JP2000263844A - Image-forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-forming apparatus which can prevent an optical scanning device from being detected wrong to be abnormal. SOLUTION: An image-forming apparatus 10 has an optical scanning device 30. A power source is supplied to an LD 36 when a process cartridge 26 is mounted to a main body. Meanwhile, the power source is supplied to a scanner motor 64 or the like when a machine cover 72 is closed. A CPU 76 monitors an ROS Fail signal output from an optical scanning device abnormality detection circuit 80, and informs by a display device 90 that the optical scanning device 30 is abnormal when the optical scanning device 30 is detected to be abnormal and a process cartridge switch 60 and a machine cover switch 70 are turned on.

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 method for forming an electrostatic latent image by scanning a recording medium such as a photosensitive member with a laser beam by an electrophotographic system such as a laser beam printer or a copying machine. And an image forming apparatus for obtaining a desired image.

[0002]

2. Description of the Related Art Conventionally, in a laser beam printer or a copying machine, a laser beam is applied by a laser exposure device (optical scanning device) on a photoreceptor uniformly charged by a charge corotron in accordance with an output image signal. By flashing and exposing, an electrostatic latent image of a digital image is formed on the photoconductor. The toner image is developed by developing the toner image, the obtained toner image is transferred onto a recording medium by a transfer corotron, and fixed by a heat roll and a pressure roll to form a digital image by a so-called electrophotographic method. .

As a light source of a laser exposure apparatus for forming a digital image on a photoreceptor, a semiconductor laser (laser diode, hereinafter referred to as LD) is generally used, and the light source is modulated according to an image to be formed. A laser beam is output. The laser beam output from the light source is
It is deflected by a rotating polygon mirror (polygon mirror) and scans the photosensitive member. As a result, an electrostatic latent image of an image to be formed on the photoconductor is formed.

In such an image forming apparatus, a process cartridge is provided between a power supply for supplying power to the LD and the LD in order to prevent light emitted from the LD from leaking from the apparatus body to the outside (Laser Safety). Provide a safety switch that is turned on when the process cartridge is attached to the main body, and when the process cartridge is removed from the main body, the LD
A technique for interrupting the supply of power to the power supply has been proposed (JP-A-5-323714).

[0005]

However, in the above-mentioned prior art, the power supply to the LD may be interrupted even when the process cartridge is mounted on the main body. This is because, for example, when a mechanical switch is used as the safety switch, the amount of pushing in when the process cartridge is mounted on the main body and the safety switch is pushed in is not appropriate, or the safety switch is worn out. , If vibration or impact occurs during the image forming operation,
Power line to LD (process cartridge detection signal)
This is because chattering may occur in itself.

By the way, the apparatus main body monitors the period of an SOS signal output from a synchronous sensor (SOS: Start Of Scan) for determining an image writing timing for each line in the main scanning direction, thereby controlling the optical scanning apparatus. An error has been detected. That is, by monitoring the cycle of the SOS signal, it is possible to simultaneously check whether the LD is emitting light, whether the rotation speed of the polygon motor is within the reference, whether the SOS sensor is responding, and the like.

If chattering occurs in the power supply line to the LD due to abrasion of the safety switch, etc.
The power supply to the LD is cut off, and the light emission of the LD is stopped. Therefore, the SOS signal of the optical scanning device is not detected, and the apparatus main body erroneously determines that the optical scanning device is abnormal even though the signal for detecting the presence or absence of the process cartridge has an error. was there. In particular, when this occurs in the market, there is a problem that wasteful time and cost are generated, such as replacement of the optical scanning device is performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an image forming apparatus which can prevent erroneous detection that an optical scanning device is abnormal. I do.

[0009]

To achieve the above object, an image forming apparatus according to the first aspect of the present invention is provided on an image carrier with a light beam emitted from a light source which emits light by being supplied with power from a power supply. An image forming apparatus provided with optical scanning means for scanning the light beam, a switch means for setting the optical scanning means to a drivable state, a scanning position detecting means for detecting a predetermined position of the light beam in a main scanning direction, and An abnormality detecting means for detecting an abnormality of the light scanning means based on a setting state of the means and a cycle of a detection signal detected by the scanning position detecting means.

