JPS61156074A - Picture formation device - Google Patents

Abstract

PURPOSE:To suppress the variation of picture density due to factors other than toner concentration by detecting an image developed on a photosensitive drum by optical sensor, comparing the output signals of the sensors with previ ously stored reference data and controlling a developing roller of a developer and the rotational number of an agitator in accordance with the compared output signal. CONSTITUTION:When signals 1D1, ID2 corresponding to the picture density outputted from the optical sensors 133, 134 are equal to reference data gamma, motors 351, 352 are rotated on the basis of previously st prescribed rotational number through a main processor group 71, a subprocessor group 73 and a pulse motor driver 80 and the developing roller 121 and the agitator 122 are rotated at the prescribed rotational number respectively. When both the output signals ID1, ID2 are lower than the reference data gamma, i.e. when the charged variable of a developer is high, the rotational number of a developing roller 121 is increased from a prescribed value on the bias of a command of a main processor group 71 and the rotational number of the agitator 122 is reduced lower than the prescribed value so that the charged variable is controlled to a proper value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image forming apparatus applied to, for example, an electronic copying machine, and particularly relates to an improvement of a developing device.

[Technical background of the invention and its problems]

As is well known, in a developing device used in an electronic copying machine, a toner concentration control device for a developer consisting of toner and carrier is used in order to maintain stable image density. This toner concentration control device maintains the toner concentration constant.

This reduces toner density dependence, which is one of the most important factors of image density fluctuations.

Incidentally, in addition to the toner concentration, factors contributing to fluctuations in image density include, for example, a decrease in the surface potential of the photoreceptor drum.Therefore, a decrease in image density is inevitable with the toner concentration control alone.Furthermore, Current inert agent band'11
Since 1iI changes depending on environmental conditions, the image density also changes accordingly. That is, in the case of low humidity, the amount of charge increases and the degree of ρ per stroke decreases, and in the case of high humidity, the amount of charge decreases and the density per stroke increases, resulting in so-called fogging.

As described above, in the conventional viewing and imaging device 1, it is difficult to prevent variations in image density due to factors other than toner density.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and its object is to provide an image forming apparatus capable of suppressing fluctuations in image density due to factors other than toner density.

[Summary of the invention]

In this invention, a reference original is provided at one end of the original table.

This reference document is scanned and developed on a photosensitive drum prior to scanning the set document.

This developed image is detected by an optical centimeter.

The output signal of this optical sensor is compared with pre-stored reference data, and the rotational speed of the developing roller and the agitator of the developing device is controlled according to this comparison output signal.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

5 and 6 schematically show an image forming apparatus, such as a copying machine, according to the present invention.

That is, 1 is a main body of a copying machine, and a document table (transparent glass) 2 is fixed to the upper surface of the main body 1 to support a document. This document table 2 has a fixed scale 2 which serves as a reference for setting the document. is established.

Furthermore, a document cover 11 that can be opened and closed is provided near the document table 2.
and a work table 12 are provided. and,
The original set on the document table 2 is exposed by an optical system consisting of a 1M light lamp 4 and mirrors 5, 6° 7 reciprocating along the lower surface of the document table 2 in the direction of arrow a. In this case, the mirrors 6 and 7 are moved so that the optical path length is kept constant.
Move at 1/2 the speed of The light reflected from the original by the scanning of the optical system, that is, the light reflected from the original by the light irradiation of the exposure lamp 4, is reflected by the mirrors 5, 6.7, passes through the variable magnification lens block 8, and then passes through the mirror 9. The light is reflected by and guided to the photoreceptor drum 10, so that an image of the document is formed on the surface of the photoreceptor drum 10, which serves as an image carrier.

The photosensitive drum 10 rotates in the direction of arrow C.

First, the surface is charged by the charging device 1).

