JP2008009255A - Multibeam optical scanner and electronic photograph apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multibeam optical scanner in which a horizontal synchronization signal period and pulse interval are easily inspected with a comparatively small circuit size, and to provide an electronic photograph apparatus using the multibeam optical scanner. <P>SOLUTION: The multibeam optical scanner has: a scanning mechanism part provided with a laser beam output part which generates a plurality of laser beams, a scanning means, a photodetecting sensor and a synchronization signal generation part; and a signal control part which is provided with a synchronization signal inspection part which inspects normality of the synchronized signal, and a video signal generation part, wherein the signal control part is provided with: a period inspection circuit which inspects the synchronization signal period of one of the plurality of laser beams; a pulse interval inspection circuit which inspects the synchronization signal pulse interval of a pair of the laser beams which are adjacent to each other among the plurality of laser beams; and a selection means which inputs the synchronization signals corresponding to the respective laser beams. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multi-beam optical scanning device used for scanning various media using a plurality of laser beams, and an electrophotographic apparatus that forms an electrostatic latent image by scanning a photoconductor with the multi-beam optical scanning device. Is.

  In recent years, as the demand for higher printing density and higher printing speed has increased, multi-beam optical scanning devices that use a plurality of scanning light beams are often used. In this apparatus, light beams of a plurality of laser beams generated from a plurality of light sources are tilted with respect to a medium scanning direction such as a photoconductor and simultaneously scanned, and each scanning light is detected by a single light detection sensor. A horizontal synchronization signal is generated by multiplexing the horizontal synchronization signal for the.

  FIG. 3 is a schematic configuration diagram showing a horizontal synchronization signal generating device in a conventional multi-beam optical scanning device, which is composed of a signal control unit 101 and a scanning mechanism unit 102. Based on the video signals 301 to 305 output from the video signal generation unit 104 of the signal control unit 101, the multi-beam laser beam is modulated by the laser beam output unit 105 of the scanning mechanism unit 102, reflected by the rotary polygon mirror 106, and aspherical. After passing through the lens 107, the light detection sensor 108 and the photoconductor 109 are scanned.

  The light receiving surface of the light detection sensor 108 is provided so as to be able to detect the scanning light over a plurality of scanning lines scanned by the scanning light 111 to 115 near the scanning start end, and is detected when the scanning light 111 to 115 scans the sensor 108. Generate output. The detection output is applied to the horizontal synchronization signal generation unit 110 to generate a horizontal synchronization signal 306, the normality of the synchronization signal is confirmed in the horizontal synchronization signal inspection unit 103, and the horizontal writing position of the scanning light in the video signal generation unit 104 Is used to determine the print data write start timing for keeping the image constant.

  FIG. 4 is a timing chart showing the relationship between the video signal and the horizontal synchronizing signal when there are five scanning lights in the conventional example. Each video signal 301 to 305 includes horizontal synchronization signal generation data 401 to 405 and print data 406 to 410. The optical detection sensor 108 is scanned with the horizontal synchronization signal generation data 401 to 405 to generate horizontal synchronization signal pulses 411 to 415 constituting the horizontal synchronization signal 306 corresponding to the video signals 301 to 305, and the print data 406 to 406. The write start position 410 is determined.

  Here, the correspondence between the pulse of the horizontal synchronizing signal and the video signal is referred to as an attribute of the horizontal synchronizing signal pulse. Each pulse of the horizontal sync signal having the same attribute has a constant period. For example, the horizontal sync signal pulse 411 having the attribute BD1 corresponding to the first video signal and the pulse 421 always have a constant period. Yes. Similarly, for example, the horizontal synchronization signal pulse 415 having the attribute BD5 corresponding to the fifth video signal and the pulse 425 have a constant cycle.

  On the other hand, as shown in FIG. 5, the pulses having the video signal attribute adjacent to the horizontal synchronization signal are also kept at a constant interval. For example, the horizontal synchronization signal pulse 501 having the attribute BD1 corresponding to the first video signal The pulse 502 having the attribute BD2 corresponding to the second video signal always maintains a constant interval. Similarly, the horizontal synchronizing signal pulse 504 having the attribute BD4 and the pulse 505 having the attribute BD5 are kept at a constant interval.

