JP2020042204A - Information processing device and image forming device - Google Patents

Abstract

To provide an image forming device for specifying a reflection plane of a plurality of rotary polygon mirrors.SOLUTION: The image forming device comprises: a laser scanner unit 109 for scanning a photosensitive drum 108 with a laser beam deflected by a reflection plane of a polygon mirror 204; an engine control part 205; and an image control part 500. The engine control part 205 generates a BD signal 208 for imaging that corresponds to a BD signal 207 outputted from the laser scanner unit 109. The image control part 500 identifies a reflection plane in accordance with the rising edge and falling edge timings of a BD delay signal 503, which is a delayed version of the BD signal 207, and the BD signal 208 for imaging. The image control part 500 corrects image data in accordance with the identified reflection plane and controls an image forming process.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus such as an electrophotographic printer, a copying machine, a facsimile machine, etc., which forms an image using a laser beam.

  An electrophotographic image forming apparatus has a laser scanner unit for exposing a photoreceptor. The laser scanner unit includes a light source that emits laser light based on image data representing an image to be formed, a rotating polygon mirror (polygon mirror) having a plurality of reflection surfaces, and a scanning lens. The laser scanner unit reflects a laser beam sequentially from each reflection surface of the polygon mirror, and irradiates and exposes the photosensitive member by transmitting the laser beam through a scanning lens. The laser scanner unit scans by moving the spot of the laser beam on the surface of the photoconductor by rotating the polygon mirror. As a result, an electrostatic latent image is formed on the photoconductor.

  An optical system such as a scanning lens is provided to correct an error in an exposure position for each reflection surface. However, for each reflection surface of the polygon mirror, a correction residual that cannot be corrected by the optical system alone occurs. This correction residual causes distortion of a formed image. Patent Literature 1 discloses a technique in which a reflection surface that scans a photoconductor is specified from a cycle of a synchronization signal based on light reflected from each reflection surface of a polygon mirror, and a magnification of an image is corrected for each reflection surface. I do.

JP 2013-117699 A

  In Patent Literature 1, if noise is mixed in the synchronization signal, there is a possibility that the reflection surface of the polygon mirror cannot be accurately specified. If the reflection surface of the polygon mirror cannot be accurately specified, appropriate correction corresponding to each reflection surface cannot be performed, and the formed electrostatic latent image may be distorted.

  The present invention has been made in view of the above problems, and has as its main object to provide an information processing apparatus that controls the operation of an image forming apparatus that specifies the reflection surfaces of a plurality of rotating polygon mirrors with high accuracy. I do.

  The information processing apparatus of the present invention is a photoreceptor, a light source that outputs light, a rotating polygon mirror that scans the photoreceptor by continuously reflecting the light output from the light source by a plurality of reflection surfaces, A detection unit that outputs a detection signal that is at a first level while detecting the light reflected by the rotating polygon mirror and that is at a second level while the light is not detected; A laser scanner unit for forming an image on a body, and control means for controlling the operation of the laser scanner unit and generating a synchronization signal in accordance with the detection signal; A delay signal generating means for generating a delay signal obtained by delaying the signal by a predetermined delay amount, a transition timing of the delay signal and the synchronization signal from the first level to the second level, and Image data representing an image to be formed by identification means for identifying the plurality of reflection surfaces in accordance with a transition timing from two levels to the first level, and correction data corresponding to the reflection surfaces identified by the identification means , And image output means for transmitting the corrected image data to the laser scanner unit.

  According to the present invention, it is possible to specify the reflection surfaces of a plurality of rotary polygon mirrors with high accuracy.

FIG. 1 is a configuration diagram of an image forming apparatus. FIG. 2 is a block diagram showing a conventional laser scanner unit and its peripheral configuration. 6 is a timing chart of a reflection surface specifying process. (A)-(c) is explanatory drawing of a reflective surface specification. FIG. 2 is a block diagram showing a peripheral configuration of the laser scanner unit according to the embodiment. FIG. 7 is an explanatory diagram of a timing comparison result. 7 is a timing chart at the time of comparing a BD delay signal with an imaging BD signal. 7 is a timing chart at the time of comparing a BD delay signal with an imaging BD signal. 7 is a timing chart at the time of comparing a BD delay signal with an imaging BD signal. 9 is a flowchart illustrating a surface identification process.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(overall structure)
FIG. 1 is a cross-sectional view illustrating a configuration of a monochrome electrophotographic image forming apparatus. The image forming apparatus 100 is, for example, a copying machine, a facsimile machine, a printing machine, a printer, or the like. Further, the image forming apparatus 100 may be in either monochrome or color format. Hereinafter, the configuration and functions of the image forming apparatus 100 will be described.

