JPH0226230B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a warning device that warns of an abnormality in a sensor that detects the concentration of developer in a developing device of a copying machine having an automatic copy density control device.

<Prior art and its drawbacks> The automatic toner density control device includes a sensor that detects the toner density in the developing device, and replenishes toner into the developing device when the density detected by this sensor becomes lower than a reference value. It consists of a toner supply device.

However, in this device, if an abnormality occurs in the sensor, density control section, etc. and the device no longer operates normally, toner will not be replenished even if the toner density in the developing device decreases (undertoner). If you continue copying in this state, not only will undertoner become more likely to deteriorate, but also, in a copying machine that uses a two-component developer, the carrier will flow out into the photoreceptor and inside the copying machine, which is the so-called "carrier build-up". This not only caused the developer to lose all its functionality, but also had an adverse effect on the copying machine itself, making it unusable.

<Purpose of the Invention> In view of the above-mentioned current situation, an object of the present invention is to provide a developer concentration control abnormality warning device that issues a warning when an abnormality occurs in a sensor, concentration control unit, etc. of a developer concentration automatic control device. shall be.

<Structure and Effects of the Invention> The present invention includes a density detection means for detecting the image density of an entire document, and an integrated value for integrating and storing a value corresponding to the original density determined by the density detection means for each copy. a storage unit; means for resetting the integrated value in the integrated value storage unit each time the developer is replenished; The invention is characterized in that it has a warning means that performs a warning operation when the maximum integrated density value that can be copied is exceeded before the density drops below a reference density.

With the above-described configuration, the present invention is capable of copying beyond the maximum density integrated value (M _MAX ) that can be made from the state in which the developing device is filled with developer until the developer concentration drops below the reference density. If the sensor does not detect this, the sensor or density control unit can determine that there is an abnormality and issue a warning. In addition to being able to prevent adverse effects on the machine, it is also possible to obtain the effect of warning users and the like of abnormalities in the automatic developer concentration control device.

<Embodiment> FIG. 2 is a structural diagram of a main part of a copying machine equipped with a warning device for abnormality in developer concentration control, which is an embodiment of the present invention. A charger, an exposure lens, a developing device 1, a transfer device, etc. are arranged around the photosensitive drum 13, and a toner concentration detection sensor 3 and a toner replenishing device 2 are attached to the developing device 1. An exposure lamp 12 that illuminates the original is mounted below the original table, and the light intensity of this exposure lamp 12 is determined by a light amount detector 9 installed near the optical path of the reflected light of the original and an exposure lamp control device that detects the density of the original. 8.

FIG. 1 is a block diagram of the control system of the copying machine. A memory 5 backed up by a battery 6, a toner concentration detection sensor 3, a toner supply device 2, a warning display device 7, and an exposure lamp control device 8 are connected to the microcomputer 4, and the light amount detector 9 is connected to an exposure lamp control circuit 8 and It is connected to an integrating circuit 10 that integrates the detected concentration value. The integrating circuit 10 integrates the density detection value corresponding to the image density of the original from the light amount detector 9 and detects the image density of the entire original. supply to. In other words, the light amount detector 9
receives the reflected light from the original when the original is optically scanned, and supplies a density detection signal corresponding to the reflected light to the integrating circuit 10, which performs optical scanning of the original. The density of the entire document will be detected. Judgment circuit 11 is an operational amplifier
An on/off circuit consisting of AMP, variable resistor R1, and resistor R2, in which the integral value input to the non-inverting input terminal of operational amplifier AMP is connected to the inverting input terminal. When it exceeds a certain value determined by , it outputs "1", and when it does not, it outputs "0". The output of this determination circuit 11 is supplied to the microcomputer 4.
The microcomputer 4 generates a value corresponding to the output state of the determination circuit 11, that is, a value corresponding to the image density of the original, and integrates the value in a density integration storage area, which will be described later, for each copy of the original. The toner concentration detection sensor 3 outputs "H" if the toner concentration in the developing device is equal to or higher than the reference value, and outputs "L" if it becomes lower than the reference value. The constant value may be set to the overall image density of a standard document, that is, the integrated density value. The memory 5 includes a density integrated value storage area (area M1) that stores values corresponding to the above density integrated values.
is set. In this embodiment, as will be described later, the determination circuit 1
When the output value D of 1 is "1", the microcomputer 4 generates "2", and when it is "0", the microcomputer 4 generates "1". It goes without saying that the value corresponding to this integrated density value may be the integrated density value itself.

