JPS63307472A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce the photographic fogging and to improve the margin of photographic fogging by using a rectangular wave voltage as the recording voltage in a device where development is performed simultaneously with exposure. CONSTITUTION:A photosensitive film 21 is carried in the direction of an arrow and a magnet roll 23a of a magnetic brush developing device 23 is rotated and a developer 26 is carried in the direction of the arrow. A minus rectangular wave voltage is applied from an electrode 27 to a recording electrode 25 and a sleeve 23b synchronously with the image exposure timing of an LED array optical system 29. Then, a toner image 30 is formed and a toner image 34 is transferred and fixed to a recording paper 31 to obtain a recorded image 36. At this time, the electrostatic charge of a remaining toner image 37 is removed by a destaticizing light source 38, and the next image is formed simultaneously with the recovery of a remaining toner 39. Consequently, the photographic fogging of the toner image is reduced and the margin of photographic fogging is increased because the recording voltage is not applied to the photoconductive layer of the photosensitive body until the exposure of the next picture element is started after the end of exposure of one picture element.

Description

Detailed Description of the Invention [Summary] The present invention provides an image forming apparatus that performs development at the same time as image exposure, by setting the first recording voltage applied to the recording electrode to be a rectangular wave voltage. Prevents the agent from adhering to the printed background part of the photoreceptor, reduces fog,
It also has a larger fogging margin.

[Industrial application field]

The present invention relates to an image forming principle in which a toner image is formed in a bright area on a photoreceptor irradiated with image light and transferred to display or recording paper.

Current copying machines and high-speed, high-printing quality printers generally use an electrophotographic recording method. In this method, a photoreceptor is used as a recording medium, and recording is performed through the steps of uniform charging, image exposure, development, transfer, fixing, neutralization, and cleaning. This is the so-called Carlson process.

The Carlson process uses a corona discharger for uniform charging, transfer, and static elimination. Since the corona discharger is configured to apply a high voltage of several kilovolts to the corona wire, it requires a high-voltage power source and is easily affected by humidity, dust, etc., so it has the disadvantage of low reliability. In addition, the toxicity of ozone generated in corona dischargers to the human body has become a problem.

Furthermore, since the above-mentioned seven steps are required, there is a drawback that the apparatus becomes complicated and large.

Recently, in view of the above problems, an image forming method has been proposed that eliminates the need for a corona discharger and focuses on miniaturizing the apparatus.

Therefore, the present invention provides one of the methods, % formula % [Conventional technology] FIG. 6 shows a schematic diagram of the prior art.

In the figure, a photoreceptor 1 includes a transparent substrate 1a and a transparent conductive layer 1b.
, a photoconductive layer 1c, and a transparent conductive layer N1b is connected to ground. The magnetic brush developing device 2 provided on the photoconductive layer lc side of the photoreceptor 1 consists of a magnet roller 2a and a sleeve 2b, and the magnet roller 2a is freely rotatable. Furthermore, a strip-shaped recording electrode 4 is provided on the surface of the sleeve 2b and is insulated from the sleeve 2b with an insulating film 3. A voltage 6 having a polarity opposite to the carrier polarity (positive polarity in the figure) of the photoconductive layer 1c is applied to the recording electrode 4, and a voltage 7 having a polarity opposite to that of the recording electrode 4 is applied to the sleeve 2b. The developing machine 2 is filled with a one-component developer or a two-component developer, and the developer 5 is conveyed in the direction of the arrow in the figure.

Image exposure means 8 is arranged on the transparent substrate 1a side of the photoreceptor 1. The WM image exposure means 8 includes an optical system using an LED, an optical system using a liquid crystal shutter, an optical system using electroluminescence, an optical system using a laser, etc. The recording electrode 4 is arranged so that the optical axis of the exposure light intersects with the recording electrode 4.

Next, the principle of image formation will be explained.

