JP2007060569A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a defect in the quality of image caused by picture data line un-inputting especially derived from disconnection of the transmission line of image data, a connector off-hook or the like. <P>SOLUTION: Since a transmission line 62 for transmitting image data to a data control device 58 from a video control unit 66 and a transmission line 60 for transmitting a control signal to an optical power device 46 from a sequence control unit 64 are provided separately, a disconnection state of transmission line 62 for transmitting image data is supervised. That is, a predetermined voltage V is applied by pull-up resistance 86. When the voltage V other than this image signal (H>V>L) is detected in the output of an image signal (H signal and L signal), the line disconnection or off-hook of connectors 82 and 84 are detected. By this way, it is made possible to solve the problem that a fault cannot be distinguished as unusual though there is a blank paper print. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides an image provided with a light output device in which image data from a video control unit that generates an image signal and sequence data from a sequence control unit that controls lighting timing are transmitted to a light source drive unit through different paths. The present invention relates to a forming apparatus.

  Conventionally, in a light source driving unit mounted in an image forming apparatus, a light beam is controlled to be turned on / off according to image data, and irradiated to a photosensitive drum as an image carrier through a scanning unit such as a polygon mirror. To do.

  Here, an electrostatic latent image is formed by rotating the photosensitive drum (sub-scanning) while scanning the light beam in the axial direction of the photosensitive drum by the polygon mirror (main scanning).

  The electrostatic latent image formed on the photosensitive drum is visualized by supplying toner, and the visualized image (toner image) is transferred to a recording sheet and recorded on the transfer unit. An image is formed by fixing the transfer image on the paper.

  Such an electrophotographic image forming apparatus can process high-quality images at high speed, and is therefore applied to a copying machine, a laser printer, and the like.

  In the image forming apparatus, various processes such as a side blanking mode, a trailing edge blanking mode, and a light amount adjustment mode are executed as work different from normal image data writing.

  Side erase mode and rear edge erase mode are modes that forcibly erase part of the image. If the image writing area is large due to the size of the recording paper, the toner is not transferred to the recording paper and the photosensitive drum. This is because it remains on the surface and causes dirt in the machine.

  Therefore, the LD is forcibly turned off at the side edge portion of the recording paper (side erase mode), or the LD is forcibly turned off at the rear edge portion of the recording paper (rear edge elimination mode). .

  In the image forming apparatus, the video control unit generates image data in accordance with an instruction received from the host computer. Further, in the sequence control unit that controls the operation of the printer and the copying machine, lighting timing and light amount adjustment control are performed outside the image forming area.

  The image data from the video control unit and the sequence data from the sequence control unit that controls the lighting timing are transmitted to a light amount control circuit (laser drive unit) through different transmission lines (Patent Document 1). reference).

For this reason, the number of components and connection points increases, and the occurrence of image quality defects due to non-input of image data lines due to transmission device failures, transmission line disconnections, connector disconnections, and the like tends to increase.
JP-A-6-166207

  However, in the image forming apparatus described in Patent Document 1, even when an abnormality occurs in the image data input, the abnormality detecting means is not provided on the transmission line of the image data separated from the transmission line from the sequence control unit. However, it was only possible to recognize that an abnormality occurred only after viewing an abnormal print such as a blank paper print.

  Further, even if an abnormal printer output such as blank paper printing is output, it is regarded as normal completion on the system, and temporarily stored image data is discarded, so that reprinting cannot be performed.

  In view of the above facts, an object of the present invention is to obtain an image forming apparatus capable of preventing a defect with image quality caused by no input of an image data line due to disconnection of a transmission line of image data, disconnection of a connector or the like.

  The first invention includes an optical output device in which image data from a video control unit that generates an image signal and sequence data from a sequence control unit that controls lighting timing are transmitted to a laser drive unit through different paths. An image forming apparatus that controls the light output device to perform an image writing lighting mode in which an image writing operation is performed in the image forming area based on the image data, and a light amount adjusting operation is performed outside the image forming area. Control means for selectively executing the light amount adjustment lighting mode, writing abnormality detection means for detecting an abnormality in image data input during execution of the image writing lighting mode by the control means, and light amount adjustment by the control means Light source abnormality detection means for detecting light quantity abnormality and synchronization interval abnormality during execution of the lighting mode, and the writing abnormality detection means Or if an error is detected by the light source abnormality detecting unit has an abnormality source discrimination means for discriminating a source of the abnormal, the.