  If an abnormality occurs in the horizontal synchronization signal signal 306 that maintains these constant cycles and pulse intervals, the print data writing position may become abnormal, and it is assumed that erroneous printing will occur. Therefore, the horizontal synchronization signal inspection unit 103 strictly checks the period and pulse interval of the horizontal synchronization signal 306, and if an abnormality is detected in the period and pulse interval of the horizontal synchronization signal 306, it reports a failure and stops printing. A control method is adopted.

  FIG. 6 is a block diagram showing a configuration of a horizontal synchronization signal inspection unit in the conventional example. The horizontal synchronization signal inspection unit 103 receives the horizontal synchronization signal 306, the period inspection unit 601 checks the period of the horizontal synchronization signal 306, and the pulse interval inspection unit 607 checks the pulse interval of the adjacent horizontal synchronization signal 306 having different attributes. When a period or pulse interval is detected to be abnormal, a BD error detection signal 613 is output.

  Here, the period inspection unit 601 includes a BD1 inspection circuit 602, a BD2 inspection circuit 603, a BD3 inspection circuit 604, a BD4 inspection circuit 605, and a BD5 inspection circuit 606, and checks the period for each attribute of the horizontal synchronization signal. Yes. When a horizontal abnormality is detected in any of the inspection circuits, a BD error detection signal 613 is output via the OR circuit 612 as a horizontal synchronization signal cycle error. Thus, in the case where the number of attributes is different, a plurality of period check circuits corresponding to the number of attributes are necessary.

  On the other hand, the pulse interval inspection unit 607 includes a BD1-BD2 inspection circuit 608, a BD2-BD3 inspection circuit 609, a BD3-BD4 inspection circuit 610, and a BD4-BD5 inspection circuit 611, and has adjacent attributes. The pulse interval is checked for each horizontal sync signal combination. When any of the inspection circuits detects an abnormality in the horizontal synchronization signal pulse interval, a BD error 613 is output via the OR circuit 612 as a horizontal synchronization signal pulse interval error. Therefore, in the case where the number of attributes is different, the number of pulse interval inspection circuits corresponding to the number of attributes is required.

  As a technique for recognizing the normality of the horizontal synchronization signal in the multi-beam optical scanning device, as shown in Patent Document 1, the number of horizontal synchronization signal pulses is counted within a certain allowable time based on the horizontal synchronization signal period. However, a configuration for detecting an abnormality when the number of pulses is less than a specified number has been proposed. Patent Document 2 discloses a technique for checking the presence / absence of a pulse for each attribute of a horizontal synchronization signal within a certain allowable time based on the horizontal synchronization signal pulse interval, and detecting an abnormality when there is no pulse.

JP 2000-111817 A Japanese Patent Laid-Open No. 2002-365568

  As described above, in the multi-beam optical scanning device, it is necessary to inspect the normality of the horizontal synchronizing signal by a circuit that inspects the multiplexed horizontal synchronizing signal period and pulse interval. The greater the number of attributes of the synchronization signal, the more complicated the circuit configuration and control. As a result, there is a problem that the circuit scale increases and the cost increases.

  An object of the present invention is to provide a multi-beam optical scanning device that can easily inspect a horizontal synchronizing signal period and a pulse interval with a relatively small circuit scale even when the number of scanning beams scanned at a time is plural. An electrophotographic apparatus using the same is provided.

  The present invention includes a laser beam output unit that generates a plurality of laser beams, a scanning unit that scans the laser beam on a medium, a light detection sensor that is disposed near a scanning start end of the laser beam, and an output of the light detection sensor. A scanning mechanism unit including a synchronization signal generation unit that generates a synchronization signal corresponding to each of a plurality of laser beams, a synchronization signal inspection unit that checks normality of the synchronization signal, and the synchronization signal corresponding to each laser beam In a multi-beam optical scanning device having a signal control unit including a video signal generation unit that generates a video signal, the signal control unit has a single cycle inspection circuit that inspects one synchronization signal cycle of the plurality of laser beams And a single pulse interval inspection circuit for inspecting the synchronization signal pulse interval of a set of adjacent laser beams of the plurality of laser beams, and corresponding to each laser beam in these inspection circuits Characterized in that a selection means for inputting that synchronization signal sequentially.

  Further, the selection means includes an inspection signal selection circuit that generates a synchronization signal corresponding to each laser beam and inputs the synchronization signal to the period inspection circuit and the pulse interval inspection circuit.

