JPS63223766A - Image forming device - Google Patents

Abstract

PURPOSE:To permit expansion of a region of a transparent conductive window member where exact developer concn. detection is possible so that the exact developer concn. detection can be executed with good responsiveness by impressing an electric field including an AC component to the transparent conductive window member. CONSTITUTION:An AC power supply AC 38 and a DC power supply DC 37 are connected in series to the transparent conductive window member 34 and the AC electric field superposed with the DC electric field is impressed by these two power supplies to the transparent conductive window member 34. The toner 22 sticking to the transparent conductive window member 34 is then removed by the rubbing of the napping part of the developer layer formed on the outside peripheral face of a developing sleeve 13 to the transparent conductive window member 34 by the magnetic pole of a magnet roller 14 and also by the oscillation of the toner itself generated between the transparent conductive window member 34 and the developing sleeve 13 by the impression of the electric field thereto. The width A of the developer concn. detection in the transparent conductive window member 34 is also greatly expanded. The detection of the developer concn. at the response speed capable of dealing with the variation in the developer concn. is, therefore, possible and is executable with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to an image forming apparatus, and in particular, for example,
It is equipped with a developing device containing a two-component developer containing toner and a carrier, and is formed into an image carrier by a so-called magnetic brush development method or a jumping development method using the toner supplied from the developer. The present invention relates to an image forming apparatus that converts an electrostatic Wi image into a visible image.

1. A developing method called the so-called magnetic brush developing method, which is a developing method that develops a static FL latent image formed on an image carrier ball by electrophotography or electrostatic recording method. As is well known, magnetic carrier and toner (e.g. colored resin fine powder)
A brush is formed by depositing a two-component developer having the above on the outer circumferential surface of the developing sleeve, and the tip of the brush is attached to the static developer on the image carrier. l! It is made visible by rubbing the image. In the magnetic brush development method described above, the toner in the two-component developer is gradually consumed, but the image quality of the developed image is 1. For example, the ratio of toner to carrier decreases. When the so-called developer concentration decreases, the concentration becomes thinner, and on the other hand, when the so-called developer concentration increases, such as when an excess of toner is replenished than the amount of consumed toner and the ratio of toner to carrier increases. is greatly affected by the developer concentration, with fog increasing as the density becomes too high. Therefore, various automatic developer concentration control devices and methods have been proposed that detect the concentration of the two-component developer stored in the developing device and control the developer concentration to an appropriate value. . Figure 7 shows Japanese Patent Application Laid-Open No. 53-107853 from among these various proposals.
The outline of the proposal will be explained below.The proposal is to explain the outline of the proposal below. Light is irradiated onto the developer layer adhering to the outer peripheral surface of the developing sleeve 113 through the transparent window 41, and the reflected light from the developer layer is filtered through an infrared transmission filter 44 according to the toner content. The light is introduced into the light receiving element sensor means 43 via the light receiving element sensor means 43 and converted into an electric signal by the means 43, and then the electric signal is inputted to the operational amplifier 19. The electrical signal is then compared with the reference voltage signal 124 in the operational amplifier 19, and as a result, a logic level signal is output from the operational amplifier 19 according to the difference between the two and becomes a drive command signal for the motor M121. M1
By controlling the drive of 21, the screw 123
Toner 1 is transferred from the inside of the hopper section 120 to the developing section 109 by
22 is adapted to be adjusted (please refer to the above-mentioned publication for details of the proposal in item 22).

By the way, the developer with the above configuration was detected once! X!
Since the raised portion of the brush of the developer layer formed on the outer peripheral surface of the developing sleeve 113 rubs against the transparent window 41 of 125, the contact portion between the transparent window 41 and the developer layer is rubbed. It is possible to eliminate the resulting adhesion of toner 122 to the transparent window 41. However, since the spikes are formed non-uniformly, the area on the transparent window 41 from which toner is removed is limited to only the area that comes into contact with the spikes.

Therefore, since streaks of spikes are formed on the transparent window 41, there is a drawback that the concentration of the developer cannot be accurately detected. Therefore, in view of these drawbacks, a transparent conductive window member is used for the transparent window 41, and a direct current power source DC137 is connected to the transparent conductive window member as shown in FIG. A method was proposed in which a DC electric field was applied to the According to this method, as shown in FIG. 8, it has become possible to make the bristles of the brush formed by the developer layer uniform, but it has not been possible to accurately detect the developer concentration. Since the area of the transparent conductive window member is limited to the width B where toner adhesion is eliminated by this bristling, a wide detection width cannot be obtained, and therefore the developing sleeve 11
3. To stably detect the developer concentration in the developer layer that is unevenly formed on the outer circumferential surface, it is necessary to wait for the developing sleeve 113 to rotate until it reaches a certain angle. There is a problem in that it takes time to detect the developer concentration.

