JP3353515B2 - Image output device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image output apparatus, and more particularly to an image output apparatus having a plurality of laser beam light sources for forming an image in a laser printer, a copying machine, or the like.

[0002]

2. Description of the Related Art Electrophotographic image formation in a laser printer, a copying machine or the like is performed in the following procedure. First,
The photoreceptor is uniformly charged, and a laser beam based on image data is exposed thereon to form an electrostatic latent image. continue,
This electrostatic latent image is developed with toner, and a digital image is obtained through the steps of transfer and fixing. In general, a laser diode is used as a light source of the laser beam exposure apparatus. The laser beam modulated and output from this light source in accordance with image data is deflected by a rotating polygon mirror, further corrected by a beam diameter and the like by an optical system, and is imaged on a photoconductor. In the laser beam exposure apparatus, a light receiving element is provided on a deflection scanning optical path of a laser beam in order to obtain an image writing timing, and horizontal synchronization is achieved by detecting a laser beam passing through the light receiving element.

On the other hand, in recent years, there has been known a laser beam exposure apparatus which realizes higher-speed image recording by simultaneously scanning a plurality of laser beams in parallel. By the way, in a device provided with a plurality of laser beam light sources, even when an abnormality occurs in one light source, the light receiving element for obtaining the horizontal synchronization performs a normal detection operation only by the laser beam from another light source. Therefore, no abnormality is detected. As described above, if an abnormal condition occurs but the device is used without being detected, the output of the image data by one failed light source remains missing, and for example, the recorded image becomes thin. Failure occurs.

In order to solve the above problem, there has been proposed an apparatus in which a plurality of light sources are sequentially and selectively turned on so that an abnormal light source can be detected (Japanese Patent Application Laid-Open No. S59-5959).
127,015, JP-A-62-240919).

[0005]

In the above-mentioned conventional apparatus,
There are the following problems that have not been solved yet. In the apparatus described in each of the above publications, the detecting means for detecting the occurrence of the abnormality in the laser beam light source is shown, but when detecting the occurrence of the abnormality in the laser beam light source, the following measures are taken. Not considered. In other words, the detection of an abnormality alone can prevent the occurrence of printing failure, but does not solve the problem that the printing operation must be stopped until the failed laser beam light source is repaired.

[0006] In order to extend the life of a laser beam light source, an apparatus has been proposed in which a plurality of light sources are provided and one of them is selected and used (Japanese Patent Laid-Open No. 4-246877). In this apparatus, even when one light source cannot be turned on, the printing operation can be continued using another light source. However, according to the method in which another light source is energized in place of the light source that cannot be turned on in this way, a light source that is not always used must be prepared, and a type in which a plurality of laser beams are simultaneously scanned is used. However, there is a problem that the image output device cannot be used.

An object of the present invention is to provide an image output apparatus which solves the above-mentioned problem and can continue the printing operation by an emergency measure until the laser beam light source which cannot be turned on is repaired. With the goal.

[0008]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems and achieving the object has a function of responding to a control signal for setting a light amount for each laser light source when the control signal is larger than an upper limit value. The first feature is that a failure detecting means for recognizing a laser light source to be performed as a failed light source, and a light amount increasing means for increasing the light amount of a normal laser light source when the failed light source is recognized by the failure detecting means. is there.

A second feature of the present invention resides in that a means for reducing a sub-scanning speed of a laser beam from a normal laser light source when a fault light source is recognized by the fault detecting means is provided.

Further, according to the present invention, there is provided an extinguishing means for extinguishing a part of a normal laser light source other than the faulty light source so that the faulty light source is turned on at equal intervals when the fault detecting means recognizes the faulty light source. A third feature is that the light emitting device further comprises a light amount increasing means for increasing the light amount of the laser light source lit at the equal interval.

Further, the present invention provides a method for controlling a part of a normal laser light source other than the failed light source such that when the failed light source is recognized by the failure detecting means, a predetermined number of continuously arranged laser light sources are turned on. A fourth feature is that the light-emitting device comprises a light-off means for turning off the light source, and means for reducing a sub-scanning speed by a laser beam from the laser light source which is continuously arranged and turned on for a predetermined number of times.