  Inside the image forming apparatus 100, a cassette sheet feeding unit 101 is provided. The recording medium stored in the cassette paper feeding unit 101 is fed by a pickup roller 102. The fed recording medium is separated and conveyed one by one by a separation roller pair 103 including a feed roller and a retard roller. The separated recording medium is conveyed to a registration roller pair (hereinafter, referred to as a “registration roller pair”) 106 in a stopped state by conveyance roller pairs 104 and 105. The leading end of the recording medium conveyed by the conveying roller pair 105 contacts the nip portion of the registration roller pair 106 in a stopped state. When the conveying roller pair 105 further conveys the recording medium while the leading end of the recording medium is in contact with the nip portion of the registration roller pair 106 in a stopped state, the recording medium is bent. As a result, an elastic force acts on the recording medium, and the leading edge of the recording medium contacts the nip portion of the registration roller pair 106. In this way, the skew of the recording medium is corrected. After the skew of the recording medium is corrected, the registration roller pair 106 starts conveying the recording medium at a timing described later. Note that a recording medium is an image on which an image is formed by the image forming apparatus 100. For example, paper, a resin sheet, cloth, an OHP sheet, a label, and the like are included in the recording medium.

  Inside the image forming apparatus 100, a charger 107 for forming an image, a photosensitive drum 108, a laser scanner unit 109, a developing unit 110, a transfer roller 111, and a fixing unit 112 are provided. The outer peripheral surface of the photosensitive drum 108 is charged by the charger 107. The laser scanner unit 109 irradiates the charged outer peripheral surface of the photosensitive drum 108 with laser light corresponding to image data representing an image to be formed. As a result, an electrostatic latent image is formed on the photosensitive layer (photoconductor) covering the outer peripheral surface of the photosensitive drum 108. The details of laser beam irradiation by the laser scanner unit 109 will be described later.

  Subsequently, a toner image is formed on the outer peripheral surface of the photosensitive drum 108 by developing the electrostatic latent image with the toner in the developing device 110. The toner image formed on the photosensitive drum 108 is transferred to a recording medium by a transfer roller 111 provided at a position (transfer position) facing the photosensitive drum 108. The registration roller pair 106 conveys the recording medium to the transfer position at a timing such that the toner image is transferred to a predetermined position on the recording medium. Between the pair of registration rollers 106 and the transfer position, a registration sensor 209 for detecting a recording medium to be conveyed is provided.

  The recording medium to which the toner image has been transferred is conveyed to the fixing device 112 and heated and pressed by the fixing device 112 to fix the toner image. The recording medium on which the toner image has been fixed is discharged to a discharge tray 113 outside the apparatus. Thus, the image is formed on the recording medium by the image forming apparatus 100. The above is the description of the configuration and functions of the image forming apparatus 100.

(Laser scanner unit)
FIG. 2 is a block diagram showing a conventional laser scanner unit 109 and its peripheral configuration. Hereinafter, the configuration of the laser scanner unit 109 will be described. The engine control unit 205 and the image control unit 212 are connected to the laser scanner unit 109. The engine control unit 205 and the image control unit 212 control the operation of the laser scanner unit 109. The image control unit 212 corresponds to the information processing device of the present invention. In the present embodiment, the engine control unit 205 and the image control unit 212 are provided on different boards.

  The laser scanner unit 109 includes a laser light source 200, a collimator lens 203, a polygon mirror 204, a photodiode (PD) 202, a beam detection (BD) sensor 206, an F-θ lens 217, and a folding mirror 218. The laser scanner unit 109 includes a laser control unit 201 that controls light emission of the laser light source 200 in accordance with image data input from the image control unit 212.

  The laser light source 200 emits laser light in two directions using light emitting elements. Laser light emitted in one direction from the laser light source 200 enters the photodiode 202. The photodiode 202 converts the incident laser light into an electric signal and transmits the electric signal to the laser control unit 201 as a PD signal. The laser control unit 201 controls the output light amount (APC: Auto Power control) of the laser light source 200 based on the PD signal so that the laser light has a predetermined light amount. Here, since well-known APC control is performed, detailed description is omitted.

