JP4808653B2 - Optical writing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an optical writing apparatus and an image forming apparatus, and more particularly to an optical writing apparatus and an image forming apparatus that remove a false signal generated on a synchronization detection signal indicating a writing start position in a main scanning direction.

  In an image forming apparatus that scans a photosensitive member with laser light and writes image information, a synchronization detection sensor is disposed at the front end position and rear end position in the main scanning direction, and the laser light emitted from the laser diode is transmitted inside the synchronization detection sensor. A signal corresponding to the detected laser beam is output as a synchronization detection signal indicating a writing start position in the main scanning direction, and writing in the main scanning direction is started based on the output synchronization detection signal. .

  Further, a mask signal for removing a false signal (noise pulse) on the synchronization detection signal is generated for a predetermined time, and the false signal on the synchronization detection signal is masked by the generated mask signal. A technique for removing this is disclosed (Patent Document 1).

JP-A-8-242343

  By the way, in an image forming apparatus that scans a photoconductor with a laser beam and writes image information, the laser beam incident on the synchronization detection sensor is repeatedly reflected in the synchronization detection sensor and then received by the light receiving unit inside the synchronization detection sensor. In some cases, a false signal is generated prior to a regular signal on the detected synchronization detection signal.

  In such a case, in Patent Document 1, a mask signal for removing the false signal on the synchronization detection signal is generated for a predetermined time from the fall of the synchronization detection signal, and the false signal is generated by the generated mask signal. Since the false signal on the synchronization detection signal is removed by masking, there is a problem that the image information writing start position cannot be set at the falling edge of the synchronization detection signal.

  The present invention has been made in view of the above problem, and when a false signal is generated on the synchronization detection signal before the regular signal, image information is written based on the falling edge of the synchronization detection signal. An object of the present invention is to provide an optical writing apparatus and an image forming apparatus capable of starting the operation.

In order to solve the above-described problems and achieve the object, the present invention is generated by a synchronization detection signal generation unit that generates a synchronization detection signal indicating a writing start position in the main scanning direction, and the synchronization detection signal generation unit. On the basis of the main scanning counter that counts the clock based on the synchronization detection signal and the synchronization detection signal generated by the synchronization detection signal generation unit, the false detection is based on the laser light incident on the synchronization detection signal generation unit through a non-regular route. signal if that occurred earlier than the normal signal, when the value of the main scanning counter reaches a predetermined value, and the mask signal generating means for generating a mask signal for removing the false signal, the mask And false signal removing means for masking and removing the false signal with a mask signal generated by the signal generating means.

  According to a preferred aspect of the present invention, the false signal removal means performs a logical product operation of the synchronization detection signal generated by the synchronization detection signal generation means and the mask signal generated by the mask signal generation means. It is desirable that the circuit is configured by an AND circuit that outputs a synchronization detection signal from which the false signal is removed.

  Moreover, according to a preferable aspect of the present invention, it is desirable to further include a setting unit that sets the predetermined value according to a condition relating to image formation.

  According to a preferred aspect of the present invention, the interval measuring means for measuring each time interval for at least two cycles for the synchronization detection signal generated by the synchronization detection signal generating means, and each time measured by the interval measuring means. It is desirable to further comprise setting means for setting the predetermined value based on the time intervals when the intervals are different.

  According to a preferred aspect of the present invention, each time interval measured by the interval measuring means is stored in a nonvolatile memory, and the setting means is provided for each time interval stored in the nonvolatile memory. It is desirable to set the predetermined value based on this.

  In order to solve the above-described problems and achieve the object, the present invention provides an image forming apparatus for removing a false signal generated on a synchronization detection signal indicating a writing start position in a main scanning direction, the optical writing Characterized by comprising an apparatus.

  According to the present invention, a synchronization detection signal is generated, and when a false signal is generated on the generated synchronization detection signal before a regular signal, the false signal is removed based on the timing at which the false signal is generated. Since the mask signal is generated and the false signal is masked and removed by the generated mask signal, when the false signal is generated before the normal signal on the synchronization detection signal, it is based on the falling edge of the synchronization detection signal. There is an effect that writing of image information can be started.