  In addition, the selection unit includes a video signal generation unit that individually generates a video signal using an output start signal for each video signal.

  Furthermore, the present invention provides an electrophotographic apparatus that forms an electrostatic latent image on a photoreceptor using the multi-beam optical scanning device.

  According to the present invention, it is possible to easily and simply inspect the horizontal synchronization signal period and the pulse interval even when the number of scanning lights scanned at a time is plural by sequentially exchanging the synchronization signals to be inspected. There is an effect that it can be realized on a circuit scale.

  An embodiment of the present invention includes a scanning mechanism unit including a laser beam output unit, a scanning unit, and a light detection sensor and a synchronization signal generation unit disposed near the scanning start end of the laser beam, a synchronization signal inspection unit, and a video signal. In a multi-beam optical scanning device having a signal control unit with a generation unit, the signal control unit includes a single periodic inspection circuit, a single pulse interval inspection circuit, and these inspection circuits correspond to each laser beam. Selection means for sequentially inputting synchronization signals to be transmitted.

  Hereinafter, the overall configuration of the multi-beam optical scanning device according to the present invention will be described, and then examples of a horizontal synchronization signal inspection unit and a video signal generation unit, which are main parts thereof, will be described.

  FIG. 1 shows an outline of the present invention when the number of scanning lights is five. Video signals LD <b> 1 to LD <b> 5 generated by the video signal generation unit 104 provided in the signal control unit 101 are added to a laser light output unit 105 provided in the scanning mechanism unit 102. The laser beam generated by the laser beam output unit 105 is reflected by the rotating polygon mirror 106 that rotates at high speed, passes through the aspherical lens 107, and scans the light detection sensor 108 and the photoconductor 109. When the scanning lights 111 to 115 scan the light detection sensor 108, the sensor 108 generates a detection signal, and the horizontal synchronization signal generation unit 110 generates a horizontal synchronization signal BD based on the detection signal. The generated horizontal synchronization signal BD is applied to a horizontal synchronization signal inspection unit 103 and a video signal generation unit 104 provided in the signal control unit 101. You may comprise the light detection sensor from multiple pieces.

  FIG. 2 is a block diagram showing an embodiment of the horizontal synchronizing signal inspection unit 103 in the multi-beam optical scanning device of the present invention. The horizontal synchronization signal BD generated by the horizontal synchronization signal generation unit 110 is added to the horizontal synchronization signal separation circuit 201, and the first horizontal synchronization signal BD1 to the fifth horizontal synchronization signal BD5 are separated and extracted. A period inspection circuit 203 for inspecting the synchronization signal period and a pulse interval inspection circuit 205 for inspecting the pulse interval are provided. In addition, an inspection signal selection circuit A 202 and an inspection signal selection circuit B 204 are provided as selection means for sequentially switching the synchronization signals to be inspected.

  First, the synchronization signal cycle inspection function will be described. The separated first horizontal synchronization signal BD1 to fifth horizontal synchronization signal BD5 are applied to the inspection signal selection circuit A202. The inspection signal selection circuit A202 selects one of the input horizontal synchronization signals BD1 to BD5, generates a horizontal synchronization signal BDX, and outputs it. Next, the synchronization signals to be inspected are sequentially replaced to generate and output a new horizontal synchronization signal BDX.

  Details of the method of generating the horizontal synchronizing signal BDX are as follows. In the timing chart showing the cycle inspection operation of the horizontal synchronization signal BD shown in FIG. 10, in the first cycle 1001 and the second cycle 1002 of the horizontal synchronization signal BD by the inspection signal selection circuit A202, BD1 is used as the BDX signal to the cycle inspection circuit 203. Output. The period inspection circuit 203 performs a period check of BD1 based on these two BDX signals having the BD1 attribute output from the inspection signal selection circuit A202. Similarly, in the third period 1003 and the fourth period 1004 of the horizontal synchronizing signal BD, BD2 is output as a BDX signal. The period inspection circuit 203 checks the period of BD2 by using the BDX signal having the BD2 attribute output from the inspection signal selection circuit A202.

  Similarly, the BDX signal having the BD3 attribute is output from the fifth cycle 1005 and the sixth cycle 1006 to check the cycle of BD3, and the BDX signal having the BD4 attribute is output from the seventh cycle 1007 and the eighth cycle 1008 to output BD4. The BDX signal having the BD5 attribute is output from the ninth cycle 1009 and the tenth cycle 1010 to check the cycle of BD5. After the period check of BD5, the process returns to the beginning, and the period check is sequentially performed from BD1.