  Laser light emitted from the laser light source 200 in another direction is applied to the polygon mirror 204 via the collimator lens 203. The polygon mirror 204 is a rotary polygon mirror having a plurality of reflection surfaces and driven to rotate by a polygon motor (not shown). The polygon mirror 204 of the present embodiment has four reflecting surfaces. The polygon motor rotates and drives the polygon mirror 204 according to a drive signal 220 output from the engine control unit 205.

  The laser light applied to the polygon mirror 204 is deflected toward the photosensitive drum 108 by the reflection surface. The rotation of the polygon mirror 204 changes the deflection angle. The laser beam scans the photosensitive drum 108 in one direction due to the change in the deflection angle. In the present embodiment, the laser beam scans the photosensitive drum 108 from right to left in FIG. The optical path of the laser light is corrected by the F-θ lens 217 so as to scan the photosensitive drum 108 at a constant speed, and the laser light is applied to the photosensitive drum 108 via the folding mirror 218.

  A part of the laser light deflected by the polygon mirror 204 is received by the BD sensor 206. The BD sensor 206 of the present embodiment is a detection unit disposed at a position where the laser beam can be detected before the laser beam starts scanning the photosensitive drum 108. More specifically, for example, as shown in FIG. 2, the BD sensor 206 scans the area outside the area where the photosensitive drum 108 is scanned and the area where the laser light reflected by the polygon mirror 204 passes. It is arranged in the region on the upstream side in the direction (main scanning direction).

  The BD sensor 206 generates a BD signal 207 having a first level and a second level based on the detected laser light, and transmits the signal to the engine control unit 205. The BD signal 207 is, for example, a negative logic signal, and is at a first level (Low) while the BD sensor 206 is detecting laser light, and is at a second level while the BD sensor 206 is not detecting laser light. (High) detection signal. The engine control unit 205 controls the polygon motor based on the obtained BD signal 207 such that the rotation cycle of the polygon mirror 204 becomes a predetermined cycle. The engine control unit 205 determines that the rotation cycle of the polygon mirror 204 is stable at the predetermined cycle when the cycle of the BD signal 207 is the predetermined cycle. That is, the engine control unit 205 performs feedback control such that the rotation of the polygon mirror 204 is stabilized at a predetermined cycle by adjusting the drive signal 220 based on the BD signal 207. When the rotation of the polygon mirror 204 is stabilized (when the rotation cycle becomes a predetermined cycle), the engine control unit 205 restarts the conveyance of the stopped recording medium by the registration roller pair 123.

  When detecting the recording medium whose conveyance has been resumed, the registration sensor 209 notifies the engine control unit 205 of the detection of the recording medium (TOP signal 210). The engine control unit 205 includes a CPU (Central Processing Unit) 211 and an imaging BD signal generation unit 219. The imaging BD signal generation unit 219 generates an imaging BD signal 208 according to the BD signal 207. The BD signal for image formation 208 is a negative logic signal similar to the BD signal 207. The relationship between the BD signal 208 for image formation and the BD signal 207 will be described later. The imaging BD signal 208 is input to the image control unit 212.

  The image control unit 212 includes a CPU 213, an image output unit 215, a surface identification unit 222, an image correction unit 227, and a dynamic random access memory (DRAM) 228. The surface identification unit 222 includes a BD width counter 223, a control register 224, and a surface determination unit 225. Upon acquiring a predetermined number of BD signals 208 for image formation, the image control unit 212 outputs image data 214 to the laser control unit 201 in synchronization with the BD signal 208 for image formation. The laser control unit 201 forms an electrostatic latent image on the photosensitive drum 108 by blinking and driving the laser light source 200 based on the image data 214.

(Surface specification processing to specify the reflection surface of the polygon mirror)
An image (electrostatic latent image) may be distorted due to individual differences in the shape of each reflecting surface of the polygon mirror 204 or inclination due to attachment. For this purpose, conventionally, each reflection surface of the polygon mirror 204 is specified, and surface correction for correcting image data is performed according to the specified result. FIG. 3 is a timing chart of the reflection surface identification processing. FIG. 4 is an explanatory diagram for specifying the reflection surface.

  Time T1: The CPU 211 of the engine control unit 205 acquires the CMD signal 221 including the print start command from the CPU 213 of the image control unit 212, and drives the polygon mirror 204 to rotate.

  Time T2: The engine control unit 205 acquires the BD signal 207 from the BD sensor 206, and starts identifying the reflective surface according to the BD signal 207. The reflection surface is identified by measuring the period of the BD signal 207.

