A part to be expressed is generated, and only one rectangular wave signal is generated for the first and second light beams according to the magnitude of the signal level and the threshold value in the part, or the first and second A rectangular wave signal is generated corresponding to each of the light beams.

  If the number of rectangular wave signals matches the number of light sources, it indicates that the light beam has been normally output from each light source, so that it can be determined that each light source is normal, while the number of rectangular wave signals is the number of light sources. If the number does not match, whether the waveform of the output signal obtained from the light receiving unit with respect to the first and second light beams overlaps with each other at the maximum signal level, the rising edge and the falling edge It is not possible to distinguish whether the light beam is not normally output from the light source.

  Based on this, when the light source abnormality detection unit determines that the number of generated rectangular wave signals does not match the number of light sources, there is a light source in which an abnormality has occurred among the plurality of light sources. It is judged that there is a possibility.

  As described above, in the conventional technique in which the process of outputting the lighting instruction and causing the scanning unit to perform an operation is performed for each light source (individually) to detect an abnormality, the scanning unit is operated as many times as the number of light sources. In the present invention, when the number of obtained rectangular wave signals matches the number of laser light sources, the number of operations of the scanning unit and the rectangular wave signal are examined. The number of times is only one, and the number of times can be greatly reduced as compared with the prior art.

According to the present invention, the light sources are grouped into two sets of light sources that output light adjacent to the target position, and lighting instructions are output to the two light sources belonging to the set in units of groups. Since the scanning unit is operated to check whether or not there is an abnormality in the set based on the obtained rectangular wave signal, the light source in which the abnormality has occurred For the group that does not exist, the number of times of checking the rectangular wave signal is only one, and it is not necessary to check the rectangular wave signal as many times as the number of light sources as in the prior art. Therefore, compared with the prior art, the number of operations of the scanning unit and the number of times of checking the rectangular wave signal can be greatly reduced.

The invention according to claim 2, the light source abnormality detecting method according to claim 1, wherein the light source abnormality detecting unit, between the fourth step and the third step, generated in the second step rectangular A wave signal is compared with a second rectangular wave signal that is set in advance and stored in the storage unit with respect to the rectangular wave signal, and when both rectangular wave signals match, the plurality of light sources Of these, when the scanning unit is operated, a light source that outputs light that should first pass through the light receiving surface and a light source that outputs light that should finally pass through the light receiving surface are normal. If both the rectangular wave signals do not match, at least one of a light source that outputs light that should first pass through the light receiving surface and a light source that outputs light that should finally pass through the light receiving surface There may be a problem with the light source. And it has a seventh step of determining that.

  According to the present invention, among the light sources, when the scanning unit is operated, the light source that outputs light that should first pass through the light receiving surface and the light that should finally pass through the light receiving surface are output. Whether or not an abnormality has occurred in at least one of the light sources to be detected can be detected.

According to a third aspect of the present invention, in the light source abnormality detection method according to the first or second aspect , the light source abnormality detection unit may include a light source in which an abnormality has occurred in the sixth step. For each light source belonging to the determined set, when an output signal is obtained from the light receiving unit by the eighth step of operating the scanning unit after outputting a lighting instruction for each light source, and the eighth step, It is determined that the light source corresponding to the output signal is normal, and if the output signal is missing from the light receiving unit, it is determined that an abnormality has occurred in the light source corresponding to the missing light receiving signal. Steps.

  According to the present invention, it is possible to identify a light source in which an abnormality has occurred.

The invention according to claim 4 is different from the light receiving unit that outputs an electric signal according to the intensity of the received light, the position in the first direction, and the position in the second direction orthogonal to the first direction. A plurality of light sources that respectively output light toward each target position; and a scanning unit that scans output light of each light source in the first direction on the light receiving surface of the light receiving unit and on the surface of the photosensitive member; A light source abnormality detection method for detecting the presence or absence of abnormality of the light source in an optical scanning device comprising: a light source abnormality detection unit that operates the scanning unit after outputting a lighting instruction to each light source. A second step of comparing the signal level of the output signal of the light receiving unit obtained in the first step with a predetermined threshold value and generating a rectangular wave signal according to the comparison result; In the second step It is determined whether or not the number of generated rectangular wave signals matches the number of light sources, and when it is determined that they match, it is determined that each of the light sources is normal, and the number of rectangular wave signals is equal to the number of light sources. If there is a discrepancy between the plurality of light sources, a third step for determining that there is a possibility that there is a light source in which the abnormality has occurred among the plurality of light sources, and an abnormality among the plurality of light sources in the third step. If it is determined that there is a possibility that there is a light source in which the light source is generated, the light sources are grouped by a combination of light sources whose target positions are not adjacent to each other, and a lighting instruction is given to each light source belonging to the group in units of groups. The tenth step of operating the scanning unit after outputting, and whether or not the number of output signals of the light receiving unit in each set obtained by the tenth step matches the number of light sources belonging to the set Judging by group unit, the number is If the number of light sources matches the number of light sources, it is determined that the light sources belonging to the set are normal. If the number does not match the number of light sources, there is a light source in which an abnormality has occurred in the set. And an eleventh step for determining that there is a possibility of the occurrence.

  According to this invention, the light sources are grouped by a combination of light sources whose target positions are not adjacent to each other, and the scanning unit is operated on a group basis after outputting a lighting instruction to each light source belonging to the group, Since it is checked whether or not the light source in which each group has an abnormality is present based on the match / mismatch of the number of output signals of the light receiving unit in each set and the number of light sources belonging to the set. For the group in which there is no light source in which an abnormality has occurred, the number of times of checking the rectangular wave signal is only one, and it is not necessary to check the rectangular wave signal as many times as the number of light sources as in the prior art. Therefore, compared with the prior art, the number of operations of the scanning unit and the number of times of checking the rectangular wave signal can be greatly reduced.

