JPH0812498B2 - Image forming device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electronic copying machine. More specifically, in the case of having a detachable developing device, the toner concentration of the developer can be accurately measured. The present invention relates to an image forming apparatus that can be controlled.

(Background of the Invention) An electronic copying machine forms an electrostatic latent image by exposing a charged photoconductor (which will be described below by taking a photosensitive drum as an example) according to document information, and a visible image is formed by toner. It is a device for converting the visible toner image into a transfer paper and fixing 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 initiates the copy process. That is, in the photosensitive drum 1 rotating in the direction of the arrow, after the residual toner on the drum is removed by the blade at the cleaning unit 2, the surface of the photosensitive drum 1 is charged by the band electrode 3.

Next, the charge erasing unit 4 erases the electric charge of the unnecessary portion on the photosensitive drum 1. Then, the charged area of the photosensitive drum 1 is exposed by the reflected light from 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 movable in the direction of the arrow shown in the figure, and the reflected light including the original information is passed through the mirrors M1 to M3 and the lens member L1.
After reaching the photosensitive dome 1, the drum surface is exposed to form an electrostatic latent image on the drum surface. This electrostatic latent image is developed by the developing unit 7.
Then, the toner is adsorbed and converted into a visible image. After that, the visible toner image on the drum surface is transferred to a transfer paper (copy paper) by the transfer unit 8. The transfer paper after the transfer is separated from the photosensitive drum 1 and sent to the fixing roller 10 by the carrying mechanism 9. Then, the transfer paper is heated by the fixing roller 10,
The toner fuses to the transfer paper and the copy process ends.

A portion (a portion surrounded by a broken line) formed by the exposure unit 5 and the mirrors M1, M2, M3 constitutes an optical unit 20, and can be moved in a direction of an arrow by a moving mechanism (not shown). It is like this. Here, the first mirror M1 and the exposure unit 5 move at twice the speed of the second and third mirrors M2 and M3 in order to always keep the optical path length constant.
Here, since the light source 21 in the exposure device 5 is composed of, for example, a rod-shaped fluorescent lamp or a halogen lamp which is perpendicular to the paper surface, the optical unit 20 can scan the entire surface of the document 6.

By the way, a two-component developer including a toner and a carrier is used in a developing device used in this type of electronic copying machine. The durability of the two-component developer sharply deteriorates when the toner concentration falls below a certain value. For example, when the toner concentration is kept at 5% and 2%, the durability of the latter may be half that of the former. Therefore, it becomes necessary to control the toner replenishment so that the toner density does not fall below a certain value. Further, in order to keep the image quality stable, it is necessary to keep the toner density at a substantially predetermined value.

As a method for detecting the toner concentration in the developing device using the two-component developer, there is a toner amount detecting method using an inductance. This utilizes the fact that the carrier contained in the developer is a magnetic substance and arranges an inductance sensor having a coil in the developer to detect the toner concentration. Specifically, when the toner concentration fluctuates, 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 obtain the toner concentration.

Then, the output voltage of the inductance sensor is compared with the reference voltage, 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 voltage of the inductance sensor varies even when a toner having a reference density is measured, and in order to keep the toner density constant by the toner density control method, It is necessary to adjust each inductance sensor so that the output voltage of each inductance sensor has a constant value when the density toner is measured.

However, when a plurality of developing devices containing toners of different colors are exchanged for use, the inductance sensor must be adjusted every time the developing devices are exchanged, and this work is complicated. Handling of the developing device during replacement is very troublesome.

The present invention has been made in view of the above problems, and an object thereof is to replace a plurality of developing devices respectively having toners of different colors and to use the developing devices of a predetermined color when using the developing devices. An object of the present invention is to realize an image forming apparatus capable of accurately maintaining the toner density and simplifying handling when replacing a developing device when using a phenomenon device other than a predetermined color.

(Means for Solving Problems) In the present invention for solving the above problems, an electrostatic latent image forming means for forming an electrostatic latent image on a photoconductor and an electrostatic latent image by a developer having toner are formed. Developing means for forming a visible image, transfer means for transferring the image visualized by the developing means onto a transfer paper, fixing means for fixing the transferred image, and toner concentration of the developer in the developing means. A toner concentration sensor provided in the developing means for detecting the non-volatile memory, a non-volatile memory, a writing means for writing a signal indicating the toner density of the reference developer into the non-volatile memory as a reference value, and an image forming device. An image forming apparatus comprising: a toner concentration control unit that controls toner concentration of a developer by supplying toner so that the toner concentration of the developer detected by the toner concentration sensor becomes equal to the reference value. , The developing means The developing device formed is removable from the image forming device, and the toner concentration sensor provided in the developing device that uses a developer having a toner of a predetermined color outputs a linear signal according to the toner concentration,
A toner concentration sensor provided in a developing device using a developer having a toner of a color other than a predetermined color is configured to output a binary signal indicating high density or low density, and is a reference for the developer having a toner of a predetermined color. The toner concentration sensor detects the toner concentration, and the signal indicating the toner concentration is written as a reference value in the non-volatile memory to form an image even when an image is formed by using a toner of a predetermined color or a color other than the predetermined color. The signal indicating the toner concentration detected by the toner concentration sensor of the developing device installed in the device is compared with the above reference value stored in the non-volatile memory, and toner is replenished according to the difference between the two, and development is performed. It is characterized in that the toner concentration of the agent is controlled.