  Exemplary embodiments of an optical writing device and an image forming apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in this embodiment include those that can be easily assumed by those skilled in the art or those that are substantially the same.

(First embodiment)
FIG. 1 is a diagram illustrating an example of a configuration of an image forming apparatus 100 according to the first embodiment of the present invention. The image forming apparatus 100 according to the first embodiment employs an electrophotographic system that forms an electrostatic latent image by irradiating a laser beam and forms a toner image corresponding to the formed electrostatic latent image on a transfer medium. It is a thing.

  As shown in FIG. 1, an image forming apparatus 100 according to the first embodiment includes a scanner unit 200 and an engine unit 300 that forms an image read by the scanner unit 200.

  The scanner unit 200 is for converting document information relating to the document 212 into an image signal by performing scanning exposure of the document 212 placed on the document table 210. An exposure lamp 220 inside the scanner unit 200 performs scan exposure along the document table 210.

  The reflected light from the document 212 is photoelectrically converted by a CCD (Charge Coupled Device) sensor 280 via a carriage mirror 230, a first half scan mirror 240, a second half scan mirror 250, an imaging mirror 260, and an optical lens 270. Thereafter, an electric signal corresponding to the reflected light is obtained. The image signal generated by the photoelectric conversion is subjected to image processing by the image processing unit 400 (see FIG. 3), and then transmitted to the engine unit 300.

  The engine unit 300 generates an electrostatic latent image by exposing the photoconductive drum 5 that is uniformly charged by the charging charger 320 that is a charging device, with laser light from the optical writing device 310. The electrostatic latent image generated on the photosensitive drum 5 is developed with toner by the developing device 321 to become a visible image.

  On the other hand, a transfer sheet 325 that has been previously fed from a sheet feed tray 323 by a sheet feed roller 322 and waited by a registration roller 324 is conveyed in synchronism with the drive of the photosensitive drum 5, and a transfer charger 326 as a transfer device. Thus, the toner on the photosensitive drum 5 is electrostatically transferred to the transfer paper 325, and the transfer paper 325 is separated from the photosensitive drum 5 by the paper separation charger 327. After the separation, the toner image on the transfer paper 325 is heat-fixed by the fixing device 328 and discharged onto the discharge tray 330 by the discharge roller 329.

  On the other hand, the toner image remaining on the photosensitive drum 5 after electrostatic transfer is removed by pressing the cleaning device 331 against the photosensitive drum 5, and the photosensitive drum 5 is neutralized by the irradiation light of the neutralizing lamp 332.

  As described above, the image forming apparatus 100 according to the first embodiment forms an image by repeating these series of processes.

  Here, the optical writing device 310 constituting the engine unit 300 scans and exposes the photosensitive drum 5 with a laser beam. Specifically, as shown in FIG. 2, the optical writing device 310 emits a laser beam L1 from a laser diode unit (hereinafter referred to as an “LD unit”) 1 as a parallel beam by a collimator lens, and emits the laser beam. The light L1 is deflected and scanned by a rotating polygon mirror (hereinafter referred to as “polygon mirror”) 2, and the laser beam L2 that has been deflected and scanned is drummed by an imaging lens composed of an f-θ lens 3 and a reflecting mirror 4. An image is formed on the charged surface of the photoconductor drum 5 in the form of a ring. At this time, the laser beam L1 is modulated on the basis of the image signal, repeatedly turned on and off, and repeatedly scanned in the main scanning direction according to the rotation of the polygon mirror 2, and the photosensitive drum 5 is rotated. By performing sub-scanning, an electrostatic latent image is formed on the photosensitive drum 5.

  The formed electrostatic latent image is developed with a charged developer (toner), and a transfer sheet 325 to which a charge opposite to that of the developer is applied is brought into close contact with the photosensitive drum 5. The developer is transferred to the transfer paper 325. Then, after the transfer paper 325 is separated from the photosensitive drum 5, the developer is fused to the transfer paper 325 by being heated, and fixing is performed.

