JPS62156674A - Electrophotographic recorder - Google Patents

Abstract

PURPOSE:To obtain a continuous variation to attain a high gradation by controlling the voltage value applied to a slit electrode to control the quantity of toner passing a slit. CONSTITUTION:When a light beam is projected from the transparent supporting body side of a photosensitive body through a polygonal mirror 7 and an f-theta mirror 8 at an image recording time, the light part has conductivity partially, and a minus electric charge having the polarity opposite to that of the electric charge charged from a transparent electrode 1b, which is biased to a negative voltage by a power source E2, by a doctor blade 10 is charged to a toner 4 in the light part, and an electrostatic force acts upon the toner 3 from a transfer roll electrode 3, and the toner is filed toward a recording medium 2. A voltage which has the same polarity as the electric charge charging the toner and corresponds to the variable density signal of the image is applied from a voltage applying means 12 to a slit electrode 11 between a photoconductive layer 1c and the recording medium 2 to control the quantity of the toner 4 passing a slit 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is used in copying machines, facsimile machines, optical printers, etc., and particularly relates to an electrophotographic recording device that performs gradation recording.

(Prior Art) Conventionally, methods for recording gradation in thermal head printers, dot printers, laser printers, etc. include density gradation method and area gradation method.

For example, in the density pattern method of the area gradation method, one pixel of an original image having gradations is made to correspond to a submatrix of NXN dots of a printer, and the density is changed depending on the number of dots printed in the matrix. i.e. 1
This method corresponds multiple output pixels to human pixel data. A density matrix pattern set for each gradation level is prepared, and the matrix pattern corresponding to the gradation level of the input pixel data is created two-dimensionally. Output to . For example, in the case of a 4x4 matrix pattern,
Depending on the gradation level of the input pixel, any pattern from PO to PIB is output as 4×4 dots, and in this case, there are 17 gradations.

(Problems to be Solved by the Invention) In the density pattern method described above, since the size of the output dot is finite, increasing the number of dots in one matrix pattern in order to obtain a high gradation will reduce the resolution. Conversely, in order to obtain high resolution, the number of dots within one matrix pattern must be reduced, that is, the gradation must be sacrificed.

The purpose of the present invention is to reduce the number of steps and print time by using a method of directly transferring toner to recording paper, which was previously proposed by the applicant as a means of reducing the number of steps and printing time. An object of the present invention is to provide an electrophotographic recording device that can obtain the desired tone.

(Means for Solving the Problems) A feature of the present invention is that charged toner is transported along the surface of a photoconductive layer of a photoreceptor consisting of an insulating transparent support, a transparent electrode, and a photoconductive layer, and a transparent In an electrophotographic recording device in which a light beam is irradiated onto a photoconductive layer from the support side, and the toner in the bright area irradiated with the light is transferred to a recording medium via a transfer means, there is a ,
A slit electrode having a slit through which the toner can pass is arranged, and a means for applying a voltage having the same polarity as the flying toner and varying in accordance with the gray level signal of the image is connected to the slit electrode. There it is.

(Function) While the toner in the bright area located on the surface of the photoconductive layer that is irradiated with light flies toward the recording medium due to the electrostatic force from the transfer means, some of the toner is removed by the voltage applied to the slit lightning. The toner particles are repelled and cannot pass through the slits and return to the surface of the photoconductive layer, and only the toner that has passed through the slits is transferred onto the recording medium. One dot corresponds to one manual pixel data, and the voltage applied to the slit electrode is a voltage value corresponding to the gray signal of one manual pixel.The gradation is obtained by the amount of toner attached to each dot, so the resolution can be improved. High gradation can be obtained without sacrificing.

(Example) An example of the electrophotographic recording apparatus according to the present invention will be described based on the following aspects.

FIG. 3 shows a principle diagram of an electrophotographic recording apparatus according to the present invention. The photoreceptor 1 has a three-layer structure, in which a transparent electrode 1b is formed on the upper surface of an insulating transparent support 1a such as glass,
A photoconductive layer IC is formed on the upper surface of this transparent electrode. A recording medium 2 is conveyed in close proximity to the photoconductive layer IC, and a transfer roller electrode connected to a power source E1 is disposed behind the recording medium 2 as a transfer means 3. Charged toner 4 is conveyed on the surface of photoconductive layer 1c of photoreceptor 1, and in this example, toner 4 is positively charged. A light beam 6 emitted from a light source (not shown) and modulated according to, for example, image character information is emitted onto a light irradiation section 5 of a photoreceptor 1 located opposite to a transfer means 3 with a recording medium 2 in between. When irradiated from the side of the transparent support 1a through a light irradiation means such as a polygon mirror 7 or an f-θ mirror 8, the bright part of the photoconductive layer IC that has been irradiated with light partially becomes conductive, and the bright part Charges of opposite polarity are injected into the toner 4 from the transparent electrode 1b, which is biased to a negative voltage by the power source E2, through the bright portion of the light irradiation portion 5 of the photoconductive layer IC. In the bright area, an electrostatic force is applied from the transfer means 3 to the four toners injected with charges of opposite polarity, and the toners are transferred onto the recording medium 2.

In other words, the photoreceptor 1 is exposed to light without being pre-charged, and the toner 4 is
is directly transferred to the recording medium 2.

FIG. 1 shows an embodiment of an electrophotographic recording apparatus based on the above principle of the present invention.