In the invention according to claim 5 , the light source abnormality detection unit turns on each light source belonging to the set determined that there is a possibility that the abnormality occurs in the eleventh step in light source units. When the output signal is obtained from the light receiving unit by the twelfth step of operating the scanning unit after outputting the instruction and the twelfth step, it is determined that the light source corresponding to the output signal is normal. And a thirteenth step of determining that an abnormality has occurred in the light source corresponding to the missing light receiving signal when the output signal is missing from the light receiving unit.

  According to the present invention, it is possible to identify a light source in which an abnormality has occurred.

According to the sixth aspect of the present invention, the light receiving unit that outputs an electrical signal corresponding to the intensity of the received light is different from the position in the first direction and the position in the second direction orthogonal to the first direction. A plurality of light sources that respectively output light toward each target position; and a scanning unit that scans output light of each light source in the first direction on the light receiving surface of the light receiving unit and on the surface of the photosensitive member; The BD sensor outputs a BD signal for adjusting a light beam scanning start timing for generating an electrostatic latent image for image formation on the surface of the photosensitive member. The light source abnormality detection unit according to any one of claims 1 to 5 , which detects presence or absence of abnormality of the light source.

  According to the present invention, it is possible to realize an optical scanning device capable of shortening the time required for detecting the abnormality of the light source as compared with the prior art. Further, the light receiving unit is originally provided because it is a BD sensor that outputs a BD signal for adjusting the start timing of light beam scanning for generating an electrostatic latent image for image formation on the surface of the photoconductor. The abnormality of the light source can be detected by using the member.

  According to the present invention, it is possible to shorten the time required for detecting the abnormality of the light source as compared with the conventional technique.

  Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is a side view schematically showing an internal configuration of a multifunction peripheral as an example of an image forming apparatus according to an embodiment of the present disclosure. The multifunction device 1 has functions such as a copy function, a printer function, a scanner function, and a facsimile function. The multi-function device 1 includes a main body 2, a stack tray 3 disposed on the left side of the main body 2, a document reading unit 5 disposed on the top of the main body 2, and an upper side of the document reading unit 5. And a document feeding unit 6 disposed.

  An operation unit 47 is provided at the front part of the multifunction machine 1. The operation unit 47 displays a start key 471 for a user to input a print execution instruction, a ten key 472 for inputting the number of copies to be printed, operation guide information for various copying operations, and the like. A display unit 473 formed of a liquid crystal display or the like having a touch panel function, a reset key 474 for resetting setting contents set in the display unit 473, and a stop key for stopping a printing (image forming) operation being executed 475 and a function switching key 477 for switching between a copy function, a printer function, a scanner function, and a facsimile function.

  The document reading unit 5 includes a scanner unit 51 including a CCD (Charge Coupled Device) sensor and an exposure lamp, and a document table 52 and a document reading slit 53 made of a transparent member such as glass. The scanner unit 51 is configured to be movable by a drive unit (not shown). When reading a document placed on the document table 52, the scanner unit 51 is moved along the document surface at a position facing the document table 52, and the document image is scanned. Image data acquired while scanning is output to an unillustrated image processing unit. Further, when reading a document fed by the document feeding unit 6, the document is moved to a position facing the document reading slit 53 and synchronized with the document feeding operation by the document feeding unit 6 via the document reading slit 53. The image of the original is acquired and the image data is output to the image processing unit.

  The document feeding unit 6 includes a document placing unit 61 for placing a document, a document discharge unit 62 for discharging a document whose image has been read, and a document placed on the document placing unit 61. A document transport mechanism 63 including a paper feed roller (not shown), a transport roller (not shown) and the like for feeding the paper one by one to a position facing the document reading slit 53 and discharging it to the document discharge section 62 is provided. The document conveyance mechanism 63 further includes a sheet reversing mechanism (not shown) that reverses the document and reversely conveys the document to a position facing the document reading slit 53, and scans both sides of the document through the document reading slit 53. 51 can be read.

  The document feeding unit 6 is provided so as to be rotatable with respect to the main body unit 2 so that the front side thereof can move upward. By moving the front side of the document feeder 6 upward to open the upper surface of the document table 52, the operator can place a read document, for example, a book in a spread state, on the upper surface of the document table 52. It has become.

  The main body 2 includes a plurality of paper feed cassettes 461, a paper feed roller 462 that feeds the recording paper from the paper feed cassette 461 one by one and transports it to the recording unit 40, and a recording paper transported from the paper feed cassette 461. And a recording unit 40 for forming an image.

  The recording unit 40 outputs a laser or the like based on the image data acquired by the scanner unit 51 or the like and exposes the photosensitive drum 43, and a developing unit 44 that forms a toner image on the photosensitive drum 43. A transfer unit 41 that transfers the toner image on the photosensitive drum 43 to the recording paper, a fixing unit 45 that heats the recording paper to which the toner image has been transferred and fixes the toner image on the recording paper, and a recording unit 40. And transport rollers 463, 464, etc. for transporting the recording paper to the stack tray 3 or the discharge tray 48.

  When forming images on both sides of the recording paper, the recording unit 40 forms an image on one side of the recording paper, and then the recording paper is nipped by the conveyance roller 463 on the discharge tray 48 side. . In this state, the conveyance roller 463 is reversed to switch back the recording paper, and the recording paper is sent to the paper conveyance path L and conveyed again to the upstream area of the recording unit 40, and an image is formed on the other surface by the recording unit 40. Thereafter, the recording paper is discharged to the stack tray 3 or the discharge tray 48.

  FIG. 2 is a configuration diagram of the optical scanning device 49. As shown in FIG. 2, the optical scanning device 49 according to the present invention includes a laser irradiation unit 491, a collimator lens 492, a prism 493, a polygon mirror (rotating polygonal mirror) 494, an f-θ lens 495, and a beam detector sensor (hereinafter referred to as “beam detector”). 496).