According to the first aspect of the present invention, the abnormality detecting means determines that the abnormality is abnormal only when the setting state of the switch means is in the drivable state and the period of the detection signal is a predetermined period. Is detected. The predetermined cycle is
This is a cycle that is too long or too short than the detection cycle detected in a normal state. That is, even if the optical scanning means is determined to be abnormal, the optical scanning means is not actually abnormal, and the optical scanning means may be determined to be abnormal due to wear of the switch means and the like. By detecting the abnormality of the optical scanning means only when the setting state of the switch means is in the drivable state, it is possible to prevent erroneous detection of the abnormality of the optical scanning means.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the switch means is connected between the power supply and the light source, and the process cartridge accommodating the image carrier is provided. A cartridge switch that is turned on when attached to the image forming apparatus main body and turned off when removed, and a cover switch that is turned on when the cover of the image forming apparatus main body is closed and turned off when the cover of the image forming apparatus main body is open At least one of the switches.

According to the second aspect of the present invention, since the switch means is at least one of a cartridge switch and a cover switch, a simple configuration can be achieved.

According to a third aspect of the present invention, in the image forming apparatus of the first or second aspect, when the abnormality detecting unit detects an abnormality, the notifying unit notifies that the optical scanning unit is abnormal. Is further provided.

According to the third aspect of the present invention, when the abnormality detecting means detects an abnormality, the notifying means for notifying that the optical scanning means is abnormal is further provided, so that abnormality processing is easily performed. be able to.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the predetermined position in the optical scanning means is a scanning start position or a scanning end position in the main scanning direction. And

According to the fourth aspect of the present invention, since the predetermined position in the optical scanning means is a scanning start position or a scanning end position in the main scanning direction, a sensor for detecting these can be shared. Can be configured at low cost.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the abnormality detecting means determines a setting state of the switch means to determine a cycle of the detection signal. It is characterized in that it is detected at a period different from the period.

According to the fifth aspect of the present invention, the abnormality detecting means detects the setting state of the switch means at a cycle different from the cycle for judging the cycle of the detection signal. Erroneous detection of abnormalities can be prevented with high accuracy.

According to a sixth aspect of the present invention, in the image forming apparatus of the first to fifth aspects, a cycle for detecting the setting state of the switch is shorter than a cycle for determining the cycle of the detection signal. It is characterized by doing.

According to the sixth aspect of the present invention, the period for detecting the setting state of the switch is made shorter than the period for determining the period of the detection signal. An abnormality caused by the removal of the cartridge can be detected with priority.

According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the image forming apparatus further includes a chattering detecting unit that detects chattering of the switch unit, and the abnormality detecting unit includes the chattering. It is characterized in that the abnormality of the optical scanning means is determined only when chattering is not detected by the detecting means.

According to a seventh aspect of the present invention, there is further provided a chattering detecting means for detecting chattering of the switch means, wherein the abnormality detecting means detects the chattering only when no chattering is detected by the chattering detecting means. Since the abnormality of the scanning unit is determined, erroneous detection of the abnormality of the optical scanning unit can be accurately prevented.

According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the chattering detecting means counts the number of chattering times, and the abnormality detecting means determines an abnormality based on the count value. It is characterized by.

According to the present invention, the chattering detecting means counts the number of chattering times, and the abnormality detecting means determines abnormality based on the count value. It can be performed.

[0025]

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

FIG. 2 shows an image forming apparatus 1 such as an electrophotographic laser beam printer or copier to which the present invention is applied.
0 is shown.

