JPS61151567A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an image forming device having the self-diagnostic function which can code with abnormal states, by providing a means, which receives the reverse rotation signal from a detecting means to cut off a power supply circuit of a rotating body driving means, and a rotation control means of a rotating body. CONSTITUTION:An abnormality detecting circuit detects the overcurrent to a motor 12 and the reverse rotation of the motor 12 as abnormality. With respect to the reverse rotation signal of the motor 12, two-phase signals, namely, a leading signal A and a lagging signal B having the phase difference of 1/4 cycle are outputted from an encoder 17, and the leading signal A is sent to the D terminal of a flip flop 48, and the lagging signal B is sent to the CK terminal of it. The level of the output from the -Q terminal of the flip flop 48 is inverted in accordance with these signals. A motor controlling CPU31d detects the reverse rotation of the motor 12 when receiving the high-level signal from the -Q terminal, and a relay 42 is operated by the reverse rotation signal to turn off the power source of the motor 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an image forming apparatus equipped with a multicolor developing device.

[Prior art]

For example, in a color copying machine using electrophotography, developing devices using a plurality of different color toners are disposed on a single latent image carrier such as a photosensitive drum. By sequentially arranging a plurality of developing devices in a row, the plurality of developing devices are supported by a rotating body, and by rotationally driving this rotating body, only the developing device corresponding to the desired color toner is hidden. The applicant has proposed a multicolor developing device that faces the image carrier (Japanese Patent Laid-Open No. 5O-93437).
).

In the latter case, since one developing device always faces the latent image carrier, the circumference of the latent image carrier can be made as small as possible.

In such a developing device, attempts have been made to perform sequence control in order to rotate a given developing device at high speed relative to the drum according to a predetermined schedule and to stop it at an accurate position without impact. However, sometimes abnormal operations such as reverse rotation of the drive motor or generation of overcurrent occur, which not only affects the control of the image forming apparatus itself, but also damages the developing device itself, or in the worst case, burns out the rotary drive motor, etc. There is also a risk of causing an accident.

〔the purpose〕

This invention was made by focusing on the above-mentioned problems.
It is an object of the present invention to provide an image forming apparatus having a self-diagnosis function that can promptly respond to an abnormal situation by cutting off the power or emergency stop when a developing device is abnormal, and also notifying a main body control unit of the abnormal state.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 is a cross-sectional view showing an example of an electrophotographic copying machine as an image forming apparatus equipped with a rotationally driven multicolor developing device.

In the figure, a photosensitive drum l, which is a latent image carrier, rotates in the direction of the arrow. Surrounding it are a charger 2, an exposure optical system 3, a developing device 4. Transcription system 5. A cleaning device 6 is also provided. The optical system 3 includes a document scanning section 3a and a color separation filter part 3b, and the developing device 4 includes a yellow developer 4Y using yellow toner, a busenta developer 4M using magenta toner, and a cyan developer using cyan toner. 4C and black developer 4B using black toner
Each developing device has a
As disclosed in Japanese Patent No. 5-20579, the toner is prevented from scattering by the action of the magnetic field by the magnet roller R, and as shown in the figure, the toner is detachably held on a rotating body 4a and rotated around a central axis 4b, thereby developing the toner. Replace the developing device for position l.

Note that S is a toner stirring screw.

On the other hand, the transfer section 5 includes a drum 5b having a gripper 5a,
It has a transfer discharger 5C inside thereof.

When forming full-color images, the color separation optical system uses blue, green, red, and ND, similar to conventional copying machines.
Color separation is performed using a color filter, and development is performed using a four-color developer using three colors: yellow, magenta, and cyan, plus black.

For example, when the photosensitive drum 1 is irradiated with blue light (exposure), a latent image is formed on the photosensitive drum 1, and the formed latent image is transferred by the yellow developer 4Y, which is rotated to the developing position at an appropriate timing. This visible image is transferred onto a transfer paper held by a transfer drum 5b by a transfer charger 5C. This transfer paper is supplied from the cassette 7. After the process from exposure to development described above cleans the photosensitive drum l, green? The magenta developer 414 is used for the light, and the cyan developer 4C is used for the red light, and transfer is performed each time the development is completed. Further, exposure is performed using the ND filter described above, and after this exposure is developed by a black developing device 4BK, transfer is performed.

The transfer material that has completed the transfer process is separated by a separating means 8 and delivered onto a tray 10 via a fixing device 9.

Figure i2 is a perspective view showing the main parts of the developing device, and 11 is a ring-shaped rear plate provided at the rear end of the rotating body 4a and having a gear 11a around the periphery. 12 is a rotary drive motor, and a gear 13 fixed to one end of the motor shaft is connected to the gear l.
The motor shaft is connected to the motor shaft through gears 14, 15, 16, and the other end of the motor shaft is provided with, for example, an encoder 17 as a means for detecting rotational speed and position. Each may be separate, but
In this embodiment, the speed is determined from the number of pulses output from the rotary encoder 17 per unit time, and the position is detected as the integrated value. Z is a positioning means for ensuring a predetermined stopping position of the rotating body 4a, and a stopper plate 18 having a groove 18a and a guide edge 18b is attached to the rear plate 11.