  In the polygon mirror 204 having four reflecting surfaces as in the present embodiment, a BD signal 207 as illustrated in FIG. 4A is generated. The BD signal 207 generated by each reflecting surface is a signal having a different period according to the characteristics of each reflecting surface. The engine control unit 205 sets the A-plane to the D-plane for four consecutive BD signals, and identifies the reflection surface. The engine control unit 205 acquires the BD signal for each of the planes A to D a predetermined number of times (for example, 32 times), and calculates the average value of the period of the acquired BD signal for each of the planes A to D. The engine control unit 205 compares the calculated average value of the period of the BD signal of the A surface to the D surface with the previously measured period of the BD signal of each of the reflecting surfaces (the first to fourth surfaces), thereby obtaining the BD signal. The reflection surface corresponding to the signal 207 is identified. FIG. 4B exemplifies the cycle of the BD signal of each reflecting surface measured in advance. FIG. 4C illustrates an example of the average value of the period of the BD signal on the A plane to the D plane. The engine control unit 205 identifies the reflection surface by comparing FIG. 4B and FIG. 4C.

  Time T3: The engine control unit 205 causes the imaging BD signal generation unit 219 to generate the imaging BD signal 208 based on the reflection surface identification result. The imaging BD signal generation unit 219 changes the pulse width of the BD signal 207 corresponding to a specific reflection surface (for example, the first surface), and does not change the pulse width of the BD signal 207 corresponding to a portion other than the specific reflection surface. Then, an image forming BD signal 208 is generated. The imaging BD signal 208 has a different pulse width, but one cycle is the same as the BD signal 207, and the transition timing from the first level to the second level (falling edge in the present embodiment) is the same as that of the BD signal 207. This is a synchronization signal for synchronization. The imaging BD signal generation unit 219 transmits the generated imaging BD signal 208 to the image control unit 212. Note that the imaging BD signal 208 is a signal that is delayed from the BD signal 207 by the circuit delay amount ΔT of the imaging BD signal generation unit 219.

  The image control unit 212 detects a difference in pulse width of the imaging BD signal 208 obtained from the imaging BD signal generation unit 219, and reflects the reflection surface of the polygon mirror 204 corresponding to each pulse of the imaging BD signal 208. Identify. The details of the specification of the reflection surface and the correction (surface correction) of the image data according to the specified reflection surface will be described.

  The surface specifying unit 222 of the image control unit 212 measures the first level width (Low width) of the BD signal 208 for image formation by using the BD width counter 223, and the measured first level width is equal to or larger than the threshold. It is determined whether or not. The operation control of the BD width counter 223 and the setting of the threshold value are performed by the control register 224. The control register 224 starts operation control of the BD width counter 223 before the CPU 213 issues a print start command, and sets a threshold value.

  When the first level width counted by the BD width counter 223 is equal to or larger than the threshold, the surface determination unit 225 determines that the image forming BD signal is reflected light of a specific reflection surface (first surface). The surface identification unit 222 transmits the determination result of the reflection surface to the image correction unit 227 as the surface identification signal 226. The image correction unit 227 corrects the image data stored in the DRAM 228 according to the correction data corresponding to the reflection surface represented by the surface identification signal 226. Thus, the specification of the reflection surface and the correction of the image data are performed.

Time T4: When the registration sensor 209 detects the recording medium and the TOP signal 210 is asserted, the engine control unit 205 transmits a CMD signal 221 including an image formation enable command to the image control unit 212. When the image output unit 215 of the image control unit 212 counts a predetermined number of the imaging BD signals 208 after receiving the imaging enable command, the image output unit 215 sends the image data 214 to the laser control unit 201 in synchronization with the imaging BD signal 208. Start sending. The image data 214 is image data after correction by the image correction unit 227.
As described above, the print job including the surface correction is performed.

  Here, the circuit scale of the BD width counter 223 will be described. The BD width counter 223 normally requires a counter circuit exceeding 30 bits, depending on the detection accuracy and the detection cycle of the BD signal. The hardware resources required for the counter circuit depend on the counting method, but are generally large. Further, since the number of logic gates for carry control increases as the number of multi-bit counters increases, the circuit scale of a counter circuit exceeding 30 bits becomes extremely large. For this reason, in the present embodiment, the scale of the surface specifying unit 222 is made smaller than in the related art by specifying the reflection surface without measuring the pulse width of the BD signal for image formation.

