JPH01147571A - Image forming device - Google Patents

Abstract

PURPOSE:To make toner concentration accurate and constant by providing a toner concentration control means and performing the control of the toner concentration based on either a value previously written in a nonvolatile memory or a value written by a writing means. 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 the nonvolatile memory 37, then an initial setting action is completed. During a copying process, the toner concentration is gradually lowered. Now, a detection output from the sensor 34 is impressed on one terminal of a comparator 39 and a voltage value written in the memory 37 is impressed on the other terminal thereof, then a comparator 39 outputs the voltage in accordance with difference between both of them. Based on the output, a toner replenishment indication means 40 instructs the replenishment of the toner to a toner replenishing means 35. In case of performing the rewriting of the memory at the time of initially setting, the replenishment of the toner is performed based on a rewritten value.

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) An electronic copying machine exposes a charged photoreceptor (hereinafter will be explained using a photoreceptor drum as an example) to light according to document information to form an electrostatic charge, which is visualized with toner. ,
This is a device that transfers and fixes this toner visible image onto transfer paper. This type of electronic copying machine is 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 illustrated device initiates a copy provision. That is, the photosensitive drum 1, which is rotating in the direction of the arrow, is removed from the band 7! after the residual toner on the drum is removed by a blade in the cleaning section 2. The i-pole 3 charges the surface U
It will be done.

Next, the charges on the photosensitive drum 1 are erased by the charge erasing section 4 . The charged area of the photosensitive drum 1 is exposed to light reflected by the original 6, and an electrostatic latent image is formed on the drum surface. That is, the original 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 the original information reaches the photosensitive drum 1 via the mirrors M1 to M3 and the lens system L1. , the drum surface is exposed to light to form an electrostatic latent image on the drum surface. This electrostatic latent image is converted into a visible image by adsorption of toner in the developing section 7. Thereafter, the toner visible image on the drum surface is transferred to the transfer paper (
transferred onto copy paper). After the transfer, the transfer paper is separated from the photosensitive drum 1 and transferred to the fixing roller 10 by the conveyance mechanism 9.
sent to. 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 mirror M1. M2. The part formed by M3 (the part surrounded by the broken line) constitutes the optical unit 20, and can be moved in the direction of the arrow in the figure by a mobile device @ (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, since the light source 21 in the exposure device 5 is constituted by, for example, a bar-shaped fluorescent lamp or a halogen lamp perpendicular to the plane of the paper, the optical unit 20 can scan the entire surface of the original 6.

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 developer 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.

2. Description of the Related Art To detect the toner concentration in a developing device using a two-component developer, there is a toner density detection method using inductance. 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) By the way, the output of the above-mentioned inductance sensor varies, and it is necessary to adjust the output using 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.

Furthermore, when the developing device is replaced, the output voltage of the sensor described above must be adjusted every time the developing device is replaced, which is extremely troublesome.

Another possible method is to perform image formation after storing the toner concentration of a developer having a reference toner concentration in a memory. However, if you forget to memorize it, accurate toner density control will not be performed.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide an image forming apparatus that can accurately keep toner density constant at all times. It is about realization.

(Means for Solving the Problems) - The present invention to solve the above problems forms an electrostatic inverse image on a photoreceptor, visualizes it with a developer, and converts the image into a visible image. In an image forming apparatus that forms an image by transferring and fixing an image onto a transfer paper, toner a of a developer is used.
r! A toner concentration sensor that detects I, a nonvolatile memory in which the reference value of toner concentration is written in advance and whose memory contents can be rewritten, and a nonvolatile memory that stores the toner concentration detected by the toner r14m sensor at the initial stage. the toner density control means for controlling the toner concentration so that the toner density detected by the toner density sensor during image formation is equal to the value stored in the nonvolatile memory; The toner concentration is controlled based on either a value written in advance in a nonvolatile memory or a value written by a writing means.

(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 supply port is controlled so that the toner concentration detected by the toner density sensor becomes equal to the reference value.

(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.
U131 is an operation input section for the operator to input various instructions, 32 is a display section for confirming the above-mentioned inputs and displaying messages from the CPU 30, and 33 is provided in the developing device 7 to display the 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 a toner replenishment sensor that is provided in the developing device 7 and replenishes toner. The 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 voltage corresponding to the detection voltage of the sensor when the reference toner is 1112 is written in advance in the D converter 37.
The toner concentration converted into a digital value by the converter 36 is C.
A non-volatile memory is written in by a write instruction from the PU 30 and read out by a read instruction from the PU 30; 38 is a D/A converter that converts the digital toner density data read from the non-volatile memory 37 into an analog value; 39 is a D/A converter; A voltage value corresponding to the toner concentration given from the inductance sensor 34 during image formation is compared with a voltage value corresponding to the reference toner concentration stored in the nonvolatile memory 37, and a voltage value corresponding to the difference between these two inputs is determined. a comparator that outputs 4
0 is the toner replenishing means 35 according to the output voltage of the comparator 39.
This is a toner replenishment instruction means for giving an instruction to replenish toner.