  According to the first invention, when receiving image data from the video control unit in the image writing / lighting mode, the image data is transmitted through the transmission path with the sequence control unit. If the image data does not reliably reach the light source drive unit due to omission or the like, the sequence control unit cannot detect this image data non-input abnormality.

  Therefore, by providing a new writing abnormality detection unit, it is possible to detect an abnormality in image data input during execution of the image writing mode by the control unit.

  According to a second aspect of the present invention, there is provided an optical output device in which image data from a video control unit that generates an image signal and sequence data from a sequence control unit that controls lighting timing are transmitted to a laser driving unit through different paths. An image writing lighting mode in which the light output device is controlled to perform an image writing operation within the image forming area based on the image data, and a light amount adjusting operation outside the image forming area A control means for selectively executing a light amount adjustment lighting mode for performing image writing, a writing abnormality detection means for detecting an abnormality in image data input during execution of the image writing lighting mode by the control means, and the control means. Light source abnormality detection means for detecting light amount abnormality and synchronization interval abnormality during execution of the light amount adjustment lighting mode, and the writing abnormality If an error is detected by known means or light source abnormality detecting unit has an abnormality source discrimination means for discriminating a source of the abnormal, the.

  According to the second invention, when receiving image data from the video control unit in the image writing / lighting mode, the image data is transmitted through a transmission path different from that of the sequence control unit. If the image data does not reliably reach the light source drive unit due to a connector dropping or the like, the sequence control unit cannot detect this image data non-input abnormality.

  Therefore, by providing a new writing abnormality detection unit, it is possible to detect an abnormality in image data input during execution of the image writing mode by the control unit.

  Further, since the function for detecting the light quantity abnormality and the synchronization interval abnormality is already provided during execution of the light quantity adjustment lighting mode by the control means, the abnormality occurrence source discrimination means of the second invention is a writing abnormality detection means or a light source. When an abnormality is detected by the abnormality detection means, the source of the abnormality is determined.

  As a result, the source of the abnormality can be specified.

  The selective execution of the image writing lighting mode and the light amount adjustment lighting mode includes a case where both lighting modes are continuously executed within one scan.

  In the first or second aspect of the invention, the writing abnormality detecting means detects an abnormality in image data input in the image writing lighting mode based on an input voltage.

  The writing abnormality detecting means detects an abnormality in image data input in the image writing lighting mode by a disconnection detection signal of an image data input line.

  The writing abnormality detection means detects an abnormality in image data input in the image writing lighting mode based on no input of image data for a predetermined period.

  As an abnormality detection means, it is possible to detect that image data is not normally input with an input voltage from the video control unit to the laser drive unit. Alternatively, by providing a disconnection detection function in the image data input line, it is possible to detect that the image data is not normally input when there is a disconnection. Further, when the image data is not input for a predetermined period, it can be predicted that there is an abnormality in the transmission line of the image data.

  In the first invention or the second invention, when the writing abnormality detecting means detects an abnormality, it further has a notifying means for notifying information of the abnormality detection.

  By receiving notification of abnormality detection information by the notification means, for example, the execution of the image writing lighting mode by the control means is stopped (stopping means), or the image data recognized as the completion of image writing is discarded. Without saving (holding means).

  Furthermore, in the first invention or the second invention, the image data is transmitted as a low voltage differential signal.

  When “0” or “1” is expressed by a low-voltage differential signal, for example, when the threshold (reference voltage) is Vr, “0” or “1” if the reference voltage is not exceeded. Cannot be determined. Therefore, when the input voltage becomes Vr or less (absolute value), it is determined that there is an abnormality, and in addition to no image data such as disconnection, abnormalities in the low-voltage differential signal source (voltage drop, etc.) are also detected can do.

  Further, in the first invention or the second invention, when the light source has a plurality of light beam emission points, the writing abnormality detection unit detects an image data input abnormality for each emission point, The light source abnormality detection means detects a light amount abnormality and a synchronization interval abnormality for each light emitting point, detects an image data input abnormality for each light emitting point, and the number of light emitting points detected as abnormal is less than a predetermined number. In this case, the image writing operation in the image writing lighting mode can be continued.

