JPH01147570A - Image forming device - Google Patents

Abstract

PURPOSE:To make toner concentration accurate and to always keep it constant by detecting the toner concentration and writing it in a memory so that the toner concentration is controlled and performing the replenishment of toner instead of the formation of an image when the residual of the toner becomes equal to a specified value or under it. CONSTITUTION:A voltage in accordance with the toner concentration of the developer of reference concentration measured in an inductance sensor 34 is converted in an A/D converter 36 and written in a nonvolatile memory 37, so that an initial setting action is completed. When a copying process is performed, the toner concentration is gradually lowered. Now, a detection output from the sensor 34 is impressed on one terminal of a comparator 39 and the detected voltage of the sensor at the time of getting the reference toner concentration written in the memory 37 is impressed on the other terminal thereof, then the voltage in accordance with difference between both of them is outputted. Based on the output, a toner replenishment indication means 40 designates that the replenishment of the toner should be performed to a toner auxiliary means 35. When the residual of the toner becomes small, a toner residual sensor 33 detects it and a CPU 30 makes a display part 32 display it. Thus, the replenishment of the toner is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus such as an electronic copying machine, and more particularly to an image forming apparatus that can accurately control toner density.

(Background of the Invention W4) An electronic copying machine exposes a charged photoreceptor (hereinafter will be explained using a photoreceptor drum as an example) to form an electrostatic latent image according to document information, and this is made visible by toner. This is a device that converts the toner into an image, transfers the visible toner image onto transfer paper, and fixes it. In recent years, this type of electronic copying machine has been used in all fields of industry.

FIG. 5 is a configuration diagram showing an example of the configuration of this type of electronic copying machine. When the operator presses a copy button (not shown), the device shown begins the copying process. That is, the photosensitive drum 1 rotating in the direction of the arrow is moved to the cleaning section 2.
After the residual toner on the drum is removed by the blade, the surface of the drum is charged with an electric charge by the charging electrode 3.

Next, the charges on the photosensitive drum 1 are erased by the charge erasing section 4 . Then, the charged area of the photosensitive drum 1 is exposed to light reflected by the original f56, and an electrostatic latent image is formed on the drum surface. That is, a document 6 is irradiated with light from the exposure unit 5, which is movable in the direction of the arrow shown in the figure, and the reflected light containing document information reaches the photosensitive drum 1 via the mirrors M1 to M3 and the lens system L1. Then, the drum surface is exposed to light to form an electrostatic latent image on the drum surface. This electrostatic latent image is
In the developing section 7, toner is adsorbed and converted into a visible image. Thereafter, the toner visible image on the drum surface is transferred to transfer paper (copy paper) by a transfer section 8. After the transfer, the transfer paper is separated from the photosensitive drum 1 and sent to the fixing roller 10 by the conveyance mechanism 9. The transfer paper is then heated by the fixing roller 10, the toner is fused to the transfer paper, and the copying process is completed.

The exposure section 5 and the mirrors Ml, M2. The portion formed by M3 (the portion surrounded by a broken line) constitutes the optical unit 20, and is movable in the direction of the arrow in the figure by a moving mechanism (not shown). Here, the first mirror M
1 and the exposure section 5 are connected to each other in order to keep the optical path length constant.
Third mirror M2. It moves at twice the speed of M3. Here, the light source 21 in the exposure device @5 is composed of, for example, a bar-shaped fluorescent lamp or a halogen lamp perpendicular to the plane of the paper, so that the optical unit 2o is a light source 8'! 6 can be scanned over the entire surface.

Incidentally, the developing device used in this type of electronic copying machine uses a two-component developer consisting of toner and carrier. The durability of this two-component phenomenon agent deteriorates rapidly when the toner concentration falls below a certain value. For example, when the toner concentration is kept at 5% and when it is kept at 2%, the durability of the latter may be half that of the former. Therefore, it is necessary to control toner replenishment so that the toner concentration does not fall below a certain value. In addition, in order to maintain stable image quality,
It is necessary to maintain the toner concentration at approximately a predetermined value.

There is a toner group detection method using inductance as a method for detecting the toner concentration in a developing device using a two-component developer. This utilizes the fact that the carrier contained in the developer is a magnetic material, and detects the toner concentration by placing an inductance sensor with a coil in the developer. Specifically, when the toner concentration changes, Focusing on the fact that the mixing ratio of toner and carrier changes and the magnetic permeability changes, the magnetic permeability of the developer is measured to determine the toner concentration.

Then, the output voltage of the inductance sensor is compared with a reference voltage, and toner is replenished so that the output voltage of the inductance sensor becomes equal to the reference voltage, and as a result, the toner concentration is controlled to be constant.