  The laser irradiation unit 491 includes a plurality of laser light sources (LD). A plurality of laser beams output from each laser light source are converted into parallel beams by a collimator lens 492, a prism 493, and the like. The parallel light is reflected toward the polygon mirror 494 by a reflection mirror (not shown) and enters the rotating polygon mirror 494. The polygon mirror 494 has a plurality of reflection surfaces that reflect the laser light output from the laser irradiation unit 491 toward the photosensitive drum 43. A plurality of laser beams are irradiated from the laser irradiation unit 491, and the plurality of laser beams are reflected toward the photosensitive drum 43 by different reflecting surfaces of the polygon mirror 494, respectively. The polygon mirror 494, for example, rotates in the direction of the arrow in FIG. 2 to reflect each laser beam sequentially on separate reflecting surfaces and scan each laser beam in the rotation axis direction (main scanning direction) of the photosensitive drum 43. . The laser light incident on the polygon mirror 494 and reflected toward the photosensitive drum 43 is imaged on the surface of the photosensitive drum 43 by the f-θ lens 495 in a spot shape having a predetermined diameter. Since the polygon mirror 494 rotates at a constant speed, the laser irradiated on the surface of the photosensitive drum 43 is scanned on the surface of the photosensitive drum 43 at a constant speed, and charges on the surface of the photosensitive drum 43 are discharged. Remove.

  The BD (Beam Detect) sensor 496 is configured using a photodiode, and is used to adjust the timing of writing image data to the photosensitive drum 43. When the laser reflected by the polygon mirror 494 rotating in the direction of the arrow shown in FIG. 2 passes through the f-θ lens 495 and enters the BD sensor 496, a detection signal is output from the BD sensor 496. The detection signal (BD signal) of the BD sensor 496 is input to the BD signal conversion unit 102 and then input to the image writing timing adjustment unit 104 to adjust the writing timing of the laser scanned on the surface of the photosensitive drum 43. Used for.

  As shown in FIG. 12, the light beams output from the laser light sources form images at different positions in the main scanning direction and the sub-scanning direction on the surface of the photosensitive drum 43 and the light receiving surface of the BD sensor 497. Is done. Therefore, since each light beam passes through the light receiving surface of the BD sensor 497 with a certain time difference, when all the light sources are operating normally, the light beam is output from the BD sensor 497 by scanning each light beam. Each BD signal is output in a state shifted by the time difference.

  Here, when a light beam is output from one laser light source for a certain period of time, the BD signal output from the BD sensor 496 has a maximum output signal of the BD sensor 496 from 0 (maximum change in signal level). The signal level of the BD sensor 496 has a trapezoidal shape having a rising edge and a falling edge. (See, for example, FIG. 5). The time difference is a pair of adjacent light receiving surfaces of the BD sensor 497 when the light beams of the respective laser light sources are scanned in the main scanning direction under standard environmental conditions such as factory shipment for higher resolution. When focusing on the spot light, each output waveform of the BD sensor 496 generated by these spot lights is set to a time difference such that the rising edge of one waveform intersects the falling edge of the other waveform. Yes.

  The optical scanning device 49 includes a reference oscillator 8 and an LD drive control circuit 10 including an image writing timing adjustment unit 104. The reference oscillator 8 outputs a reference clock signal. The LD drive control circuit 10 performs adjustment based on the reference clock signal, and drives and controls the laser irradiation unit 491 based on the image signal of the image to be written output from the image memory 9.

  The LD drive control circuit 10 includes an LD drive unit 101, a drawing unit 103, an image writing timing adjustment unit 104, and an abnormality detection processing unit 105.

  The image writing timing adjustment unit 104 adjusts the image writing timing for scanning the surface of the photosensitive drum 43 based on the BD signal input from the BD signal conversion unit 102, and outputs the image writing timing to the drawing unit 103. That is, the image writing timing adjustment unit 104 detects a BD signal, which will be described later, and then outputs an image writing signal to the drawing unit 103 after a predetermined reference clock count. The predetermined reference clock count number is determined for each machine at the time of adjustment at the time of machine manufacture.

  The drawing unit 103 starts driving of the LD driving unit 101 based on the image signal of the image to be written output from the image memory 9 by the image writing signal. The LD driving unit 101 drives and controls the laser irradiation unit 491 based on an instruction from the drawing unit 103. The BD signal conversion unit 102 outputs the BD signal output from the BD sensor 496 to the image writing timing adjustment unit 104.

  The abnormality detection processing unit 105 detects the presence or absence of abnormality such as a failure of each laser light source or the LD drive control circuit 10. If an abnormality such as a failure of each laser light source or LD drive control circuit 10 has occurred, no laser light is output from the laser light source in which the abnormality has occurred, and spot light is imaged on the light receiving surface of the BD sensor 496. The BD signal cannot be obtained from the laser light source. In the following description, not only when the laser light source itself has failed, but also when the circuit portion that drives the laser light source in the LD drive control circuit 10 fails, it is expressed as an abnormality of the laser light source. To do.

  Conventionally, if an abnormality occurs in each laser light source, a BD signal cannot be obtained from the laser light source, and a lighting instruction is output to the laser light source to rotate the polygon mirror 494 (main scanning). A laser that did not obtain a BD signal by performing a process for performing a rotation operation substantially individually equivalent to a rotation operation performed to form an image for one line on the photosensitive drum 43 in the direction (individually). Although it is determined that an abnormality has occurred in the light source, this method takes a very long time for the abnormality detection process.

  Further, as in the present embodiment, the light beams output from the laser light sources are located at different positions in the main scanning direction and the sub-scanning direction on the surface of the photosensitive drum 43 and the light receiving surface of the BD sensor 497. In the apparatus configured to form an image, when the environmental temperature of the multi function device 1 including the temperature of the laser irradiation unit 491 and the photosensitive drum 43 changes, the laser irradiation unit according to the change of the environmental temperature. The pitch (distance) between the spot lights changes due to factors such as deformation of various members in 491 and the like, and the crossing state and overlapping state of the waveform of the BD signal corresponding to each laser light source change. In particular, when the pitch between adjacent spotlights is much smaller than the appropriate value, the laser laser light is normally output based on the BD signal obtained from the BD sensor 496 at this time, as will be described later. This results in a laser light source that cannot be determined whether or not it is.