(Operation) First, the toner density of the developing device having the developer of the predetermined color as the reference is detected and written in the nonvolatile memory as the reference value. When an image is formed using any toner other than the predetermined color and the predetermined color, the signal indicating the toner concentration detected by the toner concentration sensor is compared with the reference value stored in the nonvolatile memory, and both are compared. The toner is replenished in accordance with the difference.

(Example) With reference to drawings, the Example of this invention is described in detail below.

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

In the figure, 30 is a CP that controls each part of the image forming apparatus.
U and 31 are operation input sections for the operator to input various instructions, 32 is a display section for confirming the above-mentioned input and for displaying a message from the CPU 30, and 33 is provided in the developing device 7, Toner level sensor that detects the amount of toner remaining,
Reference numeral 34 is an inductance sensor that measures the magnetic permeability of the developer and outputs a voltage according to the toner concentration. Reference numeral 35 is a toner replenishing means that is provided in the developing device 7 and replenishes toner. A / D converter that converts the voltage value according to the toner density into a digital value, 37 is the above A
The toner density converted to digital value by the / D converter 36 is CP
A non-volatile memory that is written by the write instruction of U30 and read by the read instruction, and 38 is a non-volatile memory
A D / A converter that converts the digital toner density data read from 37 to an analog value, 39 is a voltage value according to the toner density given from the inductance sensor 34 at the time of image formation, and the nonvolatile memory 37. A comparator for comparing the stored voltage value according to the reference toner concentration and outputting a voltage according to the difference between these two inputs, 40 is a toner replenishing means 35 for the toner replenishing means 35 according to the output voltage of the comparator 39. It is a toner replenishment instruction means for giving a replenishment instruction.

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 those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. Reference numeral 1 is a photosensitive drum, 7 is a developing device, 33 is a toner remaining amount sensor for detecting the toner remaining amount from the vibration during toner replenishment, 34 is an inductance sensor for detecting the toner concentration in the developer, 35 is toner replenishing means, and 35a. Reference numerals 35b and 35b are rollers driven when toner is replenished, 35c is a belt driven by rollers 35a and 35b, 35d is a carriage for replenishing toner attached to the belt 35c, 41 is a toner replenishing port, and 42 is toner replenishing. Auxiliary roller for feeding the toner replenished by the carriage 35d of the means, 43 is a main agitating section for agitating the developer consisting of toner and carrier, 44 is a sub agitating section for agitating the same, and 45 is a static roller on the photosensitive drum. A developing sleeve for developing the toner by attaching toner to the latent image, 46 is a sleeve 45
It is a spike control plate that controls the height of the developer spikes.

First, the operation of the developing device 7 will be described. The toner supplied from the toner replenishing port is moved to the auxiliary roller 42 by the carriage 35d of the toner replenishing means 35 when there is a toner replenishing instruction. At this time, the toner remaining amount sensor 33 detects the remaining amount of toner due to the vibration generated when the carriage 35d carries the toner. The rotation of the auxiliary roller 42 causes the toner to drop downward. Then, the developer (toner and carrier) already in the developing device and the toner are mixed in the main stirring section.
It is stirred by 43 and the sub-stirring section 44. Here, the inductance sensor 34 detects the toner density by measuring the magnetic permeability of the developer. The developer spikes are formed on the developing sleeve. The height of the developing agent is regulated by the bristling regulating plate 46, and the photosensitive drum 1 is driven by the developing agent passing therethrough.
The upper latent image is developed into a toner image.

The 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 CUP 30 via the connector which is brought into a coupled state when the developing device is attached to the copying main body. Therefore, color copying can be easily performed by replacing the developing device with a toner of a different color. Also, by connecting or disconnecting any two terminals of the connector on the developing device side depending on the color of the toner, it is possible to distinguish what color of the developing device is mounted from the copying machine body side. .