FIG. 2 is a sectional view showing the structure of the developing device 7 together with the photosensitive drum 1. As shown in FIG. 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 sensor that detects the remaining amount of toner from vibrations during toner replenishment; 34 is an inductance sensor that detects the toner concentration in the developer;
5 is a toner replenishing means; 35a and 35b are rollers that are driven when replenishing toner; 35C is a roller 35a;
The belt 35b is driven by the belt 35, and the belt 75d is driven by the belt 35.
Carriage 41 attached to C and replenishing toner;
42 is the toner supply port, and 42 is the carriage 3 of the toner supply means.
an auxiliary roller 4 that sends out the toner replenished by 5d;
3 is a main stirring section for stirring the developer consisting of toner and carrier; 44 is a sub-stirring section for stirring the same; 4
5 is a developing sleeve for applying toner to the electrostatic latent image on the photosensitive drum for development; 46 is a spike regulating plate for regulating the height of developer spikes on the sleeve 45;

First, the operation of the developing device 7 will be explained. The toner supplied from the toner supply port is transferred to the auxiliary roller 42 by the carriage 35d of the toner supply means 35 when there is a toner supply instruction. At this point, due to the vibration that occurs when the carriage 35d transports the toner, the toner matching M sensor 3
3 detects the remaining amount of toner. As the auxiliary roller 42 rotates, the toner is dropped 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 control plate 46, and the electrostatic latent image on the photosensitive drum 1 is developed by the developer that has passed through the spike, and becomes a toner image.

Note that 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 current device with a device containing toner of a different color, it is possible to easily support color copying.

Also, between any two terminals of the connector on the developing device side,
By connecting or opening the connection or opening according to the color of the toner, it is possible to distinguish which color of the current a device is attached from the copy supply 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 11'l E2 constant 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 standard developer 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 the instruction from the CPtJ 30. It will be done. Although an average value corresponding to the reference toner density is written in advance in the nonvolatile memory 37, this initial setting operation updates it to an accurate value. When writing to the nonvolatile memory 37 is completed, the initial setting operation ends.

Furthermore, as shown in Fig. 3, even if the sensors are of the same type, A
, B, and C, and the output voltages (VA, VB, VC) for the same concentration are different. Therefore, the values written in the dirt floor 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, the terminals 50a, 50b, 50c of the connector 50,
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, terminal 50c and 50d are short-circuited.
Leave c and 50d open.

Then, by connecting the terminals 51G and 51d to the CPU 30 and monitoring the connection between both terminals, it is possible to determine the type of developing VA device.

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 CPLI
30 gives instructions for copying to each part. As a result, 18fJ is formed by charging and exposing the photosensitive drum.

Development that attracts toner to this latent image, transfer to transfer paper,
Processing such as fixing (copy process) is then 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 toner into the developer.

Here, the detection output of the inductance sensor 3/l is applied to one input terminal of the comparator 39.

Furthermore, a voltage value written in advance in the nonvolatile memory 37 or a voltage value written at the time of initial setting 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. Based on the above instructions, the toner replenishing means 35
Toner is being replenished to the developer. As a result, the degree of toner 'fA in the developer increases, and toner replenishment is performed until the toner concentration matches the reference value.

Note that since data is written in the non-volatile memory 37 in advance, even if image formation is performed without performing the above-mentioned initial setting operation, toner replenishment is performed based on the values written in the non-volatile memory in advance. I can do it.

Furthermore, if the nonvolatile memory is rewritten during initialization, toner is replenished based on the rewritten value.

As shown in FIG. 3, since the toner Sa and the output voltage of the inductance sensor 34 have an almost linear relationship, the toner replenishment instruction based on the result of comparison with the toner concentration is also made to change linearly. Thereby, the speed at which the toner replenishing means replenishes toner can be made variable.

As described above, data is written in the non-volatile memory in advance, and the non-volatile memory is rewritten with the toner density data of the reference developer during initial settings, and the toner density at the time of image formation and the reference read from the memory are used. Since toner replenishment is performed by comparing the toner density with the toner density, the toner density can be accurately and always kept constant regardless of whether initial settings are performed or not.

(Effects of the Invention) As described above in detail, according to the present invention, reference toner density data is stored in the nonvolatile memory in advance,
Toner replenishment is performed by rewriting the non-volatile memory with the toner concentration data of the standard developer actually detected by the sensor during initial settings and comparing the toner concentration during image formation with the standard toner concentration read from the memory. By performing this, it is possible to realize an image forming apparatus that can accurately and always keep the toner density constant.

[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...
CPLJ 31...Operation input section 32...Display section 33...Toner coincidence sensor 34...Inductance sensor 35...Toner supply means 36...A/D converter 37...Nonvolatile memory 3
8...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. Chief Brewer
Patent Attorney Fuji Ijima
Figure 4 Figure 1 Bottle length 1

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 non-volatile memory in which the reference value of toner concentration is written in advance and whose memory contents can be rewritten, and a non-volatile memory that detects the toner concentration detected by the toner concentration sensor at the initial stage. and a toner concentration control means for controlling the toner concentration so that the toner concentration detected by the toner concentration sensor during image formation is equal to the value stored in the nonvolatile memory. An image forming apparatus, wherein the toner density is controlled based on either a value written in advance in a nonvolatile memory or a value written by a writing means.