  According to this configuration, since the BDX signal is generated by sequentially switching the horizontal synchronization signals to be inspected by the inspection signal selection circuit A202 in the order of generation, the period is checked by the single period inspection circuit 203 regardless of the attribute of the horizontal synchronization signal. Is possible. The cycle inspection circuit 203 performs cycle inspection of the horizontal synchronization signal BDX output from the inspection signal selection circuit A202.

  The operation will be described below using a flowchart showing the processing procedure of the periodic inspection circuit 203 in FIG. 7 and a timing chart showing the operation of the periodic inspection circuit 203 in FIG. First, when the first pulse 801 of the horizontal synchronizing signal BDX is received (S701), a counter for counting the time from the rising edge of the pulse is started (S702). Then, the counter is incremented with the passage of time, and waits until the counter value reaches a certain value A. The constant value A is determined in consideration of the period between the same attribute pulses of the horizontal synchronizing signal BD. When the counter value reaches a certain value A, it is determined that the start timing of the second pulse reception allowable range has been reached (S703), and the second pulse reception checking flag 804 is set (S704). Further, the reception of the second pulse of the horizontal synchronization signal BDX is waited (S705), and when the second pulse is received, the second pulse reception flag 805 is set (S706). On the other hand, when the second pulse is not received, the second pulse reception flag 805 is not set. The counter increments and waits until it reaches a certain value B. The constant value B is also determined in consideration of the period between the same attribute pulses of the horizontal synchronization signal BD. When the counter value reaches a certain value B, it is determined that the end timing of the second pulse reception allowable range has been reached (S707), and the second pulse reception checking flag 804 is reset (S708). Here, the state of the second pulse reception flag 805 is checked (S709), and if the flag is 1, it is determined that the cycle of the horizontal synchronization signal BDX is normal (S710). On the other hand, if the flag is 0, it is determined that the cycle of the horizontal synchronization signal BDX is abnormal (S711), and a horizontal synchronization signal cycle error detection signal is output (S712). Finally, the counter and the second pulse reception flag are cleared (S713), and the cycle inspection process for the horizontal synchronization signal BDX is completed.

  Next, the synchronization signal pulse interval inspection function will be described. The first horizontal synchronization signal BD1 to the fifth horizontal synchronization signal BD5 separated by the horizontal synchronization signal separation circuit 201 are also applied to the inspection signal selection circuit B204. The inspection signal selection circuit B204 generates and outputs a horizontal synchronization signal BDY in which combinations of adjacent horizontal synchronization signal attributes to be inspected are sequentially replaced.

  Next, details of a method of generating the horizontal synchronization signal BDY will be described.

  FIG. 11 is a timing chart showing the pulse interval inspection operation of the horizontal synchronization signal BD. In the figure, in the first period 1101 of the horizontal synchronizing signal BD, the inspection signal selection circuit B204 outputs BD1 and BD2 to the pulse interval inspection circuit 205 as BDY signals. The pulse interval inspection circuit 205 checks the pulse interval of BD1 and BD2 by inspecting the pulse interval of the BDY signal having the BD1 attribute and the BD2 attribute output from the inspection signal selection circuit B204. In the second period 1102 of the horizontal synchronizing signal BD, the inspection signal selection circuit B204 outputs BD2 and BD3 to the pulse interval inspection circuit 205 as BDY signals. The pulse interval inspection circuit 205 checks the pulse interval of BD2 and BD3 by inspecting the pulse interval of the BDY signal having the BD2 attribute and the BD3 attribute output from the inspection signal selection circuit B204. Thereafter, similarly, the pulse interval of the BD3 and BD4 is checked by checking the pulse interval of the BDY signal having the BD3 attribute and the BD4 attribute generated from the third cycle 1103, and the BD4 attribute and BD5 generated from the fourth cycle 1104 are checked. By checking the pulse interval of the BDY signal having the attribute, the pulse interval of BD4 and BD5 is checked. After checking the pulse interval of BD4 and BD5, the process returns to the beginning, and the pulse interval check is sequentially performed from BD1 and BD2.

  According to this configuration, the horizontal synchronization signals to be inspected are combined by the inspection signal selection circuit B204 and sequentially switched in the order of signal generation to generate the BDY signal. Therefore, a single pulse interval inspection is performed regardless of the attribute of the horizontal synchronization signal. The pulse interval can be checked by the circuit 205.