  As described above, the present invention has an excellent effect that it is possible to prevent defects with image quality caused by no input of an image data line due to disconnection of a transmission line of image data, disconnection of a connector or the like.

(Overall configuration of image forming apparatus)
First, the overall configuration of an image forming apparatus using the optical scanning device of the present invention will be outlined with reference to FIG.

  As shown in FIG. 1, the image forming apparatus 10 includes a casing 12, in which a cylindrical photosensitive drum 14 that rotates in the direction of arrow A and a light beam B based on desired image data. An optical scanning device 16 that irradiates the photosensitive drum 14 while performing main scanning is provided. A laser light source (LD) 20, a rotating polygonal mirror 22, and a mirror (reflecting mirror) 23 are disposed inside the housing 18 of the optical scanning device 16.

  On the other hand, a charger 24, a developing device 26, a transfer device 28, and a cleaner 30 are disposed in the vicinity of the peripheral surface of the photosensitive drum 14 in order from the upstream side in the rotation direction of the photosensitive drum 14. The photosensitive drum 14 is uniformly charged by the charger 24 and then irradiated with the light beam B from the optical scanning device 16. As a result, an electrostatic latent image corresponding to the image data is formed on the circumferential surface of the photosensitive drum 14.

  The photosensitive drum 14 on which the electrostatic latent image is formed is supplied with toner from the developing unit 26 and adheres to the portion irradiated with the light beam B by the optical scanning device 16. As a result, a toner image is formed on the peripheral surface of the photosensitive drum 14.

  The toner image formed on the photosensitive drum 14 is transferred from the paper tray 32 or the manual feed tray 34 to the conveyed paper 36 by the transfer device 28. After the transfer, the toner remaining on the peripheral surface of the photosensitive drum 14 is removed by the cleaner 30.

  The sheet 36 on which the toner image has been transferred is conveyed to a fixing device 38 provided on the downstream side in the conveying direction of the sheet 36 (see the direction of arrow C), and transferred by a pressure roller 40 and a heating roller 42 of the fixing device 38. The toner image is thermocompression bonded to the paper 36. The paper 36 on which the image has been fixed is discharged to a discharge tray 44.

(Optical scanning device 16)
As shown in FIG. 2, the optical scanning device 16 shows the structure of the light output device 46 including a control system. 48, a cylindrical lens 50, a rotary polygon mirror 22, an Fθ lens 52A, an Fθ lens 52B, and a mirror 23 are provided.

  Further, the laser light source 20 is connected to a light amount control device 56 of the laser drive unit 54, and lighting / extinguishing is controlled by the light amount control device 56.

  The laser drive unit 54 is provided with a data control device 58 in addition to the light amount control device 56. The data control device 58 includes a sequence control unit 64, a video control unit 66, and separate transmission lines 60 and 62. (The control system of the laser light source 20 including the laser drive unit 54 will be described later.

  The light beam B emitted from the laser light source 20 is made into substantially parallel light by the collimator lens 48 and further passes through the cylindrical lens 50 to become the light beam B focused in the sub-scanning direction. Irradiated onto the mirror 22.

  When the rotary polygon mirror 22 is rotated at high speed in the direction of arrow D by a motor (not shown), a plurality of light beams B irradiated on the rotary polygon mirror 22 are provided on the peripheral surface (in this embodiment, 8). Surface) is reflected by the reflecting surface 22A, and is deflected and scanned (main scanning) onto the photosensitive drum 14. The light beam B deflected by the reflecting surface 22A of the rotary polygon mirror 22 passes through the two Fθ lenses 52A and 52B, is reflected by the reflecting surface of the mirror 23, and is reflected, and passes through a dustproof glass (not shown). The image is formed on the photosensitive drum 14. An SOS sensor 68 is provided on the optical path (starting side in the main scanning direction) reflected by the mirror 23 and reaching the photosensitive drum 14. The SOS sensor 68 receives a light beam reflected by the rotary polygon mirror 22 and subjected to main scanning, and the detection result is applied as a main scanning timing parameter.

(Control system of light output device 46)
As shown in FIG. 3, the light output device 46 includes a video control unit 66 for generating image data, a sequence for controlling operations of the laser driving unit 54 and the optical scanning device 16 based on a signal from the host computer 70. A control unit 64 is connected.

  The laser drive unit 54 that drives and controls the laser light source 20 has a function that the above-described data control device 58 mainly switches the image data input to the laser light source 20 and cuts the image data. The light quantity control device 56 has a role of controlling the light quantity of the laser light source 20 to a predetermined output.