Therefore, as a result of repeated research and experiments in view of the above-mentioned problems, the present inventors have found that by applying an electric field containing at least an alternating current component to the transparent conductive window member, an accurate developer can be applied to the transparent conductive window member. It has been found that the area in which concentration detection is possible can be expanded, and developer concentration detection can be performed accurately and with good responsiveness.

The present invention is based on this new knowledge.

-j Therefore, the present invention was devised in order to improve the above-mentioned problems, and its purpose is to achieve a response speed that can sufficiently cope with changes in the developer concentration in the developing device. It is an object of the present invention to provide an image forming apparatus that is capable of detecting the developer concentration in the developing device and is capable of highly accurate developer concentration detection.

The above object is achieved by the W! according to the present invention. This is accomplished by an i-image forming device. To summarize, 1 the present invention includes an image carrier, a two-component developer containing toner and a carrier, and a developer carrier for transporting the two-component developer toward the image carrier. a developing means for converting an electrostatic latent image formed on the image carrier into a visible image; developer concentration detection means for detecting the concentration of the developer by irradiating the developer with light and receiving reflected light reflected from the developer; An image forming apparatus that controls the developer concentration in the developing means according to a signal, wherein a transparent conductive window member is provided at a portion of the developer concentration detecting means that faces the outer circumferential surface of the developer carrying member. The image forming apparatus is characterized in that an electric field containing at least an alternating current component is applied between the transparent conductive window member and the developer carrying member.

See 11 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows an image forming apparatus according to an embodiment of the present invention.The image forming apparatus according to an embodiment of the present invention will be explained by taking an image forming apparatus using Carlson electrophotography as an example. Therefore, since the overall structure is already well known, the photoreceptor drum as an image carrier according to the present invention, the developing means, that is, the developer, etc. provided near the outer edge of the photoreceptor drum will not be illustrated in detail. The illustration of the primary charging means 1 in the Carlson process, for example, image exposure means such as a laser beam scanner, cleaning means, etc., is omitted.

In FIG. 2, the image bearing member, that is, the photosensitive drum 12 is rotatably mounted on a shaft means (
(not shown), and a developing device S is disposed near the outer edge of the photosensitive drum 12.

A known photoreceptor such as OPC is used as the photoreceptor on the photoreceptor drum 12, and static electricity is applied onto the photoreceptor by a known charging means and image forming light means. ! , WI images are formed. The developing device 11 includes a developing section 9 disposed close to the outer peripheral surface of the photoreceptor drum 12, and a hopper section 20 communicating with the developing section 9 disposed adjacent to the developing section 9. It is equipped with. The developing section 9 has a rotatable member facing an opening formed in a portion of the developing section 9 facing the outer circumferential surface of the photoreceptor drum 12 so as to be rotatable in the direction of arrow a (counterclockwise) in FIG. The disposed developer carrying member, that is, the developing sleeve 13
a regulating blade 15 whose tip is attached to the upper side of the opening with its tip facing the outer peripheral surface of the developing sleeve 13; and a regulating blade 15 rotatably attached to the bottom of the developing section 9 on the side communicating with the hopper section 20. The developer conveying stirring means 8
The developer conveying and stirring means 8 and the rotary developer conveying and stirring means 7 arranged in the Y row are located at the bottom of the developing section 9 at a portion corresponding to substantially directly below the developing sleeve 13, respectively. Equipped. Inside the developing sleeve 13, a magnetic roller 14 is concentric with the developing sleeve 13 and has N poles and S poles, each having a diameter smaller than the inner diameter of the developing sleeve 13, arranged alternately at approximately equal intervals. The arrangement is fixed, and a developing bias voltage is applied to the developing sleeve 13 from a developing bias voltage applying power source z7. The developing sleeve 13 causes the two-component developer stored in the developing section 9 to be attracted to the outer peripheral surface of the developing sleeve 13 by a developing bias voltage applied from the developing bias voltage application power source 27, and rotates. By this, the developer is continuously photographed toward the outer peripheral surface of the photosensitive drum 12. The regulation blade 15 moves toward the outer peripheral surface of the photoreceptor drum 12 by the rotation of the developing sleeve 13! ! The amount of the two-component developer being transported is regulated to a certain amount or less, and the two-component developer whose discharge is regulated is continued to be held in the developing section 9.