  The pulse interval inspection circuit 205 performs a pulse interval inspection of the horizontal synchronization signal BDY output from the inspection signal selection circuit B. The operation of the pulse interval inspection circuit 205 is the same as the operation of the period inspection circuit 203 described with reference to FIGS. 7 and 8, and the constant value A and the constant value B are set to the horizontal synchronization signal adjacent to the horizontal synchronization signal BD. It works by determining the interval of attribute pulses.

  FIG. 9 is a block diagram illustrating an example of the video signal generation unit 104. In the figure, a horizontal synchronization signal BD is applied to a horizontal synchronization signal separation circuit 901, and a first horizontal synchronization signal BD1 is separated and extracted. The horizontal synchronization signal generating video output start signal ST is applied to the set terminal of the flip-flop 902a, and the flip-flop 902a is set by the output. The output of the flip-flop 902a is applied to the OR gate 903a together with the print data VD1 output from the drawing controller 904, and the output of the OR gate 903a is output to the scanning mechanism unit 102 as the first video signal LD1. The first horizontal synchronization signal BD1 output from the horizontal synchronization signal separation circuit 901 is applied to the reset terminal of the flip-flop 902a, and the flip-flop 902a is reset by the output.

  Similarly, the horizontal synchronization signal BD is applied to the horizontal synchronization signal separation circuit 901, and the second horizontal synchronization signal BD2 to the fifth horizontal synchronization signal BD5 are separated and extracted. The horizontal synchronization signal generating video output start signal ST is applied to the set terminals of the flip-flops 902b to 902e, and the flip-flops 902b to 902e are set by the output. The outputs of the flip-flops 902b to 902e are applied to the OR gates 903b to 903e together with the print data VD2 to VD5 output from the drawing controller 904, and the outputs of the OR gates 903b to 903e are the second video signal LD2 to the fifth video signal LD5. It is output to the scanning mechanism unit 102. The second horizontal synchronization signal BD2 to the fifth horizontal synchronization signal BD5 output from the horizontal synchronization signal separation circuit 901 are applied to the reset terminals of the flip-flops 902b to 902e, respectively, and the flip-flops 902b to 902e are reset by the output. .

  In the above configuration, the cycle check operation will be described with reference to a timing chart showing the cycle check operation of the horizontal synchronization signal BD in FIG. In the first period 1001 of the horizontal synchronization signal BD, the inspection signal selection circuit A202 outputs BD1 to the period inspection circuit 203 as a BDX signal. Similarly, in the second period 1002, BD1 is output as a BDX signal. The period inspection circuit 203 performs a period check of BD1 using the BDX signal having the BD1 attribute output from the inspection signal selection circuit A202. Further, in the third period 1003 of the horizontal synchronizing signal BD, the inspection signal selection circuit A202 outputs BD2 as a BDX signal to the period inspection circuit 203. Similarly, in the fourth period 1004, BD2 is output as a BDX signal. The period inspection circuit 203 checks the period of BD2 by using the BDX signal having the BD2 attribute output from the inspection signal selection circuit A202. Thereafter, similarly, the BDX signal having the BD3 attribute is output from the fifth cycle 1005 and the sixth cycle 1006 to check the cycle of BD3, and the BDX signal having the BD4 attribute is output from the seventh cycle 1007 and the eighth cycle 1008 to output BD4. The BDX signal having the BD5 attribute is output from the ninth cycle 1009 and the tenth cycle 1010 to check the cycle of BD5.

  Since this embodiment shows an example in which the number of scanning lights scanned at one time is five, after the period check of BD5, the process returns to the beginning, and the period check is sequentially performed from BD1. According to this configuration, since the BDX signal is generated by sequentially replacing the horizontal synchronization signals to be inspected by the inspection signal selection circuit A202, the period is checked by the same period inspection circuit 203 regardless of the attribute of the horizontal synchronization signal. Is possible.

  FIG. 12 is a timing chart showing the period inspection operation of the horizontal synchronization signal BD in the second embodiment, and FIG. 13 is a timing chart showing the pulse interval inspection operation of the horizontal synchronization signal BD in the second embodiment. The apparatus configuration of the second embodiment is equivalent to that of the first embodiment, and the operation differs from that of the first embodiment due to the difference in the inspection signal selection means of the inspection signal selection circuit A202 and the inspection signal selection circuit B204.

