JPH0138602Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner density control device used in electrophotographic copying machines and applied equipment thereof.

First, a general explanation of the toner density control device will be given.

An electrophotographic copying machine or telephone recording device that visualizes an electrostatic latent image using a two-component developer for dry development consisting of toner and carrier, or a developer for wet development consisting of toner and a liquid dispersion medium, etc. It is known that during repeated development operations, the density of the resulting visible image changes over time due to deterioration of the developer or because the ratio of toner in the developer decreases. It is being

Therefore, conventionally, the image density of the image pattern for density detection, which is visualized as a pattern corresponding to the reference pattern for determining developing ability, is detected, and this is compared with a certain reference value, and the image density is determined to be less than or equal to the reference value. When this is determined, the density of the visualized image corresponding to the original image is maintained at a constant level by taking appropriate measures such as replenishing toner. A configuration consisting of a series of members that work toward the above purpose is called a toner concentration control device.

By the way, in conventional toner density control devices, a photograph, paint, gray scale (trade name), etc. is used as a reference pattern, but the method of use is that it uses strong light from a halogen lamp, which is the exposure light source, and moreover, ultraviolet rays. Because they are exposed to a large amount of light each time they are exposed to light, their color tone often gradually changes with long-term use.

Also, fine toner powder is floating inside the machine.
There are cases in which these floating toners gradually adhere to the surface of the reference pattern over a long period of time, staining the surface of the reference pattern, and impairing its function as a reference pattern.

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner density control device equipped with means for preventing changes over time that occur on the surface of a reference pattern as described above.

The present invention will be explained in detail below.

The toner density control device according to the present invention is a mode switching plate provided between a reference pattern provided in a part outside the document placement area and an exposure light source, and the reference pattern is switched between the reference pattern and the exposure light source. a movable shielding plate having a shielding portion with a width sufficient to shield the light from the exposure light source and an opening large enough to expose the reference pattern to the light from the exposure light source, and means for moving the movable shielding plate, The present invention is characterized by comprising mode switching means for initial switching control between a shielding mode in which the shielding portion is overlapped with the reference pattern and an exposure mode in which the opening is overlapped with the reference pattern.

FIG. 1 shows an example in which a toner density control device according to the present invention is installed in a dry type electrophotographic apparatus.

In the figure, reference numeral 1 indicates a contact glass, and a part of the contact glass 1 that is outside the document placement area z and a part of the contact glass 1 or a part adjacent to the contact glass 1 is provided with toner concentration control. A device 2 is provided.

As shown in FIG. 2, at the right end of the contact glass 1, a part outside the document placement area z, and on the surface thereof, there is a band-shaped document size display plate 3.
is glued. This document size display board 3 is a light-opaque board, and the surface in contact with the contact glass 1 is white. A reference pattern indicated by reference numeral 4 is located at the center of the document size display plate 3 on the surface thereof in contact with the contact glass 1.
In this example, the reference pattern 4 is shown as a rectangle.

As shown in FIG. 3, in a space directly below the reference pattern 4 and close to the lower surface of the contact glass 1, there is a movable shielding plate designated by the reference numeral 5 whose surface is parallel to the surface of the contact glass 1. It is located in such a way that it is maintained.

The movable shielding plate 5 is a rectangular plate, and its longitudinal direction is aligned with the y direction perpendicular to the scanning direction x of the optical system in a plane parallel to the contact glass 1.

On the longitudinal extension of both ends of the movable shielding plate 5, rectangular block-shaped direction switching pieces 6 and 7 are fixed to arbitrary fixed members.

For example, two wires W ₁ and W ₂ are attached to one end in the longitudinal direction of the movable shielding plate 5, and the other ends of these wires W ₁ and W ₂ are carved into the direction switching piece 6, respectively. It is connected to one end of a compressible spring 8 through a guide groove provided therein. The other end of the spring 8 is
It is hung on a suitable mounting piece 900 fixed to a stationary member. Also, two wires W ₃ and W ₄ are attached to the other end in the longitudinal direction of the movable shielding plate 5 in the same way as above, and the other ends of these wires W ₃ and W ₄ are connected in the respective directions. It is connected through a guide groove cut in the switching piece 7 to a plunger 90 of a solenoid 9 fixed to a stationary member.

When the solenoid 9 is off, the plunger 90 is in a protruding state, and the wires W ₁ , W ₂ , W ₃ , and W ₄ are each stretched by the tension force of the spring 8, so that the movable shielding plate 5 also follows the reference pattern. It is stable in a state where it overlaps with 4. Note that a rectangular hole 10 is formed in the movable shielding plate to match the size of the reference pattern 4, and when the solenoid 9 is in an OFF state, the hole 10 is located at a position away from the reference pattern 4. Therefore, the reference pattern 4 is completely covered by the shielding portion on the movable shielding plate 5 in an area other than the area of the hole 10. This state is called a shield mode. In the shielding mode, light from an exposure light source, such as a halogen lamp, indicated by reference numeral 11 in FIG. 1, does not reach the reference pattern 4 because it is covered by the shielding portion of the movable shielding plate 5. or,
The movable shielding plate 5 also serves as a so-called cover, so that the pulverized toner etc.
Prevents it from adhering to the surface.