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

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

When an initial setting instruction is issued from the operation input unit 31, the CPU 30 causes the main agitating unit 43 and the sub agitating unit 44 of the developing device 7 to stay for a certain period of time (until the toner and carrier of the developer are well mixed,
Instruct stirring of the developer for 90 seconds, for example. Initially,
A developer having a reference concentration (for example, toner concentration 4%) is injected into the developing device. After the stirring, the voltage according to the toner concentration of the developer of the reference concentration measured by the inductance sensor 34 is converted into a digital value by the A / D converter 36, and C
It is written in the non-volatile memory 37 according to the instruction of OU30. When the writing to the non-volatile memory 37 is completed, the initial setting operation ends.

There are also cases in which different color toners are put in a plurality of replaceable developing devices, and the developing devices are selectively used according to the usage status. Even in this case, black is most often used. In the case of the toner other than the black toner, the latitude with respect to the toner density is wide, and it is possible to allow some deviation in the toner density. Therefore, it is sufficient to write only the reference density data of the black toner in the non-volatile memory 37. Therefore, when a developing device other than black is attached, the writing operation to the non-volatile memory 37 is not performed. That is, the CPU 30 monitors the type of developing device to be mounted, and when a developing device other than black is mounted, the CPU 30 does not give a write control signal to the non-volatile memory 37.

FIG. 3 is a characteristic diagram of the inductance sensor of the developing device in which black toner is injected. As shown in this figure, even the same type of sensor has different characteristics such as A, B, and C, and the output voltage (V _A V _B V _C ) for the same concentration is different. Therefore, the value written in the non-volatile memory 37 is slightly different depending on the sensor used.

FIG. 4 is a configuration diagram showing an example of a configuration for determining the type of removable developing device. A connector 50 is provided on the developing device 7 side, and a connector 51 is provided on the copying machine body side. When the developing device 7 is mounted on the copying machine body, the terminals 50a, 50b, 50c, 50d of the connector 50 and the connector 50 are provided. Five
One terminal 51a, 51b, 51c, 51d is configured to be connected respectively. In such a connector, for example, in the case of a developing device containing black toner, terminals 50c and 50d
Is short-circuited and terminals 50c and 50d are opened in the case of a developing device containing toner other than black. And the terminal 51c,
By connecting 51d to the CPU 30 and monitoring both terminals, it is possible to determine whether the developing device is for black toner or another developing device. In this example, writing to the non-volatile memory is performed only when the terminals 51c and 51d are in the conductive state when viewed from the CPU 30.

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

When a copy instruction is given to the operation input unit 31, the CPU 30 gives a copy instruction to each unit. As a result, processing (copying process) such as charging of the photosensitive drum, formation of a latent image by exposure, development for adsorbing toner on the latent image, transfer to transfer paper, and fixing 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 the comparator.
39 Applied to one input terminal. Also, the comparator 39
The detection voltage of the sensor at the reference toner concentration written in the non-volatile memory 37 is applied to the other input terminal of the. The comparator 39 compares the voltages applied to both input terminals,
It 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 the toner replenishing means 35 in the developing device 7 an instruction as to whether or not to replenish the toner. The toner replenishing means 35 replenishes the developer with toner based on the above instruction. As a result, the toner concentration in the developer rises, and toner is replenished until the toner concentration matches the reference value.

The output voltage of the inductance sensor of the developing device containing black toner is as shown in FIG. 3, but the output characteristic of the inductance sensor of the developing device containing color toner is as shown in FIG. The high level and the low level are output with the reference toner density (for example, 5%) of the toner as a boundary. Here, the high level is set to be larger than the value (reference value) written in the nonvolatile memory 37 at the above-mentioned initial stage, and the low level is set to be smaller than the above-mentioned reference value. As shown in FIG. 3, the reference value has some variation, so it is necessary to set the high / low level with a margin.

FIG. 6 is a block diagram showing an example of the configuration of the inductance sensor 52 of the developing device in which the color toner is injected. Like the inductance sensor 7, the inductance sensor 52 can be attached to and detached from the main body of the image forming apparatus. The inductance detector 52b outputs a voltage according to the toner concentration according to the inductance change of the coil 52a. The voltage corresponding to the toner density is converted into the high level voltage and the low level voltage by the binarizing circuit 52d. The toner concentration at which the output level is switched is adjusted by the variable resistor 52c.

In the case of a color toner developing device, the inductance sensor 52 having the above characteristics is used.
Except for the developer, the configurations other than 52 are no different from the case of the black toner. In the case of a color toner developing device, each inductance sensor 52 is used at the reference density of each color toner.
The output voltage of is not adjusted to match the value for black toner. For this reason, the work of replacing the color toner with the developing device is simple and easy to handle.