The developer conveying and agitating means 8 is driven to agitate the toner 22 supplied from the hopper section 20 via the communication portion and the carrier component remaining in the developing section 9 to achieve good mixing. The state is maintained while being conveyed to the developing sleeve 13 side. Similarly to the developer transporting and stirring means 8, the developer transporting and stirring means 7 also has the following features:
The developing sleeve 1 is driven while stirring the gear component of the two-component developer and the toner 22 staying in the developing section 9 and maintaining a good mixed state.
3.

According to one embodiment of the present invention, the aforementioned regulation blade 15
At a portion facing the outer peripheral surface of the photoreceptor drum 12, there is a developer concentration for detecting the mixing ratio of the toner 22 and the carrier component forming the two-component developer in the developing section 9. The detection means, that is, the developer concentration detector 25 has a side on which the transparent conductive window member 34 constituting the detector 25 is provided, faces the outer peripheral surface of the developing sleeve 13, and has a length of the slit 35. Although the developer sleeve 13 is attached so that its longitudinal side is along the axial direction of the developer sleeve 13, the details of the configuration of the developer concentration detector 825 will be described later.

On the other hand, the hopper section that constitutes the developing device 11 together with the aforementioned developing section 9? A screw 23 is rotatably disposed at the bottom of the O. The screw 23 is arranged to supply the toner 22 stored in the hopper section 20 into the developing section 9, and one end thereof penetrates through the frame of the hopper section 20. The hopper section 2o
A frame is connected to the rotating shaft of the motor M21 located outside the frame, and the other end side defines the developing section 9 and the hopper section 20 through a communication section where the hopper section 2o communicates with the developing section 9. It has a structure that extends to the body 8
In the two-component developer stored in the developing device 11 of the image correction forming device δ according to an embodiment of the present invention, for example, the core material is a magnetic material with low diffuse reflectance such as ferrite, and a silicon-based resin is used. Alternatively, an insulating carrier coated with a fluorine acrylic resin and a transparent resin such as polyester or polystyrene are melted and mixed with an organic pigment or dye and a small amount of a control agent if necessary, and then ground to a suitable size. A two-component developer consisting of a toner formed by The motor M21 is connected to the developer concentration detector 2.
It is driven by a logic level signal from a comparator circuit 24 consisting of an operational amplifier that receives the output signal (■) from the output signal (5) and an output signal (■) different from the output signal (■) output together with the output signal (■) and performs a comparison operation. is now under control. The comparison circuit 24 does not drive the motor M21 when a signal having a magnitude higher than or equal to a predetermined reference voltage value indicating the developer concentration reference value is output from the developer concentration detector 25, and sets the reference voltage to the reference voltage value. The motor M21 is driven to rotate only when a signal lower than the value is output from the developer concentration detector 25. The two types of output signals (1) and (2) - from the developer concentration detector 25 will be described in detail later.

FIG. 3 shows a detailed configuration of a developer concentration detector 25 used in an image forming apparatus according to an embodiment of the present invention.A developer concentration detector 25 according to an embodiment of the present invention is shown in FIG. As is clear from the reference, the detector frame 26 and the light-receiving element sensor means 32 are arranged and fixed on the back side of the elongated groove of the groove having a box-shaped cross section formed in the detector frame 26. , a light emitting element means 31 arranged and fixed on the back side of the short groove of the box-shaped groove, a slit 35 attached to the opening side of the box-shaped groove, and a slit 35 attached to the opening side of the box-shaped groove; It has a transparent conductive window member 34 made of a material such as Nesa glass that closes the opening of the window.

The light receiving element sensor means 32 is connected to the light emitting element means 31.
irradiated from the slit 35. Transparent conductive window member 34
Among the light that has reached the outer circumferential surface of the developing sleeve 34 via the toner 22 adsorbed to the outer circumferential surface of the developing sleeve 34, the toner 22 receives the light reflected by the toner 22, and the amount of the reflected light is determined according to the amount of the reflected light. In one embodiment according to the present invention, the light-receiving element sensor means 32 is configured to output an electric signal (i.e., an output signal). It has the following characteristics. The transparent conductive window member 34 is configured to receive an alternating current electric field in which a direct current electric field is superimposed by an alternating current power source AC38 and a direct current power source DC37 as shown in FIG.

In an image forming apparatus according to an embodiment of the present invention, a second
As shown in the figure, the developer concentration detector 25 is attached to the side of the regulation blade 15 that faces the outer circumferential surface of the photoreceptor drum 12, and the attachment position of the detector 25 is as described above. For example, the regulating blade 15 may be attached to the developing section 9 side.