  FIG. 5 is a block diagram illustrating a peripheral configuration of the laser scanner unit 109 of the present embodiment. 2 is different from the conventional block diagram of FIG. 2 only in the configuration of the surface specifying unit 501, and the other configurations are the same. A different configuration will be described.

  The plane identification unit 501 includes a delayed BD signal generation unit 502, a BD phase comparison unit 504, and a control register 505. The BD sensor 206 inputs a BD signal 207 to the engine control unit 205 and the image control unit 500. The BD signal 207 is input to the delayed BD signal generation unit 502 of the plane identification unit 501. The delayed BD signal generation unit 502 is a delay signal generation unit that generates a BD delay signal 503 obtained by delaying the BD signal 207 according to a set value (delay amount) set in the control register 505 by the CPU 213. The BD delay signal 503 is input to the BD phase comparison unit 504.

  The CPU 213 sets a delay amount equivalent to the circuit delay amount ΔT of the image forming BD signal generation unit 219 in the control register 505. The specific value of the circuit delay amount ΔT is stored in the engine control unit 205 in advance. The CPU 213 acquires a CMD signal 221 including a specific value from the engine control unit 205 when the image forming apparatus 100 starts up.

  The BD phase comparison unit 504 compares the rising edge and the falling edge of the BD delay signal 503 with the imaging BD signal 208. The surface identification unit 501 identifies the reflection surface by determining the pulse width of the first signal of the imaging BD signal 208 without using a counter circuit, based on the timing comparison result, and identifies the reflection surface, and identifies the identified reflection surface. The signal 226 is transmitted to the image correction unit 227.

  The wiring for transmitting the BD signal 207 from the BD sensor 206 to the image control unit 500 and the wiring for transmitting the imaging BD signal 208 from the engine control unit 205 to the image control unit 500 are as close as possible. Provided. For example, it is preferable that wiring is performed close to the same film by using an FFC (Flexible Flat Cable). This is to make the influence and timing of the external noise between the units equal between the BD signal 208 for image formation and the BD signal 207. As will be described later in detail, it is possible to determine a signal due to the influence of noise on the BD signal for image formation 208.

  FIG. 6 is an explanatory diagram of a timing comparison result in the BD phase comparison unit 504. In FIG. 6, the result of the timing comparison will be described using a matrix. As described above, the BD phase comparison unit 504 compares the rising edge and the falling edge of the BD delay signal 503 and the imaging BD signal 208 with each other. It is determined whether the signal corresponds to the signal 207 or not. Further, the BD phase comparison unit 504 can also determine whether or not the image forming BD signal 208 is noise. The comparison result is represented by nine patterns 601 to 609 shown in FIG.

  FIGS. 7 to 9 are timing charts when the BD delay signal 503 and the imaging BD signal 208 are compared.

  FIG. 7 is a timing chart when the timing comparison result is the patterns 601 and 603 in FIG. As described above, the imaging BD signal 208 is delayed from the BD signal 207 by the circuit delay amount ΔT by the imaging BD signal generation unit 219. The BD delay signal 503 is delayed by the circuit delay amount ΔT with respect to the BD signal 207 by the delayed BD signal generation unit 502 similarly to the BD signal 208 for image formation.

  The falling edge 700 of the BD signal 208 for image formation and the falling edge 701 of the BD delay signal 503 fall within a predetermined error range. The predetermined error range is a value sufficiently small with respect to the circuit delay amount ΔT, for example, a range of several% to 10% with respect to the circuit delay amount ΔT. The rising edge 703 of the BD delay signal 503 is sufficiently earlier than the rising edge 702 of the imaging BD signal 208. The time difference between the rising edge 703 of the BD delay signal 503 and the rising edge 702 of the imaging BD signal 208 is twice or more the circuit delay amount ΔT.

  In the case of such a rising edge and falling edge timing pattern 708, the BD phase comparison unit 504 determines that the imaging BD signal 208 is a signal corresponding to the BD signal 207 from a specific reflection surface. This is the pattern 603 in FIG.

  The falling edge 704 of the BD signal 208 for image formation and the falling edge 705 of the BD delay signal 503 fall within a predetermined error range. A rising edge 706 of the imaging BD signal 208 and a rising edge 707 of the BD delay signal 503 fall within a predetermined error range. In the case of such a rising edge and falling edge timing pattern 709, the BD phase comparison unit 504 determines that the imaging BD signal 208 is a signal corresponding to the BD signal 207 due to a part other than the specific reflection surface. This is the pattern 601 in FIG.