  A synchronization detection mirror 6 is disposed at the tip position in the main scanning direction of the laser light applied to the photosensitive drum 5. The laser beam L3 reflected by the synchronization detection mirror 6 is detected by a light receiving unit 71 inside the synchronization detection sensor 7, as shown in FIG. 3, in order to detect the period of one scanning of the laser beam.

  FIG. 4 is a diagram illustrating an example of the configuration of the optical writing device 310. The optical writing device 310 is roughly divided into an LD unit 1 for emitting laser light, a polygon mirror 2 for deflecting and scanning the laser light emitted from the LD unit 1, and a polygon as shown in FIG. A polygon motor 21 for rotating the mirror 2, a polygon motor driver 22 for controlling the rotation of the polygon motor 21, and a synchronization detection signal (A) corresponding to laser light emitted from the LD unit 1 and subjected to polarization scanning. And a control unit 30 for controlling the optical writing device 310 as a whole.

  The controller 30 is connected to an image processor 400 for generating a write signal from image data, as shown in FIG. In addition, the image processing unit 400 is connected to a controller 500 that controls the capture of image data. The controller 500 is connected to an operation / display unit 600 for performing display and input for the controller operator, a scanner unit 200, and a network I / F 700 for receiving a print request from the outside.

  Note that the operation / display unit 600 can accept conditions relating to image formation from the user. The operation / display unit 600 can exhibit its functions by, for example, a touch panel. Here, the conditions relating to image formation refer to printing operation conditions such as the resolution (dpi) of the output image and the size (mm) of the transfer paper.

  As shown in the figure, the LD unit 1 further includes a laser diode 11 that is a laser, and an LD driver 12 that controls lighting of the laser diode 11 and adjustment of the amount of light, and emits laser light from the laser diode 11. Is to do.

  The synchronization detection sensor 7 as the synchronization detection signal generation unit is configured to further include a light receiving unit 71 (see FIG. 3) that converts the light amount into a voltage value in response to the laser light emitted from the laser diode 11. A synchronization detection signal (A) corresponding to the laser beam is generated. The light receiving unit 71 can exhibit its function by a light receiving element such as a photodiode.

  The control unit 30 includes a ROM (Read Only Memory) 31 storing a rotation speed value and a control program of the polygon mirror 2, a RAM (Random Access Memory) 32, and a CPU (Central Processing Unit) 33 that executes the control program. And a write control ASIC (Application Specific Integrated Circuit) 34, which is a dedicated IC for controlling writing by laser light, for controlling the operation of the laser diode 11 and the polygon mirror 2 for image formation. is there. With this configuration, the CPU 33 operates while using the work area of the RAM 32 based on the program stored in the ROM 31, so that the write control ASIC 34 can control the operations of the LD driver 12 and the polygon motor driver 22.

  The writing control ASIC 34 controls the writing start timing of the laser beam scanning based on the synchronization detection signal (A) generated by the synchronization detection sensor 7. That is, the writing control ASIC 34 starts writing by controlling the LD driver 12 and the polygon motor driver 22 using the synchronization detection signal (A) generated by the synchronization detection sensor 7 as a trigger.

  However, as shown in FIG. 3, among the laser light L3 that is reflected by the synchronization detection mirror 6 and incident on the synchronization detection sensor 7 at an angle, a lead inside the synchronization detection sensor 7 as in the laser light L31. After hitting the frame 73 and the resin package 72 and reflecting, the light receiving unit 71 may be reached. In such a case, as shown in the upper part of FIG. 5, a signal (hereinafter referred to as a “false signal”) that is not a regular signal (hereinafter referred to as a “normal signal”) is properly transmitted on the synchronization detection signal (A). It may occur before the signal.

  As described above, when the false signal is generated before the normal signal on the synchronization detection signal (A), the start of writing is started by using the false signal as a trigger. Therefore, the write control ASIC 34 removes the false signal and performs write control based on the signal from which the false signal is removed (hereinafter referred to as “synchronization detection output signal (O)”).