(Problems to be Solved by the Invention) Incidentally, there are variations in the output of the above-mentioned inductance sensor, and it is necessary to adjust the output with a variable resistor or the like. That is, it was necessary to adjust the output voltage of the inductance sensor to a constant value when measuring toner of a reference density.

However, such adjustments are not very accurate. Therefore, if the output voltage of the inductance sensor is not accurate, the toner concentration will always be controlled to be a different concentration.

Further, when the developing device is replaced, the output voltage of the sensor described above must be adjusted for each replaced developing device, which is very troublesome.

By the way, as the copy process continues (and the toner supplied from the toner replenishment port is replenished into the developer and consumed, the amount of toner becomes less and less. At this time, the sensor detects the amount of toner. It is detected that the remaining amount is low and a display is made. Normally, in such a case, toner is supplied by the operator.

However, some operators may not supply toner even though the amount of toner remaining has decreased. If copying continues in such a case, the toner to be replenished into the developer runs out, and the toner concentration of the developer decreases.

When toner is supplied to the toner replenishment port after the remaining amount of toner runs out and the toner concentration has decreased to a certain extent, it takes a considerable amount of time for the toner concentration of the developer to reach the reference value. This is toner replenishment and exposure.

This is because it is performed during the copying process such as development, transfer, and fixing. For this reason, the only way to determine whether or not the toner density has reached the standard value is to actually make a copy and check the density of the transfer paper. Therefore, not only is it time consuming, but also copy paper is wasted.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to realize an image forming apparatus that can easily maintain toner density accurately and always constant.

(Means for Solving the Problems) The present invention, which solves the above-mentioned problems, forms an electrostatic latent image on a photoreceptor, visualizes it with a developer, and creates the visible image. In an image forming apparatus that forms an image by transferring and fixing the toner onto a transfer paper, there are a toner density sensor that detects the toner concentration of the developer, a toner remaining amount sensor that detects the amount of toner remaining in the developing device, and a toner sensor that detects the toner concentration of the developer. a non-volatile memory in which a density reference value is written; a toner density control means for controlling the toner density so that the toner 11 degrees detected by the toner density sensor is equal to the reference value; control means that instructs each part to stop image forming operation and perform only toner replenishment operation when the remaining amount of toner detected by the sensor becomes less than a certain value; is detected by a toner density sensor, this detected value is written in a non-volatile memory, and the toner density is controlled so that the toner density detected by the toner'arx sensor during image formation is equal to the reference value, The present invention is characterized in that when the remaining amount of toner falls below a certain value, only toner replenishment is performed.

(Function) First, a toner concentration that serves as a reference is detected by a toner concentration sensor, and this detected value is written into a nonvolatile memory.

During image formation, the toner density is controlled so that the toner density detected by the toner density sensor becomes equal to the reference value. Here, if the remaining amount of toner falls below a certain value,
Image formation is not performed, and only toner replenishment is performed.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the electrical configuration of one embodiment of the present invention.

In the figure, 30 is a CP that controls each part of the image forming apparatus.
U, 31 is an operation input unit for the operator to input various instructions; 32 is a display unit for confirming the inputs and for displaying messages from the CPU 30; 33 is provided in the developing device 7; A toner remaining amount sensor detects the remaining amount of toner; 34 is an inductance sensor that measures the magnetic permeability of the developer and outputs a voltage according to the toner concentration; 35 is provided in the developing device 7 and replenishes toner. The toner replenishing means 36 is an A/D converter that converts a voltage value corresponding to the toner concentration detected by the inductance sensor 34 into a digital value.
A D converter 37 is a non-volatile memory into which the toner density converted into a digital value by the A/D converter 36 is written in response to a write instruction from the CPLI 30 and read out in response to a read instruction; A D/A converter 39 converts the digital toner density data into an analog value, and a D/A converter 39 converts a voltage value corresponding to the toner density given from the inductance sensor 34 during image formation and a reference stored in the nonvolatile memory 37. A comparator 40 which compares the voltage value according to the toner concentration and outputs a voltage according to the difference between these two inputs, gives an instruction to replenish toner to the toner replenishing means 35 according to the output voltage of the comparator 39. This is a toner supply instruction means.

FIG. 2 is a sectional view showing the structure of the developing device @7 together with the photosensitive drum 1. In this figure, the same parts as in FIG. 1 are given the same numbers, and detailed explanations are omitted. 1 is a photosensitive drum; 7 is a developing device; 33 is a toner coincidence top sensor that detects residual toner from vibrations during toner replenishment; 34 is an inductance sensor that detects toner concentration in developer; 35
35a and 35b are rollers driven when replenishing toner, and 35c are rollers 35a and 3.
5b is driven by a belt; 35d is a carriage attached to the belt 35c and replenishes toner; 41 is a toner replenishment port; 42 is a carriage 35d serving as a toner replenishment means.
43 is a main stirring section for stirring the developer consisting of toner and carrier; 44 is a sub-stirring section for stirring the same; 45 is a roller for stirring the electrostatic latent image on the photosensitive drum; A developing sleeve 46 for carrying out development by adhering toner is a spike regulating plate that regulates the height of spikes of developer on the sleeve 45 .

First, the operation of the developing device u7 will be explained. The toner supplied from the toner supply port is transferred to the auxiliary row 542 by the carriage 35d of the toner supply means 35 when there is a toner supply instruction. At this time, due to vibrations generated when the carriage 35d carries toner, the toner remaining amount sensor 3
3 detects the remaining amount of toner. The rotation of the auxiliary O-ra 42 causes the toner to fall downward. Then, the developer (toner and carrier) already in the developing device and the toner are stirred by the main stirring section 43 and the sub-stirring section 44 . Here, the inductance sensor 34 measures the magnetic permeability of this developer to detect the toner concentration. Ears of developer are formed on the developing sleeve. The height of the spikes of the developer is regulated by the spike regulating plate 46, and the latent image on the photosensitive drum 1 is developed by the developer that has passed through this plate to become a toner image.

Incidentally, this developing device 7 can be easily attached to and detached from the main body of the copying machine. Then, the detection output of each sensor is supplied to the CPU 30 via a connector that becomes connected when the developing device is attached to the copying machine main body.

Therefore, by replacing the developing device with a developing device containing toner of a different color, it is possible to easily handle color copying.

Also, between any two terminals of the connector on the developing device side,
By connecting or opening the toner depending on the color of the toner, it is possible to distinguish which color developing device is installed from the copying machine main body side.

The operation of this embodiment will be described below with reference to FIGS. 1 and 2.

First, at the initial stage or after replacing the replaceable developing device, the following initial setting operation is performed.

When an initial setting instruction is received from the operation input section 31, the CPU 3
0 instructs the main stirring section 43 and the sub-stirring section 44 of the developing device 7 to stir the developer for a certain period of time (for example, 90 seconds until the toner and carrier of the developer are well mixed). At the initial stage, a developer having a standard concentration (for example, a toner concentration of 4%) is injected into the developing device. After the stirring is completed, the voltage corresponding to the toner concentration of the developer having the reference concentration measured by the inductance sensor 34 is converted into a digital value by the A/D converter 36, and written into the nonvolatile memory 37 according to instructions from the CPU 30. . When the reading into the nonvolatile memory 37 is completed, the initial setting operation ends.

Furthermore, as shown in Fig. 3, even if the sensor is of the same type,
The characteristics are different like A, B, and C, and the output voltages (V, V, V) for the same m degrees are different. Therefore, the values written in the nonvolatile memory 37 differ slightly depending on the sensor used.

FIG. 4 is a configuration diagram showing an example of a configuration for determining the type of a detachable developing device. A connector 50 is provided on the developing device 7 side, and a connector 51 is provided on the copying machine main body side. When the developing device 7 is attached to the copying machine main body by 5A, terminals 50a, 50b, 50c of the connector 50 are provided.
, 50d and the terminals 51a, 51b, 51c of the connector 51
, 51d are connected to each other.

In such a connector, for example, in the case of a developing device containing black toner, terminals 50c and 50d are short-circuited, and in the case of a developing device containing toner other than black, terminals 50c and 50d are short-circuited.
Leave c and 50d open.

The type of developing device can be determined by connecting the terminals 51c and 51d to the CPU 30 and monitoring the terminals.

Next, toner density control operation during image formation (copying) will be explained.

When a copying instruction is given to the operation input unit 31, the CPU 3
0 gives copy instructions to each part. As a result, a latent image is formed by charging the photosensitive drum and exposing it to light.

Development that attracts toner to this latent image, transfer to transfer paper,
A process such as fixing (copy process) is performed. At this time, the toner in the developer has been consumed, and the toner concentration is gradually decreasing. Therefore, it becomes necessary to replenish the developer with toner.

Here, the detection output of the inductance sensor 34 is applied to one input terminal of the comparator 39.

Furthermore, the voltage detected by the sensor when the reference toner m11 stored in the nonvolatile memory 37 is used is applied to the other input terminal of the comparator 39. The comparator 39 compares the voltages applied to both input terminals and outputs a voltage according to the difference between the two. Based on the output of the comparator 39, the toner replenishment instructing means 40 gives an instruction to the toner replenishing means 35 in the developing device 7 as to whether or not toner replenishment is to be performed. The toner replenishing means 35 replenishes toner to the developer based on the above instructions. As a result, the toner concentration in the developer increases by 711 degrees, and toner replenishment is performed until the toner concentration matches the reference value.