As shown in FIG. 2, the image forming apparatus 10
The photosensitive member 12 includes a charging device (charge corotron) 14, a developing device 16, a transfer device (transfer corotron) 18, and a cleaning device 20. A fixing device 24 including a heat roll and a pressure roll is disposed downstream of the sheet 22 in the transport direction. Photoconductor 1
An optical scanning device 30 is arranged above the optical scanning device 2, and the optical scanning device 30 has a main control unit (hereinafter, MC).
U) 32 are connected. In addition, the photoconductor 12,
Charging device 14, developing device 16, and cleaning device 2
Reference numeral 0 is integrated as a process cartridge 26 and is detachable from the main body of the image forming apparatus 10.

The photosensitive member 12 is rotating in the direction of arrow A in FIG. In this uniformly charged state, the image data signal output from the MCU 32 is output to the optical scanning device 30, and the laser beam 38 modulated according to the image data signal is output. The photosensitive member 12 is scanned and exposed by the laser beam 38 to form an electrostatic latent image. The electrostatic latent image formed on the photoconductor 12 is visualized by the developing device 16, and a toner image is formed on the photoconductor 12.

Then, the toner image formed on the photosensitive member 12 is transferred by the transfer device 18 to a sheet 22 conveyed in the direction of arrow C in FIG. Thereafter, the sheet 22 is subjected to a fixing process by a fixing device 24 to obtain a final output image. On the other hand, the photoconductor 12 is cleaned of unnecessary toner by the cleaning device 20, and prepares for the next image output.

As shown in FIG. 3, the optical scanning device 30
D36 is provided. The LD 36 is driven by the LD driving unit 28 shown in FIG.
And outputs a laser beam 38 modulated in accordance with the image data output to.

Laser beam 38 output from LD 36
Is an arrow B in FIG.
The light enters the reflecting surface of the polygon mirror 42 rotating at a predetermined speed in the direction, and is deflected. The deflected laser beam 38 passes through the fθ lens 44, is turned back by the plane mirror 46, and is further turned by the cylindrical mirror 48 to the photosensitive member 12
, And scans and exposes the surface of the photoconductor 12. It should be noted that the scanning start side of the laser beam 38 is SOS
(Start Of Scan) sensor 50 is arranged. When the laser beam 38 turned back by the plane mirror 46 and the plane mirror 54 enters the SOS sensor 50, the modulation of the laser beam 38 is started.

Therefore, the writing of an image is started when a predetermined time has elapsed since the detection of the laser beam 38 by the SOS sensor 50. As described above, by detecting the laser beam 38 by the SOS sensor 50, horizontal synchronization is obtained for each line, and the image writing timing is determined.

The light emission power of the laser beam 38 is set to a value of an optical output necessary for image formation on the photoconductor 12 by controlling a current for driving the LD 36 by the LD drive unit 28. Specifically, a monitor current corresponding to the optical output is output from the LD 36 to the LD drive unit 28, the monitor current is converted into a voltage by the LD drive unit 28, and is fed back to the MCU 32 as a monitor voltage via a signal line (not shown). . In the MCU 32, the monitor voltage and the photosensitive member 1
2 and sequentially compares the desired voltage reference value Vref required for image formation with a drive current setting voltage value such that the monitor voltage matches the voltage reference value Vref to the LD drive unit 28. Then, the LD drive unit 28 sets the drive current of the LD 36 according to the drive current setting voltage value. For example, when the monitor voltage is 3 V when the required light output on the photoconductor 12 is 0.5 mW, the drive current of the LD 36 is set so that the monitor voltage becomes 3 V. By performing feedback control (APC control) in this manner, LD3
The drive current of No. 6 is optimally set, and the amount of light required for image formation on the photoconductor 12 can be set. In addition,
The voltage reference value Vref may be output from the MCU 32 to the LD drive unit 28, and the LD drive unit 28 may perform feedback control.

As shown in FIG. 1, when the process cartridge switch (hereinafter referred to as CRU switch) 60 is turned on, that is, as shown in FIG. 4, the process cartridge 26 is pushed into the LD 36 in the direction of arrow P in FIG. When the image forming apparatus 10 is mounted on the main body of the image forming apparatus 10, a predetermined DC voltage (for example, 5
V) is supplied via the LD drive unit 28.