  FIG. 6 is a diagram illustrating an example of the configuration of the write control ASIC 34. As shown in the figure, the write control ASIC 34 of the first embodiment includes a mask signal generation circuit 35 that generates a mask signal (M) for removing a false signal, and a synchronization signal generated by the synchronization detection sensor 7. A synchronization detection signal (hereinafter referred to as “synchronization detection output signal (O)”) obtained by performing a logical product operation of the detection signal (A) and the mask signal (M) generated by the mask signal generation circuit 35 to remove the false signal ), A main scanning counter 37 that counts clocks based on the synchronization detection signal (A), and a value that controls the generation timing of the mask signal (M) (hereinafter, “signal generation count value”). Register 38 (hereinafter referred to as “signal generation register”), and a comparator 39 that compares the count value of the main scanning counter 37 with the signal generation count value set in the signal generation register 38. It consists of.

  The comparator 39 outputs H when the count value of the main scanning counter 37 is larger than the signal generation count value set in the signal generation register 38.

  As shown in FIG. 5, in order to output the synchronization detection output signal (O) from which the false signal is removed from the output terminal of the AND circuit 36, the AND circuit of the false signal generated on the synchronization detection signal (A). It is necessary to input the mask signal (M) in accordance with the input timing to 36. Further, in order to input the mask signal (M) in synchronization with the input timing of the false signal, it is necessary to control the generation timing of the mask signal (M).

  Since the laser light L31 that repeatedly reflects inside the synchronization detection sensor 7 has a predetermined route to reach the light receiving unit 71, the generation timing of the false signal can be grasped in advance. Therefore, the mask signal generation circuit 35 generates a mask signal (M) when H is output from the comparator 39.

  As described above, the path for the laser beam L31 reflected inside the synchronization detection sensor 7 to reach the light receiving unit 71 is determined in advance. On the other hand, when the printing operation conditions, particularly the image resolution (dpi) and the transfer paper size (mm) are changed, the main scanning cycle is also changed. Accordingly, when the printing operation condition is changed, the generation timing of the false signal is also changed. Therefore, the signal generation register 38 is set with a signal generation count value corresponding to the printing operation condition received by the operation / display unit 600 described above. The signal generation count value corresponding to the printing operation condition is recorded in advance in the ROM 31, and the signal generation count value corresponding to the printing operation condition is set in the signal generation register 38 with reference to the ROM 31. .

  The mask signal generation circuit 35 functions as a mask signal generation unit. The AND circuit 36 functions as a false signal removal unit. The CPU 33 functions as a setting unit.

  In the above configuration, the write start process performed by the optical writing device 310 of the first embodiment will be described with reference to FIG. FIG. 7 is a flowchart illustrating a procedure of a write start process performed by the optical writing device 310 according to the first embodiment. It is assumed that the false signal is generated before the regular signal on the synchronization detection signal (A).

  First, printing operation conditions such as the resolution (dpi) of the output image and the size of the transfer paper are accepted by the operation / display unit 600 (step SA-1).

  Next, a signal generation count value based on the printing operation condition received in step SA-1 is set in the signal generation register 38 with reference to the ROM 31 by the processing of the CPU 33 (step SA-2).

  Next, the LD driver 12 is controlled to emit laser light from the laser diode 11 (step SA-3). When the laser beam emitted in step SA-3 is received by the light receiving unit 71 of the synchronization detection sensor 7 via the synchronization detection mirror 6, the synchronization detection signal sensor 7 detects the synchronization detection signal ( A) is generated (step SA-4). When the synchronization detection signal (A) is generated, the main scanning counter 37 starts counting in order to control the generation timing of the mask signal (M) (step SA-5).

  When the count value by the main scanning counter 37 reaches the signal generation count value set in step SA-2, that is, when H is output from the comparator 39 (step SA-6: Yes), the mask signal generation circuit 35 A mask signal (M) is generated (step SA-7).