  For example, it is assumed that four laser light sources 1 to 4 are provided in the laser irradiation unit 491, and as shown in FIG. 12, the spot light by the laser beam of each laser light source 1 to 4 is expressed as spot light 1 to 4. . The spot light 1 and the spot light 2 are adjacent to each other, the spot light 2 and the spot light 3 are adjacent to each other, and the spot light 3 and the spot light 4 are adjacent to each other.

  In this case, when the light beams of the laser light sources 1 to 4 are scanned in the main scanning direction, the pitch between the adjacent spot lights becomes very smaller than the appropriate value, so that each laser light source is shown in FIG. When the BD signals corresponding to the laser beams output from 1 to 4 overlap each other, as shown by the solid line in FIG. 4A, the BD signal actually output from the BD sensor 496 The signal waveform is determined by the light receiving timing of the spot lights 1 and 4 passing through the light receiving surface of the BD sensor 496 in the first (first) and fourth (last), and the light received by the BD sensor 496 in the second and third. The spot lights 2 and 3 passing through the surface do not affect the BD signal output from the BD sensor 496 at all. That is, the signal waveform of the BD signal actually output from the BD sensor 496 is abnormal in the laser light source that generates the second and third spot lights 2 and 3 that pass through the light receiving surface of the BD sensor 496. However, this is the same as when no abnormality has occurred in the laser light sources 2 and 3, and in this case, the BD sensor 496 is the second and third BD sensor 496 from the signal waveform of the BD signal actually output from the BD sensor 496. It is impossible to distinguish whether or not an abnormality has occurred in the laser light sources 2 and 3 that generate the spot lights 2 and 3 that pass through the light receiving surface.

  Therefore, in the present embodiment, the following abnormality detection method can be used to shorten the abnormality detection time and identify the laser light source in which an abnormality has occurred even when the pitch between the spotlights changes. ing. In the following description, it is assumed that the process of outputting a lighting instruction to the laser light source and causing the polygon mirror 494 to perform the rotation operation is performed for each light source. The BD signal obtained in response to the above is called an individual BD signal, and is actually output from the BD sensor 496 when the waveforms of the individual BD signals intersect or overlap each other due to a narrow pitch between spot lights. A BD signal obtained by combining the individual BD signals is referred to as a combined BD signal.

  As shown in FIG. 5, two individual BD signals that are temporally continuous (individual BD signals generated by adjacent spot lights on the light receiving surface of the BD sensor 497) are separated from the rising edge of one BD signal and the other. When intersecting with the falling edge of the BD signal, as shown in FIG. 6A, the output waveform of the combined BD signal output from the BD sensor 496 has a constant protruding portion P that is locally protruded. The waveform has a time interval.

  The abnormality detection processing unit 105 instructs each laser light source to turn on the light, performs scanning in the main scanning direction, and uses a synthesized BD signal obtained by this scanning and a predetermined threshold value to perform laser scanning. A rectangular wave signal for detecting the presence or absence of abnormality of the light sources 1 to 4 is generated. That is, the abnormality detection processing unit 105 compares the signal level of the combined BD signal with a predetermined threshold value, and outputs an H (high) signal when the threshold value is larger.

  Here, as shown in FIG. 6A, when the predetermined threshold value is the threshold value 1, the threshold value 1 is higher than the level of the protruding portion P. Therefore, as shown in FIG. From the timing (point A) at which the falling edge of the individual BD signal corresponding to 1 and the threshold value 1 intersect to the timing (point B) at which the rising edge of the individual BD signal corresponding to beam light 4 and the threshold value 1 intersect , H (high) rectangular wave signal. In this case, the individual BD signals by the spot lights 2 and 3 that pass through the light receiving surface of the BD sensor 496 second and third are masked, and it is impossible to detect the presence or absence of abnormality in each of the laser light sources 1 to 4.

  On the other hand, as shown in FIG. 6A, when the predetermined threshold is, for example, a threshold 3 lower than the signal level of the protrusion P, the protrusion P is shown in FIG. 6C. As a result, the number of rectangular wave signals equal to the number of laser light sources is obtained. Thereby, it is possible to detect that the beam light is normally output from the laser light sources 1 to 4 due to the presence of each rectangular wave signal, and it is possible to detect that the laser light sources 1 to 4 are operating normally. it can.

  Further, as shown in FIGS. 3 and 4A, when the pitch of the light beams is relatively narrow, the protruding portion P as described above does not appear in the combined BD signal by each light beam. Therefore, even if the threshold value is changed, a period of L (low) temporarily does not occur, and abnormality of each laser light source cannot be detected.

  In this way, as shown in FIG. 5, when two individual BD signals output continuously in time intersect at the rising edge of one BD signal and the falling edge of the other BD signal, When the predetermined threshold value is lower than the signal level of the protruding portion P, the same number of rectangular wave signals as the number of laser light sources are obtained, and in other cases, the number of obtained rectangular wave signals and the number of laser light sources Does not match the number.

  When the number of obtained rectangular wave signals matches the number of laser light sources, the abnormality detection processing unit 105 determines that each laser light source is normal, while the number of obtained rectangular wave signals is equal to the number of laser light sources. If the predetermined threshold value is higher than the signal level of the protrusion P or the pitch of the beam light is relatively narrow, a laser in which an abnormality has occurred in the laser light source is detected. It is determined that there is a possibility that a light source exists, and the following processing is performed.

  First, a laser light source (here, laser light source 1) that generates spot light that passes through the light receiving surface of the BD sensor 496, and finally, a laser light source that generates spot light that passes through the light receiving surface of the BD sensor 496 (here, the laser light source 4). ) Is normal, the H (high) continuation time of the rectangular wave signal is constant. On the other hand, if an abnormality has occurred in at least one of the two laser light sources, the other laser light sources output. The magnitude relationship between the signal level of the individual BD signal by the spot light and the threshold value determines the rising timing or falling timing of the rectangular wave signal, and as a result, the H (high) duration of the rectangular wave signal changes. To do.

  For example, when the threshold value is the threshold value 1 shown in FIG. 4A and the laser light sources 1 and 4 are normal, the rising timing of the rectangular wave signal corresponds to the threshold value 1 and the spot lights 1 and 4. The timing (points C and D) at which the falling and falling edges of the individual BD signals intersect, and the H (high) duration T of the rectangular wave signal is the point C as shown in FIG. , D is a time determined.