[0012]

According to the first feature, when the control signal is increased until the control signal exceeds the upper limit, it is determined that a laser light source that cannot be turned on is generated, and the light amount of the remaining normal laser light source is increased. As a result, the shortage of the light amount reduced by the failed light source is compensated.

Similarly, according to the second feature, it is determined that an unlighted laser light source has occurred, and the sub-scanning speed of the laser light source is reduced. As a result, a decrease in image density is prevented.

According to the third feature, when it is determined that a laser light source that cannot be turned on has been generated, the normal laser light source is partially turned off and turned on at equal intervals. Then, each laser light source is turned on so that the amount of light becomes larger than usual. As a result, the shortage of the light amount reduced by the failed light source is compensated.

Further, according to the fourth feature, when it is determined that a laser light source that cannot be turned on has been generated, a part of the normal laser light source is turned off and the remaining laser light sources that are continuous with each other are turned on. I do. In this case, the sub-scanning speed of the laser light source is reduced, and a decrease in image density is prevented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 3 is a plan view showing a main part configuration of an image output apparatus according to one embodiment of the present invention, and FIG. 4 is a side view of the same. 3 and 4, the semiconductor laser array 1 includes two laser diodes LDa and LDb, and a photodiode (not shown) for detecting the light emission amount of the laser diodes LDa and LDb. Laser beams 9 and 10 emitted from the laser diodes LDa and LDb respectively pass through common lenses 2 and 3 and are reflected by a mirror 4 to reach a rotating polyhedron 5. The rotating polyhedron 5 has eight reflecting surfaces, and is rotated in the direction of arrow A by a driving source (not shown). As a result, the laser beams 9 and 10 reflected by the mirror 4 and reaching the reflecting surface of the rotating polyhedron 5 are scanned in the direction of arrow B on the medium to be scanned, that is, the photoconductor 11. Here, an example in which the laser beam is scanned on the drum-shaped photoconductor 11 as the medium to be scanned has been described, but the same applies to a planar photoconductor.

A scanning lens 6 and a cylinder lens 7 are provided between the rotating polyhedron 5 and the photoreceptor 11 in order to scan the laser beam on the photoreceptor 11 at a constant speed. Optical position detector 8 composed of a photoelectric conversion element such as a photodiode
Detects the laser beam reflected by the mirror 8a,
A detection signal (SOS) necessary for synchronizing the optical laser beam generation position with the modulation signal is generated.

The drum-shaped photoconductor 11 is rotatably supported, for example, by a housing (not shown) of the image forming apparatus, and is rotated at a predetermined speed in a direction indicated by an arrow D by a drive source (not shown). Around the photoreceptor 11, a charger for uniformly charging the surface layer of the photoreceptor 1, an exposure unit, a developing unit, a transfer unit, and the like are provided.
The illustration is omitted because it is not a main part of this embodiment. In FIG. 4, the axis of the rotating polyhedron 5 is illustrated as being inclined for convenience in order to clearly show the optical path of the laser beam.

Next, an automatic light quantity control device (APC) for setting the light quantity of the laser beam emitted from the semiconductor laser array 1 will be described. FIG. 5 is a block diagram showing a circuit of the light amount control device. In FIG. 1, a semiconductor laser array 1 includes two laser diodes LD.
a and LDb, and the laser diode LDa,
A photodiode PD to which both of the rear outputs of the LDb can enter is provided. The laser diode LDa,
The switch 12 and the constant current circuit 14 are connected in series between the power supply and the ground, and similarly, the laser diode LDb,
The switch 13 and the constant current circuit 15 are also connected in series between the power supply and the ground. The photodiode PD has a cathode connected to a power supply, and an anode connected to one input side of a comparator 19 via a current / voltage converter (I / V) 16.

The video control circuit 22 controls the video signals Video.a and V based on image information supplied from the outside.
Outputs video.b. These video signals Video
A and Videob are switches 12 and 1
3 respectively. The switches 12 and 13 are closed when the video signals Video · a and Video · b are at a high level, and as a result, current flows through the laser diodes LDa and LDb.

The current flowing through the laser diode LDa is:
It is determined by the control signal Da supplied to the constant current circuit 15. The control signal Da is supplied from the CPU 21 via the D / A converter 17. Similarly, the current flowing through the laser diode LDb is supplied to the C / D
It is determined by the control signal Db supplied from the PU 21 to the constant current circuit 14.

When a current flows through the laser diodes LDa and LDb, a laser beam having an intensity corresponding to the current is emitted, and a current by receiving the laser beam flows through the photodiode PD. This current is converted into a voltage as described above and input to the comparator 19.

A reference voltage Vref corresponding to a target light quantity is supplied to the other input side of the comparator 19. The reference voltage Vref is obtained by D / A converting the signal Dd output from the CPU 21 by the D / A converter 20. The output signal Dc of the comparator 19 becomes a high level signal "H" when one of the input signals Vmon of the comparator 19, that is, a signal having a magnitude corresponding to the amount of light detected by the photodiode PD is larger than the reference voltage Vref. The output signal of the comparator 19 is a CPU
21. The CPU 21 controls the comparator 19
Until the output signal Dc becomes "H", the control signals Da and Db are increased stepwise in a predetermined cycle, and fixed when the output signal Dc becomes "H".

The CPU 21 includes a laser diode LDa,
When the LDb has failed and is not turned on, the laser abnormality signal FAIL is output. That is, the control signals Da,
Db is compared with an upper limit value, and when the control signals Da and Db are larger than the upper limit value, the abnormal signal FAIL
Output. It is preferable that the abnormality signal FAIL be able to determine which of the laser diodes LDa and LDb indicates an abnormality. The abnormal signal FAIL is supplied to the video control circuit 22, the alarm 23, and the drive circuit 24 of the photoconductor 11. Further, the CPU 21 operates to change the control signals Da and Db to predetermined values at the time of abnormality when the laser diodes LDa and LDb are not turned on due to a failure. The operation of each unit supplied with the abnormal signal FAIL and the operation of the CPU 21 will be further described later.

Next, the light amount control operation at the time of starting the image output apparatus will be described. First, the control timing when both the laser diodes LDa and LDb are normal will be described with reference to FIG. In the figure, at a timing t1, the video signal Video · a is turned “ON” and the control signal Da is increased stepwise to increase the light amount of the laser diode LDa. That is, the signal Vmon also increases. And the signal Vm
When on reaches the reference signal Vref, that is, at the timing t2, the output signal Dc of the comparator 19 changes to “H”. After the output signal Dc changes to “H”, at timing t3, the video signal Video · a is turned “off” to fix the control signal Da. When the video signal Video · a is turned “off”, no current flows through the laser diode LDa, and the output signal Dc of the comparator 19 becomes “L”.
Changes to

Similarly, at timing t4, the video signal V
When the signal i.b is turned on and the control signal Db is increased stepwise to increase the light amount of the laser diode LDb, the signal Vmon also increases accordingly. Then, at timing t5 when the signal Vmon reaches the reference signal Vref.
As a result, the output signal Dc of the comparator 19 changes to "H". After the output signal Dc changes to “H”, the timing t
In step 6, the video signal Video · b is turned “off” to fix the control signal Db. When the video signal Video · b is turned “off”, no current flows through the laser diode LDb, and the output signal Dc of the comparator 19 changes to “L”.

Next, the light amount control operation will be described with reference to a flowchart. First, an example will be described in which, when one of the laser diodes fails, the amount of light of the other is doubled. In FIG. 7, in step S1, the control signal Da is increased by a predetermined value. In step S2, it is determined whether the signal Vmon is larger than the reference signal Vref. If this determination is negative, the process proceeds to step S5, where it is determined whether the control signal Da is greater than a predetermined maximum value Damax. If the control signal Da has reached the maximum value Damax, step S
6, the signal F indicating the abnormality of the laser diode LDa
AIL · a is output. The alarm 23 is, for example, a liquid crystal display, and outputs a scheduled failure display based on the abnormal signal FAIL · a. Further, in step S7,
In order to increase the light amount of the other laser diode LDb, the reference signal Vref is doubled. On the other hand, the control signal D
If a has not reached the maximum value Damax, the process proceeds from step S5 to step S1, where the control signal Da is increased by a predetermined value. If the determination in step S2 is affirmative, the process proceeds to step S3, where the reference signal Vref is made equal. That is, the reference signal Vref is not changed. In step S4, the reference signal Vref is rewritten with the value updated in step S3 or S7.

In step S8, the control signal Db is increased by a predetermined value. In step S9, it is determined whether the signal Vmon is larger than the reference signal Vref. If this determination is negative, the process proceeds to step S10, where it is determined whether the control signal Db is greater than a predetermined maximum value Dbmax.
If the control signal Db has reached the maximum value Dbmax, the process proceeds to step S11, where it is determined whether or not the other laser diode LDa has failed based on whether or not the abnormal signal FAIL · a has been output. If this determination is affirmative, it is determined that both laser diodes have failed, and the process proceeds to step S12 to stop the operation of the image output device (M / C).

On the other hand, if the determination in step S11 is negative, it is determined that only the laser diode LDb has failed. Therefore, the flow advances to step S13 to output a signal FAIL · b indicating an abnormality of the laser diode LDb. The alarm 23 outputs a scheduled failure indication based on the signal FAIL · b. Further, in step S14, in order to increase the light amount of the other laser diode LDa,
The reference signal Vref is doubled. In step S15,
The reference signal Vref is rewritten with the updated value in step S14. In step S16, the control signal Da is increased. In step S17, the signal Vmon is changed to the reference signal Vr.
It is determined whether it is greater than ef. When this judgment is affirmative, or when the above-mentioned judgment 9 is affirmative, the process proceeds to step S18 to start the printing operation.

According to the above-described embodiment, when one of the laser diodes fails, the resolution in the sub-scanning direction is halved. Thus, the apparent image density can be maintained as in the normal state.

Next, an example in which the rotational speed of the photoconductor 11 is reduced when one of the laser diodes has failed will be described. Here, an example in which the speed is changed to half of the normal speed has been described. 8, steps S20 to S20
In step 23, steps S1 and S2 and step S2 are performed.
5, the same processing as that of S6 is executed, and thus the detailed description is omitted. If the abnormality of the laser diode LDa is displayed in step S23, the process proceeds to step S24, and the photoconductor 1
1 to reduce the rotation speed of the photosensitive member 11 by half.
To the drive circuit 24. This command may be the abnormal signal FAIL · a itself. However, in this case, it is a matter of course that the drive circuit 24 is configured so that the speed of the photoconductor 11 is reduced to half by the abnormal signal FAIL · a.

In steps S25 to S30 and S32, steps S8 to S13 and S1
8, the detailed description is omitted. If step S28 is negative and an abnormal signal FAIL · b of the laser diode LDb is output in step S30, a command to halve the rotation of the photoconductor 11 is issued to the drive circuit 24 of the photoconductor 11 in step S31. .
Also in this case, the command to the drive circuit 24 may be the abnormal signal FAIL · b.

The abnormal signal FAIL · a or FAI
When the rotation of the photoconductor 11 is reduced by L · b,
The video control circuit 22 controls the video signals Video · a, Vi
deo.b is output at the timing shown in FIG.

In FIG. 9, the numbers in the figure indicate the number of lines. In a normal state, video signals Video.a and Video.b for two lines are output simultaneously after the image signal is fetched. However, when a failure occurs, the video signals Video.a.
A signal corresponding to a laser diode that has not failed out of Video · b is output for each line. Therefore, although the image output speed is reduced by half, the image output operation can be continued while maintaining the same resolution.