In the A section of the apparatus having the above configuration, when the photoconductive layer 1c is imagewise exposed, photocarriers are generated in the photoconductive layer lc. Among the photocarriers, carriers having a polarity opposite to the voltage 6 applied to the recording electrode 4 move to the surface of the photoconductive layer 1c and form an electrostatic latent image 9. In this way, in the exposed area (A), since the capacitance of the photoconductive layer 1c apparently increases, the amount of adhering toner increases, and a toner image with a certain degree of contrast is created between the exposed area and the non-exposed area. becomes.

Next, in section B, by applying a reverse voltage 7 to the sleeve 2b and creating a reservoir of developer, excess toner in the non-exposed section is collected into the magnetic brush developing device 2 by electrostatic force and magnetic force. At this time, a small amount of toner in the exposed area is also collected, but
Due to the electrostatic binding force between the latent image charge 9 and the toner charge, most of the toner remains on the photoreceptor 1, and a toner image 10 is formed.

[Problem that the invention seeks to solve]

In the conventional image forming apparatus shown in FIG. 6, the first recording voltage 6 applied to the recording electrode 4 is a direct current.

Therefore, an electric field is applied to the photoconductive layer 1c even when the image exposure means 8 is not performing image exposure.
As shown in FIG. 7, the charged toner adheres to the photoreceptor 1 due to the electrostatic force between the negatively charged developer on the surface of the photoreceptor 1 and the ten charges present on the transparent conductive layer 1c of the photoreceptor 1. As a result, during image exposure and simultaneous development (A part), more developer than necessary adheres to the printed background area on the photoreceptor, and it cannot be collected in the next stage of developer collection and development (B part), resulting in a slight problem. This has the drawback of causing fog, which deteriorates the contrast of the toner image 10.

[Means for solving problems]

FIG. 1 is a diagram explaining the principle of the present invention.

In the figure, 1 is a photoreceptor, and 8 is an image exposure means, which is the same as the prior art shown in FIG. The difference from the prior art is that in place of the conventional first voltage applying means 6, a voltage applying means 11 that generates a rectangular wave voltage is provided. This rectangular wave voltage applying means 11 is configured to generate a rectangular wave voltage in synchronization with the image exposure timing by a control system. That is, voltage is applied to the recording electrode 4 only while the image exposure means 8 is performing image exposure.

[Function] As described above, the configuration is such that a rectangular wave voltage is generated in synchronization with the image exposure timing, and the voltage is applied only when exposure is performed. That is, the recording voltage application timing is as shown in FIG. 5, and no recording voltage is applied to the photoconductive layer 1c from the end of exposure of one pixel to the start of exposure of the next pixel. In (Part A),
The developer adhering to the printed background portion on the photoreceptor 1 can be kept to a minimum, thereby reducing fog or increasing the fog margin.

〔Example〕

FIG. 2 shows an example in which the present invention is implemented in an image recording apparatus.

In the figure, 21 is an endless photoreceptor film. As shown in FIG. 3, this photoreceptor film 21 has a thickness of 100 μm.
- A transparent conductive layer 21b of ITO (indium oxide) vapor deposited film on a transparent substrate 21a of polyethylene terephthalate.
and a CGL (charge generation layer) as a photoconductive layer.
21c and a CTL (charge transport layer) 21d, it is a functionally separated type with a thickness of approximately 10 μm and is provided with a hole transfer type organic photoconductive layer. Photoreceptor film 2 as above
The first transparent conductive layer 21b is connected to ground, and the photoreceptor film 21 itself is conveyed in the direction of the arrow in the figure by a power system (not shown) connected to a film drive roller 22.

23 is a magnetic brush developing machine, and a magnet roller 23a provided inside is rotatable. As shown in FIG. 4, a strip-shaped recording electrode 25 made of W4WI and insulated with a polyimide film 24 is pasted on the surface of the sleeve 23b. A two-component developer 2 consisting of a conductive resin carrier and an insulating magnetic toner is installed in the magnetic brush developing machine 23 as described above.
6 is filled and conveyed in the direction of the arrow in the figure by rotation of the magnet roller 23b.

For the photoconductive layers 21c and 21d of this example, a genuine plate moving type was used. Therefore, a negative voltage is applied to the recording electrode 25 by a first power source 27 that generates a rectangular wave voltage. Further, a positive voltage is applied to the sleeve 23b by the second power supply 28. This voltage is DC, 0 to +50V
is appropriate.