A toner container 9 is disposed at one end of the photoconductive layer 1c of the photoreceptor 1, and a doctor blade 10 connected to a power source E3 is disposed within the toner container 9. The toner 4 stored in the toner container 9 is transported along the surface of the photoconductive layer IC toward the light irradiation unit 5, while its layer thickness is adjusted by the doctor blade 10, and a positive charge is injected into the toner 4. Becomes positively charged. A recording medium 2 is conveyed closely facing the surface of the photoconductive layer 1c of the photoreceptor 1, and a transfer roller electrode 3 serving as a transfer means is provided behind the recording medium 2, facing the light irradiation section 5. The transfer roller electrode 3 is connected to a power source E1. Photoreceptor 1
A light beam 6 emitted from a light source (not shown) and modulated according to image character information is irradiated onto the light irradiation unit 5 via a light scanning means consisting of a polygon mirror 7 and an f-θ mirror 8. Ru. Further, a slit electrode 11 is interposed between the photoconductive layer IC and the recording medium 2, and a slit 11a is provided in the middle of the toner flight path facing the light irradiation section. The slit 11B is narrow and extends in the width direction of the recording paper. A voltage applying means 12 applies a voltage to the slit electrode 11 that has the same polarity as the charged toner 4 and corresponds to the density signal of the image.

When recording an image, when a light beam is irradiated from the transparent support side of the photoreceptor through the polygon mirror 7 and the f-theta mirror 8, the bright areas irradiated with light partially exhibit conductivity,
A negative charge having a polarity opposite to that injected by the doctor blade 10 is injected into the toner 4 in the bright area from the transparent electrode 1b which is biased to a negative voltage by the electric current K E 2. Electrostatic force acts from the transfer roller electrode 3 on the negatively charged toner 4 injected with negative charges of opposite polarity, and the toner flies toward the recording medium 2. However, a slit electrode 11 is interposed between the photoconductive layer 1c and the recording medium 2, and a voltage is applied to the slit electrode 11 by means 12, which has the same polarity as the charge on the toner.
And since a voltage corresponding to the gray level signal of the image is applied,
The amount of toner 4 passing through the slit 11a is controlled.

That is, when recording a dark image, a correspondingly lower voltage is applied to the slit 11, so that most of the toner 4 flying toward the recording medium is transferred to the slit 11).
, and is transferred to the recording medium 2 to record a dark image. When recording a pale image, a correspondingly high voltage is applied to the slit electrode 11, and for this reason, most of the toner 4 that has flown toward the recording medium 2 is repelled by the slit electrode 11 and passes through the slit lla. Only a small amount of toner passes through the slit lla and is transferred to the recording medium 2, resulting in a pale image recording. Since the voltage is continuously variable, the amount of toner 4 that can pass through the slit lla can be continuously controlled.

Furthermore, gradation can be obtained by the amount of toner deposited on each dot, and since the amount of toner deposited is continuously variable, high gradation can be obtained and the resolution will not deteriorate.

In this way, the photoconductor is exposed to light without being charged beforehand, and the toner 4 in that part flies toward the recording medium 2, and a part of it becomes a slit in response to the voltage applied to the slit electrode 11.
The toner 4 passes through the slit lla, and the rest returns onto the photoreceptor, and only the toner 4 that passes through the slit lla is transferred to the recording medium 2.

In FIG. 1, members that are substantially the same as those in the principle diagram shown in FIG. 3 are given the same reference numerals.

FIG. 2 shows another embodiment of the present invention, in which a slit electrode 101 is provided with a slit 101a, and a positioning protrusion 101b is provided in front of the light irradiation section 5 so as to contact the recording medium 2. It also functions as a positioning member for the recording medium 2. This allows the distance between the toner 4 and the recording medium 2 to be controlled with high precision. Light irradiation part 5
A gap is provided behind the toner 4 so that the toner 4 transferred to the recording medium 2 does not come into contact with the toner 4 . The other structures are the same as those shown in the first figure.

Further, in FIG. 2, members that are substantially the same as those in the embodiment shown in FIG. 1 are given the same reference numerals.

(Effects of the Invention) As described above, according to the electrophotographic recording device according to the present invention, by controlling the voltage value applied to the slit electrode, the toner can fly from the photoreceptor toward the recording medium. It is possible to control the amount of toner that can pass through the slit during the process, and it is possible to obtain a continuous change in the amount. Since the gradation is obtained by the amount of toner adhered to each dot, high gradation can be obtained without deteriorating the resolution. Further, when the recording medium is positioned by bringing the slit electrode into contact with the recording medium in front of the light irradiation section, the positional accuracy of the recording medium can be easily obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of one embodiment of the present invention, FIG. 2 is a sectional view of a main part of another embodiment, and FIG. 3 is a principle diagram of an electrophotographic recording apparatus according to the present invention. 1... Photoreceptor, 1a... Transparent support, 1b.
...transparent electrode, IC...photoconductive layer, 2...recording medium, 3...transfer means, 4...□toner,
6... Light beam, 11.101... Slit electrode, 11a, 101a-medium φ slit, 101b... Positioning protrusion, 12... Means for applying voltage. that's all

Claims (1)

[Scope of Claims] Charged toner is conveyed along the surface of the photoconductive layer of a photoreceptor comprising an insulating transparent support, a transparent electrode, and a photoconductive layer, and the photoconductive layer is conveyed from the side of the transparent support. In an electrophotographic recording apparatus in which a layer is irradiated with a light beam and the toner in a bright area irradiated with the light is transferred to a recording medium via a transfer means, the toner is A slit electrode having a slit through which the toner can pass is arranged, and a means for applying a voltage to the slit electrode that has the same polarity as the charge of the flying toner and changes in accordance with the density signal of the image. An electronic photographic recording device characterized in that: