JP2002149012A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To identify the cause of a failure with a comparatively simple constitution and to carry out specified notification when an immediate recovery is possible. SOLUTION: When an overflow signal is fed from a laser driving circuit 41 and the corrector voltage of a transistor Tr1 that is provided in a detecting circuit 35 is higher than a specified value, a control circuit 34 displays 'image forming unit not loaded' on a control panel 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to a laser printer having a safety switch for shutting off a laser drive power supply in response to opening of an opening / closing member and removal of an image forming unit. The present invention relates to a suitable image forming apparatus.

[0002]

2. Description of the Related Art Generally, an image forming apparatus using laser scanning deflects a laser beam modulated by image data on a photosensitive member using a deflecting device such as a polygon mirror to scan an image. Form. As an image forming process, an electrophotographic method of forming an electrostatic latent image on a charged photoreceptor and developing with a toner is generally used.

[0003] In order to prevent the laser beam from affecting the human body, the image forming apparatus is required to have a structure so that an operator or the like is not exposed to the laser beam. Specifically, the image forming apparatus requires a housing having a shielding structure that does not directly or indirectly emit a laser beam to the outside. Here, the indirect emission of a laser beam refers to emission of reflected light by a member of an apparatus or an inserted tool.

The image forming apparatus is configured so that an operator can open and close the cover of the housing to remove a paper jam, or can replace an image forming unit made of a consumable photosensitive member or the like. However, when the opening / closing cover is opened, the laser beam shielding structure may not function. For this reason, the image forming apparatus is provided with a safety switch for shutting off the drive power supply of the laser light source in conjunction with these operations when the opening / closing cover of the housing is opened or the image forming unit is removed. I have.

Further, the image forming unit has a structure
When removed from the main body of the apparatus, the optical path of the laser beam is largely exposed. Therefore, a safety switch is provided in conjunction with the removal.

[0006] In such an image forming apparatus, when the safety switch operates, the emission of the laser beam is stopped. The safety switch operates not only when a failure occurs partially or when the opening / closing cover is opened, but also when the mounting of the image forming unit is incomplete. Therefore, if the image forming apparatus cannot determine whether the laser is out of order or the mounting of the opening / closing door or the image forming unit is incomplete, the image forming apparatus can easily return by a predetermined operation. , The operation stops completely. For this reason, there occurs a problem that the operation is not performed for a long time until an expert checks the cause of the failure.

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-described problem, and it is possible to identify the cause of a failure with a relatively simple configuration and to issue a predetermined notification when the failure can be recovered immediately. It is an object to provide an image forming apparatus.

[0008]

The reliability of a laser used in an image forming apparatus is generally said to have a cumulative failure rate of 1% or less in 1000 hours. On the other hand, assuming that the design life of the device is 5 to 10 years, the time during which the laser is turned on until the life is only during image formation, and is estimated to be several hundred hours. Therefore, in consideration of the fact that a failure of the laser itself is rare, a predetermined failure is reported to an operator.

According to a first aspect of the present invention, there is provided an image forming unit including a laser light emitting means for emitting laser light, a photoreceptor irradiated with the laser light emitted by the laser light emitting means, and the image forming unit comprises: A unit switch that is turned on when it is attached to a regular position and turned off when it is not attached to a regular position, and is connected in series with the unit switch, and is turned on when the maintenance door is closed. Through a door switch that is turned off when the door is opened, the unit switch and the door switch,
Power supply means for supplying laser driving power to the laser light emitting means, and the door switch is turned on, and, when the laser light is not emitted by the laser light emitting means,
And a notification means for performing a predetermined notification.

The image forming unit can be mounted on the main body of the image forming apparatus. When the image forming unit is mounted at a proper position, the unit switch is turned on. When the image forming unit is not mounted at the proper position, the unit switch is turned off. . Further, the image forming apparatus includes a maintenance door. When the maintenance door is closed, the door switch is on, and when it is open, the door switch is off.

Here, a plurality of maintenance doors may be provided. At this time, a door switch is provided corresponding to each maintenance door. Preferably, each door switch is connected in series.

[0012] The power supply means supplies power to the laser emission means via the unit switch and the door switch. The laser emitting means emits laser light when the power is supplied. Here, even when the door switch is turned on, the laser emitting unit may not emit the laser.
This is probably because the laser light emitting means itself rarely breaks down, and the unit switch is not turned on. Therefore, the notifying unit performs a predetermined notification so that the image forming unit is properly mounted at the position. Further, since it is only necessary to detect whether the door switch is turned on or the laser light is emitted, the cause of the failure can be determined with a simple configuration.

Further, there is no problem even if it is considered impossible for a plurality of lasers to fail at the same time, except for an exceptional event such as an extremely large mechanical or electrical external force applied to the device. Therefore, the invention according to claim 2 provides one or a plurality of image forming apparatuses each including a plurality of laser light emitting means for emitting laser light, and a photoreceptor to which the laser light emitted by each of the laser light emitting means is irradiated. A unit, provided corresponding to each of the image forming units, turned on when each of the image forming units is mounted in a proper position, and turned off when not mounted in a proper position, A plurality of unit switches, each connected in series, and connected in series with the plurality of unit switches, and are turned on when the maintenance door is closed,
A door switch that is turned off when the door is opened; a power supply unit that supplies laser driving power to the laser emission unit via the plurality of unit switches and the door switch; and the door switch is turned on, and each of the door switches is turned on. Notification means for performing predetermined notification when laser light is not emitted by the laser emission means.

One or more image forming units include:
Each unit can be attached to the image forming apparatus main body, and when it is attached to a regular position, each unit switch is turned on,
If the unit is not installed in the correct position, turn off each unit switch. Further, the image forming apparatus includes a maintenance door. When the maintenance door is closed, the door switch is on, and when it is open, the door switch is off. In addition, similarly to the first aspect of the present invention, a plurality of maintenance doors may be provided.

The power supply means supplies power to each laser light emitting means via each unit switch and door switch. When this power is supplied to each laser emitting means,
Emit laser light. Here, even when the door switch is turned on, all the laser light emitting units may not emit laser light. This is probably because at least one unit switch is not turned on because it is rare that all the laser light emitting means themselves fail at the same time. Thus, the notifying unit performs a predetermined notification so that all the image forming units are properly mounted.

In this case, the apparatus further comprises a light quantity control means for detecting the laser light emitted by the laser light emission means and controlling the light quantity of the laser light based on the detection result. Then, the notifying unit may detect that the laser beam is not emitting based on the laser beam detected by the light amount controlling unit.

Further, in the case where the apparatus further comprises a beam detection signal interval detecting means for generating a beam detection signal generation state signal when the cycle of the laser light is within a predetermined time, the notifying means May detect that no laser light is emitted when the beam detection signal generation state signal is not generated by the beam detection signal interval detection means.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIG. 1 is an external perspective view of an image forming apparatus according to a first embodiment of the present invention. The image forming apparatus includes a housing 10 formed so as to cover the entirety, a door cover 11 and a unit door cover 12.
And a control panel 13.

The door cover 11 is configured to be opened and closed, for example, when taking out paper when a paper jam occurs, and to turn on / off a first safety switch described later in conjunction with the opening and closing. The unit door cover 12 is configured to be opened and closed when the image forming unit 14 is attached to and detached from the apparatus main body, and to turn on and off a second safety switch described later in conjunction with the opening and closing. The control panel 13 is a so-called touch panel, and receives, for example, an operation command from an operator and displays a control result.

FIG. 2 is a view showing a cross section in a direction perpendicular to the detaching direction of the image forming unit. The first safety switch 16 is turned on when the door cover 11 is closed, and turned off when the door cover 11 is opened. The second safety switch 17 is turned on when the unit door cover 12 is closed, and turned off when the unit door cover 12 is opened.

The laser scanning unit 20 emits a laser beam and irradiates the laser beam to the photoreceptor 21 in each image forming unit 14 to form an electrostatic latent image. The electrostatic latent image is developed in each image forming unit 14 by an electrophotographic process. The photoreceptor 21 sandwiches the printing paper 23 together with the transport rollers 22 disposed opposite to each other, transfers the developed image to the printing paper 23, and prints the image on the printing paper 23.
Is transported in a predetermined direction. The printing paper 23 printed in this manner is discharged outside by a pair of discharge rollers 24.

FIG. 3 is a diagram showing a circuit configuration of the image forming apparatus. The image forming apparatus includes a constant voltage generation circuit 32 that generates a constant voltage based on power supplied from an AC power supply 31.
And the first safety switch 16 and the second safety switch 16 connected in series.
Safety switch 17, image forming unit 14, laser scanning unit 20, control circuit 34, door cover 1
1 and a detection circuit 35 for detecting the opening and closing of the unit door cover 12.

The constant voltage generating circuit 32 supplies a power of, for example, 5 V to the control circuit 34. Further, the constant voltage generation circuit 32 supplies the power of 5V to the first safety switch 16.
Then, the power is supplied to the image forming unit 14 via the second safety switch 17.

The image forming unit 14 turns on / off a drawer connector 33 for turning on / off a power supply line for driving a laser. That is, the image forming unit 14 turns on the drawer connector 33 when the image forming unit 14 is attached to a regular position of the apparatus main body, and turns off the drawer connector 33 when the image forming unit 14 is not attached to the regular position. The drawer connector 33 is connected to the second
And the power supply from the second safety switch 17 is supplied to the laser scanning unit 20. Therefore, when the image forming unit 14 is not mounted at the proper position, the power supply for driving the laser of the laser scanning unit 20 is cut off.

The laser scanning unit 20 includes a laser driving circuit 41, a laser emitting section 42 for emitting laser light, and a polygon mirror 43 for scanning laser light.
The laser drive circuit 41 emits laser light from the laser emitting unit 42 when power is supplied via the drawer connector 33, and stops emitting laser light from the laser emitting unit 42 when power is not supplied. Polygon mirror 43
Is rotated by a polygon motor (not shown), and deflects and scans the laser beam from the laser emitting section 42 on the photoconductor 21 charged in advance to form an electrostatic latent image.

The detection circuit 35 is a circuit for detecting whether the door cover 11 and the unit door cover 12 are both closed, and includes a second safety switch 17 and a drawer connector 3.
3, a diode D1 having an anode connected to the transistor D3, and a transistor Tr1 having a base connected to the cathode of the diode D1. The emitter of the transistor Tr1 is grounded, and the collector of the transistor Tr1 is connected to the control circuit 34. The diode D1
When another circuit element is damaged, a current flows backward so that power for driving the laser is not supplied to the laser scanning unit 20.

When both the door cover 11 and the unit door cover 12 are closed, the first safety switch 16
And the second safety switch 17 are both turned on. At this time, since a current flows to the base of the transistor Tr1 via the diode D1, the transistor Tr1 is turned on, and the voltage of the collector of the transistor Tr1 becomes extremely low. The control circuit 34 thus operates the transistor Tr1
When the collector voltage is very low, the door cover 11
And that the unit door cover 12 is closed.

When at least one of the door cover 11 and the unit door cover 12 is open, the transistor Tr1 is turned off, and the voltage at the collector of the transistor Tr1 increases. When detecting that the voltage of the collector of the transistor Tr1 is high, the control circuit 34 can detect that at least one of the door cover 11 and the unit door cover 12 is open.

As described above, in the image forming apparatus, when at least one of the door cover 11 and the unit door cover 12 is open, or when at least one of the image forming units 14 is not mounted at a proper position, It has a double safety function to cut off the power supply line for driving the laser.

Here, as shown in FIG. 4, the laser driving circuit 41 counts the voltage detected by the photodiode PD1 based on the comparison result of the comparator 51 which compares the voltage detected by the photodiode PD1 with the reference voltage Vref. A counter 52 for up or down counting, and a D / A converter 5 for digital / analog conversion of the count value of the counter 52
3 and a voltage / current conversion circuit 54 for converting a voltage into a current.
And a switch 55. The laser emitting section 42 includes a laser diode LD1, a photodiode PD1, and a variable resistor R1.

The anode of the laser diode LD1 and the cathode of the photodiode PD1 are connected to a laser drive power supply line. Laser diode LD
One cathode is connected to a voltage / current conversion circuit 54 via a switch 55. Voltage / current conversion circuit 54
Controls the drive current of the laser diode LD1 according to the voltage output by the D / A converter 53. further,
The switch 55 turns on / off the drive current of the laser diode LD1 based on the image data, and modulates the laser light emitted from the laser diode LD1.

On the other hand, the anode of the photodiode PD1 is grounded via the variable resistor R1. Comparator 51
When the voltage at the anode of the photodiode PD1 is smaller than the reference voltage Vref, the counter 5
2 is counted up, and when it is larger, the counter 52 is counted down according to the difference. The D / A converter 53 converts the count value of the counter 52 into a voltage that is an analog signal, and converts this voltage into a voltage / current conversion circuit 5.
4

As described above, the count value of the counter 52 corresponds to the drive current of the laser diode LD1. Further, the counter 52 generates an overflow signal when the count value becomes equal to or more than a predetermined value. For example, when the power supply line for driving the laser is cut off and the laser diode LD1 does not emit light, the counter 52 generates an overflow signal,
It is supplied to the control circuit 34.

When the overflow signal is supplied and the collector voltage of the transistor Tr1 provided in the detection circuit 35 is higher than a predetermined value, the control circuit 34 indicates that "the image forming unit is not mounted" on the control panel 13. "Is displayed. Even if the overflow signal is supplied, if the collector voltage of the transistor Tr1 is lower than the predetermined value, the control circuit 34 opens the control panel 13 because at least one of the door cover 11 and the unit door cover 12 is open. "Do not close the door cover" may be displayed.

As described above, when the image forming apparatus according to the present embodiment determines that the laser diode LD1 does not emit light due to the generation of the overflow signal, the opening and closing of the door cover 11 and the unit door cover 12 are performed. The state can be detected, and a predetermined notification can be given to the operator according to the cause of the failure. As a result, the operator can immediately understand the cause of the failure, and can perform the operation of returning the image forming apparatus by himself if possible.

[Second Embodiment] Next, a second embodiment of the present invention will be described.

The image forming apparatus according to the second embodiment has
As shown in FIG. 5, a housing 100 configured to cover the entire device includes a door cover 101, a unit door cover 102, and a control panel 103.

The door cover 101 is opened and closed, for example, when taking out paper when a paper jam occurs, and is configured to turn on / off a first safety switch described later in conjunction with the opening and closing. The unit door cover 102 is opened and closed when the image forming units 104Y, 104M, 104C, and 104K are attached to and detached from the apparatus main body, and is configured to turn on / off a second safety switch described later in conjunction with the opening and closing. ing. The control panel 103 is a so-called touch panel, which receives, for example, an operation command from an operator and displays a control result.

FIG. 6 is a diagram showing a cross section in a direction perpendicular to the attaching / detaching direction of the image forming unit. The first safety switch 106 is turned on when the door cover 101 is closed,
Turns off when it is open. Second safety switch 10
7 turns on when the unit door cover 102 is closed, and turns off when it is open.

The laser scanning unit 110 emits laser beams corresponding to yellow (Y), magenta (M), cyan (C), and black (K), and outputs these laser beams to the photoconductor 111Y in each image forming unit 104. , 111M,
Irradiation is performed on 111C and 111K to form an electrostatic latent image. These electrostatic latent images are developed in each image forming unit by an electrophotographic process. The photoconductor 111 superimposes the developed electrostatic latent image on the intermediate transfer body 112 and transfers the same to form a full-color image. The intermediate transfer body 112 sandwiches the print paper 114 together with the transport roller 113 that is grounded oppositely, and transfers a full-color image while transporting the print paper 114 in a predetermined direction. The printing paper 114 printed in this way is discharged to the outside by a pair of discharge rollers 115.

FIG. 7 is a diagram showing a circuit configuration of the image forming apparatus. The image forming apparatus includes a constant voltage generating circuit 121 that generates a constant voltage based on an AC power supplied from an AC power supply 120, first and second safety switches 106a and 106b, and second safety switches 107a and 107b. A unit 104, a laser scanning unit 110, a control circuit 128, a first detection circuit 129 for detecting opening and closing of the door cover 101, and a second detection circuit 130 for detecting opening and closing of the unit door cover 102 are provided. ing.

The constant voltage generating circuit 121 supplies a power supply of 24 V to a high voltage power supply (not shown), a main motor, and a polygon described later via a first safety switch 106a and a second safety switch 107a connected in series. Supply to motor. The constant voltage generating circuit 121 supplies a power of 5 V to the control circuit 128, and further supplies a first serially connected first voltage.
Safety switch 106b and second safety switch 107
The power of 5 V is supplied to the image forming unit 104 via the terminal b.

Each image forming unit 104 has a drawer connector 125 for turning on / off a power supply for driving a laser.
Y, 125M, 125C, 125K are turned on / off.
That is, each of the image forming units 104 turns on the corresponding drawer connector 125 when the image forming unit 104 is attached to the proper position of the apparatus main body, and when the image forming unit 104 is not attached to the proper position, the corresponding drawer connector Turn 125 off. Each drawer connector 125Y, 12
5M, 125C, and 125K are connected in series, and output the power from the second safety switch 107b to the laser scanning unit 110. Therefore, the image forming unit 10
When any one of the laser scanning units 110 is not mounted at a regular position, the laser scanning unit 110 is configured to shut off the laser driving power supply.

The laser scanning unit 110 includes laser driving circuits 131Y, 131M, 131C, and 131K, and laser emitting units 132Y, 132M, and 13 for emitting laser light.
2C, 132Y, a polygon mirror 133 for scanning the laser beam, and beam sensors 134Y, 134M, 134C, 134K for detecting the timing of the laser beam.

When the power is supplied from the drawer connector 125, the laser driving circuit 131
When the power supply is stopped, the driving of the laser emitting unit 132 is stopped. The polygon mirror 133 is
Rotated by a polygon motor (not shown), the laser beam from the laser emitting unit 132 is deflected and scanned on the photoconductor 111 charged in advance to form an electrostatic latent image.

The beam sensor 134 generates a beam detection signal upon detecting a laser beam in order to synchronize the writing timing of each laser beam. The control circuit 128 detects the interval between the beam detection signals generated by the beam sensor 134, and generates a beam detection signal generation state signal when the beam detection signal is generated within a predetermined time.

The first detection circuit 129 includes the door cover 10
1 is a circuit for detecting the opening and closing of the first safety switch 1
A diode D2 whose anode is connected between the second safety switch 107b and the second safety switch 107b, and a transistor Tr2 whose base is connected to the cathode of the diode D2. The emitter of the transistor Tr2 is grounded, and the collector of the transistor Tr2 is connected to the control circuit 128. It should be noted that the diode D2 prevents the current from flowing backward so that laser driving power is not supplied to the laser scanning unit 110 when other circuit elements are damaged.

When the door cover 101 is closed, the first safety switch 106b is turned on. At this time, the diode D2 and the transistor Tr2 are also turned on, and the voltage at the collector of the transistor Tr2 becomes very low.
When the voltage of the collector of the transistor Tr2 is extremely low, the control circuit 128 can detect that the door cover 101 is closed.

When the door cover 101 is open, the first safety switch 106b is turned off. At this time, the diode D2 and the transistor Tr2 are also turned off, and the voltage at the collector of the transistor Tr2 increases.
When the voltage of the collector of the transistor Tr2 is high, the control circuit 128 can detect that the door cover 101 is open.

The second detection circuit 130 is a circuit for detecting the opening and closing of the unit door cover 102, and includes a Zener diode D3 having a cathode connected to the output side of the second safety switch 107a, and an anode of the Zener diode D3. And a transistor Tr3 having a base connected to the transistor Tr3. The emitter of the transistor Tr3 is grounded, and the control circuit 128 constantly detects the voltage of the collector of the transistor Tr3.

The second detection circuit 130 detects the unit door cover 10 based on a relatively high voltage (24 V) power supply.
Although a zener diode D3 for generating a predetermined zener voltage is provided to detect the opening and closing of the second detection circuit 2, the operation is substantially the same as that of the first detection circuit 129. Therefore, when the voltage of the collector of the transistor Tr3 is very low, the control circuit 128 detects that the door cover 101 and the unit door cover 102 are both closed, and when the voltage of the collector is high, at least one of these is detected. One can be detected as open.

As described above, the image forming apparatus has at least one of the door cover 101 and the unit door cover 102.
If one of them is open, or if at least one of the image forming units 104 is not mounted in a proper position,
It has a dual safety function to cut off the power supply line for driving the laser.

Here, as shown in FIG. 8, the laser drive circuit 131 compares the power supply check circuit 141 for checking the power supply voltage for laser drive with the reference voltage Vref of the voltage detected by the photodiode PD2. A comparator 142 and a charge pump 14 for generating a charge voltage
3, an amplifier 144 for amplifying the voltage stored in the capacitor C, and a voltage / current conversion circuit 1 for converting the voltage into a current.
45 and a switch 146. Here, the charge pump 143, the capacitor C, and the amplifier 144 function as a sample and hold circuit. The laser emitting section 132 includes a laser diode LD2, a photodiode PD2, and a variable resistor R2.

The power supply check circuit 141 controls the laser drive power supply voltage supplied from the drawer connector 125 to a predetermined voltage or less to prevent the laser diode LD2 from being damaged by an overcurrent in a transient state. Check if there is. Then, when the voltage falls below the predetermined voltage, the charge pump 143 and the voltage / current conversion circuit 145 are reset, and the drive current flowing through the laser diode LD2 is set to zero.

The anode of the laser diode LD2 and the cathode of the photodiode PD2 are connected to a power supply line for driving a laser. The cathode of the laser diode LD2 is connected to the voltage / current conversion circuit 145 via the switch 146. The voltage / current conversion circuit 145 controls the drive current of the laser diode LD2 according to the voltage output from the amplifier 144. Further, the switch 146 turns on / off the drive current of the laser diode LD2 based on the image data, and modulates the laser light emitted from the laser diode LD2.

On the other hand, the anode of the photodiode PD2 is grounded via the variable resistor R2. Comparator 14
2 compares the voltage of the anode of the photodiode PD2 with the reference voltage Vref. The charge pump 143 is connected to the comparator 14 in synchronization with the sample hold (S / H) pulse.
2 and the anode voltage is changed to the reference voltage Vref.
When the voltage is lower than the reference voltage Vref, the charge voltage is increased. The charge voltage output from the charge pump 143 is stored in the capacitor C and supplied to the voltage / current conversion circuit 145 via the amplifier 144. The voltage / current conversion circuit 145 increases the current flowing through the laser diode LD2 when the voltage from the amplifier 144 is high, and decreases the current flowing through the laser diode LD2 when the voltage is low.

As described above, the laser drive circuit 131 detects a voltage corresponding to the amount of laser light, compares this voltage with the reference voltage Vref, and determines the magnitude of the drive current of the laser diode LD2 according to the comparison result. Is controlled, the light amount of the laser beam can be controlled to a predetermined value.

In the image forming apparatus configured as described above, when the power is turned on or when the image forming sequence operates, the control circuit 128 executes the processing from step ST1 shown in FIG.

At step ST1, the control circuit 128
Performs initial setting of each control value, and proceeds to step ST2. This process is unnecessary if each initial value is fixed in the circuit configuration.

At step ST2, the control circuit 128
Determines whether the door cover 101 is closed and the unit door cover 102 is also closed, and if this is not the case, that is, if at least one is open, the process proceeds to step ST3. On the other hand, if both are closed, the process proceeds to step ST4.

In step ST3, the control circuit 128
Outputs a stop instruction signal to each part in the device,
“The door cover is open” is displayed on the control panel 103. Note that the control circuit 128 may not only display on the control panel 103 a sentence urging the user to close the door cover, but also notify the operator via a host computer (not shown). Even when the open door cover is closed, the operation is not immediately restarted because the stop instruction signal is supplied to each unit of the apparatus. Therefore, the control circuit 128
Detects that the open door cover is closed, starts a predetermined sequence again.

In step ST4, control circuit 128
Activates the laser scanning unit 110 and proceeds to step S
Proceed to T5. Here, specifically, the control circuit 128
Turns on a polygon motor (not shown), and activates the laser drive circuit 131 after a predetermined time elapses after the number of rotations increases. At this time, the laser lighting signal is continuously turned on,
The sample hold circuit is activated, and the drive current of the laser emitting unit 132 is set so that the laser light has a predetermined light amount. Note that the laser emitting section 132 emits light continuously.

When the rotation speed of the polygon motor reaches a predetermined value,
When the amount of laser light reaches a predetermined value, the beam sensor 1
34 generates a beam detection signal. Further, a laser lighting signal is generated in synchronization with the beam detection signal, and the laser emitting unit 132 lights the laser light for beam position detection. The control of each laser beam may be performed simultaneously or sequentially.

Next, the lighting state of each laser beam is checked. Specifically, the control circuit 128 checks the interval between the beam detection signals, and if the beam detection signal is generated within a predetermined time, generates a beam detection signal generation state signal. The control circuit 128 can confirm the intervals of the beam detection signals of the respective laser beams, and generate a beam detection signal generation state signal for each color.

At step ST5, the control circuit 128
Performs an abnormality detection process and proceeds to step ST6. Here, specifically, the processing from step ST11 shown in FIG. 10 is executed.

In step ST11, the control circuit 12
8 is an abnormality detection count Y, M, C, K for each color.
Are initialized to zero, respectively, and the process proceeds to step ST12.

In step ST12, the control circuit 12
Step 8 determines whether a predetermined time (for example, 100 ms) has elapsed during the operation of the laser scanning unit 110, and proceeds to step ST13 when it has elapsed.

