JP2719241B2 - Abnormal stop detection 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 abnormal stop detecting device provided in an image forming apparatus such as a copying machine or a printer using a photosensitive drum and capable of detecting an abnormal stop of the photosensitive drum.

[0002]

2. Description of the Related Art In an electrophotographic copying machine using a two-component developer obtained by mixing a toner and a carrier as a developer, when a power supply is turned off during a copying operation, a photosensitive drum stops in the process. However, there arises a problem that negative charges remain on the drum surface between the charging charger and the developing unit. In this state, when the copying operation is restarted, the carrier stored in the developing unit is attracted to the negative charges remaining on the drum surface, so that the carrier is rapidly reduced and the image quality may be deteriorated. .

In order to prevent this, the copying machine stores an abnormal stop of the photosensitive drum during a copying operation.
When the copying operation is restarted after the abnormal stop, a negative charge is applied to the carrier in the developing unit so that the carrier is not attracted to the negative charge remaining on the drum surface.

Here, as a device for storing an abnormal stop of operation, a power supply voltage is monitored, and a sudden decrease in the power supply voltage due to the power OFF is performed.
(NV-RAM) is used.

[0005]

However, such an electronic circuit is expensive, and its use causes a significant increase in the cost of electric equipment such as an image forming apparatus.

An object of the present invention is to solve the above-mentioned disadvantages of the prior art, and an object of the present invention is to provide an abnormal stop detecting device which is inexpensive and which can reliably detect an abnormal stop of operation in an electric device. .

[0007]

An abnormal stop detecting apparatus according to the present invention comprises a driving means having an output shaft capable of rotating forward and reverse, and turning on and off power supply to the driving means. A power source for rotating the output shaft in the normal direction and, when normally turned off, for rotating the output shaft in reverse; a rotating body connected to the output shaft so as to be capable of frictional movement; A first stopper for stopping the rotating body, which is rotated in the forward direction from the standby position at the time of forward rotation, at a predetermined position, and provided in a rotation area of the rotating body; A second stopper for stopping at the standby position, and a second stopper disposed at the standby position;
A detecting means for detecting the presence or absence of the rotating body, and a detecting means for detecting an abnormal stop in which the rotating body does not return to the standby position based on a detection result of the detecting means, whereby the object is achieved. .

[0008]

In the above configuration, when the power supply is turned on and power is supplied to the driving means from the power supply, the output shaft is rotated forward and the rotating body rotated by the output shaft is stopped at the position of the first stopper. Becomes In this state, the output shaft continues idling. When the power is normally turned off from this state, the output shaft rotates in the reverse direction until the power is turned off, and the rotating body rotates in the reverse direction. Along with this, the rotating body separates from the first stopper, and then is stopped at the standby position by the second stopper, and in this state, the detecting means detects the rotating body. Then, the abnormality detecting means receiving the detection result of the detecting means detects that the rotating body has returned to the standby position normally.

On the other hand, if the power supply is abnormally disconnected due to the operation of the safety device or the inadvertent disconnection of the outlet during the operation of the electric equipment, the driving means is suddenly stopped, and the output shaft and the output shaft are stopped. The rotating body is not reversely rotated from the position of the first stopper. Therefore, in this case, the rotating body does not return to the standby position and is not detected by the detecting means.

Therefore, an abnormal stop state in which the rotating body is not returned to the standby position can be detected based on the detection result of the detecting means. Therefore, the subsequent response can be easily performed by using the detection result.

[0011]

The present invention will be described below with reference to examples.

FIG. 3 shows an embodiment in which the abnormal stop detecting apparatus of the present invention is applied to an electrophotographic copying machine using a two-component developer. Prior to exposure, a charging charger 2 for uniformly charging the surface of the photosensitive drum 1 to a negative charge state is provided in the rotation region. Thereafter, the surface of the photosensitive drum 1 is exposed to light corresponding to the document image from the direction of arrow B, and an electrostatic latent image is formed on the exposed portion. Then, the toner stored in the developing unit 3 is supplied to the electrostatic latent image, and a toner image is formed. Thereafter, the toner image is transferred to the sheet, and the fixing device fixes the toner image transferred to the sheet. The sheet after fixing is discharged outside the apparatus.

FIG. 1 shows an abnormal stop detecting device provided in the copying machine. The abnormal stop detecting device has a motor 10 driven by a main power supply 50 for driving the photosensitive drum 1. The motor 10 is composed of, for example, a stepping motor capable of normal rotation and reverse rotation. The driving of the motor 10 is controlled by the CPU 60. The photosensitive drum 1 is driven via a main motor M.

When the main power supply 50 is turned on, the motor 10 rotates the output shaft 11 in the forward rotation direction (counterclockwise) X. On the other hand, if the main power supply 50
When F is pressed, the output shaft 11 is rotated in the reverse rotation direction (clockwise) Y until it is completely turned off. An arm-shaped rotating body 20 is attached to the output shaft 11. This attachment is performed by inserting the output shaft 11 into a split groove 21 formed on the base end side of the rotating body 20. A spring 22 that pulls the split groove 21 in the closing direction is locked to the base end of the split groove 21. The rotating body 20 is connected to the output shaft 11 so as to be capable of frictional movement by the tensile force of the spring 22. That is, in a state where the rotating body 20 does not receive an external force,
In a state where the rotating body 20 rotates in the rotation direction with the rotation of the output shaft 11 and the rotating operation of the rotating body 20 is blocked,
The output shaft 11 is connected so that a frictional motion in which the output shaft 11 idles is possible. On the other hand, the tip of the rotating body 20 is a sensitive part 23 sensed by a sensor.