  Subsequently, the logical product circuit 36 performs a logical product operation of the mask signal (M) generated in step SA-7 and the synchronization detection signal (A) generated in step SA-4 (step SA-8), and performs synchronization. A detection output signal (O) is output (step SA-9).

  Next, writing of image information is started based on the fall of the normal signal on the synchronization detection output signal (O) output from the AND circuit 36 in step SA-9 (step SA-10).

  As described above, according to the image forming apparatus 100 of the first embodiment, when the false signal is generated before the regular signal on the synchronization detection signal (A), the timing at which the false signal is generated. Based on this, the mask signal is generated and the false signal is removed by the generated mask signal, so that writing of image information can be started based on the falling edge of the normal signal on the synchronization detection signal (A). it can.

  Further, according to the image forming apparatus 100 of the first embodiment, a signal generation count value for controlling the generation timing of the mask signal (M) is set in the signal generation register 38 and generated by the synchronization detection sensor 7. Since the mask signal (M) is generated when the value of the main scanning counter 37 based on the synchronization detection signal (A) reaches the signal generation count value, the generation timing of the mask signal (M) is controlled. can do.

  Further, according to the image forming apparatus 100 of the first embodiment, the signal generation count value based on the printing operation condition is generated by referring to the ROM 31 that records the signal generation count value corresponding to each printing operation condition. Since it is set in the register 39, the generation timing of the mask signal (M) can be controlled even if the printing operation condition is changed.

  Further, as shown in FIG. 8, not only the synchronization detection mirror 6 and the synchronization detection sensor 7 disposed at the front end position in the main scanning direction, but also the synchronization detection mirror 8 disposed at the rear end position in the main scanning direction. In the case where the synchronization detection sensor 9 is also provided, the synchronization detection signal (A) detected by the synchronization detection sensor 9 disposed at the rear end position is not subjected to false signal removal, and the front end position is synchronized. The false signal is removed only from the synchronization detection signal (A) generated by the detection sensor 7. In such a case, the false signal may be removed only from the synchronization detection signal (A) generated by the synchronization detection sensor 7 at the rear end position.

  As described above, when a plurality of synchronization detection signals (A) are generated by the plurality of synchronization detection sensors 7, only a false signal generated on a part of the synchronization detection signals (A) is removed. Thus, the circuit configuration for removing the false signal from the synchronization detection signal (A) can be simplified.

(Second Embodiment)
Next, an image forming apparatus 100 according to a second embodiment of the present invention will be described. In the description of the second embodiment, the description overlapping the description of the image forming apparatus 100 of the first embodiment described above may be omitted.

  In the first embodiment, the signal generation count value is set in the signal generation register 38 based on the printing operation condition received by the operation / display unit 600.

  On the other hand, in the second embodiment, each time interval for two cycles is measured for the synchronization detection signal (A), and when each measured time interval is different, signal generation is performed based on each time interval. The count value is set in the signal generation register 38.

  It is considered that a false signal is generated when each time interval for two cycles is measured for the synchronization detection signal (A) and the measured time intervals are different. The minimum time interval among the measured time intervals is considered to indicate the time interval from the false signal to the normal signal, as shown in FIG. Further, among the measured time intervals, the maximum time interval is considered to indicate the time interval from the normal signal to the false signal, as shown in FIG. Therefore, in the second embodiment, the signal generation count value is set in the signal generation register 38 based on each measured time interval so that the mask signal (M) can be generated before and after the false signal.

  FIG. 10 is a diagram illustrating an example of the configuration of the optical writing device 310 according to the second embodiment. As shown in the figure, the optical writing device 310 of the second embodiment includes a non-volatile storage (Non-Volatile storage) 40 in addition to the configuration of the optical writing device 310 of the first embodiment. Furthermore, it is configured.

  The CPU 33 of the second embodiment measures each time interval for two cycles for the synchronization detection signal (A) generated by the synchronization detection sensor 7. When the measured time intervals are different, the CPU 33 sets a signal generation count value based on each time interval in the signal generation register 38.