In step ST13, the control circuit 12
8 determines whether a beam detection signal generation state signal has been generated for each color, and if not generated, increments the abnormality detection count by one, and when it is generated, clears the abnormality detection count, It proceeds to step ST14. For example, when the beam detection signal generation state signal is not generated only for Y and the beam detection signal generation state signals are generated for other colors, the abnormality detection count Y increases by one and the abnormality detection counts M, C, K goes to zero.

In step ST14, the control circuit 12
8 indicates that the abnormality detection counts Y, M, C, and K are all “5”.
It is determined whether they are less than 5. If all of them are less than "5", the process proceeds to step ST15, and if not all of them are less than "5", the process proceeds to step ST16. That is, when any one of the abnormality detection counts becomes “5”, step ST1
Proceed to 6.

In step ST15, the control circuit 12
Step 8 determines whether the abnormality detection processing has been completed. If the abnormality detection processing has been completed, the process exits this subroutine and proceeds to step ST6 shown in FIG. On the other hand, when it is determined that the abnormality detection processing has not been completed, the process returns to step ST12.
The reason for repeating the processing from step ST12 to step ST15 is to prevent noise and the like from being erroneously detected.

In step ST16, the control circuit 12
8 is at least one of the abnormality detection counts Y, M, C, and K
It is determined whether or not one of them is zero, and if it is in that state, the process proceeds to step ST17, and if it is not, the process proceeds to step ST19. That is, the process proceeds to step ST17 when there is an abnormality in the laser light corresponding to some colors.

In step ST17, the control circuit 12
8 selects an abnormality detection count that is not zero and proceeds to step ST18.

At step ST18, the control circuit 12
8 determines that there is an abnormality in the laser light of the color corresponding to the selected abnormality detection count, stops the operation of the entire image forming apparatus, and further causes the control panel 103 to display that a failure has occurred. . At this time, the image forming apparatus does not operate normally, and there is a high possibility that an image is not formed normally.
If the operation is terminated in this state, the image data may be lost. Therefore, at this time, the image data may be stored in a memory (not shown). Further, information indicating which color of the laser light has caused the abnormality may be stored in the nonvolatile memory.

If the determination in step ST16 is negative, whether the laser drive power is not normally supplied or not is determined.
Alternatively, it is considered that the polygon mirror is not rotating normally. The polygon motor is controlled at a constant rotation speed by PLL control. When the PLL control is performed normally, a polygon motor synchronization signal is generated. When the PLL control is not performed normally, a PLL unlock signal is generated. appear. Therefore, the control circuit 128 makes the following determination using the polygon motor synchronization signal.

In step ST19, control circuit 12
8 is to determine whether the polygon motor is generating a polygon motor synchronization signal.
The process proceeds to step ST20, and if not, the process proceeds to step ST20.

At step ST20, control circuit 12
No. 8 determines that the polygon motor is abnormal. At this time, the fact that the polygon motor is abnormal is recorded in the memory, and the image forming apparatus is stopped.

On the other hand, in step ST21, the control circuit 128 determines that the image forming unit is not mounted or is not correctly mounted, and
03 is displayed to prompt the user to confirm the mounting state of the image forming unit 104. As a result, recovery can be performed by the operator or administrator of the apparatus.

When the above-described processing is completed, the control circuit 128 exits this subroutine and proceeds to step ST6 shown in FIG.

In step ST6, control circuit 128
Determines whether or not the entire device is normal. If not, the process proceeds to step ST7. If the device is normal, the process proceeds to step ST7.
Proceed to T8. In step ST7, as described with reference to FIG. 10, a display indicating that there is an abnormality is performed, and the operation of each unit in the apparatus is stopped.

At step ST8, the control circuit 128
Stops the laser drive and polygon motor rotation,
Proceed to step ST9. In step ST9, the control circuit 128 causes the control panel 103 to display "printable" and enters a print standby state.

As described above, the image forming apparatus according to the present embodiment can determine whether there is an abnormality in the laser scanning unit 110 or the polygon motor or simply whether the mounting of the image forming unit 104 is bad. If the image forming unit 104 is improperly mounted, the operator is notified of this fact, and the image forming unit 104 can be returned in a short time.

Further, the image forming apparatus performs an abnormality display process, an emergency stop of the device, a data preservation, etc., only when an abnormality is continuously detected for a certain period of time.
It is possible to prevent the device from becoming inoperable due to noise or a minor abnormality, and to reliably detect the abnormality.