Next, when the solenoid 9 is turned on, the plunger 90 retracts against the tension force of the spring 8, and the movable shielding plate 5 slides in the y direction accordingly.
It stops at the position where the hole 10 matches the reference pattern 4. In this state, the reference pattern 4 is exposed to light from the exposure light source 11, and the reflected light is transmitted from the first mirror 12 to the second mirror 13 to the through lens 14 to the third mirror shown in FIG. 15→
It advances in the order of the fourth mirror 16 and is in a state where it can reach the photosensitive drum 17. When the movable shielding plate 5 is in this state, it is called exposure mode. Also, in the exposure mode, if the solenoid 9 is turned off, the spring 8
The movable shielding plate 5 moves back due to the tightening force and returns to the shielding mode.

In the above explanation, solenoid 9, wire
W ₁ to _{W 4} , spring 8, direction switching pieces 6, 7, mounting piece 9
00 etc. are an example of mode switching means for controlling switching between the shielding mode and the exposure mode.

Next, the configuration of a toner density control device 2', which is another embodiment of the present invention, will be described.

In FIG. 4, the movable shielding plate 18 is shaped like a partially cut out disc. A rotating shaft of a motor M is fixed to the center of the arc. Since the motor M is attached to a stationary member, the movable shield plate 18 is moved by the motor M around the motor shaft and the fixed part at a position corresponding to the movable shield plate 5 in FIG. It can be rotated freely. A compressible spring 80 is hung between one end of the movable shielding plate 18 and a stationary member (not shown), and when the motor M is off, the rotation of the movable shielding plate 18 caused by being pulled by the spring 80 is stopped. 19
It is stopped by. This state corresponds to the shielding mode in the above example, and the opening (not shown) formed in the movable shielding plate is connected to the contact glass 1'.
It is located at a position different from a reference pattern (not shown) formed on a document size display plate 3' attached to the document size display plate 3'.

When the motor M is turned on, the rotational force of the motor M causes the movable shielding plate 18 to rotate against the tension force of the spring 80, and stops at a position where the opening matches the reference pattern. This stop position is determined, for example, by the movable shielding plate 18 coming into contact with the stopper 190. This state corresponds to the exposure mode in the above example.

Switching between the shield mode and the exposure mode is controlled by turning the motor M on and off. When the motor M is turned off in the exposure mode, the movable shielding plate 18 is rotated by the tension force of the spring 80 until the stopper 19 functions and then stops, and this state is the shielding mode.

Note that it is not always necessary to use the stoppers 19, 190.

In this example, the motor M, the spring 80, etc. constitute an example of mode switching means.

As explained above, the toner density control device 2 shown in FIG. 3 or the toner density control device 2' shown in FIG. 4 is installed and used outside the document placement area Z in FIG. 1.

Figure 1 shows the configuration of a well-known copying machine.
For reference, examples of other component names are as follows.

20 is a toner tank, 21 is a developing unit, 22 is a lower paper feed roller, 23 is an upper paper feed roller, 24 is a pair of registration rollers, 25 is a transfer charger, 26 is a separation charger, and 27 is a A conveyor belt, numeral 28 is a fixing unit,
Reference numeral 29 is a paper ejection roller, reference numeral 30 is a copy tray, reference numeral 31 is a cleaning unit, reference numeral 32 is
33 is a static elimination charger, and 33 is a charging charger.
Reference numeral 34 indicates a static elimination lamp, 35 indicates a lamp cooling fan motor, 36 indicates a main motor, 37 indicates a lower paper feeding cassette, 38 indicates an upper paper feeding cassette, and 39 indicates a separating claw.

Note that reference numeral 40 indicates a light emitting diode, and reference numeral 41 indicates a phototransistor, which are part of a detection device that detects the image density of the density detection image pattern based on the reference pattern.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a dry electrophotographic apparatus as an example suitable for implementing the present invention, FIG. 2 is a perspective view of a contact glass portion explaining a reference pattern, and FIG. 3 is a toner density control device according to the present invention. FIG. 5 is a perspective view of a toner concentration control device according to another embodiment of FIG. 4; 4... Reference pattern, 5, 18... Movable shielding plate, 6, 7... Direction switching piece, 8, 80... Spring,
9...Solenoid, 900...Mounting piece, M...Motor, _W1 , _W2 , _W3 , _W4 ...Wire.

Claims (1)

[Claims for Utility Model Registration] Detecting the image density of an image pattern for density detection, which is visualized as a pattern corresponding to a reference pattern for determining developing ability, and comparing this with a certain reference value. , by taking appropriate measures such as replenishing toner when it is determined that the level is below the standard value.
In the toner density control device of an electrophotographic copying machine, etc., which maintains the density of the visualized image corresponding to the original image at a constant level, a reference pattern is provided in a part outside the original placement area. and an exposure light source, the shielding portion having a width sufficient to shield the reference pattern from the light from the exposure light source and exposing the reference pattern to the light from the exposure light source. a movable shielding plate having an opening of a desired size; and a means for moving the movable shielding plate, the movable shielding plate being configured to operate in a shielding mode in which the shielding portion is overlapped with the reference pattern, and in an exposure mode in which the opening is overlapped with the reference pattern. A toner density control device comprising a mode switching means for switching control.