  The light amount controller 56 adjusts the light amount so that the light amount of the laser light source 20 does not become a predetermined output before image writing, and then performs a light amount adjustment lighting mode for performing light amount adjustment control for each scan outside the image forming area.

  In the light amount adjustment lighting mode, it is possible to turn on the laser light source regardless of the presence or absence of image data. By measuring the drive current when the light source is turned on in this light amount adjustment lighting mode, the laser light source 20 is deteriorated. It is possible to detect a failure due to.

  On the other hand, a video control unit 66 is connected to the data control device 58 of the laser drive unit 54. The image data input from the video control unit 66 to the data controller 58 is sent to the data detector 72 and the light amount controller 56.

  The data detection unit 72 detects the presence of image data, and sends the detection result to the abnormality determination unit 76, so that the abnormality determination unit 76 determines the presence or absence of a failure. An abnormality display unit 78 is connected to the abnormality determination unit 76, and when an abnormality occurs, an abnormality signal is sent to the abnormality display unit 78 to notify (display) the abnormality.

  Further, when receiving the image data, the light quantity control device 56 drives the laser light source 20 in an image writing lighting mode for forming an image in the image forming area based on the image data.

  That is, in the present embodiment, the image data is directly input to the data control device 58 through another transmission line 62 without using the sequence control unit 64, and the physical length of the transmission line 62 is Therefore, the generation of unnecessary radiation from the transmission line 62 can be suppressed.

  On the other hand, the sequence control unit 64 sends an image data switching signal for supporting the switching of the image data of the laser light source 20 to the data control device 58, and sends an ROS control signal for controlling the operation of the optical system to the optical scanning device 16. Send it out.

  Further, the sequence control unit 64 sends an output control signal such as an image writing timing signal and an automatic light amount control timing signal to the data control device 58.

  The data control device 58 has a function for forcibly turning on the laser light source 20 and a function for forcibly turning off the laser light source 20. That is, in accordance with the mode switching signal received from the sequence control unit 64, the laser light source 20 is forcibly activated regardless of the presence or absence of the image writing lighting mode in which the laser light source 20 is driven based on the image data. Switching to a forced lighting mode for lighting or a forced lighting mode for forcibly turning off the laser light source 20 regardless of the presence or absence of image data is executed.

  Here, in the light output device 46 configured as described above, even when an abnormality occurs in the image data input, the abnormality is detected on the transmission line 62 of the image data separated from the transmission line 60 from the sequence control unit 64. There is no means, and even if a blank print is output, it is regarded as a normal end in the system, and the temporarily stored image data is discarded and reprinting cannot be performed.

  Therefore, in the present embodiment, the video data control unit 66 and the image data transmission monitoring unit 80 (see FIG. 4) are provided on the transmission line 62 connected to the data control device 58.

  As shown in FIG. 4A, the video data control unit 66 and the data control device 58 are electrically connected by a transmission line (electric wire) 60 having connectors 82 and 84 connected to both ends.

  A pull-up resistor 86 is provided between the video data control unit 66 and the connector 82, and a predetermined voltage is applied.

  A voltage detector 88 is provided between the data control device 58 and the connector 84.

  Here, in the video data, the H signal turns off the laser light source 20, and the ON signal turns on the laser light source 20, and the transmission line 62 is normal (no disconnection and the connectors 82 and 84 are securely connected). If the video signal is an ON signal, as shown in the target table of the output signal-voltage V (detected voltage of the voltage detector 88) in FIG. Is L (approximately 0 V), and when the video signal is an OFF signal, the voltage V is H (voltage value applied by the pull-up resistor 86).

  On the other hand, when the transmission line 62 is abnormal (a state in which disconnection or disconnection of the connectors 82 and 84 has occurred), as shown in FIG. An intermediate voltage that is not any of the above. This intermediate voltage value depends on the electrical component configuration of the data controller 58.

  As shown in FIG. 3, the transmission monitoring unit 80 is connected to the abnormality determining means 76 (see FIG. 3). As a result, the abnormality determining means 76 indicates that an abnormality has occurred in the image data transmission system. Recognizing and notifying the transmission system abnormality of the image data using the abnormality display unit 78.