  Specifically, when a false signal is generated in the synchronization detection signal (A), the time interval of the minimum value and the time interval of the maximum value shown in FIG. 9 can be measured. The CPU 33 refers to these time intervals and sets a signal generation count value in the signal generation register 38 in accordance with the input timing of the false signal to the AND circuit 36.

  Further, the CPU 33 records the signal generation count value set in the signal generation register 38 in the nonvolatile memory 40. If the printing operation condition is changed, the generation timing of the false signal on the synchronization detection signal (A) changes, so the input timing of the false signal to the AND circuit also changes. Therefore, it is necessary to change the generation timing of the mask signal (M). Therefore, when the printing operation condition received from the user by the operation / display unit 600 is changed, the CPU 33 reads the signal generation counter value corresponding to the changed printing operation condition from the nonvolatile memory 40 and reads it out. The signal generation counter value is set in the signal generation register 38.

  Note that the nonvolatile memory 40 can exhibit its function by, for example, an EPROM (Erasable Programmable Read Only Memory).

  With the above configuration, a write start process performed by the optical writing device 310 according to the second embodiment will be described with reference to FIG. FIG. 11 is a flowchart illustrating a procedure of a writing start process performed by the optical writing device 310 according to the second embodiment.

  First, a printing operation condition is received from the user by the operation / display unit 600 (step SA-1). Next, the write control ASIC 34 executes a signal generation count value setting process (see FIG. 12) (step SA-20). In addition, since the procedure of step SA-3 to step SA-10 has been described in the first embodiment, the description thereof is omitted here.

  Here, the signal generation count value setting process performed in the second embodiment will be described with reference to FIG. FIG. 12 is a flowchart illustrating a procedure of signal generation count value setting processing performed in the second embodiment.

  First, when there is a change in the printing operation condition received in Step SA-1 (see FIG. 11) (Step SA-21: Yes), the LD driver 12 is controlled to emit laser light from the laser diode 11 (Step S21). SA-22). When the laser beam emitted in step SA-22 is received by the light receiving unit 71 of the synchronization detection sensor 7 via the synchronization detection mirror 6, the synchronization detection sensor 7 detects the synchronization detection signal (A ) Is generated (step SA-23).

  Next, the CPU 33 measures the time interval of each cycle of the synchronization detection signal (A) generated at step SA-23 (step SA-24). The main scanning counter 37 can be used for measuring the time interval.

  In step SA-24, the time interval for two cycles is measured (step SA-25: Yes). If each time interval is different (step SA-26: Yes), the processing of CPU 33 causes step SA-25 to With reference to each measured time interval, a signal generation count value corresponding to the input timing of the false signal is set in the signal generation register 38 (step SA-27).

  Next, by the processing of the CPU 33, the signal generation count value set in step SA27 and the printing operation condition received in step SA-1 are associated with each other and recorded in the nonvolatile memory 40.

  In step SA-24, the time interval for two cycles is measured (step SA-25: Yes), and when each time interval is not different (step SA-26: No), the processing procedure is the write start process. Return to

  If there is no change in the printing operation condition received in step SA-1 (see FIG. 11) (step SA-21: No), a signal generation count corresponding to the printing operation condition from the nonvolatile memory 40 is processed by the CPU 33. The value is read (step SA-29), the signal generation count value read in step SA-29 is set in the signal generation register 38 (step SA-30), and the processing procedure returns to the write start processing.

  As described above, according to the image forming apparatus 100 of the second embodiment, the time interval for two cycles is measured for the synchronization detection signal (A) generated by the synchronization detection sensor 7, and each measured time is measured. Since the signal generation count value is set in the signal generation register 38 based on the interval, the ROM 31 that records the signal generation count value corresponding to the printing operation condition can be made unnecessary.