Thereafter, the image of the original document is exposed to slit light to form an electrostatic latent image, and this electrostatic latent image is made visible by applying toner by a developing device 12. On the other hand, the paper (image forming object) P is stored in the selected upper paper feed cassette 13 or lower paper feed cassette 1.
4, one sheet at a time is taken out by a delivery roller 15 or 16, guided through a paper guide path 17 or 18 to a pair of registration rollers 19, and sent to a transfer section by this pair of rollers 19. Here, each of the paper feed cassettes 13 and 14 is as follows.

It is removably provided at the lower right end of the main body 1, and it is possible to select one of the above-mentioned paper feed cassettes 13, 14 by placing an operation panel (=) to be described later.
are respectively cassette size detection switches 601.60□
The cassette size is detected by This detection switch 60. ．． 60□ is constituted by a plurality of microswitches that are turned on and off according to the insertion of cassettes of different sizes.

On the other hand, the paper P sent to the transfer section comes into close contact with the surface of the photoreceptor drum 10 at the transfer charger 20, so that
The toner image on the photosensitive drum 10 is transferred by the action of the charger 20. The transferred paper P is peeled off from the photoreceptor drum 1O by the action of the peeling household appliance 2 and is conveyed on the conveyor belt 22, and is sent to a pair of fixing rollers 23 as a fixing device provided at the terminal end of the conveyor belt 22. By passing through this, the transferred image is fixed. Then, the paper P after fixing is
The paper is discharged to a tray 25 outside the main body 1 by a pair of paper discharge rollers 24 . Further, after the photosensitive drum 10 has been transferred, the static electricity is removed by the static electricity removal charger 26, residual toner on the surface is removed by the cleaner 27, and the residual image is erased by the static electricity removal lamp 28, so that the drum returns to its initial state. I'm here. Note that 29 is a cooling fan for preventing the temperature inside the main body 1 from rising.

FIG. 7 shows the operation panel 30 provided on the main body 1. 30t is a copy key for commanding the start of copying, 10
t is the numeric keypad for setting the number of copies, etc. (/,
is a display section that displays the operating status of each part and paper jams, etc.
304 is the upper row.

30. a cassette selection key for selecting the lower paper feed cassettes 13 and 14; 306 is a cassette display section that displays the selected cassette, and 306 is an enlargement of the copy.

A magnification setting key that sets the reduction magnification in a predetermined relationship.

30 is a zoom key for steplessly setting the enlargement/reduction magnification; is a display section that displays the set magnification, 3θ. is a density setting section that sets the number of copies to be made once.

FIG. 8 shows an example of the configuration of a drive source for each drive section of the copying machine configured as described above, and is composed of the following motors. That is, 3) is a lens motor, which is a motor for moving the position of the lens block 8 for changing the magnification. A mirror motor 32 is a motor for changing the distance (optical path length) between the mirror 5 and the mirror 6.7 for changing the magnification. 33
is a scanning motor, which connects the exposure lamp 4 and the mirror 5.
This is a motor for moving the mirror 6.7 for scanning the original. A shutter motor 34 is a motor for moving a shutter (not shown) for adjusting the charging width of the photosensitive drum IQ by the charger 1 during zooming. 35. A developing motor is a motor for driving the developing roller 121 of the developing device 12. 35
2 is an agitator 12 of the developing device 12. This is the motor that drives the.

A drum motor 36 is a motor for driving the photosensitive drum 10. 37 is a fixing motor that connects the paper conveyance path 22. This is a motor for driving the fixing roller pair 23 and the paper ejection roller pair 24. 38 is a paper feed motor, which is connected to the feed roller 15. This is a motor for driving J6. 39 is a paper feed motor (regis)
This is a motor for driving the CF-RA counter 9. A fan motor 40 is a motor for driving the cooling fan 29.

FIG. 9 shows a drive mechanism for reciprocating the optical system. That is, the mirror 5 and the exposure lamp 4 are supported by the first carriage 41.degree., and the mirror 6.7 is supported by the second carriage 412, respectively, and these carriages 411.degree. and 412 are supported by the guide rails 42. ．． It is guided by 422+2 and can freely move in parallel in the direction of arrow a. That is, the four-phase pulse motor 33 drives the pulley 43. An endless belt 45 is stretched between the pulley 43 and the idle pulley 44, and one end of a first carriage 411 that supports the mirror 5 is fixed to a midway portion of the belt 45.

On the other hand, the rail 42. of the second carriage 4 supporting the mirror 6.7. The guide portion 46 of the rail 42. Two pulleys 47.degree. 47 are rotatably provided apart from each other in the axial direction, and a wire 48 is stretched between these pulleys 47,47.

One end of this wire 48 is fixed to a fixed part 49, and the other end is fixed to the fixed part 49 via a coil spring 50. Further, one end of the @1 carriage 4 is fixed to the middle part of the wire 48. Therefore, as the pulse motor 33 rotates, the belt 45 rotates and the first carriage 411 moves, and the second carriage 41. also move. At this time, boo')4
7.47 serves as a dynamic anti-slip, so the first carriage 4
The second carriage 41. move in the same direction at 1/2 the speed. In addition, 1. 2nd carriage 4 no.

The moving direction of No. 4 is controlled by switching the rotation direction of the pulse motor 33.

Further, on the document table 2, a copyable range corresponding to the specified paper is displayed. That is, the paper size specified by the paper selection key 304 is (" x + P y )
Set 1 magnification *-,? 0. .

If the copy magnification specified by 307 is K, then the copyable range (x, y) is.

x=Px/K to y=Py/ becomes. Of this copyable range (x, y).

In the X direction, there is a pointer 5 arranged on the back side of the document table 2.

52, and the X direction is indicated by the first carriage 4.
11 is displayed on a scale 53 provided on the top surface.

The above-mentioned pointers 51 and 52 are as shown in Figure 9iIJ10.

It is provided on a wire 57 that is stretched between pulleys 54 and 55 via a spring 56.

The pulley 55 is rotated by a motor 58, and by driving this motor 58 according to the paper size and magnification, the distance between the pointers 51 and 52 can be changed.

In addition, the first carriage 41. is moved to a predetermined position (home position according to the magnification) by driving a motor 33 according to the paper size and magnification. and.

When the copy key 301 is pressed, the first carriage 41 first transfers the S2 cartridge 41. After that, the lamp 4 is turned on and the second carriage 4 is moved away from the second carriage 4.

When scanning of the original is completed, the lamp 4 is turned off and the first lamp is turned off.
The carriage 41m is returned to the home position.

Figure 11 shows the overall control circuit.

Main processor group 7 and 1. It is mainly composed of a second sub-processor group 72 and 73. The main processor group 7 includes an operation panel 30 and various switches and sensors, such as the cassette size detection main f601.6.
0. A high-voltage transformer 76 detects input from input devices 75 such as 1 and drives various chargers, and the static elimination lamp 2
8. The blade solenoid 27a of the cleaner 27, the heater 23a of the fixing roller pair 23, and the exposure lamp 4.
．． and controls each of the motors 3 to 40, 511, etc. to perform the above-mentioned copying operation, as well as the outputs of optical sensors J 31 and 132 (I and memory 140, which will be described later).
The developing roller 12. , which controls the rotation of the stirrer 12 degrees.

Among the above motors 3) to 40.58, motor 37.40
and a toner motor 7 that supplies toner to the developing device 12.
7 is controlled by the main processor group 7 via a motor driver 28.

The motors 31 to 34 are controlled by the first sub-processor group 72 via a pulse motor driver 79, and the motors 35.
．． 35. ．． 36,3B.

39.58 is the second
It is controlled by a sub-processor group 73.

Also,! ! The light lamp 4 is controlled by a main processor group 71 via a lamp layer inverter 8.