  Here, in the abnormality determination, as shown in FIG. 5, a disconnection detection signal is output outside the actual image recording area in the image writing lighting mode to determine the presence or absence of disconnection. This is because the laser light source 20 is repeatedly turned on and off at the time of image recording. Therefore, other times such as the time when the laser light source 20 is continuously turned on are set separately, and the laser light source is as commanded (according to image data). Whether or not 20 lights up is determined.

  Such determination of the presence or absence of abnormality is performed by the abnormality determination unit 76 (see FIG. 3). That is, in the image writing lighting mode, the abnormality determination unit 76 sets a time when the image data is intentionally transmitted as described above (see FIG. 5), and determines whether there is input image data during this period. .

  The operation of this embodiment will be described below.

  In the image forming apparatus, when an image formation is instructed from the sequence control unit 66, drive control of the optical scanning device 16 is started. As a result, the photosensitive drum 14 is uniformly charged by the charger 24, and the image data generated by the video control unit 66 passes through the data control device 58 and is controlled to a predetermined light amount by the light amount control device 56. Then, the laser light source 20 is driven to irradiate the light beam corresponding to the image to be formed on the paper 36. Thereby, an electrostatic latent image is formed on the photosensitive drum 14.

  The electrostatic latent image formed on the photosensitive drum 14 is developed by supplying toner by the developing device 26. The developed toner image is transferred onto the paper 36 by the transfer device 28. In addition, the sheet 36 onto which the toner image has been transferred is fixed by the fixing device 38 during the conveyance to the discharge tray 44 and is discharged.

  In the image forming process, there are a light amount adjustment lighting mode area and an image writing lighting mode area (see FIG. 5) as a range in which the light beam is scanned. In the present embodiment, the video control unit 66 to the data control device. Toward 58, a disconnection detection signal is output at the non-image formation time in the image writing lighting mode area. The presence or absence of a disconnection is detected in the detection state of the transmission monitoring unit 80 when the disconnection detection signal is output.

  FIG. 6 is a flowchart showing the flow of the disconnection detection control. In this flowchart, the light amount adjustment (light amount abnormality) in the light amount adjustment lighting mode is also executed at the same time.

  In step 100, the light amount (monitor voltage value MO corresponding to the detected light amount) is detected in the light amount adjustment lighting mode, and then the process proceeds to step 102 where the threshold value Vth is compared with the detected voltage value MO.

  If it is determined in this step 102 that Vth> MO, it is determined that the light amount is not appropriate, and the routine proceeds to step 104 where it is determined whether the light amount can be adjusted. If the light amount can be adjusted in step 104, the process proceeds to step 106, where the light amount is adjusted, and the process returns to step 102 and is compared with Vth.

  If it is not possible to adjust the amount of light in step 104, the process proceeds to step 108 to instruct NG display, printing is stopped, and this routine ends.

  As another determination method, there is a method of determining an abnormality by measuring a synchronization interval. The synchronization interval is measured by the SOS 20. Here, when the light quantity abnormality occurs and the light quantity decreases, the SOS 20 may not detect the light quantity, and the light quantity abnormality may be determined.

  If it is determined in step 102 that Vth ≦ MO (positive determination), it is determined that the amount of light is appropriate, and the process proceeds to step 110.

  In step 110, an operation of detecting a disconnection state of the transmission line 62 of the video control unit 66 having another transmission line 62 from the transmission line 60 of the sequence control unit 64 for adjusting the light amount is executed.

  That is, in step 110, the image writing lighting mode is set, and a disconnection detection signal is output in the non-image forming area (see FIG. 5).

  The disconnection detection signal is detected by the transmission monitoring unit 80 and sent to the abnormality determination unit 76, thereby executing abnormality determination based on the table of FIG.

  In the next step 112, it is determined whether or not an abnormality has been detected. If a negative determination is made in step 112, there is no abnormality, so that the process proceeds to step 114 to execute printing.

  If an affirmative determination is made in step 112, there is an abnormality, so that the process proceeds to step 116 to instruct NG display, printing is stopped, and this routine ends.