FIG. 3 is a flowchart showing the operation of the microcomputer. Here, it is assumed that the density integrated value stored in the density integrated value storage area of the copied original is M, and the maximum density integrated value is _MMAX . This M is stored in area M1 of the memory 5. This is to integrate the copy density integral value since the last toner replenishment regardless of whether the copying machine is powered on or off.

In step n1 (hereinafter, step ni is simply referred to as ni), it is determined whether M is greater than M _MAX , and if it is less than M _MAX , proceed to n2, and if it is greater than M _MAX , it is determined that there is an abnormality. immediately proceed to n14. n2 performs warm-up (JOB1) such as preheating the fuser, and n3 performs standby operation such as display operation (JOB2)
and standby until the print key is pressed. At this time, the replenishment operation of the toner replenishing device 2 is turned off. When the print key is pressed on n4,
Proceed to n5. n5 to n9 are operations in the copying process. n5
Then, a copying operation (JOB3) such as rotation of the photosensitive drum and power supply to the charger is performed, and the level of the toner concentration detection sensor 3 is checked at n6. If the level checked in n6 is "H", it is determined that the toner concentration in the developing device is above the reference value and the process proceeds to n7; if it is "L", it is determined that the toner concentration in the developing device is lower than the reference value. and proceed to n8. At n7, the toner supply device 2 is turned off to stop toner supply to the developing device, while at n8, the toner supply device 2 is turned on to supply toner to the developing device, and the M
Let be 0. After n7 or n8, the operations from n5 onwards are repeated until it is determined at n9 that the copying is complete.

When the end of copying is determined at n9, the process proceeds to n10 and subsequent steps. At n10, the output value P of the determination circuit 11 is judged, and if it is "1", it means that the original is a copy with high density, so the value "2" corresponding to the integrated density value is added to M.
If it is "0", it is a copy of a low-density original, so a value "1" corresponding to the density integral value is added to M.
In n13, M and M _MAX are compared, and if M is larger than M _MAX , the toner concentration detection sensor 3 is abnormal and copying is performed beyond the integrated density value of M _MAX without toner replenishment. If M is less than M _MAX , it is determined to be normal and returns to n3 standby. n14 corresponds to the warning means of this invention. At n14, the warning display device installed on the outside of the copying machine is turned on and the operation of the copying machine is stopped. After inspection at n15, the maintenance staff resets the microcomputer 4 and releases the state at n14, clearing M to 0 (n16) and returning to n1.

If the developer concentration abnormality warning device with the above configuration is used in a copying machine, even if the toner concentration in the developing device drops below the reference value due to an abnormality in the toner concentration detection sensor or concentration control section, the toner It is possible to prevent the deterioration of the copied image and the carrier build-up that would occur when the developer is not replenished, and to prevent the accompanying negative effects on the copying machine, and to warn the user of an abnormality in the automatic developer concentration control device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a control system of a copying machine that is an embodiment of the present invention and is equipped with a warning device for abnormality in developer concentration control; FIG. 2 is a structural diagram of the main parts of the copying machine;
The figure is a flowchart showing the operation of the microcomputer of the copying machine. 1...Developing device, 2...Toner (developer) supply device, 3...Toner (developer) concentration detection sensor, 4...
Microcomputer, 5...Memory, 9...Light amount detector, 10...Integrator circuit, 11...Judgment circuit.

Claims (1)

[Scope of Claims] 1. An original density detection sensor that detects the density of an original, a density control unit that controls copying density based on the detected value of the original density sensor, and a density control unit that detects the density of developer in a developing device. In a copying machine having a developer concentration sensor and a developer replenishment device that replenishes developer to the development device when the concentration detected by the developer concentration sensor is lower than a reference value, a density detection means for detecting density; an integrated value storage unit that integrates and stores a value corresponding to the document density determined by the density detection unit for each copy; and an integrated value storage unit that integrates and stores a value corresponding to the original density determined by the density detection unit for each copy; means for resetting the value; and a means for resetting the integrated value in the integrated value storage section, which exceeds the maximum density integrated value that can be copied from a state in which the developing device is filled with developer until the developer concentration falls below the reference density. A warning device for an abnormality in developer concentration control, comprising: a warning means for performing a warning operation when a warning operation is performed;