JPH01147569A - Image forming device - Google Patents

Abstract

PURPOSE:To always make toner concentration accurate and constant by writing the reference toner concentration of developer in a nonvolatile memory, comparing the toner concentration at the time of forming an image with the reference toner concentration read out from the memory and replenishing the toner. CONSTITUTION:When initial setting is instructed from an operation input part 31, a voltage in accordance with the developing toner of the reference concentration measured by an inductance sensor 34 passes through an A/D converter 36 and written in the nonvolatile memory 37 according to the indication of a CPU 30. During development, the toner concentration gradually lowers. Now, a detection output from the sensor 34 is impressed on one terminal of a comparator 39. Meanwhile, 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 of the comparator 39. The comparator 39 outputs the voltage in accordance with the difference between both of them and a toner replenishment indication means 40 issues the indication whether or not the replenishment of the toner is performed to a toner replenishing means 35. Based on the instruction, the replenishment of the toner to the developer is performed.

Description

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

(Background of the Invention) An electronic copying machine exposes a charged photoreceptor (hereinafter, a photoreceptor drum will be explained as an example) to light according to document information to form an electrostatic latent image, which is then converted into a visible image using toner. 5A4, in which this toner visible image is transferred to transfer paper and fixed. In recent years, this type of electronic copying machine has been used in all fields of industry.

FIG. 6 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 . 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 sink 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 to 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. Then, the transfer paper is heated by the fixing roller 10, the toner is fused to the transfer paper, and the covey process is completed.

The exposure section 5 and the mirror M1. 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, since the light source 21 in the exposure position R 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, a two-component developer consisting of toner and carrier is used in a developing device used in this type of electronic vision imaging. The durability of this two-component developer deteriorates significantly when the toner 11 degrees falls below a certain value. For example, when the toner 14 degree 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. Furthermore, in order to maintain stable image quality, it is necessary to maintain the toner density at approximately a predetermined 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 amount detection method using inductance. This utilizes the fact that the carrier contained in the developer is a magnetic material, and places an inductance sensor with a coil in the developer to detect the toner temperature of 11 degrees.Specifically, the toner T of 14 degrees is The toner concentration is determined by measuring the magnetic permeability of the developer, focusing on the fact that the mixing ratio of toner and carrier changes and the magnetic permeability changes as the magnetic permeability changes.

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 kept 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. In other words, the I is set so that the output voltage of the inductance sensor becomes a constant value when measuring the toner of the reference density.
I! i! I had to keep Lt.

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 different. It will be controlled so that it becomes I.

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.

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 accurately and always keep toner density 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. An image forming apparatus that forms an image by transferring and fixing the toner to a transfer paper has a toner density sensor that detects the toner density of the developer, a replaceable developing means, and a reference value of the toner density is written. a nonvolatile memory; a control means for supplying a write control signal to the nonvolatile memory when a predetermined developing means is installed; and a control means for controlling the toner concentration so that the toner concentration detected by the toner concentration sensor becomes equal to the reference value. and a toner replenishment instruction means for controlling the toner replenishment instruction means, which first detects a reference toner concentration using a toner concentration sensor, and writes the detected toner concentration in a nonvolatile memory when a predetermined developing means is installed. The toner density detected by the toner density sensor during image formation is as above! This apparatus is characterized in that the toner density is controlled by fl and II so that it becomes equal to the three quasi-values.

(Function) First, the toner density of the reference developer is detected by the toner density sensor, and if the developing means at this time is in a predetermined state, the detected toner density is written into the 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.

(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 each f1 instruction, 32 is for confirming the above input, and CPLI3
33 is a toner residual sensor provided in the developing device 7 and detects the remaining amount of toner; 34 is a toner residual sensor that measures the magnetic permeability of the developer and responds to the toner replenishment port; an inductance sensor that outputs a voltage, 3
5 is a toner replenishing means provided in the developing device 7 and replenishes toner; 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; 37 is the above-mentioned The toner density converted into a digital value by the A/D converter 36 is written into a non-volatile memory in response to a write instruction from the CPU 30 and read out in response to a read instruction. A D/A converter 39 converts data into an analog value, and a voltage value corresponding to the "toner density" given from the inductance sensor 34 during image formation, and a reference toner v:J value stored in the nonvolatile memory 37. 40 is a toner replenishment instruction that instructs the toner replenisher 8i35 to replenish toner according to the output voltage of the comparator 39. It is a means.

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 concentration 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; 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, and 42 is a carriage 35 of toner replenishment means.
an auxiliary roller 43 that sends out the toner replenished by d;
44 is a main stirring section for stirring the developer consisting of toner and carrier; 45 is a sub-stirring section for stirring the same; 45
Reference numeral 46 denotes a developing sleeve for attaching toner to the electrostatic latent image on the photosensitive drum F to perform development, and numeral 46 denotes a spike regulating plate for regulating the height of the spikes of the developer □ on the sleeve 45.