  Further, according to the image forming apparatus 100 of the second embodiment, the signal generation count value set in the signal generation register 38 and the printing operation condition are associated and recorded in the nonvolatile memory 40, and the printing operation condition is changed. In this case, since the signal generation count value corresponding to the changed printing operation condition is read from the nonvolatile memory 40 and the read signal generation count value is set in the signal generation register 38, the synchronization detection signal (A) The time for measuring the cycle can be omitted. Further, if the signal generation count value corresponding to the printing operation condition can be read from the nonvolatile memory 40 in this way, the signal generation count value corresponding to the printing operation condition that is initially set after the image forming apparatus 100 is turned on. Can be set in the signal generation register 38 without measuring the period of the period detection signal.

(Third embodiment)
Next, an image forming apparatus 100 according to a third embodiment of the present invention will be described. In the description of the third embodiment, the description overlapping the description of the image forming apparatus 100 of the first embodiment or the second embodiment described above may be omitted.

  In the first embodiment, the mask signal (M) is generated, the logical product operation of the generated mask signal (M) and the synchronization detection signal (A) is performed, and the false signal is removed.

  In contrast, in the third embodiment, a delay signal (D) is generated by delaying the false signal on the synchronization detection signal (A) generated by the synchronization detection sensor 7 by at least the time width of the false signal. Then, a logical product operation of the generated delay signal (D) and the synchronization detection signal (A) is performed to remove the false signal.

  As shown in FIG. 13, the logical product circuit 36 performs a logical product operation of the delay signal (D) delayed by at least the time width of the false signal and the synchronization detection signal (A), and removes the false signal, thereby detecting the synchronization detection output. Outputs signal (O). If the delay signal (D) is used, it is not necessary to generate the mask signal (M), so that it is not necessary to set a signal generation count value.

  FIG. 14 is a diagram illustrating an example of the configuration of the write control ASIC 34 according to the third embodiment. The write control ASIC 34 according to the third embodiment includes a logical product circuit 36, a main scanning count 37, and a delay signal generation circuit 41 that generates a delay signal (D) delayed by at least the time width of a false signal. Has been.

  As shown in the figure, the input destination of the synchronization detection signal (A) generated by the synchronization detection sensor 7 is a logical product circuit 36 and a delay signal generation circuit 41. As shown in FIG. 13, the delay signal generation circuit 41 generates and generates a delay signal (D) delayed by the time width of the false signal generated on the synchronization detection signal (A) from the synchronization detection sensor 7. The delay signal (D) is output to the AND circuit 36.

  The AND circuit 36 performs a logical product operation of the synchronization detection signal (A) generated by the synchronization detection sensor 7 and the delay signal (D) generated by the delay signal generation circuit 41, and outputs the synchronization detection output signal (O). Output.

  With the above configuration, a write start process performed by the optical writing device 310 according to the third embodiment will be described with reference to FIG. FIG. 15 is a flowchart illustrating a procedure of a write start process performed by the optical writing device 310 according to the third embodiment.

  First, printing operation conditions such as the resolution (dpi) of the output image and the size of the transfer sheet are received by the operation / display unit 600 (step SB-1).

  Next, the LD driver 12 is controlled to emit laser light from the laser diode 11 (step SB-2). When the laser beam emitted in step SB-2 is received by the light receiving unit 71 of the synchronization detection sensor 7 via the synchronization detection mirror 6, the synchronization detection sensor 7 detects the synchronization detection signal (A ) Is generated (step SB-3).

  Next, the delay signal generation circuit 41 generates a delay signal (D) delayed by the time width of the false signal generated on the synchronization detection signal (A) generated in step SB-3 (step SB-4). . Next, the logical product circuit 36 performs a logical product operation of the delay signal (D) generated in step SB-4 and the synchronization detection signal (A) generated in step SB-3 (step SB-5), and the synchronization detection signal. (A) The synchronization detection output signal (O) from which the false signal generated above is removed is output (step SB-6).

  Next, writing of image information is started based on the fall of the normal signal on the synchronization detection output signal (O) output from the logical product circuit 36 in step SB-6 (step SB-7).

  As described above, according to the image forming apparatus 100 of the third embodiment, the delay signal (D) delayed by the time width of the false signal on the synchronization detection signal (A) generated by the synchronization detection sensor 7. And the false signal is removed using the generated delay signal (D), so that writing of image information can be started based on the fall of the normal signal on the synchronization detection signal (A). Further, it is possible to eliminate the need for setting the signal generation count value.