FIG. 2 shows two partially broken stopper plates.

On the other hand, Z1 is a rotating body holding mechanism that engages with this stopper plate 18 (see Fig. 3 for details), and 19 is an L-shaped stopper arm, which is inserted into a long hole 19a formed in a part of the elbow. One end of the pin 20 is fixed to the main body of the device, and the other end is inserted through the pin 20. Also.

A stopper pin 2 is attached to one end of this stopper arm 19.
1, the roller 22 is rotatably attached to the shaft.

A tension coil Yagi 23 is stretched between the cono stopper pins 21 and 720. At the other end of the stopper arm 19, a long trenoid 25 serving as a holding/releasing means is pivoted by a pin 27 via a connecting member 26, and a Yagi 28 allows the roller 22 to be attached to the stopper plate 1.
It is biased so that it comes into contact with the periphery of 8. A photointerrupter 29 serves as a detection means for detecting engagement and release of the rotating body 4a and the stopper arm 19, and is arranged so that light is interrupted in accordance with movement of the end 24 of the stopper arm 19. has been done.

To rotate the rotating body 4a, first turn on the lock solenoid 2.
5 to remove the stopper pin 21 from the groove 18a of the stopper plate 18, and then rotate the rotating body 4a.
8 comes to the position of the stopper pin 21, the magnetic force of the lock solenoid 25 is released. Then, the roller 22 rotates once along the arcuate edge of the stopper plate 18 rotating in the N direction, and the roller 22 eventually engages the engagement groove 18a. 2
2, one section of the arcuate edge is cut out to form a guide edge 18b.

At the moment when the roller 22 enters the engagement groove 18a, the stopper arm 19 blocks the optical path of the photointerrupter (lock sensor) 29 attached to the main body, and when the stopper arm 19 shifts to the zero-order rotation to detect the engagement of the positioning means Z. , first, the lock solenoid 25 is energized, and the stopper arm 19 is connected to the pin 20.
Rotate around the center to release the engagement between the engagement groove 18a of the stopper plate 18 and the roller 22. This action causes the stopper arm to shield the photo ink club 29.

19 moves away from the optical path of the photo interrupter 29, and it can be detected that the engagement between the engagement groove 18a and the roller 22 is released.

Figure 4 shows the control system. 3G is a driver for driving the rotating body driving motor 12. 31 is a rotating body drive control circuit of the developing device 4;

Vector detection circuit 31a1 position counter 31b, speed counter 31c, motor control CPU (central
It consists of a processing unit ) 31d, a home position sensor xO, a timer 31f5, and a D/A converter 31g.

The vector detection circuit 31a inputs two-phase pulses from the rotary encoder 17 and outputs data regarding the forward and reverse rotation directions of the rotating body 4a. Data regarding the rotational direction and pulses output from the encoder 17 are input via the vector detection circuit 31a, and rotational movement position data based on the home position (HP) of the one-rotating body 4a is output to the motor control CPU 31d. . The home position sensor XO is disposed at the reference position HP, and inputs a clear signal to the position counter 31b when the rotating body 4a reaches the HP.

The timer 31f outputs a signal every time a set time elapses.

This signal is input to the speed counter 31 cc and clears the speed counter 31c, as well as to the motor control CPU 3.
It is also input to the interrupt terminal INT of 1d. CP for motor control
U31d thereby executes the interrupt program and adds speed data and position data from speed counter 31C1 and position counter 31b. Based on this data, motor 1
2 control is performed. This timer 31f is set and reset by the motor control CPU 31d. The speed counter 31c inputs the pulses output from the encoder 17 via the vector detection circuit 31a, and sends the rotational speed data of the rotating body 4a to the motor control CPU.
31d. Also, the ROM (read0111!) in the CPU 31d for controlling the rotating body drive motor.
mem + ory) 31 d l has 4 from monochrome copy
The relationship between the color mode that can be set up to color copying and the rotation amount, and the relationship between the rotation amount and rotation speed when moving the developer from the development position of one color to the development position of another color is stored as a control data table. The motor 12 is controlled according to this control data table and the detected speed data and position data.

32 is a control circuit of the main body of the copying machine, and is a sequence controller (not shown) that inputs signals to the motor control CPU 31d via the machine port 10 and the load drive circuit to control the motor control CPU 31d.

FIG. 5 shows a circuit that forms part of the driver 30 that controls the drive of the rotating body drive motor 12 and is used to detect abnormalities in the motor 12. This abnormality detection circuit detects overcurrent to the motor 12 and reverse rotation of the motor 12 as abnormalities. A power source 40 is connected to the motor 12 via a relay 42 and a resistor 43. Resistance 4 depending on the magnitude of the current
The potential difference generated across the transistor 3 is applied between the emitter and base of the transistor 44, and when the value exceeds a specified value, the transistor 44 is turned on.

Now, when the transistor 44 is turned on due to overcurrent,
The collector output changes from LOW to old GI, the signal is input to the motor control CPU 31d via the signal line 45, and overcurrent is detected. On the other hand, this overcurrent signal is
The signal is sent from the R gate 46 to the relay 42 via the buffer 47, and is configured to cut off the power supply circuit of the motor 12.