First, the operation of the developing device 7 will be explained. The toner supplied from the toner replenishing port is transferred to the auxiliary row 542 by the carriage 35d of the toner replenishing means 35 when there is a toner replenishing instruction. At this time, due to the vibration that occurs when the carriage 35d transports the toner, the toner remaining hanging 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 detects 33! of this developer! The toner concentration is detected by measuring the magnetic skewer. 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 the connector that becomes connected when the current I34 device is attached to the main body of the copying machine.

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 cleaning agent for a certain period of time (until the toner and carrier of the developer are thoroughly mixed, for example, 90 seconds).At the initial stage, A standard 1 degree developer (for example, 4% toner concentration) is injected into the developing device.After stirring is completed, the voltage corresponding to the toner concentration of the standard concentration developer measured by the inductance sensor 34 is A/ It is converted into a digital value by the D converter 36 and written into the non-volatile memory 37 according to instructions from the CPU 30. When the writing into the non-volatile 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 value written in the non-volatile memory 37 is
It differs slightly depending on the sensor used.

In some cases, different colors of toner are stored in a plurality of replaceable developing devices, and a developing device is used to assign different numbers depending on usage conditions. Even in such cases, black is the most frequently used color.

In the case of toner other than black toner, the latitude with respect to toner Ha is wide, and a certain degree of deviation in toner density can be tolerated. Therefore, it is sufficient to write only the data of the reference density of black toner into the nonvolatile memory 37. In such a case, if a developing device injected with something other than black toner is installed during initial settings, this toner density will be written to the nonvolatile memory 37, and the developing device containing black toner will be installed again during image formation. Even if it is, accurate toner density control is not performed. In order to prevent such a problem, in the present invention, when a developing device other than black is installed, the writing operation to the nonvolatile memory 37 is not performed. That is, as shown in FIG.
30 monitors the type of developing device installed (step ■), and when a developing device containing black toner is installed, stirring (step ■) and toner concentration detection (step ■) are performed.
) and write to the nonvolatile memory (step ■). When a developing device other than black is installed, CPU30
The write control signal is not applied to the nonvolatile memory 37. At the same time, the CPU 30 displays an error message on the display unit 32 (step ■) indicating that the initial setting operation has not been performed because the type of the installed developing device is different.
Ru. Thereby, it is possible to prevent abnormal values from being stored in the nonvolatile memory, and it is also possible to prevent a situation where control is performed based on abnormal values during image formation.

FIG. 5 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 installed in the copying machine main body, terminals 50a, 50b, 50c, and terminals of the connector 50 are provided.
50d and terminals 51a, 51b, 51c of the connector cover 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.

Then, connect the terminals 51c and 51d to the CPLI30,
By monitoring between both terminals, it is possible to determine the type of current @5A position. In this example, writing to the nonvolatile memory is performed only when the terminals 51C and 51d are in a conductive state as viewed from the CPU 30.

Next, the toner depth 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,
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 the developing agent with toner.

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

Further, to the other input terminal of the comparator 39, the detection voltage of the sensor at the time of the reference toner art1 written in the nonvolatile memory 37 is applied. The comparator 39 compares the voltages applied to the re-input terminals and outputs a voltage according to the difference between the two. Based on the output of the comparator 39, the toner replenishment instruction means 40 instructs the toner replenishment means 35 in the developing device 7 to
Gives an instruction as to whether or not to replenish toner. 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, and toner replenishment is performed until the toner concentration matches the reference value.

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

As described above, when a developing device containing black toner is installed during initial settings, the toner concentration of the reference developer is written to the nonvolatile memory, and the toner concentration at the time of image formation and read from the memory are stored. Since toner is replenished by comparing the toner concentration with the reference toner concentration, the toner concentration can be kept accurately and always constant.

(Effects of the Invention) As described above in detail, according to the present invention, at the time of initial setting, the toner concentration of the reference developer of a predetermined developing device is written in the nonvolatile memory, and the toner concentration at the time of image formation and the memory are stored. By performing toner replenishment by comparing the reference toner density that has been read, it is possible to realize an image forming apparatus that can accurately and always keep the toner i11 degrees 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 structure of the developing device, Fig. 3 is a characteristic diagram of the inductance sensor, and Fig. 4 is the operation at initial setting. 7
FIG. 5 is a block diagram of a connector, and FIG. 6 is a block diagram of a conventional electronic copying machine. 1... Photosensitive drum 7... Phenomenon device 30...
CPU 31...Operation input unit 32...Display unit 33...Toner matching ff1t 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...a! S2 regulation plate 50.51...
・Connectors 50a to 50d, 51a to 51d--Terminals Fig. 3 Fig. 5 Fig. 7 Developing cage Fig. 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. It has a toner concentration sensor that detects the toner concentration of the agent, a replaceable developing means, a non-volatile memory in which the reference value of the toner concentration is written, and when the prescribed developing means is installed, the non-volatile memory The toner concentration control means includes a control means for supplying a write control signal, and a toner concentration control means for controlling the toner concentration so that the toner concentration detected by the toner concentration sensor becomes equal to the reference value. The toner density detected by the density sensor is written into a nonvolatile memory when a predetermined developing means is installed, so that the toner density detected by the toner density sensor during image formation becomes equal to the reference value. An image forming apparatus characterized in that the image forming apparatus is configured to control toner density.