  FIG. 8 is a timing chart in the case where the result of the timing comparison is patterns 604 to 606 in FIG. As described above, the wiring for transmitting the BD signal 207 from the BD sensor 206 to the image control unit 500 and the wiring for transmitting the imaging BD signal 208 from the engine control unit 205 to the image control unit 500 are possible. It is provided as close as possible. In this case, the influence of the external noise between the wirings is substantially the same, and noise is generated in the BD signal 208 for image formation and the BD signal 207 with the same influence amount and timing. The BD signal for image formation 208 is delayed from the BD signal 207 by a circuit delay amount ΔT. In the present embodiment, the influence of noise is suppressed based on the delay amount.

  The pulse including the falling edge 800 of the BD signal 207 and the pulse including the falling edge 801 of the BD signal 208 for image formation are not affected by the circuit delay amount ΔT, and thus are generated by the influence of the external noise. It is. The pulse including the falling edge 804 of the BD delay signal 503 is generated by the delayed BD signal generation unit 502 as a pulse including the circuit delay amount ΔT with respect to the falling edge 800. In the case of such a falling edge timing pattern 806, the BD phase comparison unit 504 determines that the imaging BD signal 208 is noise. This is the patterns 604 to 606 in FIG.

  FIG. 9 is a timing chart when the timing comparison result is the pattern 602 in FIG. The pulse including the rising edge 900 of the BD signal 207 and the pulse including the rising edge 901 of the imaging BD signal 208 are pulses generated by the influence of external noise because the circuit delay amount ΔT does not affect the pulse. . A pulse including the rising edge 904 of the BD delay signal 503 is generated by the delayed BD signal generation unit 502 as a pulse including the circuit delay amount ΔT with respect to the rising edge 900. In the case of such a rising edge timing pattern 906, the BD phase comparison unit 504 determines that the imaging BD signal 208 is noise. This is the pattern 602 in FIG.

  Note that the patterns 607 to 609 in FIG. 6 are patterns that cannot normally occur even if the influence of noise is included. When such a pattern is detected by the BD phase comparison unit 504, an illegal process described later is executed.

(Surface identification processing)
FIG. 10 is a flowchart illustrating the surface identification processing performed by the image control unit 500. This process is executed by using a print start command from the CPU 213 of the image control unit 500 as a trigger.

  The BD phase comparison unit 504 of the plane identification unit 501 determines whether any of the falling edges of the imaging BD signal 208 and the BD delay signal 503 has been detected (S100). When the falling edge of any of the BD signal 208 for image formation and the BD delay signal 503 is detected (S100: Y), the BD phase comparison unit 504 detects the falling edge in the processing of S100. It is determined whether or not the falling edge of is detected (S101). For example, when the falling edge of the BD signal 208 for image formation is detected in the process of S100, the BD phase comparison unit 504 determines whether the falling edge of the BD delay signal 503 is detected in the process of S101. The BD phase comparison unit 504 determines whether or not a falling edge is detected within a predetermined standby time after detecting a falling edge in the process of S100. The standby time until the falling edge is detected in the process of S101 is a time of about ± several to 90% of the circuit delay amount ΔT from the time when the falling edge is detected in the process of S100.

  When the falling edge is not detected (S101: N), the BD phase comparison unit 504 detects in the processing of S100 and determines whether or not the falling edge is the imaging BD signal 208 (S102). When the falling edge detected in the processing of S100 is the BD signal 208 for image formation (S102: Y), the BD phase comparison unit 504 determines that the BD signal 208 for image formation including the edge is noise. In this case, the CPU 213 of the image control unit 500 performs a noise process (S106). In the relationship between the falling edge 801 and the falling edge 804 in FIG. 8, the BD phase comparison unit 504 makes this determination. The noise processing of the present embodiment is processing in which the CPU 213 issues a CMD signal 221 including a print cancel command and a print retry command to the CPU 211 of the engine control unit 205. Since the print cancel operation and the retry operation are known, their description will be omitted.

  If the falling edge detected in the processing of S100 is not the imaging BD signal 208 (S102: N), the BD phase comparison unit 504 determines that the signal pattern including the edge is illegal. In this case, the CPU 213 of the image control unit 500 executes an illegal process (S107). When the pattern is not any of the patterns described with reference to FIGS. 7 to 9, the BD phase comparison unit 504 makes this determination. In the illegal processing according to the present embodiment, the CPU 213 issues a CMD signal 221 including a print cancel command to the CPU 211 of the engine control unit 205 and notifies the user of an error code. The notification of the error code is performed by, for example, displaying on a display. Since these operations are well known, their description is omitted.