1 is a diagram illustrating an example of a configuration of an image forming apparatus 100 according to a first embodiment. 6 is a diagram for explaining the operation of the optical writing device 310. FIG. It is a figure which shows an example of a structure of the synchronous detection sensor. 2 is a diagram illustrating an example of a configuration of an optical writing device 310. FIG. It is a figure which shows a synchronous detection signal (A), a mask signal (M), and a synchronous detection output signal (O). It is a figure which shows the signal input into a logical product circuit, and the signal output from a logical product circuit. 4 is a flowchart illustrating a procedure of a write start process performed by the optical writing device 310 according to the first embodiment. It is a figure which shows the optical writing device 310 which provided the synchronous detection sensor in the front-end | tip position and back end position of the main scanning direction, respectively. It is a figure which shows the time interval of the minimum value, and the time interval of the maximum value. 2 is a diagram illustrating an example of a configuration of an optical writing device 310. FIG. It is a flowchart which shows the procedure of the write-in start process performed with the optical writing device 310 of 2nd Embodiment. It is a flowchart which shows the procedure of the signal generation count value setting process performed in 2nd Embodiment. It is a figure which shows a synchronous detection signal (A), a delay signal (D), and a synchronous detection output signal (O). It is a figure which shows the signal input into a logical product circuit, and the signal output from a logical product circuit. It is a flowchart which shows the procedure of the write-in start process performed with the optical writing device 310 of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 LD unit 2 Polygon mirror 3 f- (theta) lens 4 Reflection mirror 5 Photosensitive drum 6 Synchronization detection mirror 7 Synchronization detection sensor 11 Laser diode 12 LD driver 21 Polygon motor 22 Polygon motor driver 31 ROM
32 RAM
33 CPU
34 Write control ASIC
35 mask signal generation circuit 36 AND circuit 37 main scanning counter 38 signal generation register 39 comparator 40 nonvolatile memory 41 delay signal generation circuit 100 image forming apparatus 200 scanner unit 300 engine unit 310 optical writing device 400 image processing unit 500 controller 600 Operation / Display 700 Network I / F

Claims (6)

Synchronization detection signal generating means for generating a synchronization detection signal indicating a writing start position in the main scanning direction ;
A main scanning counter that counts clocks based on the synchronization detection signal generated by the synchronization detection signal generation means;
Wherein the synchronization detection signal synchronization detection signal over generated by the generation means, said synchronization detection signal generating means places a false signal based on the incident laser beam in a non-regular route occurs earlier than normal signal in case, the main Mask signal generating means for generating a mask signal for removing the false signal when the value of the scanning counter reaches a predetermined value ;
A false signal removing means for masking and removing the false signal by the mask signal generated by the mask signal generating means,
An optical writing device. The false signal removal means performs a logical product operation of the synchronization detection signal generated by the synchronization detection signal generation means and the mask signal generated by the mask signal generation means, and outputs a synchronization detection signal from which the false signal is removed. Composed of AND circuit,
The optical writing device according to claim 1. Further comprising setting means for setting the predetermined value in accordance with the conditions of the image forming, it optical writing device according to claim 1 or claim 2, characterized in. Interval measuring means for measuring each time interval for at least two cycles for the synchronization detection signal generated by the synchronization detection signal generating means;
A setting unit that sets the predetermined value based on each time interval when each time interval measured by the interval measurement unit is different;
The optical writing device according to claim 1 , wherein the optical writing device is an optical writing device. Each time interval measured by the interval measuring means is stored in a nonvolatile memory,
The setting means sets the predetermined value based on the time intervals stored in the nonvolatile memory;
The optical writing device according to claim 4 , wherein: An image forming apparatus that removes a false signal generated on a synchronization detection signal indicating a writing start position in a main scanning direction,
An optical writing device according to any one of the claims 1 to claim 5,
An image forming apparatus.

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