  However, when an abnormality occurs in the laser light source 1, the beam light is not output from the laser light source 1, and the individual light beams by the spot light 2 of the laser light source 2 that passes on the light receiving surface of the BD sensor 496 next to the laser light source 1 are used. The timing (point E) at which the falling edge L1 of the BD signal intersects the threshold 1 is the rising timing of the generated rectangular wave signal. As a result, as shown in FIG. 4C, the H (high) duration of the rectangular wave signal changes from the duration T to the duration T1.

  In addition, when an abnormality occurs in the laser light source 4, the beam light is not output from the laser light source 4, and the individual light beams by the spot light 3 of the laser light source 3 passing on the light receiving surface of the BD sensor 496 before the laser light source 4 are used. The timing (point F) at which the rise L2 of the BD signal intersects the threshold 1 is the fall timing of the generated rectangular wave signal. As a result, as shown in FIG. 4C, the duration time of H (high) of the rectangular wave signal changes from the duration time T to the duration time T2.

  In this embodiment, using this, first, a laser light source that generates a spot light that passes through the light receiving surface of the BD sensor 496 and a spot light that passes through the light receiving surface of the BD sensor 496 are generated first. It is detected whether an abnormality has occurred in the laser light source.

  That is, H (high) continuation time (hereinafter referred to as an appropriate value T) of the rectangular wave signal when each of the laser light sources 1 to 4 is normal is examined in advance, and the abnormality detection processing unit 105 determines the appropriate value. A laser that first generates spot light that passes through the light-receiving surface of the BD sensor 496 when T and the duration time of H (high) of the actually obtained rectangular wave signal are compared, and they match. When it is determined that there is no abnormality between the light source and the laser light source that finally generates the spot light that passes through the light receiving surface of the BD sensor 496, if the two do not match, for example, H in the obtained rectangular wave signal When the (high) duration is the duration T1 or T2, the laser light source that first generates the spot light that passes through the light receiving surface of the BD sensor 496 and the light passing through the light receiving surface of the BD sensor 496 are finally passed. To Abnormality in at least one of the laser light source is determined that has occurred to generate the Tsu bets light. Hereinafter, the abnormality detection processing so far is referred to as abnormality detection processing 1.

  In the abnormality detection process 1, the abnormality detection processing unit 105 first generates a laser light source that generates a spot light that passes through the light receiving surface of the BD sensor 496, and finally generates a spot light that passes through the light receiving surface of the BD sensor 496. When it is determined that an abnormality has occurred in at least one of the laser light sources, a laser light source that outputs two beam lights adjacent to each other on the light receiving surface of the BD sensor 496 is executed as a process to be executed next. As a set, a lighting instruction is output to the two laser light sources belonging to the set as a set, and the polygon mirror 494 is rotated.

  For example, after turning on the laser light sources 1 and 2, the polygon mirror 494 is rotated, and after turning on the laser light sources 3 and 4, the polygon mirror 494 is rotated.

  FIG. 7A shows an individual BD signal (upper stage) obtained by the spot light generated by the laser light sources 1 to 4 by the processing as described above when the laser light sources 1 to 4 are normal, and the individual BD signal. The rectangular wave signal (lower stage) obtained from is shown.

  When the laser light sources 1 to 4 are normal using the same concept as the abnormality detection processing 1, the duration time of H (high) of each rectangular wave signal obtained for each set matches the appropriate value Tα. On the other hand, if an abnormality occurs in any of the laser light sources 1 to 4, the laser light sources 1 to 4 are based on the presence of a rectangular wave signal whose duration of H (high) does not match the appropriate value Tα. The operation of detecting the presence or absence of abnormality 4 is performed.

As shown in FIG. 7A, for example, when the laser light sources 1 and 2 are normal, a rectangular shape is formed at a timing (timing corresponding to the point X1) at which the falling edge of the BD signal by the light beam 1 intersects the threshold value. The wave signal rises, and the rectangular wave signal falls at the timing (timing corresponding to the point X2) at which the rising of the individual BD signal by the beam light 2 intersects the threshold value. At this time, the duration of the H (high) in the rectangular wave signal generated in that time T _12.

Further, as shown in FIG. 7A, when the laser light sources 3 and 4 are normal, the timing at which the falling edge of the individual BD signal by the beam 3 intersects the threshold (timing corresponding to the point X3). Then, the rectangular wave signal rises, and the rectangular wave signal falls at the timing (timing corresponding to the point X4) at which the rising of the individual BD signal by the light beam 4 intersects the threshold value. At this time, the duration of the H (high) in the rectangular wave signal generated in that time T _34.

When the laser light sources 1 to 4 are normal, these durations T ₁₂ and T ₃₄ are T ₁₂ = T ₃₄ = T _α .

However, for example, if an abnormality occurs in the laser light source 3, the beam light 3 is not output even if a lighting instruction is output to the laser light sources 3, 4. The signal rises at the timing when the fall of the signal and the threshold intersect (timing corresponding to the point X5 shown in FIG. 7B). As a result, the duration T ₃₄ ′ of H (high) in the rectangular wave signal is The duration is shorter than the duration T ₃₄ (T ₁₂ = T _α , T ₃₄ <T _α ). Hereinafter, the abnormality detection process from the end of the abnormality detection process 1 to the past is referred to as an abnormality detection process 2.

  Here, the description has been made on the assumption that the laser irradiation unit 491 has four laser light sources 1 to 4 mounted thereon, but the number of laser light sources mounted on the laser irradiation unit 491 is generally expressed as n. In this abnormality detection processing 2, when n is an even number, the polygon mirror 494 is rotated (n / 2) times (in order to form an image for one line on the photosensitive drum 43 in the main scanning direction). When n is an odd number, the polygon mirror 494 only needs to be rotated {(n-1) / 2 + 1} times. Further, when n is an even number, the duration of H (high) for (n / 2) rectangular wave signals, and when (n) is an odd number, {(n-1) / 2 + 1} rectangular wave signals. It is only necessary to check the duration of H (high) for each. Therefore, the number of rotations of the polygon mirror 494 and the number of rectangular wave signals for checking the H (high) duration time are approximately halved as compared with the conventional technique for checking the H (high) duration time for n rectangular wave signals. Can be reduced.