  When the falling edge is detected in the process of S101 (S101: Y), the BD phase comparison unit 504 determines whether any of the rising edges of the imaging BD signal 208 and the BD delay signal 503 is detected. (S103). The BD phase comparison unit 504 determines whether or not a rising edge is detected within a predetermined standby time after detecting a falling edge in the process of S101. The standby time is a sufficient time-out time of about seconds, starting from the time when the falling edge is detected in the processing of S101. When a rising edge is not detected (S103: N), the BD phase comparison unit 504 determines that the signal pattern including the edge is illegal. In this case, the CPU 213 of the image control unit 500 executes an illegal process (S107). When the rising edge is not detected after the falling edge is detected, the BD phase comparison unit 504 makes this determination.

  When the rising edge is detected (S103: Y), the BD phase comparison unit 504 determines whether or not the rising edge of the signal for which the rising edge has not been detected in the process of S103 is detected (S104). For example, when the rising edge of the imaging BD signal 208 is detected in the process of S103, the BD phase comparison unit 504 determines whether the rising edge of the BD delay signal 503 is detected in the process of S104. The BD phase comparison unit 504 determines whether a rising edge has been detected within a predetermined standby time after detecting a falling edge in the process of S103. The standby time until the rising edge is detected in the process of S104 is a time of about ± several percent to 90% of the circuit delay amount ΔT from the time when the rising edge is detected in the process of S103.

  When a rising edge is detected in the process of S104 (S104: Y), the BD phase comparison unit 504 converts the image forming BD signal 208 including the edge into a signal corresponding to a BD signal by a reflective surface other than a specific reflective surface. It is determined that there is (S108). In the case of the timing pattern 709 in FIG. 7, the BD phase comparison unit 504 makes this determination. In this case, the surface identification unit 501 generates and outputs a surface identification signal 226 using a value obtained by incrementing the surface number obtained from the determination result of the immediately preceding reflection surface by one.

  When the rising edge is not detected in the process of S104 (S104: N), the BD phase comparison unit 504 determines whether or not the rising edge detected in the process of S103 is the imaging BD signal 208 (S105). ). When the rising edge detected in the processing of S103 is the BD signal 208 for image formation (S105: Y), the BD phase comparison unit 504 determines that the BD signal 208 for image formation including the edge is noise. In this case, the CPU 213 of the image control unit 500 performs a noise process (S106). In the case of the timing pattern 906 of FIG. 9, the BD phase comparison unit 504 makes this determination.

  When the rising edge detected in the processing of S103 is not the imaging BD signal 208 (S105: N), the BD phase comparison unit 504 determines that the signal pattern including the edge is a signal corresponding to the BD signal by the specific reflection surface. It is determined that there is (S109). In the case of the timing pattern 708 in FIG. 7, the BD phase comparison unit 504 makes this determination.

  Thus, depending on the detection timing of the rising edge and the falling edge of the imaging BD signal 208 and the BD delay signal 503, whether the reflection surface is a specific reflection surface or another reflection surface is determined. Is determined. Therefore, the conventionally used BD width counter 223 becomes unnecessary, and the circuit scale of the image control unit 212 is greatly reduced. Further, it is possible to suppress the influence of noise generated in the BD signal 208 for image formation and the BD signal 207, and to accurately detect the reflection surface.

  In the above description, the BD signal 207, the imaging BD signal 208, and the BD delay signal 503 are negative logic signals, but they may be positive logic signals. In the case of a positive logic signal, the rising edge and the falling edge are reversed. That is, the plane identifying unit 501 responds to the transition timing of the BD signal 207, the BD signal 208 for image formation, and the BD delay signal 503 from the first level to the second level and the transition timing from the second level to the first level. To identify a plurality of reflective surfaces.