The heater 23a is controlled by the main processor group 71 via the heater control section 82. Then, the first processor from the main processor group 7. Commands to drive and stop each motor are sent to the 2nd-9th processor group 72.73, and the 1st. A status indicating the drive or stop state of each motor is sent from the second sub-processor group 72, 73 to the main processor group 7. Also, in the $1f processor group 72.

A position sensor 8 that detects each initial position of the motors 31 to 34
Location information from 3 has been input.

FIG. 12 shows an example of the configuration of the main processor group 7. That is, numeral 9 is a one-chip microcomputer (hereinafter simply referred to as microcomputer), which detects human input of keys on an operation panel (not shown) and controls various displays via an input/output board 92. Further, the microcomputer 9 is expanded by input/output ports 93 to 96. The input/output boat 93 includes a high voltage transformer 76% motor driver 78. A lamp regulator 8 and other outputs are connected, a size switch for detecting the paper size and other inputs are connected to the input/output boat 94, and a copying condition setting switch and other inputs are connected to the input/output boat 95. Ru. Note that the input/output port 96 is for optical I/M.

FIG. 13 shows an example of the configuration of the first sub-processor group 72. That is, 101 is a microcomputer, which is connected to the main processor group 7. 102 is a programmable interval timer for controlling the phase switching interval time of the pulse motor, and when a set value is set from the microcomputer 10, it counts based on it, and when it has counted out, the end pulse is divided into the microcomputer 10. output to the included line. A reference clock pulse is input to the timer 1θ2. In addition, the microcomputer 101 has
At the same time as position information from the position sensor 83 is input.

Input/output boats 103 and 104 are connected.

The input/output boat 104 is connected to the motors 3 to 34 via the pulse motor driver 79 described in iii. Note that the input/output board 103 is used, for example, when outputting status signals of each pulse motor to the main processor group 71.

FIG. v114 shows an example of the configuration of the second sub-processor group 73. That is, numeral 11 is a microcomputer, which is connected to the main processor group 71. Reference numeral 112 is a programmable interval timer for controlling the phase switching interval time of the pulse motor, and when a set value is set by the microcomputer 111, it outputs an end pulse when it counts out. This termination pulse is latched by the latch circuit 113, and its output is supplied to the interrupt line and input/output board input line of the microcomputer 11).

Further, an input/output boat 114 is connected to the microcomputer III, and the input/output boat IJ4 is connected to the motor 35. ．． 35. ．． 36,
38, 39, and 58 are connected.

The M2S diagram shows the control circuit of the pulse motor.
O4, equivalent to 114) has a pulse motor driver knob 22.
(corresponding to the pulse motor driver 79.FIO in FIG. 11) is connected to this pulse motor driver 122, and a pulse motor 123 (the pulse motors 31 to 34° 35,
,,? 5. , 36. ．． 111,39. The windings A, A, B, and B of the windings (corresponding to Ell) are connected.

Figure 16 shows the speed control force method for a pulse motor.
(a) shows the speed curve of the pulse motor, and (b) shows the phase L; IJ4>interval. As is clear from this figure, the phase switching interval is long at first.

They gradually become shorter, then become evenly spaced, then gradually become longer again, and then stop. That is, this indicates the through-up and through-down of the pulse motor, starting from the self-starting region, being used in the high-speed region, and finally falling down. In addition.

'lt'l...tx indicates the time of the phase switching interval.

Next, the main parts of this invention will be de-furnaced. In this invention, before scanning the original set on the original platen 2, first,
A reference original is to be scanned. That is, as shown in FIGS. 1 and 2, on the back surface of one end of the document table 2 and located on the back surface of the fixed scale 2, there are reference documents 131, J, ?, as shown in FIG. 2 is provided.

These reference originals 131 and 132 have original densities (0, D,
) are set to, for example, 0, 5, and 1.2, respectively.

These standard manuscripts 7,? 7, l,? 2, when the copy key 301 is operated and the copy operation is started,
Fixed scale2. The document set along the original is optically scanned one unit ahead, and a corresponding electrostatic latent image is formed on the photoreceptor drum 10. Toner is attached to this electrostatic latent image by a developing device 12 and the image is developed. This developed reference original 1,
? As shown in FIG. 3, the images J and J 32 are arranged at the lower end of the multi-image device 12 at a portion facing the photoreceptor drum 10 at approximately the same interval as the setting interval of the scratched reference documents 131 and 132. optical centimeter J 33 as a detection means,
Detected by J34. These optical sensor 133
, 1.14 output signals corresponding to the image densities I, D, respectively, are sent to the main processor group 7 (the 11th
(as shown in the figure) and is compared with reference data previously stored in memory 140. That is, the memory 140 has a fourth
As shown by dotted lines in the figures (al to (dl), reference data γ indicating the relationship between ideal document density (0, D,) and image a degree (I, D,) is stored.

This reference data r and the detected image density (I, D,
) is compared with the signal corresponding to 5 and based on the result, the developing roller (so-called non-magnetic sleeve) 12 of the developing device 12 is compared. ,
The rotation speed of the stirrer 122 is controlled. This developing roller 1
21. Stirrer 12. The control is performed as follows.

For example, the signal ID1, I corresponding to the image density (1, D,) output from the optical sensor l j j , 1.74
D2 are both equal to the reference data r as shown in FIG. Motor 15 via pulse motor driver 80
．． ．． 352 is operated at a predetermined rotation speed,
Developing roller 121. Stirrer 12. are each operated at a predetermined rotation speed.

In addition, as shown in FIG. 4 (bl), the optical sensor J33°13
When the output signals ID, LD, and output signals 4 are both lower than the reference data r, that is, when the amount of charge of the developer is high, the rotational speed of the developing roller 12I (motor 35) is changed according to a command from the main processor group 7). is raised above a predetermined value, and the stirrer 1
22 (motor 35.) is controlled to be lower than a predetermined value so that the amount of charge becomes an appropriate value.

Furthermore, as shown in FIG.
34 output signals ID1 and ID are both higher than the reference data γ, that is, the rotation speed of the toner is lowered than the predetermined value, and the rotation speed of the stirrer 12° (motor 35.) is increased above the predetermined value. . Therefore, scattering of toner caused by the developing roller 121 is suppressed, and the amount of charge of the developer is controlled to an appropriate value.

In addition, as shown in FIG. 4 (dl), the optical sensor 133°13
Among the output signals 1D1 and ID2 of 4, ID.

is higher than the reference data r, and when ID2 is equal to the reference data r, the developing roller 12. The rotation speed of the stirrer 12.degree. (motor 35.) is maintained at a predetermined value, and the rotation speed of the stirrer 12.degree. (motor 35.) is kept below the predetermined value.

Therefore, the amount of charge on the developer is controlled to an appropriate value.

As described above, the developing roller 121.
Stirrer 12. After the operation control is performed, the copying operation of the original image described above is subsequently performed.

In addition, the motor 35. ．． 35. As for control.

For example, a signal ID corresponding to one image density.

motor 35 according to the error between the reference data γ and the reference data γ. .

35 is stored in the memory in advance.

This is read out by the main processor group 71 according to the actually detected error, and then supplied to the sub-processor group 73 (2).

In addition, the criteria for the manuscript a degree of ID, , ID, are ID,
is the central part of the slope of the reference data r.

ID, may be selected at a portion where the reference data r reaches saturation.

Furthermore, the error between ID, , ID, and the reference data r is ±1.
If it is within 0, it is considered normal.

In other words, the reference data γ corresponding to 0, for example, ID.

If so, consider it to be normal and set the stirrer to the normal rotation speed of 12°.

If so, output a signal to correct the rotation speed. The same applies to ID.

According to the above embodiment, the reference original 13 is mounted on the photosensitive drum 10.
1,132 is developed, and the image density of this actually developed image is detected by optical sensors 33 and 134, and the detected image density ID, , ID, and reference data r are In comparison, the developing roller 121. Stirrer 12
．． The number of revolutions is controlled. therefore.

