JPH0535100A - Image forming device - Google Patents

Abstract

PURPOSE:To form an image even if a toner concentration sensor is out of order by providing a fixed quantity replenishment device replenishing toner with a fixed quantity to a developing unit at every developing actions, when the toner concentration sensor is out of order. CONSTITUTION:When the toner concentration sensor 30 has a fault and a specific mode is set by a mode setting switch 36 such as a display switch, a microcomputer 12 changes over the control of a toner concentration from the control by the toner concentration sensor 30 to the control for replenishing the toner with the fixed quantity to the developing unit. In other words, time data for rotating a toner supplying motor 34 is set in the arbitrary area of a RAM 18. Then, the toner is replenished with the fixed quantity to the developing unit whenever one developing action of copying, printing, etc., is executed. Thus, even if the toner concentration sensor has the fault, the toner can be replenished, and even during a period until the repair of the toner concentration sensor 30 is completed, a user can use an image forming device.

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,
In particular, the present invention relates to an image forming apparatus for developing a latent image with a toner in a developing device.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine and a printer is provided with a toner density control mechanism for detecting a toner density by a toner density sensor and supplying toner according to the detected density.

[0003]

If the toner concentration sensor fails for some reason and needs to be repaired, the image forming apparatus cannot be used because toner is not replenished until the repair is completed. There was a problem.
Therefore, a main object of the present invention is to provide an image forming apparatus capable of forming an image even when the toner density sensor fails.

[0004]

SUMMARY OF THE INVENTION According to the present invention, an image forming apparatus having a toner density sensor and supplying toner to a developing device in response to the output thereof sets a specific mode when the toner density sensor fails. An image forming apparatus comprising: a mode setting unit; and a fixed amount replenishing unit that replenishes a developing device with a fixed amount of toner for each developing operation when a specific mode is set by the mode setting unit.

[0005]

In an image forming apparatus such as a copying machine or a printer,
When the toner concentration sensor fails, for example, when a specific mode is set by a mode setting means including a DIP switch or a keyboard, the microcomputer quantitatively replenishes the toner concentration control from the toner concentration sensor to the developing device. Switch to control. Then, the toner is replenished to the developing device in a fixed amount for each developing operation such as one copying or printing. This allows the toner to be replenished even when the toner concentration sensor fails.

[0006]

According to the present invention, the toner can be replenished to the developing device in a fixed amount even when the toner concentration sensor fails, so that the user can use the image forming apparatus even while the toner concentration sensor is completely repaired. can do. The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a control unit 10 of a copying machine according to an embodiment of the present invention includes an MPU (Micro Proccessor Unit) 12 which is composed of a microcomputer and performs various controls. ROM 16 and R are provided to the MPU 12 via the bus 14.
The AM 18 and the I / O interface 20 are connected. The ROM 16 stores programs for various controls performed by the MPU 12. RAM18 has MP
Data necessary for control by U12 is temporarily stored. Further, the RAM 18 has a flag area for storing various flags necessary for control. The RAM 18 is backed up by a backup battery 22 such as a lithium battery. Therefore, when the voltage V _CC generated from the main power supply is no longer supplied, the voltage of the backup battery 22 is given to the RAM 18. Therefore, the data in the RAM 18 is retained even when the main power of the copying machine is turned off.

Data from the key matrix 24 and outputs from the sensor circuit 26 including a jam sensor are input to the input ports of the I / O interface 20. Output data from the toner density detection sensor 30 is input to the input port of the I / O interface 20 via the analog / digital converter 28.
Then, at the output port of the I / O interface 20,
A plurality of drive devices 32 such as motors and solenoids and a toner supply motor 34 are connected.

Further, a mode setting switch 36 such as a dip switch is connected to the MPU 12, and the MPU 12 switches the toner density control by switching the mode setting signal by turning on / off the mode setting switch 36. However, the mode setting signal may be given to the MPU 12 through the key matrix 24 by the ten keys or other function keys (not shown). Further, whether or not the specific mode is set may be determined according to the setting of a predetermined flag in the RAM 18 by a mode setting signal.

FIG. 2 is a flow chart showing the main routine of the control procedure of the MPU 12. After the main routine is started, it is determined in step S1 whether or not the copy operation start key (not shown) is pressed by the key signal from the key matrix 24. If the copy operation start key is not pressed, it waits until it is pressed. When the pressing of the copy operation start key is detected in step S1, the process proceeds to step S3, and the subroutine is called.

Step S11 of the subroutine shown in FIG.
At, it is determined whether the mode setting switch 36 is turned on. If the mode setting switch 36 is not turned on in step S11, step S1
Proceeding to step 3, the toner density control based on the sensor output is executed, and the process returns. On the other hand, if the mode setting switch 36 is turned on in step S11, the process proceeds to step S15, the quantitative supply mode is started, the interrupt routine A is permitted, and the process returns.

In step S21 of the interrupt routine A shown in FIG. 4, time data for rotating the toner supply motor is set in a timer provided in an arbitrary area of the RAM 18. Then, in step S23, the toner supply motor is operated. Then step S25
Then, the routine proceeds to step S11 to inhibit the interrupt routine A, permit the interrupt routine B, and end.

Then, in step S31 of the interrupt routine B shown in FIG. 5, the timer set in the RAM 18 is counted. Then, step S3
In step 3, it is determined whether the timer count has ended. If the timer has not finished counting, it ends as it is, and if the timer has finished counting, the process advances to step S35 to end the operation of the toner supply motor. Then, in step S37, the interrupt routine B
After banning, end.

The interrupt routines A and B
Is a timer interrupt that interrupts the main routine at a predetermined cycle by an internal timer of the MPU 12 and performs a predetermined process. By the operation of the MPU 12 as described above,
In a normal case, the toner concentration control is performed by the toner concentration sensor, and when the toner concentration sensor fails, the toner can be quantitatively replenished to the developing device by switching to the constant replenishment mode.

Then, returning to the main routine of FIG.
When the copying operation is executed in step S5 and it is detected in step S7 that the copy is continuous (the number of copies is set to 2 or more), the operations in step S3 and thereafter are repeated. Therefore, when the quantitative replenishment mode is set, the toner is quantitatively replenished for each copy (each image forming operation).

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a main routine of an operation of MPU.

FIG. 3 is a flowchart showing a subroutine shown in FIG.

FIG. 4 is a flowchart showing an interrupt routine A.

5 is a flowchart showing an interrupt routine B. FIG.

[Explanation of symbols]

 10 ... Control unit 12 ... MPU 16 ... ROM 18 ... RAM 20 ... I / O interface 24 ... Key matrix 30 ... Toner density detection sensor 34 ... Toner supply motor 36 ... Mode setting switch

Claims (1)

Claim: What is claimed is: 1. An image forming apparatus comprising a toner density sensor, wherein toner is supplied to a developing device in response to an output of the toner density sensor. A mode for setting a specific mode when the toner density sensor fails. An image forming apparatus comprising: a setting unit; and a fixed amount replenishing unit that replenishes the developing device in a fixed amount for each developing operation when the specific mode is set by the mode setting unit.