  First, the period inspection operation of the horizontal synchronization signal BD in the second embodiment will be described with reference to FIG. In the first period 1201 of the horizontal synchronization signal BD, the inspection signal selection circuit A202 outputs BD1 to the period inspection circuit 203 as a BDX signal. In the second period 1202, BD1 and BD2 are output as BDX signals. In the synchronous check circuit 203, the period of BD1 is checked by the first and second pulses of the BDX signal having the BD1 attribute. Subsequently, in the third period 1203, the inspection signal selection circuit A202 outputs BD2 and BD3 as BDX signals. The synchronization check circuit 203 checks the period of BD2 by using the third pulse and the fourth pulse of the BDX signal having the BD2 attribute. Thereafter, similarly, the inspection signal selection circuit A202 outputs BD3 and BD4 as the BDX signal in the fourth period 1204 and BD4 and BD5 in the fifth period 1205. Also, in the sixth period 1206, BD5 is output, and in the seventh period 1207, the process returns to the beginning and BD1 is output as the BDX signal. In the eighth period 1208, BD1 and BD2 are output as BDX signals, and so on. The synchronization inspection circuit 203 also checks the period of each attribute of the horizontal synchronization signal BD by sequentially inspecting the BDX signal output from the inspection signal selection circuit A202.

  According to this configuration, since a plurality of pulses having different attributes are extracted simultaneously, the sampling time can be shortened to increase the number of cycle checks per unit time as compared with the first embodiment, and the cycle check efficiency can be increased. .

  Next, the pulse interval inspection operation of the horizontal synchronization signal BD according to the second embodiment will be described with reference to FIG. In the first period 1301 of the horizontal synchronizing signal BD, the inspection signal selection circuit B204 outputs BD1 to BD4 to the pulse interval inspection circuit 205 as BDY signals. The pulse interval inspection circuit 205 checks the pulse interval of BD1 and BD2 by the first pulse and the second pulse of the BDY signal output from the inspection signal selection circuit B204, and BD3 by the third pulse and the fourth pulse of the BDY signal. Check the pulse interval of BD4. In the second period 1302 of the horizontal synchronization signal BD, the inspection signal selection circuit B204 outputs BD2 to BD5 to the pulse interval inspection circuit 205 as BDY signals. The pulse interval inspection circuit 205 checks the pulse interval of BD2 and BD3 based on the fifth pulse and the sixth pulse of the BDY signal output from the inspection signal selection circuit B204, and determines the interval between the seventh pulse and the eighth pulse of the BDY signal. The pulse interval between BD4 and BD5 is checked. Thereafter, by repeating the same operation, it is possible to check the interval between adjacent horizontal synchronization signal attribute pulses of the horizontal synchronization signal BD.

  According to this configuration, the number of pulse interval checks per unit time can be increased as compared with the first embodiment, and the pulse interval check efficiency can be increased.

  FIG. 14 is a block diagram of the video signal generation unit 104 according to the third embodiment. In the figure, a horizontal synchronization signal BD is applied to a horizontal synchronization signal separation circuit 901, and a first horizontal synchronization signal BD1 is separated and extracted. The BD1 generation video output start signal ST1 is applied to the set terminal of the flip-flop 902a, and the flip-flop 902a is set by the output. The output of the flip-flop 902a is applied to the OR gate 903a together with the print data VD1 output from the drawing controller 904, and the output of the OR gate 903a is output to the scanning mechanism unit 102 as the first video signal LD1. The first horizontal synchronization signal BD1 output from the horizontal synchronization signal separation circuit 901 is applied to the reset terminal of the flip-flop 902a, and the flip-flop 902a is reset by the output.

  Similarly, the horizontal synchronization signal BD is applied to the horizontal synchronization signal separation circuit 901, and the second horizontal synchronization signal BD2 to the fifth horizontal synchronization signal BD5 are separated and extracted. The BD generation video output start signals ST2 to ST5 are applied to set terminals of the flip-flops 902b to 902e, and the flip-flops 902b to 902e are set by the output. The outputs of the flip-flops 902b to 902e are applied to the OR gates 903b to 903e together with the print data VD2 to VD5 output from the drawing controller 904, and the outputs of the OR gates 903b to 903e are the second video signal LD2 to the fifth video signal LD5. It is output to the scanning mechanism unit 102. The second horizontal synchronization signal BD2 to the fifth horizontal synchronization signal BD5 output from the horizontal synchronization signal separation circuit 901 are applied to the reset terminals of the flip-flops 902b to 902e, respectively, and the flip-flops 902b to 902e are reset by the output. .