FIG. 1 shows an electric field applied to the developer concentration detector 25 used in an image forming apparatus according to an embodiment of the present invention and a transparent conductive window member 34 constituting the developer concentration detector 25. The above-mentioned AC power supply AC38 and DC power supply DC37 are connected in series to the transparent conductive window member 34, and the AC power supply AC38 and the DC power supply DC37 are connected in series to the transparent conductive window member 34. and DC power supply DC
37, an alternating current electric field in which a direct current electric field is superimposed is applied to the transparent conductive window member 34.

In the image forming apparatus configured as described above, the AC power supply AC 38 is connected to the transparent conductive window member 34 as described above.
The reason why it was decided to connect the and DC power supply DC37 in series and apply an alternating current electric field in which a direct current electric field was superimposed to the transparent conductive window member 34 using these two power supplies is as follows.

That is, 1. As described above by the present inventors, the transparent conductive window member 3
An alternating current power source AC3g and a direct current power source DC37 are connected in series to the transparent conductive window member 3.
When an experiment was conducted by applying an AC electric field with a DC electric field superimposed on the toner 22 attached to the transparent conductive window member 34,
In addition to rubbing against the transparent conductive window member 34 by the raised portion of the developer layer formed on the outer peripheral surface of the developing sleeve 13 by the magnetic pole of the magnet roller 14, the transparent conductive window member 34 is made transparent by applying the electric field. Conductive window member 3
The toner 22 is also removed by the vibrations of the toner 22 itself generated between the developing sleeve 13 and the developer sleeve 13. Therefore, the developer concentration detection width in the transparent conductive window member 34 described above is also the same as that shown in FIG. 8B as shown in FIG. 1A. It was found that the size was significantly larger than that shown in the figure. Such a vibration phenomenon of the toner 22 occurs when the present inventors applied only a DC electric field to the transparent conductive window member 34, and when only an AC electric field or when the DC electric field is heavy as described above. The experiment was conducted separately when an alternating current electric field was applied, and the detection output response characteristics of the developer concentration detector 25 as shown in FIG. 6 were obtained. I also found that it can happen. In other words, as is clear from FIG. 6, the initial value of the developer concentration is set to 4W.
Set it to 10% and change it to 8W 10% for a while.
The response of the detection output of the developer concentration detector 25 when variable again to 4W 10% at Comparing and contrasting the two methods (shown in the figure), it was found that the response was better when an alternating current electric field was applied.

As is clear from the above-described contents, according to one embodiment of the present invention, an AC electric field or an AC electric field with a DC electric field superimposed thereon is applied between the transparent conductive window member 34 and the developing sleeve 13. Therefore, the transparent conductive window member 3
The detection range of the developer concentration in 4 can be greatly expanded compared to the conventional one, and as a result, it is possible to sufficiently receive the diffusely reflected light from the developer, and the light amount efficiency is improved. First, the response of the detection output is good, and furthermore, by vibrating the toner 22, the developing sleeve 1
Since the adhering toner 22 can also be removed from the parts of the transparent conductive window member 34 where the raised portions of the brush of the developer layer formed on the outer peripheral surface of the developer layer 34 do not rub, it is possible to remove the toner 22 adhered to the part of the transparent conductive window member 34, which is formed on the outer peripheral surface of the developer layer. Concentration detection is now possible.

By the way, as mentioned above, the output signal from the light-receiving element sensor means 32 included in the developer concentration detector 25 according to the embodiment of the present invention having the configuration shown in FIG. 3 is shown in FIG. The output signal has a developer concentration-output signal voltage characteristic as shown in FIG. The signal is output from the circuit 24. However, there is a possibility that a change in the amount of light may occur in the light emitting element means 31 or a drift may occur in the light receiving element sensor means 32 due to changes in the environment or the like.

Therefore, in view of the above-mentioned facts, it was decided to improve the developer concentration detector 25 shown in FIG. 3 as shown in FIG. 4. That is, as shown in FIG. 4, a groove portion having an S-shaped cross section is formed in the detector frame 26, and a bidirectional light emitting element means is adopted as the light emitting element means 31 shown in FIG. and the bidirectional light emitting element means 3
A reference reflecting plate 36 is provided for reference on the side opposite to the slit 35 side of 1, and a light receiving element sensor means 33 having the same characteristics as the light receiving element sensor means 32 for receiving the reflected light from the reference reflecting plate 36 is provided. Bidirectional light emitting element means 3
1 is detected by the light receiving element sensor means 33, and an output signal (2) corresponding to the change in the light amount of the bidirectional light emitting element means 31 is obtained from the sensor means 33. Then, by using the output signal (2) as a reference voltage signal of the comparison circuit 24, a logic level signal is output from the comparison circuit 24 according to the difference between the reference voltage signal and the output signal (2) from the light receiving element sensor means 33. The toner 22 is output from the hopper section 20 to the developing section 9 according to the logic level signal.
The decision was made to either replenish or suspend supply. Note that the developer concentration detector 25 having the above-mentioned configuration is connected to the developing sleeve 13.
The present invention can also be applied to an image forming apparatus that employs a so-called jumping development method in which development is performed by applying an electric field containing an alternating current component to the side.