  As described above, in the present embodiment, the transmission line 62 that transmits image data from the video control unit 66 to the data control device 58, and the transmission line 60 that transmits the control signal from the sequence control unit 64 to the light output device 46. Are separately provided, the disconnection state of the transmission line 62 for transmitting image data is monitored. That is, when a predetermined voltage V is applied by the pull-up resistor 86 (see FIG. 4) and a voltage V (H> V> L) other than the image signal is detected when the image signal (H signal, L signal) is output. In addition, disconnection or disconnection of the connectors 82 and 84 is detected. As a result, it is possible to solve the problem that there is a blank print and this cannot be determined as abnormal.

(Modification)
In the above embodiment, the abnormality determination unit 76 determines the presence or absence of abnormality based on the image data (L signal or H signal) based on the table of FIG. 4B. A circuit configuration for determining an abnormality in the case of low-voltage differential signal transmission (LVDS) level data transmission will be described.

  FIG. 7A shows an example of a data transmission line at a low voltage differential signal transmission (LVDS) level.

  In the LVDS transmission method, signals (voltage and current) in opposite directions are sent using two copper wires 90 and 92.

  Further, in the LVDS transmission method, since only the potential difference between the two signals of the receiver 94 is considered, there is a characteristic that the influence of the common-mode noise is eliminated and the influence of the noise is difficult.

  Furthermore, in the LVDS transmission system, a predetermined current is supplied from the current source from the driver side. The receiver 94 has a termination resistor, and a predetermined voltage is applied between both input terminals. For example, when a current of 3.5 mA is supplied from a current source to a terminal resistance of 100Ω, a voltage of 350 mV is applied to both input terminals.

  Here, when the data transmission line is disconnected, no current flows through the terminating resistor, and no voltage is applied to both input terminals. For this reason, the potential difference between the two input terminals is measured, a predetermined threshold level lower than 350 mV is determined, and if the level is lower than this level, it can be determined that the circuit is disconnected.

  FIG. 8 shows a circuit configuration using a flip-flop circuit for disconnection determination by the LVDS transmission method. In this circuit, an image data input abnormality is detected by the absence of input image data for a predetermined period in the image writing lighting mode.

  The image data from the video control unit 64 is at the LVDS level, and signals indicated by DATA-A + and DATA-A- are generated (see FIG. 7B).

  In recent image forming apparatuses, it is common to have a plurality of light sources, and in FIG. 8, there are two channels of DATA-A and DATA-B.

  The DATA signal is distributed to two systems, separately from being used for original image writing, the LVDS is converted to the TTL level by the receivers 96A and 96B, and is input to the SR flip-flops 98A and 98B.

  When the TTL level becomes L, the laser light source 20 is turned on, and the logic for image formation is set.

  In DATA-A, when there is image data, the S input of the SR flip-flop 98A becomes active, and the output Q of the SR flip-flop 98A is inverted.

  The PCONT signal is input to the R input of the SR flip-flop 98A every scan, and the output Q is initialized. DATA-B performs the same operation.

  The output Q of the SR flip-flops 98A and 98B of the DATA-A and DATA-B is input to the OR circuit 99, and if one of the DATA-A and DATA-B exists even in one pixel, the S of the SR flip-flop 97 Input and output Q is inverted. This output becomes the DATA detection signal. A PAGE-SYNC signal is used for the R input of the SR flip-flop 97 to detect the presence or absence of image data for each page. FIG. 9 is a signal timing chart of each part of the circuit.

  In the embodiment, the disconnection detection signal is output and the presence / absence of disconnection is determined outside the actual image recording area in the image writing / lighting mode, but the disconnection detection is executed during actual image recording. Also good.

  That is, as shown in FIG. 3, the abnormality determination means 72 is connected to the video control unit 66 and sends a data storage instruction signal when an abnormality occurs in the transmission system of the image data. The video control unit 62 that has received this data storage instruction signal executes an operation of storing the image data in the temporary storage unit without discarding the image data that has been transmitted (actually not transmitted due to an abnormality). In other words, the image data that has been transmitted is immediately discarded and the next image data is accepted, but before entering the acceptance state, a storage operation in the temporary storage unit is interposed.

  As a result, when there is a blank paper print, the image data is saved, so that it can be easily reprinted based on a re-predict instruction or the like.

  If it is determined that there is an abnormality, printing is not stopped immediately, and if the user desires to continue printing even if the print quality deteriorates, the number of light sources may be reduced to continue printing. .