  The difference between the video signal generation unit 104 in the present embodiment and the video signal generation unit 104 in the first and second embodiments shown in FIG. 9 is that an independent BD for each video signal is connected to the set terminals of the flip-flops 902a to 902e. This is a configuration in which a terminal for inputting a video output start signal for generation is provided. This makes it possible to specify and scan in advance a laser beam to be inspected.

  FIG. 15 is a timing chart illustrating the period inspection operation of the horizontal synchronization signal BD according to the third embodiment. In this figure, an LD1 signal 1501 is output from the video signal generation unit 104 to generate BD1, and BD1 is obtained as a component of the BD signal output from the horizontal synchronization signal generation unit 110. In the next period, the LD1 signal 1502 and the LD2 signal 1503 are output to obtain BD1 and BD2. In the next period, the LD2 signal 1504 and the LD3 signal 1505 are output to obtain BD2 and BD3. In the next cycle, the LD3 signal 1506 and the LD4 signal 1507 are output to obtain BD3 and BD4. In the next cycle, the LD4 signal 1508 and the LD5 signal 1509 are output to obtain BD4 and BD5. In the last cycle, the LD5 signal 1510 is output to obtain BD5. The BD signal obtained in this way is input to the cycle inspection circuit 203 to check each horizontal synchronization signal cycle. The period of BD1 is checked by the first pulse and the second pulse of the BD signal having the BD1 attribute. Next, the period of BD2 is checked by the third pulse and the fourth pulse of the BD signal having the BD2 attribute. Next, the period of BD3 is checked by the fifth pulse and the sixth pulse of the BD signal having the BD3 attribute. Next, the period of BD4 is checked by the seventh pulse and the eighth pulse of the BD signal having the BD4 attribute. Finally, the period of BD5 is checked by the ninth pulse and the tenth pulse of the BD signal having the BD5 attribute.

  In this way, the BD signal obtained by scanning only a specific laser beam can be directly input to the periodic inspection circuit 203 for inspection, and a horizontal synchronization signal to be inspected is inspected by the inspection signal selection circuit A202. There is an advantage that it is not necessary to sequentially generate BDX signals.

  FIG. 16 is a timing chart illustrating the pulse interval inspection operation of the horizontal synchronization signal BD according to the third embodiment. In this figure, an LD1 signal 1601 and an LD2 signal 1602 are output for generating BD1 and BD2 from the video signal generation unit 104, and BD1 and BD2 are obtained as components of the BD signal output from the horizontal synchronization signal generation unit 110. In the next cycle, the LD2 signal 1603 and the LD3 signal 1604 are output to obtain BD2 and BD3. In the next cycle, the LD3 signal 1605 and the LD4 signal 1606 are output to obtain BD3 and BD4. In the last cycle, the LD4 signal 1607 and the LD5 signal 1608 are output to obtain BD4 and BD5.

  The BD signal obtained in this way is input to the pulse interval inspection circuit 205 to check the pulse interval. A pulse interval check between BD1 and BD2 is performed by the first pulse and the second pulse of the BD signal having the BD1 attribute and the BD2 attribute. Next, a pulse interval check between BD2 and BD3 is performed by the third pulse and the fourth pulse of the BD signal having the BD2 attribute and the BD3 attribute. Next, a pulse interval check between BD3 and BD4 is performed by the fifth pulse and the sixth pulse of the BD signal having the BD3 attribute and the BD4 attribute. Finally, the pulse interval between BD4 and BD5 is checked by the seventh pulse and the eighth pulse of the BD signal having the BD4 attribute and the BD5 attribute.

  As described above, the BD signal obtained by scanning only a specific laser beam can be directly input to the pulse interval inspection circuit 205 and inspected in the same manner as described above. There is an advantage that it is not necessary to combine the horizontal synchronizing signals to be generated and to sequentially generate the BDY signal.

  The third embodiment described above is effective as a means for confirming the normality of the horizontal synchronizing signal, particularly in initial diagnosis immediately after the apparatus power is turned on.