Claims (12)

A photoreceptor,
A light source that outputs light, a rotating polygon mirror that scans the photoconductor by continuously reflecting the light output from the light source by a plurality of reflecting surfaces, and the light reflected by the rotating polygon mirror. A laser scanner unit for forming an image on the photoreceptor, comprising a detection unit that outputs a detection signal at a first level during detection and at a second level when the light is not detected; ,
Controlling the operation of the laser scanner unit, and control means for generating a synchronization signal according to the detection signal, and is connected to an image forming apparatus,
Delay signal generating means for generating a delay signal obtained by delaying the detection signal by a predetermined delay amount;
Identification means for identifying the plurality of reflection surfaces according to a transition timing of the delay signal and the synchronization signal from the first level to the second level and a transition timing from the second level to the first level; ,
Correction means for correcting image data representing an image to be formed, with correction data corresponding to the reflection surface identified by the identification means;
Image output means for transmitting the corrected image data to the laser scanner unit,
Information processing device. The delay signal generation unit delays the detection signal by a delay amount equivalent to a delay amount when the control unit generates the synchronization signal from the detection signal, and generates the delay signal. Do
The information processing device according to claim 1. The controller generates the synchronization signal by changing the pulse width of the detection signal corresponding to a specific reflection surface and not changing the pulse width of the detection signal corresponding to a reflection surface other than the specific reflection surface. And
The identification unit is characterized in that the specific reflection surface and the reflection surface other than the specific reflection surface is identified,
The information processing device according to claim 1. The identification unit transmits a surface identification signal representing the value of the specific reflection surface to the correction unit when the specific reflection surface is identified, and performs one of the operations when a reflection surface other than the specific reflection surface is identified. A surface identification signal representing a value obtained by incrementing the surface number of the reflection surface identified immediately before by 1 is transmitted,
The correction means corrects the image data with correction data corresponding to a reflection surface corresponding to a value represented by the surface identification signal,
The information processing device according to claim 3. The identification means detects a transition of the delay signal and the synchronization signal from the first level to the second level within a predetermined first time, and thereafter, changes the second level of the delay signal to the first level. Detecting the transition from the second level to the first level of the synchronization signal within a predetermined second time, and then identifying the specific reflection surface. And
The information processing apparatus according to claim 3. The identification means detects a transition of the delay signal and the synchronization signal from the first level to the second level within a predetermined first time, and thereafter, changes the second level of the synchronization signal to the first level. A transition to the first level is detected within a predetermined second time, and then it is determined that a noise process is to be performed when a transition from the second level to the first level of the delay signal is not detected. Do
The information processing device according to claim 3. The detecting means detects a transition of the delay signal and the synchronization signal from the first level to the second level within a first time, and then detects the transition of the delay signal and the synchronization signal from the second level. When a transition to the first level is detected within a predetermined second time, a reflection surface other than the specific reflection surface is identified.
The information processing apparatus according to claim 3. The identification means detects a transition of the delay signal and the synchronization signal from the first level to the second level within a predetermined first time, and thereafter, within a predetermined standby time, the delay signal and the synchronization signal. If no transition from the second level to the first level of a signal is detected, it is determined that an illegal process is performed.
The information processing apparatus according to claim 3. The detecting means detects a transition of the delay signal from the first level to the second level within a predetermined first time after detecting a transition of the synchronization signal from the first level to the second level. If not detected, it is determined that the noise processing is executed,
The information processing apparatus according to claim 3. The detecting means detects the transition of the synchronization signal from the first level to the second level within a predetermined first time after detecting the transition of the delay signal from the first level to the second level. Characterized in that it is determined that illegal processing is to be performed when no detection is performed.
The information processing apparatus according to claim 3. The identification unit identifies the plurality of reflection surfaces according to detection timing of a falling edge and a falling edge of the delay signal and the synchronization signal.
The information processing apparatus according to claim 1. A photoreceptor,
A laser scanner unit for forming an image on the photoconductor,
First control means for controlling the operation of the laser scanner unit;
And second control means.
The laser scanner unit includes a light source that outputs light, a rotating polygon mirror that scans the photoconductor by continuously reflecting the light output from the light source by a plurality of reflecting surfaces, and the rotating polygon mirror. A detecting unit that outputs a detection signal that is at a first level while detecting the reflected light and is at a second level while not detecting the light;
The first control means generates a synchronization signal according to the detection signal,
The second control means includes:
Delay signal generating means for generating a delay signal obtained by delaying the detection signal by a predetermined delay amount;
Identification means for identifying the plurality of reflection surfaces according to a transition timing of the delay signal and the synchronization signal from the first level to the second level and a transition timing from the second level to the first level; ,
Correction means for correcting image data representing an image to be formed, with correction data corresponding to the reflection surface identified by the identification means;
Image output means for transmitting the corrected image data to the laser scanner unit,
Image forming device.

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