1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment. 3 is a block diagram illustrating a control system of an optical scanning device of the image forming apparatus. FIG. It is a block diagram which shows the detail of a control system centering on a laser drive unit. (A) is a wiring diagram showing the outline of the transmission monitoring unit according to the present embodiment, and (B) is a target chart with voltage image data detected in FIG. It is a timing chart which shows each area | region of light quantity adjustment lighting mode and image writing lighting mode. It is a disconnection monitoring control flowchart by a transmission monitoring unit. (A) is a wiring diagram showing an outline of a transmission monitoring unit according to a modification, and (B) is a target diagram with voltage image data detected in FIG. It is a detailed circuit diagram of the transmission monitoring unit of FIG. It is a timing chart which shows the state of the signal by the circuit of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Casing 14 Photosensitive drum 16 Optical scanning device 18 Case 20 Laser light source (LD)
22 rotating polygon mirror 23 mirror 24 charger 26 developing device 28 transfer device 30 cleaner 32 paper tray 34 manual feed tray 36 paper 38 fixing device 40 pressure roller 42 heating roller 44 discharge tray 46 light output device 48 collimator lens 50 cylindrical lens 52A, 52B Fθ lens 54 Laser drive unit 56 Light quantity control device 58 Data control device 60, 62 Transmission line 64 Sequence control unit 66 Video control unit (control means)
68 SOS sensor 70 Host computer 72 Data detection unit 76 Abnormality determination unit (light source abnormality detection means, abnormality source determination means)
78 Error display 80 Transmission monitoring unit (Writing error detection means)
82, 84 Connector 86 Pull-up resistor

Claims (11)

An image forming apparatus having a light output device in which image data from a video control unit that generates an image signal and sequence data from a sequence control unit that controls lighting timing are transmitted to a light source drive unit through different paths. And
Control means for controlling the light output device and executing an image writing lighting mode for performing an image writing operation in an image forming area based on the image data;
Write abnormality detection means for detecting an abnormality in image data input during execution of the image writing lighting mode by the control means;
An image forming apparatus. An image forming apparatus having an optical output device in which image data from a video control unit that generates an image signal and sequence data from a sequence control unit that controls lighting timing are transmitted to a laser drive unit through different paths. And
The light output device is controlled to selectively select an image writing lighting mode for performing an image writing operation within an image forming area based on the image data, and a light amount adjustment lighting mode for performing a light amount adjusting operation outside the image forming area. Control means to execute;
Write abnormality detection means for detecting an abnormality in image data input during execution of the image writing lighting mode by the control means;
Light source abnormality detection means for detecting light quantity abnormality and synchronization interval abnormality during execution of the light quantity adjustment lighting mode by the control means,
When an abnormality is detected by the writing abnormality detection unit or the light source abnormality detection unit, an abnormality source determination unit that determines a source of the abnormality;
An image forming apparatus.   The image forming apparatus according to claim 1, wherein the writing abnormality detection unit detects an abnormality in image data input in the image writing lighting mode based on an input voltage.   3. The image formation according to claim 1, wherein the writing abnormality detection unit detects an abnormality in image data input in the image writing lighting mode by a disconnection detection signal of the image data input line. apparatus.   3. The image forming apparatus according to claim 1, wherein the writing abnormality detecting unit detects an abnormality in image data input in the image writing lighting mode based on no input of image data for a predetermined period. .   6. The image forming apparatus according to claim 1, further comprising a notification unit configured to notify information on abnormality detection when the writing abnormality detection unit detects abnormality.   The image forming apparatus according to claim 6, further comprising a canceling unit that cancels the execution of the image writing lighting mode by the control unit based on the abnormality detection information notified by the notification unit.   7. The image processing apparatus according to claim 6, further comprising a storage unit that stores the image data recognized as having been written based on the abnormality detection information notified by the notification unit without discarding the image data. 8. The image forming apparatus according to 7.   The image forming apparatus according to claim 1, wherein the image data is transmitted as a low voltage differential signal.   The light source has a plurality of light beam emission points, the writing abnormality detection means detects an image data input abnormality for each light emission point, and the light source abnormality detection means has a light amount for each light emission point. The image forming apparatus according to claim 1, wherein an abnormality and a synchronization interval abnormality are detected.   The light source has a plurality of light beam emission points, and the writing abnormality detection unit detects an image data input abnormality for each emission point, and the number of detected emission points is less than a predetermined number. The image forming apparatus according to claim 1, wherein the image writing operation in the image writing lighting mode is continued.

Images