The main functions of the CPU 21 for executing the operations shown in FIGS. 7 and 8 will be described with reference to block diagrams. FIG. 1 shows the functions of the embodiment in which the light amount of the laser diode that has not failed is increased and the function of the embodiment in which the rotation speed of the photoconductor is reduced, but either one of them may be provided, Both may be provided so that they can be selectively used depending on the desired image quality. In the figure, a laser diode LDa, LD
The values of the control signals Da and Db that determine the current b are read. Then, the values of these control signals Da and Db are compared with respective upper limit values Damax and Dbmax. The upper limit values Damax and Dbmax are, for example, CPU
It is set in advance in an upper limit value storage unit 27 provided in a ROM in the storage unit 21. As a result of the comparison, the control signal Da becomes the upper limit value Dama.
The failure of the laser diode LDa can be determined based on whether it is larger than x. On the other hand, when the control signal Db is
Laser diode LD depending on whether it is greater than max
b can be determined. And the laser diode LD
If any of a and LDb is determined to be faulty, an abnormal signal is output. This abnormal signal allows to identify which laser diode has failed.

When the abnormal signal is supplied, the reference value changing section 26 doubles the light amount of the laser diode which has not failed in response to the abnormal signal, so that the voltage corresponding to the target light amount, that is, the reference signal Vref is changed. Double. When an abnormal signal is supplied to the alarm 23, the laser diode L
Abnormal display of Da or LDb is performed. Further, when an abnormal signal is supplied to the photoconductor driving circuit 24, the photoconductor 11
, A command to reduce the rotation speed is output. The upper limit values Damax and Dbmax may not be set respectively, but may have only one identical value.

Subsequently, the light source, that is, the laser diode is 4
Two cases will be described. Here, four examples of controlling the amount of light other than the failed laser diode will be described. You. FIG. 10 shows laser beams from the laser diodes LD1, LD2, LD3, and LD4 in order from the top in the figure. The size of the ellipse indicates the intensity of the laser beam, and the interval between the laser beams corresponds to the resolution width in the sub-scanning direction. Further, a broken line ellipse indicates a broken laser diode, a solid line arrow indicates continuation of laser beam irradiation, and a dotted line arrow indicates stop of laser beam irradiation.

FIG. 10A shows a laser beam when all four laser diodes are normal. FIG. 10 (b)
Shows a processing example (case A) when the laser diode LD1 breaks down. If one laser diode fails, an image corresponding to the laser diode LD1 is not output, so that the image density becomes thinner for every three lines and unevenness becomes noticeable. Therefore, in order to make the density uniform, the laser diode LD3 is turned off, and the light amounts of the laser diodes LD2 and LD4 are doubled. By doing so, the resolution is reduced by half, but the density can be made uniform. Similarly, when the laser diode LD2 fails, the laser diode LD4 is turned off, and the light amounts of the laser diodes LD1 and LD3 are doubled. In short, it is better to turn off the laser diode at a position one space away from the failed laser diode and to double the remaining light amount.

FIG. 10C shows another processing example (case B) when the laser diode LD1 fails. In this case B, the failed laser diode LD
The laser diode LD2 adjacent to 1 is turned off, and the rotation speed of the object to be scanned, that is, the photosensitive member 11, is reduced by half. By doing so, the image output speed is reduced, but the resolution can be maintained and the image density can be made uniform.

FIG. 10D shows a processing example (case C) when the laser diodes LD1 and LD3 fail. In this case C, the light amounts of the laser diodes LD2 and LD4 that have not failed are doubled. By doing so, an image similar to the case A is output.

FIG. 10E shows a processing example (case D) when the laser diodes LD1 and LD2 fail. In this case D, the rotation speed of the photoconductor 11 is reduced by half while the light amounts of the laser diodes LD3 and LD4 that have not failed remain unchanged. By doing so, an image similar to the case B is output. Note that when the laser diodes LD2 and LD3 are out of order,
Should be handled in the same way as.

Next, the operation when there are four laser diodes will be described with reference to a flowchart. It should be noted that the presence or absence of a failure of the four laser diodes can be executed in the same procedure as described with reference to FIGS. 7 and 8, and the following description assumes that failure detection has been performed.