When the safety switch is operated momentarily due to looseness of the door cover or the like, since a momentary abnormality cannot be detected, a problem such as a local loss of an image may occur.

At this time, since there is no safety problem, if the confirmation period of the beam detection signal generation state signal is set short, the emergency stop of the apparatus is not performed in the abnormality handling procedure, and only the abnormality display and data maintenance are performed. Good. Thus, only the detection of an abnormality can be performed without impairing the operation of the image forming apparatus. As described above, the setting of the confirmation cycle of the beam detection signal generation state signal may be appropriately set according to the purpose of use of the apparatus.

Further, in the second embodiment, the case where there are four image forming units 104 has been described. However, the present invention can be similarly applied to a case where only one image forming unit 104 is provided.

[0087]

According to the present invention, the door switch is turned on,
In addition, when the laser light is not emitted by the laser emitting unit, the predetermined notification is performed, so that the interruption of the power supply line is detected, and when the power line can be recovered immediately, the predetermined notification can be performed. As a result, even if it is possible to return immediately, it is possible to prevent the device from being left for a long time. In addition, since there is no need to use a complicated configuration, costs can be suppressed, and there is no possibility that safety will be impaired.

[Brief description of the drawings]

FIG. 1 is a perspective view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of the image forming apparatus.

FIG. 3 is a diagram illustrating a circuit configuration of the image forming apparatus.

FIG. 4 is a diagram illustrating a circuit configuration of a laser driving circuit.

FIG. 5 is a perspective view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 6 is a schematic sectional view of the image forming apparatus.

FIG. 7 is a diagram illustrating a circuit configuration of the image forming apparatus.

FIG. 8 is a diagram showing a circuit configuration of a laser driving circuit.

FIG. 9 is a flowchart illustrating the operation of the control circuit.

FIG. 10 is a flowchart illustrating an operation content of a control circuit.

[Explanation of symbols]

 14 Image forming unit 16 First safety switch 17 Second safety switch 20 Laser scanning unit 33 Drawer connector 34 Control circuit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G03G 15/04 F term (Reference) 2C362 AA74 BA90 DA02 DA27 DA28 DA43 EA04 EA12 2H027 DA01 DA26 DA27 EC06 ED06 GB08 ZA01 ZA07 2H071 AA17 BA03 BA13 BA17 BA20 BA29 DA02 DA15 DA32 DA34 EA16 EA18 2H076 AB05 AB58 EA01 EA21

Claims (4)

[Claims] 1. An image forming unit including a laser emitting unit that emits a laser beam, a photoconductor irradiated with the laser beam emitted by the laser emitting unit, and the image forming unit is mounted at a regular position. A unit switch that is turned on when the device is in a normal position and turned off when the device is not mounted in a proper position. A door switch, power supply means for supplying laser driving power to the laser light emitting means via the unit switch and the door switch, and the door switch is turned on, and laser light is emitted by the laser light emitting means. An informing unit that performs a predetermined informing when the light is not emitted. 2. One or more image forming units each including a plurality of laser light emitting means for emitting laser light, and a photosensitive member to which the laser light emitted by each of the laser light emitting means is irradiated. Each is provided corresponding to the image forming unit,
A plurality of unit switches which are turned on when the respective image forming units are mounted in their proper positions, turned off when they are not mounted in their proper positions, and which are respectively connected in series; and A door switch that is connected in series with the switch and that is turned on when the maintenance door is closed and turned off when the maintenance door is opened; and a laser driving power source for the laser emitting unit through the plurality of unit switches and the door switch. An image forming apparatus comprising: a power supply unit that supplies power; and a notification unit that performs a predetermined notification when the door switch is turned on and the laser light is not emitted by each of the laser emission units. 3. The apparatus according to claim 2, further comprising a light amount control unit configured to detect the laser light emitted by the laser light emitting unit and to control a light amount of the laser light based on a result of the detection. The image forming apparatus according to claim 1, wherein the image forming apparatus detects that the laser light is not emitted based on the performed laser light. 4. A beam detection signal interval detecting means for generating a beam detection signal generation state signal when a cycle of a laser beam is within a predetermined time, wherein said notifying means detects a beam by said beam detection signal interval detecting means. When the signal generation status signal is not generated,
3. The image forming apparatus according to claim 1, wherein the image forming apparatus detects that no laser light is emitted.