An LED array optical system 29 is installed as an image exposure means at a position facing the magnetic brush developing device 23 with the photoreceptor film 21 in between. The LED array optical system 29 uses an LED array as an exposure light source and a SELFOC lens array as a condenser lens. The optical axis of the LED array optical system 29 is arranged so as to intersect the center of the recording electrode 25, which is set to have a width of 1 to 5 sm+.

The power supply 27 that generates the rectangular wave voltage is caused to generate the rectangular wave voltage in synchronization with the image exposure timing of the LED array optical system 29 by a control system (not shown). This situation is shown in FIG. 5, and a negative recording voltage is applied to the recording electrode 25 only while image exposure is being performed by the LED array optical system 29.

At this time, if the carrier mobility of the photoconductive layers 21c and 21d is high, the start and end of application of the recording voltage and the start and end of image exposure may be completely synchronized.
However, when the carrier mobility of the photoconductive layers 21c and 21d is small, it is necessary to take the photocarrier movement time into consideration and make the recording voltage application time longer than the image exposure time as shown in FIG. In addition, the voltage during exposure is -200V ~
-700V, the voltage during non-exposure was around Ov. however,
This voltage depends on the characteristics of the photoreceptor 21 and the developer 26.
It needs to be moved up and down.

30 is a toner image formed on the photoreceptor film 21. 31 is recording paper, commonly known as plain paper.
2 is a conductive rubber roller for transfer, to which a voltage (+200 to +600 V) is applied by a power source 33;
is a toner image electrostatically transferred onto the recording paper 31, which is fixed onto the recording paper 31 by a heat roller fixing device 35, and becomes a semi-permanent recorded image 36.

37 is a residual toner image remaining on the photoreceptor film 21 after transfer. 38 is the charge of the residual toner image 37 and the photoconductive layer 2;
This is a static eliminating light source that removes latent image charges in 1c and 21d. 39 is a toner image which has been neutralized and has lost its electrostatic binding force.

Next, the image recording procedure will be described.

By transporting the photoreceptor film 21 in the direction of the arrow and rotating the magnet roller 23a of the magnetic brush developing device 23, the developer 26 is transported in the direction of the arrow, and a voltage is applied to each of the recording electrode 25 and the sleeve 23b. Then, the LED array optical system 29 performs image exposure. Then (see FIG. 3), photocarriers are generated in the CGL 21c, and their internal pressure holes move within the CTL 21d to near the surface of the photoreceptor and become latent image charges. Based on the principle described in the section on prior art below, a charged toner image 30 held by the electrostatic force of the latent image charge is formed on the surface of the photoreceptor film 21.

Next, the toner image 30 is transferred to a recording paper 3 using a transfer roller 32.
1 is electrostatically transferred. The transferred toner image 34 is fixed onto the recording paper 31 by a fixing device 35, forming a semi-permanent recorded image 3.
6 is obtained.

On the other hand, the residual toner image 37 remaining on the photoreceptor film 21 after the transfer is neutralized using the static eliminating light source 38. The toner image 39, which has been neutralized and has lost its electrostatic binding force, is transferred to the magnetic brush developing device 2.
3, the scraping of the developer 26, and the electrostatic force caused by the voltage applied to the sleeve 23b collect and reuse the 0
The next image formation is performed at the same time as the residual toner image 39 is collected. There is no problem in collecting the residual toner image 39 and forming the next image at the same time, since the LED array optical system 29 and the developing device 23 are located opposite each other with the photoreceptor film 21 in between.

According to the embodiment described above, if a rectangular wave voltage is used as the recording voltage applied to the recording electrode 25 and the recording voltage is applied only during image exposure, exposure of the next pixel starts from the end of exposure of one pixel. Until then, the photoconductive layer 21c of the photoreceptor,
Since no recording voltage is applied to 21d, the amount of developer adhering to the printed background portion on the photoreceptor 21 can be kept to a minimum.