As shown in FIGS. 1 and 4, a scanner motor 64 for rotating and driving the polygon mirror 42, a main motor 66, and an HVPS 68 for supplying high-voltage power are provided with a machine cover switch (hereinafter referred to as an interlock switch). Is turned on, that is, when the machine cover 72 is closed, a predetermined DC voltage (for example, 24 V) is supplied from the DC supply 74.

The ON / OFF signal of the CRU switch 60 (hereinafter referred to as the CRU switch signal)
The signal is input to the PU 76 directly or via the chattering detection circuit 78. That is, the CPU 76 can recognize whether or not the process cartridge 26 is mounted.

The chattering detection circuit 78 includes, for example, a flip-flop circuit 82 as shown in FIG. A CRU switch signal is input to a 1A terminal of the flip-flop circuit 82, and a constant voltage (for example, 5V) power supply (not shown) is connected to a 1B terminal. The Cex terminal is connected to one terminal of the capacitor 84 and grounded, and the Rex terminal is connected to the capacitor 8.
4 and one terminal of the variable resistor 86 are connected. The other terminal of the variable resistor 86 is connected to a constant voltage (5 V) power supply (not shown). Further, an ON / OFF signal of the interlock switch 70 (hereinafter referred to as an interlock switch signal) is input to the CLEAR terminal.

In the chattering detection circuit 78 configured as described above, as shown in FIG. 5, when chattering occurs in the CRU switch signal, the constant value of the resistance value R of the variable resistor 86 and the capacitance C of the capacitor 84 are reduced. Is output from the Q terminal to the CPU 76. Note that the resistance value R and the capacitance C are set such that a signal having a pulse width longer than the cycle monitored by the CPU 76 is output.

As shown in FIG. 1 and FIG.
The SOS signal from the sensor 50 is input to the optical scanning device abnormality detection circuit 80. The optical scanning device abnormality detection circuit 80
In a state where the polygon mirror 42 is constantly rotating,
The cycle of the SOS signal according to the image resolution is monitored. If the cycle is too long or too short, or if the SOS signal is not detected, the optical scanning device 30 is determined to be abnormal, and the ROS_Fail signal is output. Output to CPU76.

Further, a display device 90 is connected to the CPU 76, and can notify that an abnormality has occurred.

Next, the operation of this embodiment will be described with reference to the timing chart shown in FIG.

First, as shown in FIG.
CRU switch 60 is turned on at the timing of
When the process cartridge 26 is mounted, the power of the optical scanning device 30 is turned on. Thereby, the CPU 76 determines whether or not the interlock switch 70 is turned on at predetermined intervals (for example, 2 msec) indicated by the arrow in the drawing as shown in FIG.
Start monitoring whether or not is closed. CPU7
In 6, when the high level is detected a predetermined number of times (for example, three times) continuously, it is determined that the interlock switch 70 is on, that is, the machine cover 72 is closed. The interlock switch 70
After it is determined that is turned on, the subsequent monitoring may be stopped.

Next, as shown in FIG. 6B, when the interlock switch 70 is turned on at the timing of t2, that is, when the machine cover 72 is closed, the CPU 76
A predetermined interval (for example, 2 msec) indicated by an arrow in FIG.
To start monitoring whether the CRU switch 60 is turned on, that is, whether the process cartridge 26 is attached to the main body of the image forming apparatus 10. CPU7
In 6, when the high level is detected a predetermined number of times (for example, three times) continuously, it is determined that the CRU switch 60 is turned on, that is, the process cartridge 26 is mounted on the apparatus main body. If the high level is not detected continuously for a predetermined number of times (for example, three times), the display device 90 notifies the fact that the mounting of the process cartridge 26 is defective. After determining that the CRU switch 60 is on, the subsequent monitoring may be stopped.

When the CRU switch 60 is turned on and the interlock switch 70 is turned on, that is, when it is determined that the process cartridge 26 is mounted on the apparatus main body and the machine cover 72 is closed, the process proceeds to the next step. As shown in FIG. 6 (C), at the timing of t3, LD3
6 is turned on, the above-described APC control is performed, and the light amount of the light beam emitted from the LD 36 is set to be a specified light amount required for image formation.

Then, as shown in FIG. 6D, when the polygon mirror 42 is rotated at a regular time (not shown) at the timing of t4, the CPU 76 causes the optical scanning device abnormality detecting circuit 8 to operate.
0, the optical scanning device abnormality detection signal (ROS_F
ai signal) is monitored at a predetermined interval (for example, 4 msec) longer than the interval for monitoring whether the CRU switch 60 and the interlock switch 70 are on.

Then, as shown in FIG. 6D, the ROS_Fail signal goes high at the timing of t5, and a high level is detected a predetermined number of times (for example, three times) at the timing of t6. Is detected, it is further determined whether or not the CRU switch 60 and the interlock switch 70 are turned on. When both are turned on, as shown in FIG. Is abnormal, and the display device 90 is notified of that.

That is, only when the power is normally supplied to the LD 36, the original abnormality of the optical scanning device 30, for example, the abnormality of the SOS sensor 50, the abnormal rotation of the polygon motor 42, and the light beam entering the SOS sensor 50 Not
An abnormality such as an abnormality of the board of the MCU 32 or a connection failure, or a failure or control failure of the LD 36 is notified. For this reason, when power is not supplied to the LD 36, that is, in the case of an abnormality such as a mounting failure of the process cartridge 26, it is possible to prevent the abnormality of the optical scanning device 30 from being erroneously notified.

As shown in FIGS. 7A, 7D, and 7E, the case where chattering has occurred even once in the CRU switch 60 and the case where an abnormality has occurred in the optical scanning device 30. Does not notify that the optical scanning device 30 is abnormal. Then, when the optical scanning device 30 is determined to be abnormal at the timing of t7 and chattering does not occur, the abnormality of the optical scanning device 30 is notified.

That is, if chattering occurs, it is conceivable that the error is not an abnormality of the optical scanning device 30 but an error such as a mounting failure of the process cartridge 26. Please do so. "Is displayed on the display device 90. Then, only when the optical scanning device 30 is determined to be abnormal and chattering has not occurred, the abnormality of the optical scanning device 30 is notified.

The abnormal processing may be changed according to the number of occurrences of chattering. For example, a normal operation is performed until the detected number of chattering is three, and when the detected chattering occurs four times, a message such as "Reset the process cartridge."
If this occurs more than once, the image forming operation may be stopped.

As described above, by changing the abnormal processing in accordance with the number of occurrences of chattering, it is desired to use the image forming apparatus by giving the user a method of use, that is, giving priority to image quality, or to use the image forming apparatus while minimizing stoppage of the image forming apparatus. Optimal control can be performed according to the priority such as the degree of priority.

[0052]

As described above, according to the first aspect of the present invention, the abnormality detecting means is provided when the setting state of the switch means is in the drivable state and the period of the detection signal is a predetermined period. Since the abnormality is detected only by determining that the abnormality occurs, the erroneous detection of the abnormality of the optical scanning means can be prevented.

According to the second aspect of the present invention, since the switch means is at least one of a cartridge switch and a cover switch, there is an effect that the configuration can be simplified.

According to the third aspect of the present invention, when the abnormality detecting means detects an abnormality, the notifying means for notifying that the optical scanning means is abnormal is further provided, so that abnormality processing is easily performed. Has the effect of being able to

According to the fourth aspect of the present invention, since the predetermined position in the optical scanning means is a scanning start position or a scanning end position in the main scanning direction, a sensor for detecting these can be shared. Can be configured at low cost.