1 is a schematic configuration diagram illustrating the overall configuration of a multi-beam optical scanning apparatus and an electrophotographic apparatus according to the present invention. It is a block diagram which shows the Example of the horizontal synchronizing signal test | inspection part in this invention. It is a schematic block diagram of a prior art example. It is a timing chart which shows the video signal and horizontal synchronizing signal in a prior art example. It is a timing chart which shows the horizontal synchronizing signal pulse interval in a prior art example. It is a block diagram which shows the Example of the horizontal synchronizing signal test | inspection part in a prior art example. It is a flowchart which shows the process sequence of the period inspection circuit in this invention. It is a timing chart which shows operation | movement of the period inspection circuit in this invention. It is a block diagram which shows one Example of the video signal generation part in this invention. It is a timing chart explaining BD period inspection operation of the 1st example of the present invention. It is a timing chart explaining the BD pulse interval test | inspection operation | movement of 1st Example of this invention. It is a timing chart explaining BD period inspection operation of the 2nd example of the present invention. It is a timing chart explaining the BD pulse interval test | inspection operation | movement of 2nd Example of this invention. It is a block diagram which shows the video signal generation part of 3rd Example of this invention. It is a timing chart explaining BD period inspection operation of the 3rd example of the present invention. It is a timing chart explaining the BD pulse interval test | inspection operation | movement of 3rd Example of this invention.

Explanation of symbols

101: signal control unit, 102: scanning mechanism unit, 103: horizontal synchronization signal inspection unit,
104: video signal generation unit, 105: laser beam output unit, 106: rotating polygon mirror,
107: aspheric lens, 108: light detection sensor, 109: photoconductor,
110: horizontal synchronization signal generation unit, 111-115: scanning light,
201: horizontal synchronizing signal separation circuit, 202: inspection signal selection circuit A,
203: periodic inspection circuit, 204: inspection signal selection circuit B, 205: pulse interval inspection circuit,
206: Periodic error detection signal, 207: Pulse interval error detection signal,
208: OR gate, 209: BD error detection signal, 301-305: video signal,
306: horizontal synchronization signal, 401 to 425: video signal and horizontal synchronization signal,
501 to 505: horizontal synchronization signal, 601: period check unit,
602 to 606: BD check circuit, 607: pulse interval check unit,
608 to 611: BD-BD check circuit, 612: OR gate,
613: Error detection signal, 801 to 802: BDX signal, 803: Counter,
804: Second pulse reception checking flag, 805: Second pulse reception flag,
901: horizontal synchronizing signal separation circuit, 902a to 902e: flip-flop,
903a to 903e: OR gate, 904: drawing controller,
1001-1024: BD signal and BDX signal,
1101 to 1110: BD signal and BDY signal,
1201-1216: BD signal and BDX signal,
1301-1308: BD signal and BDY signal,
1501-1520: LD signal and BD signal,
1601 to 1616: LD signal and BD signal.

Claims (4)

A laser beam output section for generating a plurality of laser beams, a scanning means for scanning the laser beams on a medium, a light detection sensor disposed near a scanning start end of the laser beams, and an output of the light detection sensor A scanning mechanism unit including a synchronization signal generation unit that generates a corresponding synchronization signal, a synchronization signal inspection unit that checks normality of the synchronization signal, and a video signal corresponding to each laser beam is generated by the synchronization signal In a multi-beam optical scanning device having a signal control unit including a video signal generation unit
In the signal control unit, a single period inspection circuit that inspects one synchronization signal period of the plurality of laser beams, and a single period inspection circuit that inspects a synchronization signal pulse interval between a pair of adjacent laser beams of the plurality of laser beams. A multi-beam optical scanning device comprising: a pulse interval inspection circuit; and selection means for sequentially inputting a synchronization signal corresponding to each laser beam to the inspection circuit.   2. The multi-beam optical scanning according to claim 1, wherein the selection unit includes an inspection signal selection circuit that generates a synchronization signal corresponding to each laser beam and inputs the synchronization signal to the period inspection circuit and the pulse interval inspection circuit. apparatus.   2. The multi-beam optical scanning device according to claim 1, wherein the selection unit includes a video signal generation unit that individually generates a video signal using an output start signal for each video signal. An electrophotographic apparatus that forms an electrostatic latent image on a photosensitive member using the multi-beam optical scanning device according to claim 1.

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