Even when the surface potential of the photosensitive drum 10 decreases or the amount of charge of the developer changes due to changes in humidity, it is possible to reliably suppress fluctuations in the density of one image.

In addition, two reference originals 131 and 132 with different original M degrees are used.
Since the image densities ID, , ID2 corresponding to these are detected, the relationship with the reference data γ can be detected accurately. Moreover, the developing roller 12. and stirrer 1
2° by separate motors 351, . 15. Therefore, the developing roller 121 can be efficiently controlled to control the image density and toner scattering, and the agitator 12t can be controlled to control the amount of charge, depending on the image density ID1 to ID2.

Furthermore, the reference originals J 3 J and J 32 are placed on the original table 2.
It is provided on the back side of one end and is scanned prior to scanning the original to control the developing roller agitator and the agitator 122.
Copies can always be made with appropriate image density.

Note that the document densities of the reference documents 131 and 132 are not limited to those in the above embodiment.

It goes without saying that other modifications can be made without departing from the gist of the invention.

〔Effect of the invention〕

As described above in detail, the present invention (2) provides an image forming apparatus capable of suppressing fluctuations in image density due to factors other than toner density.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of an image forming apparatus according to the present invention.
The figure is a bottom view of the main parts shown to explain the standard manuscript B111 Figure 3 is a front view of the main parts shown to explain the optical sensor, and Figure 4 is to explain the control of the developing roller and agitator. , FIG. 5, and FIG. 6 show the configuration of the image forming apparatus. FIG. 5 is a perspective view of e, and FIG. 6 is a side sectional view.
FIG. 7 is a plan view showing the configuration of the operation panel. FIG. 8 is a perspective view showing the configuration of the drive unit, FIG. 9 is a perspective view schematically showing the drive mechanism of the optical system, and FIG. 10 is a perspective view schematically showing the drive P mechanism of the pointer. Fig. 11 is a block diagram showing the overall control circuit, Fig. 12 is a block diagram of the main processor group, Fig. 13 is a block diagram of the first sub-processor group, and Fig. 14 is a block diagram of the second sub-processor group. FIG. 15 is a schematic configuration diagram showing a control circuit of a pulse motor, and FIG. 16 is a diagram for explaining a method of controlling strayness of a pulse motor. 1...Copying machine main body, 2...Original table, 2. ...Fixed scale, io/°/photosensitive drum, 12...Developer. 121・°°Developing roller, 12. ···mixer,,? ,
5. 35! . . . Pulse motor, 4), . . . 1st carriage, 7. . . . Main processor group, 131, 132.
...Reference manuscript, JJ,? , J j 4...
Optical sensor, 140...memory. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 (a) (b) (c)
(d) Original S3 left (τj(0,Q)
9g7 Sea urchin, no ((U, O) Fig. 5 [ Fig. 13 Fig. 14

Claims (3)

[Claims] (1) The document placed on the document table is optically scanned by a scanning means that moves along the document table, and a reflected light image from the document is formed on a charged image carrier. In an image forming apparatus that forms an electric charge pattern, develops the electric charge pattern by attaching a developer charged with an agitator to the electric charge pattern using a developing roller, and transfers and fixes the image onto a transfer material, the scanning means scans the electric charge pattern. A detection means for detecting the image density of a reference original developed on the image carrier and an image corresponding to the reference original developed on the image carrier, and an output signal of this detection means and pre-stored reference data are compared. An image forming apparatus comprising: a control means for controlling the rotational speed of the developing roller and the agitator in accordance with an error output. (2) The image forming apparatus according to claim 1, wherein the reference document is provided on the back side of one end of the document table at a position where it is scanned before the document is scanned. (3) The reference originals are made up of a plurality of originals with different densities, and the detection means is made up of a plurality of pieces in order to detect images corresponding to these reference originals. The image forming apparatus described in .