As shown in FIG. 3, since there is a nearly linear relationship between the toner il 1 degree and the output voltage of the inductance sensor 34, the toner replenishment instruction based on the result of comparison with the reference toner 113 degrees is also made to change linearly. This allows the speed at which the toner replenishing means replenishes toner to be variable.

As described above, the toner density of the reference developer is written into the nonvolatile memory during initial settings, and toner replenishment is performed by comparing the toner density during image formation with the reference toner density read from the memory. So, toner 1
It is possible to realize an image forming apparatus that can maintain 1a accurately and always constant.

By the way, as the copying process continues, the toner supplied from the toner supply port is replenished into the developer by the toner supply means 35 and is consumed, so the remaining amount of toner supplied from the toner supply port decreases. It's getting less. At this time, the toner matching sensor 33 detects that the remaining amount of toner is low, and the CPU 30 detects this 1-toner remaining R.
This is displayed on the display unit 32 based on the detection result of the sensor 33.

However, some operators may not supply toner even though the remaining amount of toner is low. If copying continues in such a case, the toner to be replenished into the developer by the toner replenishing means 35 runs out, and the toner concentration of the developer decreases.

Therefore, in the present invention, only the toner replenishment operation is performed separately from the copy process. That is, when a toner replenishment operation is instructed from the operation input unit 31 after toner is supplied from the toner replenishment port, the CPU 30 performs exposure, development,
It instructs the toner replenishing means 35 to only replenish toner to the developer without performing copying processes such as transfer and fixing.

Then, by toner replenishment, the inductance sensor 34
When the toner concentration of the developer detected at reaches the reference value, toner replenishment is stopped, and at the same time, the CPU cancels the toner replenishment only operation and returns to a state in which copying is possible. By doing so, the toner replenishing means 35 can continuously replenish toner without waiting for other operations.

Therefore, toner replenishment can be performed in a short time, and copy paper is not wasted.

Also, when the above-mentioned toner replenishment is being performed, the toner concentration detected by the inductance sensor or the reference toner concentration written in the non-volatile memory is displayed on the display unit 32 via the CPLI 30 according to an instruction from the operation input unit. do.

This makes it possible to confirm that toner replenishment is being performed.

Note that the toner replenishment operation may be automatically stopped by an instruction from the CPU 30 when the toner concentration reaches a reference value, but the operator may check the toner concentration display on the display unit 32 and manually stop the toner replenishment operation. If the configuration is such that it stops, there is no need to worry about the toner concentration rising too much due to some kind of failure.

(Effects of the Invention) As described in detail above, according to the present invention, by performing only toner replenishment in addition to toner replenishment during image formation, the toner concentration of the developer can be accurately and constantly maintained. It is possible to realize an image forming apparatus that can easily maintain a constant value.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a sectional view showing the configuration of a developing device, FIG. 3 is a characteristic diagram of an inductance sensor, and FIG. 4 is a configuration diagram of a connector. FIG. 5 is a block diagram of a conventional electronic copying machine. 1... Photosensitive drum 7... Developing device 30...
- CPU 31... Operation input section 32... Display section 33... Toner coincidence hanging sensor 34... Inductance sensor 35... Toner supply means 36... A/D converter 3
7... Nonvolatile memory 38... D/A converter 39
... Comparator 40 ... Toner replenishment instruction means 41 ... Toner replenishment port 42 ... Auxiliary roller 43
...Main stirring section 44...Sub-stirring section 45...
Developing sleeve 46...Standing regulation plate 50.51.
...Connectors 50a to 50d, 51a to 51d...Terminal patent applicant Konica Co., Ltd. Ceremony
Patent Attorney Fuji Ijima
Extraterritorial 1 name angle q3 Figure 4

Claims (1)

[Claims] In an image forming apparatus that forms an electrostatic latent image on a photoreceptor, visualizes it with a developer, and transfers and fixes the visualized image onto transfer paper, a developing process is performed. a toner concentration sensor that detects the toner concentration of the agent; a toner remaining amount sensor that detects the remaining amount of toner in the developing device; a nonvolatile memory in which a reference value of toner concentration is written; and a toner concentration sensor that detects the toner concentration. a toner concentration control means for controlling the toner concentration so that the toner concentration is equal to the reference value; and a toner concentration control means for stopping the image forming operation and replenishing toner when the remaining amount of toner detected by the toner remaining amount sensor falls below a certain value. First, the toner concentration of the developer serving as a reference is detected by a toner concentration sensor, and this detected value is written into a non-volatile memory, and the The toner concentration is controlled so that the toner concentration detected by the toner concentration sensor is equal to the reference value, and when the remaining amount of toner falls below a certain value, only toner replenishment is performed. Image forming device.