A first stopper 3 for preventing rotation of the rotating body 20 in the forward rotation direction X is provided in the rotation range of the rotating body 20.
0a and a second stopper 30b for preventing the rotating body 20 from rotating in the reverse rotation direction Y are provided. The disposition position of the second stopper 30b is the first stopper 30a.
Is slightly deviated in the reverse rotation direction from the disposition position, and the deviation angle is substantially the same as or slightly smaller than the rotation angle of the output shaft 11. Therefore, the first stopper 3
If the output shaft 11 switches from forward rotation to reverse rotation with the rotating body 20 stopped at 0a, the rotating body 20 comes into contact with the second stopper 30b and stops at this position.

In addition, a sensor 40 for detecting that the rotating body 20 has stopped is provided at the stop position (standby position). The sensor 40 is composed of, for example, a photo sensor. The detection result of the sensor 40 is input to the CPU 60.

The abnormal stop detecting device having the above-described structure operates as follows in a copying machine. The main power supply 50 is turned on,
When the photosensitive drum 1 rotates, the motor 10
Output shaft 11 rotates in the forward rotation direction X. At this time, the rotating body 20 is rotated in the forward rotation direction X by the output shaft 11 until it comes into contact with the first stopper 30a. When the rotating body 20 comes into contact with the first stopper 30a, the output shaft 11
Only the rotation continues.

On the other hand, when the main power supply 50 is normally turned off after completing the copy operation, as shown in FIG. 2, the forward rotation of the output shaft 11 is stopped, and the main power supply 50 is completely turned off.
In the meantime, the output shaft 11 rotates about 30 degrees in the reverse rotation direction Y. With this, the rotating body 20 rotates in the same direction Y, and comes into contact with the second stopper 30b and stops. Thus, the rotating body 20 is detected by the sensor 40. Then, the detection result of the sensor 40 is input to the CPU 60, and the CPU 60 receiving the detection result stops the rotating body 20 normally,
In addition, it is configured to detect that the main power supply 50 is normally turned off after the copy operation. In this state, the photosensitive drum 1 is stopped at a predetermined position, and there is no problem that negative charges remain on the drum surface between the charging charger 2 and the developing unit 3.

On the other hand, if the main power supply 50 is suddenly switched from the ON state to the OFF state during the copy operation due to a malfunction of the operator or the operation of the safety device of the copier,
In this case, although the output shaft 11 of the motor 10 stops the forward rotation with the switching, the output shaft 11 does not perform the reverse rotation following the stop of the forward rotation. Thereby, the rotating body 20 is in a state of being in contact with the first stopper 30a,
It does not rotate to the position of the second stopper 30b. Therefore, the detection of the rotating body 20 is not performed by the sensor 40.

Then, when the main power supply 50 is turned on again from this state, the CPU 60 does not input the detection signal of the rotating body 20 from the sensor 40 at that time, so that the CPU 60 determines that the abnormal stop state has occurred. When detecting an abnormal stop, the CPU 60 sets the carrier in the developing unit 3 to a negatively charged state. As a result, there is no problem that the carrier is wasted and the copy image quality is impaired.

In the above configuration, a backup power supply is connected to the CPU 60, and the main power supply 50 is turned on and off.
The abnormal stop of the rotating body 20 and the photosensitive drum may be detected based on the F state and the detection signal from the sensor 40. Further, in the above embodiment, the case where the present invention is applied to an electrophotographic copying machine has been described. However, the present invention can be similarly applied to abnormal stop detection of other electric devices.

[0022]

According to the abnormal stop detecting apparatus of the present invention described above, the abnormal stop of the electric equipment is detected by detecting the mechanical stop state of the rotating body. Expensive circuit elements such as a stop detection device are not required. Therefore, significant cost reduction is possible.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an abnormal stop detection device of the present invention.

FIG. 2 is a schematic diagram for explaining the operation of the abnormal stop detection device of the present invention.

FIG. 3 is a schematic cross-sectional view of an electrophotographic copying machine using the abnormal stop detection device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Charging charger 4 Developing unit 10 Motor 11 Output shaft 20 Rotating body 30a First stopper 30b Second stopper 40 Sensor 50 Main power supply 60 CPU

Claims (1)

(57) [Claims] 1. A driving means having an output shaft capable of rotating forward and reverse, power supply to the driving means being turned on and off, the output shaft being rotated normally when turned on, and an output being outputted when the output shaft is normally turned off. A power source for rotating the shaft in the reverse direction, a rotating body connected to the output shaft so as to be capable of frictional movement, and a rotating body provided in a rotation range of the rotating body, which is rotated in a normal direction from the standby position when the output shaft rotates forward. A first stopper for stopping the rotating body at a predetermined position, a second stopper provided in a rotation range of the rotating body, and stopping the rotating body at the standby position when the output shaft rotates in a reverse direction; An abnormal stop detection device, which is provided at a position and includes detection means for detecting the presence or absence of the rotating body, and detecting means for detecting an abnormal stop in which the rotating body does not return to the standby position based on a detection result of the detecting means.