According to the fifth aspect of the present invention, the abnormality detecting means detects the setting state of the switch means at a cycle different from the cycle for judging the cycle of the detection signal. This has the effect that erroneous detection of abnormalities can be accurately prevented.

According to the present invention, the period for detecting the setting state of the switch is made shorter than the period for determining the period of the detection signal. This has the effect that an abnormality caused by the removal of the cartridge can be detected with priority.

According to the seventh aspect of the present invention, there is further provided a chattering detecting means for detecting chattering of the switch means, wherein the abnormality detecting means is configured to detect the chattering only when the chattering detecting means does not detect the chattering. Since the abnormality of the scanning unit is determined, erroneous detection of the abnormality of the optical scanning unit can be accurately prevented.
It has the effect of.

According to the present invention, the chattering detecting means counts the number of chattering times, and the abnormality detecting means determines abnormality based on the count value. Can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an MCU.

FIG. 2 is a schematic configuration diagram of an image forming apparatus.

FIG. 3 is a schematic configuration diagram of an optical scanning device.

FIG. 4 is a view for explaining attachment and detachment of a process cartridge.

FIG. 5 is a circuit diagram of a chattering detection circuit.

FIG. 6 is a timing chart showing the operation timing of each unit.

FIG. 7 is a timing chart showing the operation timing of each unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Photoreceptor 14 Charging device 16 Developing device 18 Transfer device 20 Cleaning device 22 Paper 24 Fixing device 26 Process cartridge 28 LD drive unit 30 Optical scanning device 32 MCU 36 LD 50 SOS sensor 60 Process cartridge switch 70 Machine cover switch 76 CPU 78 Chattering detection circuit 80 Optical scanning device abnormality detection circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C362 AA03 BA04 BB32 DA45 EA04 2H027 DA21 DA26 DA27 DA38 DA41 DE07 GA30 GB07 HA02 HA04 HA12 2H045 AA01 CA88 DA41 5C072 AA03 BA02 BA04 BA20 HA02 HB08 XA01 XA04

Claims (8)

[Claims] 1. An image forming apparatus comprising: an optical scanning unit that scans an image carrier with a light beam emitted from a light source that emits light when power is supplied from a power supply, wherein the optical scanning unit is set in a drivable state. Switch means, and a scanning position detecting means for detecting a predetermined position of the light beam in the main scanning direction, based on a setting state of the switch means, and a period of a detection signal detected by the scanning position detecting means, An image forming apparatus comprising: an abnormality detection unit configured to detect an abnormality of the optical scanning unit. 2. The switch device is connected between the power supply and the light source, and is turned on when a process cartridge containing the image carrier is mounted on the image forming apparatus main body, and is removed. 2. The cartridge switch according to claim 1, wherein the switch is at least one of a cartridge switch that is turned off when the cover is closed and a cover switch that is turned on when the cover of the image forming apparatus is closed and is turned off when the cover is open. The image forming apparatus as described in the above. 3. The image according to claim 1, further comprising a notifying unit for notifying that the optical scanning unit is abnormal when the abnormality detecting unit detects an abnormality. Forming equipment. 4. The image forming apparatus according to claim 1, wherein the predetermined position in the optical scanning unit is a scanning start position or a scanning end position in a main scanning direction. . 5. The apparatus according to claim 1, wherein said abnormality detecting means detects a setting state of said switch means at a cycle different from a cycle for determining a cycle of said detection signal. Item 10. The image forming apparatus according to item 1. 6. The image according to claim 1, wherein a cycle for detecting a setting state of the switch means is shorter than a cycle for determining a cycle of the detection signal. Forming equipment. 7. A chattering detecting means for detecting chattering of the switch means, wherein the abnormality detecting means determines an abnormality of the optical scanning means only when chattering is not detected by the chattering detecting means. The image forming apparatus according to any one of claims 1 to 6, wherein: 8. The image forming apparatus according to claim 7, wherein the chattering detection unit counts the number of chattering times, and the abnormality detection unit determines an abnormality based on the count value.