In FIG. 11, in step S100,
Determine the presence or absence of a failed laser diode. If there is no failure, the flow shifts to step S210 to start the printing operation. If there is a failure, proceed to step S110,
It is determined whether only one laser diode has failed. If this determination is affirmative, the process proceeds to step S120, and it is determined which of the cases A and B is to be performed. This determination is made based on the settings of the CPU 21 registered in advance as system data. If the system data is set to perform processing in Case A,
Proceeding to step S130, the processing of case A is performed. That is, the laser diodes at positions one after the failed laser diode are turned off, and the light amounts of the remaining two laser diodes are doubled. If the system data is set to perform the process in case B, the process proceeds to step S140, and the process in case B is performed. That is, the laser diode adjacent to the failed laser diode is turned off, and the rotation speed of the photoconductor 11 is reduced to half.

On the other hand, if the determination in step S110 is negative, the process proceeds to step S150. In step S150, it is determined whether there are two failed laser diodes. If this determination is affirmative, the process proceeds to step S160, and it is determined whether the failed laser diode is adjacent. If they are adjacent, step S
Proceeding to 170, the processing of case D is performed. That is, the rotation speed of the photoconductor 11 is reduced by half. On the other hand, if the failed laser diode is not adjacent, step S16
The determination of 0 is negative, and the process proceeds to step S180. In step S180, it is determined whether the failed laser diode is at both ends, that is, whether the laser diode is the laser diode LD1 or LD4. If this determination is affirmative, step S17
The process proceeds to 0, and the process of the case D is executed. If the determination in step S180 is negative, the process proceeds to step S190, and the process of case C is executed. That is, the light amounts of the two laser diodes that have not failed are doubled.

Further, if the determination in step S150 is negative, it is considered that a failure has occurred in three or more laser diodes, and any of the cases A to D cannot be dealt with. Stop the device.

Next, the CP for executing the operation of FIG.
The function of the main part of U will be described with reference to FIG. 2, the same reference numerals as those in FIG. 1 denote the same or equivalent parts. The failure detection unit 25 compares the control signals D1 to D4 for determining the currents of the laser diodes LD1 to LD4 with the upper limit values D (n) max (n = 1 to 4) of the respective control signals. as a result,
When the control signal is larger than each upper limit value, a predetermined bit of the register 28 corresponding to each laser diode is set. The upper limit D (n) max is set in the upper limit storage 27 in advance. The upper limit may be a common value for all laser diodes.

The failed light source identification section 29 reads the bit of the register 28 and determines the failed laser diode. The processing unit 30 performs the determination shown in the flowchart based on which of the failed laser diodes,
A command for executing the scheduled processing in the cases A to D is output to the reference value changing unit 26, the photoconductor driving circuit 24, and the video control circuit 22. That is, by giving a command to the reference value changing unit 26 to increase the reference signal Vref, the light amount of the laser diode that has not failed is increased. At this time, a command is given to the video control circuit 22 together with the command to increase the reference signal Vref to turn off one of the non-failed laser diodes. Further, a command to reduce the rotation speed of the photoconductor 11 is issued to the photoconductor drive unit 24, and the video control circuit 22
To turn off a predetermined one of the laser diodes that have not failed. Each of the above commands is also supplied to the alarm 23 to display a failure.

As described above, in this embodiment, when an abnormality is found, the light amount of the normal laser diode is increased or the rotation speed of the photosensitive member is reduced. In this embodiment, the abnormality detection of the laser diode is performed on the basis of the judgment that the control signals Da, Db, etc. exceed the predetermined upper limit, but the present invention is not limited to such means.
For example, the magnitude of the output signal of the photodiode PD when the control signals Da, Db, etc. of the predetermined values are given is detected, and when this output signal is equal to or less than a threshold value set for failure determination, a failure is detected. You may comprise so that it may judge.

[0049]

As is apparent from the above description, according to the first or third aspect of the present invention, when a failure occurs in the laser light source, the amount of light of the normal laser light source is increased. The shortage of the reduced light amount is compensated for by the reduced laser light source. As a result, a decrease in the density of the output image can be prevented. In particular, according to the third aspect of the present invention, when one of a large number of laser light sources is turned off, for example, a part of the normal laser light source is turned off and turned on at equal intervals, so that the light amount of the remaining laser light sources is By simply increasing the value, it is possible to prevent the problem of uneven density.