As described above, according to the present invention, a transparent conductive window member is provided at a portion of the developer concentration detection means that faces the outer circumferential surface of the developer carrying member, and the transparent conductive window Since an electric field containing at least an alternating current component is applied to the member, the concentration of the developer in the developing means is detected at a response speed that can sufficiently respond to variations in the concentration of the developer in the developing means. Accordingly, it is possible to provide an image forming apparatus that is capable of detecting developer concentration with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a main part of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a partial vertical sectional view showing a developing device and a photosensitive drum of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a longitudinal sectional view showing the structure of a developer concentration detector used in an image forming apparatus according to an embodiment of the present invention. FIG. 4 is a longitudinal sectional view showing the structure of a developer concentration detector used in an image forming apparatus according to another embodiment of the present invention. FIG. 5 is a diagram showing the developer concentration-output signal voltage characteristic of the light receiving element sensor means of the developer concentration detector used in the image forming apparatus according to the present invention. FIG. 6 is a diagram showing the detection output response characteristics of the developer concentration detector used in the image forming apparatus according to the present invention. FIG. 7 is a partial vertical sectional view showing a developing device and a photosensitive drum of a conventional image forming apparatus. FIG. 8 is a partial vertical sectional view showing a developer concentration detector and a developing sleeve of a conventional image forming apparatus. ll: Developing device 12: Photosensitive drum 13: Developing sleeve 25: Developer concentration detector 34: Transparent conductive window member 37: DC power supply DC Fig. 1Δ Fig. 2 Fig. 3 Steel Fig. 4 Fig. 5> Development Agent concentration (W+'/,) Fig. 6 O-sleeve rotation time - Fig. 7

Claims (1)

[Scope of Claims] 1) An image carrier, and a developer carrier that accommodates a two-component developer having toner and a carrier and conveys the two-component developer to the image carrier. a developing means comprising a member for converting an electrostatic latent image formed on the image carrier into a visible image; and a developer disposed at a position facing the outer peripheral surface of the developer carrying member and carried by the developer carrying member. a developer concentration detection means for detecting the concentration of the developer by irradiating the developer with light and receiving reflected light reflected from the developer; The image forming apparatus controls the developer concentration within the developing means in accordance with a signal output from the developing means, wherein a transparent conductive member is provided at a portion of the developer concentration detecting means that faces the outer circumferential surface of the developer carrying member. 1. An image forming apparatus characterized in that a transparent conductive window member is provided, and an electric field containing at least an alternating current component is applied between the transparent conductive window member and the developer carrying member. 2) The image carrier is a rotatably supported photosensitive drum, and the toner of the two-component developer is made by melt-mixing a transparent resin, an organic pigment or dye, and a small amount of a control agent. 1
The carrier of the two-component developer is an insulating carrier made of a magnetic material with low diffuse reflectance coated with silicone or fluorine acrylic resin. The image forming apparatus according to claim 1, wherein an image forming apparatus is used. 3) A patent characterized in that a magnetic brush development method or a jumping development method is adopted as a development method for converting the electrostatic latent image formed on the image carrier by the development means into a visible image. An image forming apparatus according to claim 1 or 2. 4) The developer concentration detection means includes a light emitting element means for irradiating light toward the developer on the outer peripheral surface of the developer carrying member through the transparent conductive window member; The patent is characterized in that it is equipped with a light-receiving element sensor means that receives the reflected light that is reflected and enters through the transparent conductive window member and outputs an electric signal according to the amount of the received reflected light. An image forming apparatus according to any one of claims 1 to 3. 5) The developer concentration detecting means is configured to irradiate light toward the developer on the outer peripheral surface of the developer carrying member through the transparent conductive window member and on the opposite side of the developer carrying member. bidirectional light emitting element means for irradiating light also to the side; and a bidirectional light emitting element means for receiving reflected light reflected by the developer and incident through the transparent conductive window member, and generating electricity according to the amount of the received reflected light. a light receiving element sensor means for outputting a signal;
Other light receiving element sensor means having the same characteristics as the light receiving element sensor means for receiving light emitted from the bidirectional light emitting element means on a side opposite to the side of the developer carrying member and outputting an electric signal according to the amount of the received light. The image forming apparatus according to any one of claims 1 to 3, further comprising a light receiving element sensor means.