Compared to the conventional case where a DC voltage is used as the recording voltage, simply applying a rectangular wave pulse has an effect, but the effect is even greater when applied at the same time as exposure, and the toner image 30
It is possible to reduce fog and increase fog margin. As a result, the recorded image 36 formed on the recording paper 31 becomes a clear image with high contrast.

In the above example, a two-component developer consisting of a conductive resin carrier and an insulating magnetic toner was used, but other two-component developers, such as iron powder, ferrite, etc. Magnetic Toner Furthermore, even if a conductive magnetic toner or an insulating magnetic toner is used as the -component developer, the same effects as in the above embodiments can be obtained.

Photoreceptor materials are also organic materials, including phthalocyanine materials and
PVK-TNF, azo dye, thiapyrylium dye, etc.
As the inorganic material, it is possible to use a selenium-based photoreceptor, a-5t-CdS, zinc oxide, etc.

Furthermore, as an image recording process, in the above embodiment, the residual toner remaining on the photoreceptor after transfer was collected by a magnetic brush developing machine, but a recording process in which the residual toner is removed by a brush cleaner, blade cleaner, etc. may also be used. In the transfer process, a roller transfer method was used in the embodiment, but the same effects as in the above embodiment can also be obtained by using a corona transfer method.

Further, the present invention can be applied not only to an image recording apparatus as in the above embodiment, but also to a display apparatus in which a toner image is directly formed on a photoreceptor without a transfer step, and sufficient effects can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, a rectangular wave voltage is used as the recording voltage applied to the recording electrode, and the recording voltage is applied only during the time when image exposure is performed.

Note that since no recording voltage is applied to the photoconductive layer of the photoreceptor from the end of exposure of one pixel to the start of exposure of the next pixel, the amount of developer adhering to the printed background area on the photoreceptor is kept to a minimum of silver. be able to. Therefore, compared to the case where a DC voltage is used as the recording voltage, it is possible to reduce the fogging of the toner image and increase the fogging margin, so that a clear image with high contrast can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is a configuration diagram of an embodiment of the image recording apparatus of the present invention, FIG. 3 is a sectional view of the photoreceptor film of FIG. 2, and FIG. FIG. 5 is a diagram of the recording voltage application timing of the present invention, FIG. 6 is a schematic diagram of the prior art, and FIG. 7 is a diagram illustrating a state in which no image is exposed. In the figure, ■ is a photoreceptor, 3 is an insulating film, 4 is a recording electrode, 5 is a developer, 8 is an image exposure means, 9 is a latent image charge, 1O is a toner image, 11 is a square wave voltage application means, 21 is a Photosensitive film, 22 is a film drive roller, 24 is a polyimide film, 25 is a recording electrode, 26 is a developer, 27, 28, 33 is a power supply, 29 is an LED array, an optical system, 30, 34, 39 is a toner image, 31 is a recording paper, 32 is a transfer roller, 35 is a fixing device, 36 is a recorded image, 37 is a residual toner image, and 38 is a static elimination light source. f' go fr burushi masu digits - construction 2 illustrations 3 illustrations 4 figures

Claims (2)

[Claims] (1) Transparent substrate (1a), transparent or semitransparent conductive layer (
1b) and a photoconductive layer (1c).
), a magnetic brush developing device (2) disposed on the photoconductive layer side of the photoreceptor (1), and a record provided on the sleeve (2b) of the magnetic brush developing device (2) insulated from the sleeve. an electrode (4) and the recording electrode (
4) and a reservoir of developer (5) provided downstream in the moving direction of the photoreceptor (1); and a first voltage application means (6) for applying a voltage to the recording electrode (4). , a second voltage applying means (7) having a polarity opposite to that of the first voltage applying means (6) for applying a voltage to the sleeve (2b), and a second voltage applying means (7) on the conductive layer side of the photoreceptor (1) and on the recording Electrode (4)
In the image forming apparatus, the first voltage applying means (6) for applying a voltage to the recording electrode (4) is configured to generate a rectangular wave. An image forming apparatus characterized in that it is a voltage output means (11). (2) A control system for synchronizing the image exposure timing of the image exposure means (8) with the rectangular wave voltage output timing of the rectangular wave voltage output means (11). The image forming apparatus according to item 1).