According to the second or fourth aspect of the present invention, when a failure occurs in the laser light source, the sub-scanning speed is reduced, so that the image density is reduced. In particular, according to the invention of claim 4, for example, when one of a large number of laser light sources is not turned on, only a part of the normal laser light source is turned off and only the laser light sources arranged continuously are turned on. Simply lowering the sub-scanning speed can prevent the problem of uneven density.

As described above, according to the present invention, even when some of the plurality of laser light sources cannot be turned on, full-scale repair is performed with the quality maintained at a certain level using only the remaining normal laser light sources. An image can be output as soon as possible.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating main functions of an image output apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating main functions of an image output apparatus according to a second embodiment of the present invention.

FIG. 3 is a plan view showing a hardware configuration of a main part of the image output apparatus according to one embodiment of the present invention.

FIG. 4 is a side view showing a hardware configuration of a main part of the image output apparatus according to one embodiment of the present invention.

FIG. 5 is a block diagram illustrating a relationship between an image output device and an automatic light amount control device according to an embodiment of the present invention.

FIG. 6 is a timing chart showing an operation of the automatic light amount control device.

FIG. 7 is a flowchart illustrating an automatic light amount control operation of the image output apparatus according to the present invention.

FIG. 8 is a flowchart showing an automatic light amount control operation of the image output device according to the present invention.

FIG. 9 is a timing chart showing an output timing of a video signal.

FIG. 10 is a schematic diagram showing a processing example when a laser light source fails.

FIG. 11 is a flowchart showing an operation of selecting a process when a laser light source fails.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser array, 11 ... Photoconductor, 21 ... CPU,
22: video control circuit, 23: alarm, 24:
Photoconductor drive circuit, 25: failure detection unit, 26: reference value change unit, 27: upper limit value storage unit, 29: failure light source identification unit

Claims (4)

(57) [Claims] 1. An image output apparatus for simultaneously scanning a medium to be scanned with laser beams output from a plurality of laser light sources to obtain an image, wherein an amount of the laser beam output from each of the laser light sources is set to a predetermined value. A failure detection unit that compares a control signal to be performed with an upper limit value and recognizes a laser light source corresponding to a control signal that is larger than the upper limit value as a failure light source. And a light amount increasing unit for increasing the light amount of the normal laser light source. 2. An image output apparatus for simultaneously scanning a medium to be scanned with laser beams output from a plurality of laser light sources to obtain an image, wherein an amount of the laser beam output from each of the laser light sources is set to a predetermined value. A failure detection unit that compares a control signal to be performed with an upper limit value and recognizes a laser light source corresponding to a control signal that is larger than the upper limit value as a failure light source. A driving unit for reducing a driving speed of a medium to be scanned in order to reduce a sub-scanning speed of a laser beam from a normal laser light source. 3. An image output apparatus for simultaneously scanning a medium to be scanned with laser beams output from a plurality of laser light sources to obtain an image, wherein an amount of the laser beam output from each of the laser light sources is set to a predetermined value. A failure detection unit that compares a control signal to be performed with an upper limit value and recognizes a laser light source corresponding to a control signal that is larger than the upper limit value as a failure light source; Light-off means for turning off a part of the normal laser light source other than the failed light source so as to be lit at intervals; and light-amount increasing means for increasing the light quantity of the laser light sources lit at the equal intervals. Characteristic image output device. 4. An image output apparatus for simultaneously scanning a medium to be scanned with laser beams output from a plurality of laser light sources to obtain an image, wherein an amount of the laser beam output from each of the laser light sources is set to a predetermined value. A failure detection unit that compares a control signal to be performed with an upper limit value and recognizes a laser light source corresponding to a control signal that is larger than the upper limit value as a failure light source, and when the failure light source is recognized by the failure detection unit, the laser light sources are continuously arranged. An extinguishing means for extinguishing a part of a normal laser light source other than the failed light source so that a predetermined number of laser light sources are turned on; An image output device comprising: a driving unit configured to reduce a driving speed of a medium to be scanned in order to reduce a scanning speed.