Even in the case of color toner developing devices,
Toner replenishment is performed by comparing the output voltage of the inductance sensor 52 and the voltage value (reference value; for black toner) stored in the nonvolatile memory. However, since the inductance sensor 52 outputs a binary signal indicating high density or low density, the toner density of the color toner in the developing device is between the high density and the low density when the output level of the inductance sensor 52 is high. It is controlled so as to match the density (boundary density) that is switched by. That is,
Inductance sensor 52 indicates high or low concentration 2
Since the value signal is output, the output signal of the comparator (39) also becomes a binary signal, the toner density is so-called ON / OFF controlled, and the boundary density settles down. Therefore, the toner concentration of the color toner in the developing device is determined regardless of the voltage value (reference value) stored in the non-volatile memory. The boundary density may be set for each manufacturing unit of the developer when the developing device is shipped.

In the above embodiment, the reference density of the black toner is written in the non-volatile memory at the time of initial setting, and the toner density of each color is controlled based on this, but the present invention is not limited to this. For example, the toner densities may be controlled after the reference densities of toners of other colors are written in the nonvolatile memory.

(Effects of the Invention) As described in detail above, according to the present invention, the toner concentration sensor provided in the developing device using the developer having the toner of the predetermined color (for example, black) is linear in accordance with the toner concentration. A toner density sensor provided in a developing device that uses a developer having a toner of a color other than a predetermined color is configured to output a binary signal indicating high density or low density. The toner concentration that is the reference of the developer having the toner is detected by the toner concentration sensor, the signal indicating the toner concentration is written as a reference value in the non-volatile memory, and an image is formed using any toner other than the predetermined color and the predetermined color. Even in the case of performing the above, the signal indicating the toner concentration detected by the toner concentration sensor of the developing device mounted on the image forming apparatus and the reference value stored in the non-volatile memory And toner is replenished according to the difference between the two,
Since the toner concentration of the developer is controlled, it is possible to maintain the toner concentration accurately when using a developing device of a predetermined color when replacing and using a plurality of developing devices respectively having toners of different colors. Therefore, it is possible to realize the image forming apparatus which is easy to handle when replacing the developing device when the developing device other than the predetermined color is used.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, FIG. 2 is a sectional view showing a configuration of a developing device, FIG. 3 is a characteristic diagram of an inductance sensor, FIG. 4 is a configuration diagram of a connector, and FIG. FIG. 5 is an output characteristic diagram of the inductance sensor, FIG. 6 is a block diagram showing an example of the configuration of the inductance sensor, and FIG. 7 is a configuration diagram of a conventional electronic copying machine. 1 ... Photosensitive drum 7 ... Developing device 30 ... CPU 31 ... Operation input section 32 ... Display section 33 ... Toner level sensor 34 ... Inductance sensor 35 ... Toner supply means 36 ... A / D conversion Unit 37 …… Non-volatile memory 38 …… D / A converter 39 …… Comparator 40 …… Toner supply instruction means 41 …… Toner supply port 42 …… Auxiliary roller 43 …… Main stirring section 44 …… Sub stirring section 45 …… Developing sleeve 46 …… Brushing control plate 50 …… Connectors 50a to 50d …… Terminal 51 …… Connectors 51a to 51d …… Terminal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 61-201277 (JP, A) JP-A 60-69666 (JP, A) Actually opened 61-22051 (JP, U)

Claims (1)

[Claims] 1. An electrostatic latent image forming means for forming an electrostatic latent image on a photoconductor, a developing means for visualizing the electrostatic latent image with a developer having toner, and a visible image by the developing means. Transfer means for transferring the imaged image onto a transfer paper, fixing means for fixing the transferred image, toner concentration sensor provided in the developing means for detecting the toner concentration of the developer in the developing means, The non-volatile memory, a writing unit that writes a signal indicating the toner concentration of the reference developer into the non-volatile memory as a reference value, and the toner concentration of the developer detected by the toner concentration sensor during image formation are An image forming apparatus comprising: a toner concentration control unit that controls toner concentration of a developer by replenishing toner so as to be equal to a reference value. The developing unit that constitutes the developing unit is detachable from the image forming apparatus. Is possible and The toner concentration sensor provided in the developing device using a developer having a constant color toner outputs a linear signal according to the toner concentration, and is provided in the developing device using a developer having a toner other than a predetermined color. The toner concentration sensor is configured to output a binary signal indicating high concentration or low concentration, and the toner concentration sensor detects a reference toner concentration of the developer having a toner of a predetermined color and indicates the toner concentration. The toner detected by the toner density sensor of the developing device installed in the image forming apparatus is used when the image is formed using the toner of the predetermined color and the toner other than the predetermined color by writing the signal in the non-volatile memory with the reference value. Compare the signal indicating the concentration with the reference value stored in the non-volatile memory,
An image forming apparatus characterized in that a toner is replenished according to a difference between the two, and a toner concentration of a developer is controlled.