  After that, when there is a rectangular wave signal whose duration of H (high) is shorter than the appropriate value, the abnormality detection processing unit 105 turns on the two laser light sources belonging to the set corresponding to the rectangular wave signal. A process of outputting an instruction to cause the polygon mirror 494 to rotate is performed in units of light sources (individually). Then, the abnormality detection processing unit 105 obtains an individual BD signal for each light beam output from each laser light source, further generates a rectangular wave signal from the individual BD signal, and H (high) in the rectangular wave signal. It is determined whether or not the continuation time of the laser light source matches an appropriate value when the laser light sources are individually turned on, and if they match, it is determined that the laser light source corresponding to the rectangular wave signal is normal. If they do not match, it is determined that an abnormality has occurred in the laser light source corresponding to the rectangular wave signal. This makes it possible to detect which laser light source is abnormal in each group.

  In addition, when the process of outputting the lighting instruction to the laser light source and causing the polygon mirror 494 to perform the rotation operation is performed for each light source, the BD signal corresponding to the laser light source in which an abnormality has occurred is lost. Based on whether the number of BD signals obtained in the target set matches the number of laser light sources belonging to the set without generating a rectangular wave signal, A method of checking the presence or absence may be used.

  8 and 9 are flowcharts showing the abnormality detection process. In the following description, it is assumed that four laser light sources are provided in the laser irradiation unit 491 as in the above example.

  As shown in FIGS. 8 and 9, the abnormality detection processing unit 105 instructs each laser light source to turn on, and then rotates the polygon mirror 494 (images for one line in the main scanning direction are photosensitive drums 43). (Step # 1), a rectangular wave signal is generated based on the BD signal output from the BD sensor 496 (step # 2).

  Next, the abnormality detection processing unit 105 determines whether or not the number of rectangular wave signals generated in step # 2 is the same as the number of laser light sources (here, four) (step # 3). (YES in step # 3), while it is determined that all of the laser light sources 1 to 4 are normal (step # 4), and if they do not exist (NO in step # 3), H ( High) is calculated (step # 5).

  Abnormality detection processing unit 105 determines whether or not the duration calculated in step # 5 matches the appropriate value obtained in advance (step # 6). If they match (YES in step # 6), First, a laser light source (here, laser light source 1) that generates spot light that passes through the light receiving surface of the BD sensor 496, and finally, a laser light source that generates spot light that passes through the light receiving surface of the BD sensor 496 (here, the laser light source 4). ) Is determined to be normal (step # 7), but if they do not match (NO in step # 6), an abnormality has occurred in at least one of the laser light sources (here, laser light sources 1 and 4). (Step # 8).

  After the processing of step # 7 or # 8, the abnormality detection processing unit 105 sets each laser light source as one set of laser light sources that output two beam lights adjacent to the spot light on the light receiving surface of the BD sensor 496. Rotation operation of the polygon mirror 494 after instructing lighting of two laser light sources (rotation operation substantially equivalent to the rotation operation performed to form an image for one line on the photosensitive drum 43 in the main scanning direction) Are performed in pairs (steps # 9 to # 12), and a rectangular wave signal is generated based on the BD signal output from the BD sensor 496 (steps # 13 and # 14). Then, abnormality detection processing unit 105 calculates the duration of H (high) in the rectangular wave signal generated in steps # 13 and # 14 (steps # 15 and # 16).

  After the processing of step # 15, the abnormality detection processing unit 105 determines whether or not the duration time of H (high) for all the rectangular wave signals matches the appropriate value (step # 17). On the other hand (YES in step # 17), it is determined that all of the laser light sources 1 to 4 are normal (step # 18). A process of outputting a lighting instruction to each laser light source of the set corresponding to the rectangular wave signal and causing the polygon mirror 494 to rotate is performed for each light source (step # 19).

  In addition, after the process of step # 16, the abnormality detection processing unit 105 detects a rectangular wave signal whose duration of H (high) does not match the appropriate value (step # 20), and executes the process of step # 19. . Then, the abnormality detection processing unit 105 determines that an abnormality has occurred in the laser light source for which the rectangular wave signal has not been obtained after the process of step # 19 (step # 21).

  As described above, after instructing each laser light source to turn on, the polygon mirror 494 is rotated, and a rectangular wave signal is generated based on the BD signal output from the BD sensor 496. Since the number of rectangular wave signals obtained matches the number of laser light sources, that is, when each laser light source is normal, the number of operations of the polygon mirror 494 and the rectangular wave signal are Only one check is required. As a result, since the number of times can be significantly reduced as compared with the prior art, the time required for detecting the abnormality of the light source can be shortened.

  Also, if the number of rectangular wave signals and the number of laser light sources do not match by this processing, a set of laser light sources that output two beam lights adjacent to each other on the light receiving surface of the BD sensor 496, Since a lighting instruction is output to two laser light sources belonging to the set for each set and the polygon mirror 494 is rotated, the set of polygon mirrors with no abnormality in the laser light source The number of operations 494 and the number of times of checking the rectangular wave signal are one. As a result, since the number of times can be reduced as compared with the prior art, the time required for detecting the abnormality of the light source can be shortened.

  In addition, this case includes the following forms instead of or in addition to the above embodiments.

  (1) In the above embodiment, when the rectangular wave signal is generated using a predetermined threshold, and the number of the rectangular wave signals does not match the number of laser light sources, the abnormality detection processing 1 However, the present invention is not limited to this. For example, the threshold value is changed from the threshold value 1 shown in FIG. 6A to the threshold value 3, and the rectangular wave signal is generated again using the changed threshold value. When the number of wave signals and the number of laser light sources are repeatedly checked, the abnormality detection is performed when the number of rectangular wave signals and the number of laser light sources does not match and the changeable threshold is exhausted. Processing 1 may be executed.

  (2) As a process to be performed when the number of rectangular wave signals does not match the number of laser light sources, a lighting instruction is output to the laser light source as in the past, in addition to the processes shown in FIGS. Then, the process of causing the polygon mirror 494 to perform the rotation operation may be performed for each light source. FIG. 10A corresponds to the beam light output from each laser light source when the process of outputting a lighting instruction to the laser light source and causing the polygon mirror 494 to rotate is performed in units of light sources. FIG. 10B is a diagram showing a rectangular wave signal generated based on the BD signal shown in FIG. 10A. In this case, each laser light source is normal. It is judged that there is.

  FIG. 10C shows a case where a BD signal is obtained for a certain laser light source when a process of outputting a lighting instruction to the laser light source and causing the polygon mirror 494 to rotate is performed in units of light sources. FIG. 10D shows a state in which a rectangular wave signal is not generated correspondingly, and FIG. 10D shows a laser light source in which this rectangular wave signal has not been generated. It is detected that an abnormality has occurred.

  (3) In the embodiment described above, there is an abnormality in the laser light source that first generates the spot light that passes through the light receiving surface of the BD sensor 496 and the laser light source that generates the spot light that passes through the light receiving surface of the BD sensor 496. Although the abnormality detection process 2 is performed after detecting whether or not it has occurred, the present invention is not limited to this. First, a laser light source that generates spot light that passes through the light receiving surface of the BD sensor 496, and finally, The abnormality detection process 2 may be performed without detecting whether or not an abnormality has occurred in the laser light source that generates the spot light that passes through the light receiving surface of the BD sensor 496.

  (4) As shown in FIG. 5, two individual BD signals that are temporally continuous (individual BD signals generated by adjacent spot lights on the light receiving surface of the BD sensor 497) are rising edges of one BD signal. In a state where the signal intersects with the falling edge of the other BD signal, the abnormality can be detected by the following method.

  That is, a pair is generated between laser light sources that generate spot lights that are not adjacent on the light receiving surface of the BD sensor 496, and each laser light source is grouped (the number of sets is not limited to two). A lighting instruction may be output to cause the polygon mirror 494 to perform a rotation operation in pairs.

  For example, as shown in FIG. 11, the abnormality detection processing unit 105 uses laser light sources 1 to 4 as a set of laser light sources 1 and 3 (hereinafter referred to as a first set) and a set of laser light sources 2 and 4 (hereinafter referred to as a second set). First, in the first group, a lighting instruction is output to the laser light sources 1 and 3 to cause the polygon mirror 494 to perform the rotation operation in units of groups, and then in the second group Then, a lighting instruction is output to the laser light sources 2 and 4 to cause the polygon mirror 494 to perform the rotation operation in pairs.

  FIG. 11A shows a BD signal obtained when the laser light from the laser light sources 1 and 3 is scanned in the main scanning direction when the laser light sources 1 and 3 are normal. ) Shows a BD signal obtained when the laser light from the laser light sources 2 and 4 is scanned in the main scanning direction when the laser light sources 2 and 4 are normal.

  In each group, when the laser light sources belonging to the group are normal, the number of laser light sources belonging to the group coincides with the number of BD signals. On the other hand, when an abnormality has occurred in any of the laser light sources, the BD signal corresponding to the laser light source in which the abnormality has occurred is missing from the BD signals shown in FIGS. FIG. 11C is a diagram illustrating a waveform of a BD signal when an abnormality occurs in the laser light source 3 or the laser light source 4. Therefore, a laser in which an abnormality has occurred based on whether or not the number of BD signals obtained for each set matches the number of laser light sources belonging to the set without generating a rectangular wave signal. The presence or absence of a light source can be checked for each set.

  Although the number of laser light sources is four here, the number of laser light sources is not limited. As another example of the laser light source grouping method, for example, when a number is assigned to the arrangement direction of the spot light on the light receiving surface of the BD sensor 496, the laser corresponding to the spot light to which the odd number is assigned. A group of light sources and a group of laser light sources corresponding to spot lights to which even numbers are assigned may be grouped, or for example, a number represented by 3n (n is an integer) is assigned. A set of laser light sources corresponding to the spot light, a set of laser light sources corresponding to the spot light assigned the number represented by 3n + 1, and a laser light source corresponding to the spot light assigned the number represented by 3n + 2 A method of grouping into groups is assumed.

  In addition, for the group that has been determined that there is a possibility that an abnormal laser light source may exist due to this processing, the polygon mirror 494 is rotated by outputting a lighting instruction for the laser light source of the group. The presence or absence of an abnormal laser light source is determined based on whether or not the number of BD signals obtained in the set matches the number of laser light sources belonging to the set. Check it out.

1 is a side view schematically showing an internal configuration of a multifunction peripheral as an example of an image forming apparatus according to an embodiment of the present disclosure. It is a block diagram of an optical scanning device. It is a figure which shows the state in which each BD signal corresponding to each laser beam output from each laser light source has overlapped with each other most. It is a figure which shows an example of the signal waveform of the BD signal actually output from a BD sensor, and an example of the square wave signal produced | generated. It is a figure which shows the state in which each BD signal corresponding to each laser beam output from each laser light source intersects at a rising edge and a falling edge. It is a figure which shows an example of the signal waveform of the BD signal actually output from a BD sensor, and an example of the square wave signal produced | generated. It is explanatory drawing of the abnormality detection process. It is a flowchart which shows an abnormality detection process. It is a flowchart which shows an abnormality detection process. It is explanatory drawing of the abnormality detection processing method which concerns on a deformation | transformation form. It is explanatory drawing of the abnormality detection processing method which concerns on a deformation | transformation form. It is a figure which shows the state in which each light beam output from each said laser light source is imaged in a position which is each different in the main scanning direction and a subscanning direction on the surface of a photoconductive drum, or the light-receiving surface of a BD sensor.

49 Optical Scanning Device 101 LD Drive Unit 105 Abnormality Detection Processing Unit 496 BD Sensor

Claims (6)

A light receiving unit that outputs an electrical signal according to the intensity of the received light, and light toward each target position in which the position in the first direction and the position in the second direction orthogonal to the first direction are different. The light source in an optical scanning device comprising: a plurality of light sources to output; and a scanning unit for scanning the output light of each light source in the first direction on the light receiving surface of the light receiving unit and on the surface of the photoreceptor. A light source abnormality detection method for detecting the presence or absence of abnormality of
The light source abnormality detection unit
A first step of operating the scanning unit after outputting a lighting instruction to each of the light sources;
A second step of comparing the signal level of the output signal of the light receiving unit obtained in the first step with a predetermined threshold value and generating a rectangular wave signal according to the comparison result;
It is determined whether or not the number of rectangular wave signals generated in the second step matches the number of light sources. If it is determined that the number of rectangular wave signals matches, it is determined that each light source is normal and the number of rectangular wave signals is If the number of light sources does not match, the third step of determining that there is a possibility that there is a light source in which an abnormality has occurred among the plurality of light sources;
In the third step, when it is determined that there is a possibility that there is a light source in which an abnormality has occurred among the plurality of light sources, the two light sources that output light adjacent to the target position are set as one set. A fourth step of grouping the light sources and outputting the lighting instruction to the two light sources belonging to the group in units of groups and operating the scanning unit;
A fifth step of comparing the signal level of the output signal of the light receiving unit in each set obtained in the fourth step with a predetermined threshold and generating a rectangular wave signal according to the comparison result;
When the rectangular wave signal generated in the fifth step is compared with the first rectangular wave signal that is set in advance and stored in the storage unit for the rectangular wave signal, and the two rectangular wave signals match. Determines that the two light sources of the set corresponding to the target rectangular wave signal compared with the first rectangular wave signal are normal, and if the two rectangular wave signals do not match, the first light source A light source abnormality detection method comprising: a sixth step of determining that there is a possibility that a light source having an abnormality exists in a set corresponding to a target rectangular wave signal compared with a rectangular wave signal . The light source abnormality detection unit is
Between the third step and the fourth step,
When the rectangular wave signal generated in the second step is compared with the second rectangular wave signal that is preset with respect to the rectangular wave signal and stored in the storage unit, and both rectangular wave signals match Among the plurality of light sources, when the scanning unit is operated, a light source that outputs light that should first pass through the light receiving surface and a light that should finally pass through the light receiving surface are output. If both the rectangular wave signals do not match, the light source that outputs light that should first pass through the light receiving surface and the light that should finally pass through the light receiving surface are determined. The light source abnormality detection method according to claim 1 , further comprising a seventh step of determining that there is a possibility that an abnormality has occurred in at least one of the light sources that output the light. The light source abnormality detection unit is
An eighth step of operating the scanning unit after outputting a lighting instruction in units of light sources for each light source belonging to the group for which it is determined that there is a possibility that a light source having an abnormality in the sixth step exists; ,
When an output signal is obtained from the light receiving unit in the eighth step, it is determined that the light source corresponding to the output signal is normal, and when the output signal is missing from the light receiving unit, the missing signal light source abnormality detecting method according to claim 1 or 2 and a ninth step of determining that an abnormality has occurred in the light source corresponding to the received light signal. A light receiving unit that outputs an electrical signal according to the intensity of the received light, and light toward each target position in which the position in the first direction and the position in the second direction orthogonal to the first direction are different. The light source in an optical scanning device comprising: a plurality of light sources to output; and a scanning unit for scanning the output light of each light source in the first direction on the light receiving surface of the light receiving unit and on the surface of the photoreceptor. A light source abnormality detection method for detecting the presence or absence of abnormality of
The light source abnormality detection unit
A first step of operating the scanning unit after outputting a lighting instruction to each of the light sources;
A second step of comparing the signal level of the output signal of the light receiving unit obtained in the first step with a predetermined threshold value and generating a rectangular wave signal according to the comparison result;
It is determined whether or not the number of rectangular wave signals generated in the second step matches the number of light sources. If it is determined that the number of rectangular wave signals matches, it is determined that each light source is normal and the number of rectangular wave signals is If the number of the light sources does not match, the plurality of light sources in the third step and the third step for determining that there is a possibility that there is a light source having an abnormality among the plurality of light sources. If it is determined that there is a possibility that there is a light source in which an abnormality has occurred, each light source is grouped by a combination of light sources whose target positions are not adjacent to each other, and each light source belonging to the group is grouped A tenth step of operating the scanning unit after outputting a lighting instruction to
Whether the number of output signals of the light receiving unit in each set obtained in the tenth step matches the number of light sources belonging to the set is determined for each set, and the number matches the number of light sources If it is determined that the light sources belonging to the set are normal, and if the number does not match the number of the light sources, there is a possibility that there is a light source having an abnormality in the set A light source abnormality detection method comprising: an eleventh step of determining. The light source abnormality detection unit is
A twelfth step of operating the scanning unit after outputting a lighting instruction in units of light sources for each light source belonging to the set determined that there is a possibility that the light source in which the abnormality has occurred in the eleventh step is present. When,
When an output signal is obtained from the light receiving unit in the twelfth step, it is determined that the light source corresponding to the output signal is normal, and when the output signal is missing from the light receiving unit, the missing signal The light source abnormality detection method according to claim 4 , further comprising a thirteenth step of determining that an abnormality has occurred in the light source corresponding to the light reception signal. A light receiving unit that outputs an electrical signal according to the intensity of the received light, and light toward each target position in which the position in the first direction and the position in the second direction orthogonal to the first direction are different. An optical scanning device comprising: a plurality of light sources for outputting; and a scanning unit for scanning the output light of each light source in the first direction on the light receiving surface of the light receiving unit and on the surface of the photoreceptor. ,
The light receiving unit is a BD sensor that outputs a BD signal for adjusting a light beam scanning start timing for generating an electrostatic latent image for image formation on the surface of the photoreceptor,
Optical scanning apparatus comprising a light source abnormality detecting unit according to any one of claims 1 to 5 for detecting the presence or absence of abnormality of the light source.

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