On the other hand, the reversal signal of the motor 12 is outputted from a knee two-trigger D flip-flop 48 serving as a reversal detection means into which the two-phase signal from the low-reverse encoder 17 is input. That is, from the encoder 17,
As shown in FIG. 6, a two-phase signal consisting of a leading signal A and a delayed signal B having a phase shift of 174 cycles is output, the former leading signal A being sent to the D terminal of the flip-flop 48, and the latter signal B being Sent to the CK terminal. When the motor 12 rotates forward and backward, the rising edge of the delayed signal B as a clock signal is reversed with respect to the levels L and H of the advance signal, so the level of the output from the Q terminal of the D flip-flop 48 changes accordingly. is also reversed. Therefore, the motor control CPU
31d detects the reversal of the motor 12 upon receiving the H level signal from the Q terminal, and on the other hand, the reversal signal activates the relay 4.
2 is also activated to cut off the power to the motor 12.

Next, the operation will be explained based on the flowchart of the motor control CPU 31d shown in FIG.

The motor control CPU 31d is a copying machine main body control circuit 32.
A mode signal MO1M1. which detects a start signal from MO1M1.
The receiver accepts M2 (S-1).

Then, the lock solenoid 25 of the positioning means Z is turned on.
5-2), this releases the engagement between the rotating body 4a and the locking roller 22 of the positioning means Z, and the rotating body 4a becomes rotatable. Here, since the rotational movement of the single rotating body 4a must be completed within a predetermined time specified in relation to the control of the copying machine main body, the predetermined time is set in a timer set in the RAM 31dz in order to detect an abnormality. (S-3) (As will be described later, when the set time of this timer elapses, a jump will be made to the abnormality processing routine.) Then, while detecting an error (S-4) as described later, the lock roller 22 is Wait until the lock roller 22 is completely disengaged from the rotating body 4a (S-8). When the photo interrupter 29 confirms that the lock roller 22 is disengaged, the motor 12 is started to stop the rotating body 4a from rotating. Start the movement and move to the target development position d while controlling the rotational speed (S-7).During this time, are the encoder pulses being received normally to the position counter 31b, and has the timer set time elapsed? It always performs error detection as described below, and jumps to the abnormality processing routine in the event of an abnormality (S-8 to S-10). When the rotating body 4a reaches the target position, the lock solenoid 25
0FFL, further cuts off the power to the motor 12, resets the timer, and outputs EN indicating the completion of 8 rotations of the main body control circuit 32.
A D signal is output (S-11 to S-15). With this, the movement of the rotating body 4a to the predetermined development position is completed, and preparations for predetermined color development are completed.

Next, the flow of error detection will be described. The motor control CPU 31d uses an overcurrent detection circuit and a reverse rotation detection circuit as shown in FIG. (S-17) If these errors are detected, jump to the normal processing routine.

In the abnormality handling routine.

First, the power to the motor 12 is cut off (S-18), and then the lock solenoid 25 is turned off (S-ta), thereby activating the positioning means Z and stopping the single rotating body 4a.

Thereafter, an error signal consisting of, for example, 3 bits as shown in Table 1 is output to the main body control circuit 32 depending on the nature of the abnormality (S-20).

As a result, an abnormality warning is issued and countermeasures against the abnormality are taken. If the motor control CPU 31 d is reset (
S-21) The abnormality processing routine returns to the normal rotation M control routine.

〔effect〕

As explained above, according to the present invention, when there is an abnormality in the developing device, it can be detected immediately, so it is possible to respond immediately to the abnormality itself, and it is possible to prevent damage to the image forming apparatus main body or the rotary developing device itself. Effects can be obtained.

[Brief explanation of the drawing]

1 to 7 show an embodiment of this invention. Fig. 1 is a side sectional view of the image forming apparatus, Fig. 2 is a perspective view of the main parts of the developing device, Fig. 3 is a partially enlarged view of Fig. 2, Fig. 4 is a block diagram of the control system, and Fig. 5 is a block diagram of the control system. An abnormality detection circuit diagram of the rotating body drive motor, FIG. 6 is a diagram for explaining signal input to the reverse rotation detection means, and FIG. 7 is a rotating body control flowchart. 4a...Rotating body 12...Rotating body driving means 17...
......Rotation detection means (encoder) 31f...Rotation time detection means (timer) 31cl...Rotation control means Fig. 6

Claims (2)

[Claims] (1) In an image forming apparatus that performs multicolor development using a plurality of developing devices attached to a rotating body, there is provided a means for driving the rotating body, a means for detecting reversal of the driving means, and a means for detecting reversal of the driving means, and a means for detecting reversal of the driving means. An image forming apparatus comprising: means for cutting off a power supply circuit of a rotating body driving means in response to a reverse rotation signal; and a rotation control means for the rotating body. (2) The image forming apparatus according to claim 1, wherein the rotation control means outputs predetermined abnormality notification data to the main body control circuit when receiving the reverse rotation signal.