JPS58127954A - Electrostatic recorder - Google Patents

Abstract

PURPOSE:To assure accurate controlling by disposing an original platen for placing of originals thereon, and a scanning optical system including a light source for exposure of originals provided so as to face the original platen relatively movably. CONSTITUTION:An electrostatic recorder consists of a stationary original platen 1 consisting of glass, an origi cover 2 which is hinged to the machine frame so as to be opened or closed, a semitransparent original 3 to be copied, etc. The platen 1 and a light source 4 for exposure of originals provided by facing the plate 1 are disposed relatively movably. Said optical system is moved forward in a nonenergized state, and when the system arrives at the neighborhood of one end part of the original, the light emitted by an illuminating means which emits light already is detected with a photodetector, whereby the accurate controlling is assured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a static recording device such as an electrophotographic copying device or a device that utilizes the principles of electrophotography, and specifically relates to:
For example, even if a thin original is in the form of a sheet of 45 yen paper or less, it will appear as a band or line on a recording medium made of photoconductive insulator due to shadows occurring at the leading edge and/or trailing edge. The present invention relates to an electrostatic recording device configured to reduce or eliminate toner adhesion that tends to occur.

For convenience, an electrophotographic copying device will be taken as an example to clarify the problems related to the present invention. In order to improve the copying speed or make the copy more compact, recent electrophotographic copying machines have been designed to keep the document table fixed while scanning by moving the optical system including the light source for exposing the document.
A format in which an electrostatic charge pattern corresponding to the original to be copied placed on the original platen is created on a recording medium; (11) an original placed along a second original light source in a fixed state; It is well known that the mainstream method is to create an electrostatic charge pattern by moving a table and guiding light reflected from the document onto a recording medium through a predetermined optical system.

However, regardless of which type of copying device is used,
Due to various factors such as the positional relationship between the document scanning system, that is, the document table and the light source for exposing the document, and especially the irradiation angle of the emitted light accompanying the activation of the light source with respect to the document surface, the leading edge and/or trailing edge of the document. Shadows tend to appear at the edges, and as a result, the amount of light that hits the recording medium corresponding to these areas is insufficient, and during the development operation, toner adheres there, making the recorded matter ugly. Although it has a drawback, it is good. In order to eliminate such problems, for example, in a device such as a transfer type copying device that is configured to transfer the toner image on the recording medium onto a transfer material such as plain paper and fix it to obtain a recorded matter, A possible solution to this problem would be to use a transfer material of a size that matches the size of the original and to use a control system to ensure that the image range correctly overlaps with the image area on the recording medium. Alternatively, one electrode in the developing device (for example, in a magnetic brush type developing device, a non-magnetic and electrically conductive sleeve used for conveying developer) is applicable. ) is disposed facing the recording medium and the so-called bias voltage applied thereto is reduced, thereby solving the above problem. I have 1 strength,
The former method is affected by external factors such as unstable driving of the transfer material feeding thread (control system) and slipping of the transfer material during feeding, so it is difficult to obtain accurate superimposition. Even if it is theoretically possible, it is extremely difficult in practical terms.

Furthermore, this problem becomes even more obvious when considering the case where a transfer material larger than the size of the original is used and the margin outside the original image area is used as a memo field. In addition, although the latter method is effective, it may have to be operated each time depending on the thickness of the original, resulting in poor operability, or if the bias voltage is increased, the desired optical density cannot be achieved. There is a risk that a satisfactory image may not be obtained, and this is not a fundamental solution. In addition, as one form of the apparatus, for example, the amount of displacement of the exposure light source is set to be longer than the length of the document table, which is usually made of glass, and the pressure is controlled so that exposure scanning is performed after the amount of light has stabilized. A device configured as shown above is known, but it has been found that even this type of device causes the problem of marking.

An object of the present invention is to provide an electrostatic recording device that reduces or eliminates the drawbacks of conventional devices as described above, and specifically includes a document table for placing a document to be copied; A scanning optical system including a light source for exposing the original, which is provided opposite to the original table, is disposed so as to be relatively movable, and an illumination means is provided integrally with the original holding cover, and at least one of the above-mentioned original exposure is provided during operation. When the light emitted from the light source reaches the leading edge and/or trailing edge of the document, the illumination means is controlled to be energized within the same time period when the light emitted from the light source reaches the leading edge and/or trailing edge of the document. It is an object of the present invention to provide an electrostatic recording device configured to eliminate charges previously applied to a corresponding recording medium and eliminate the appearance of shadows caused by the thickness of a document.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below using an electrophotographic copying apparatus as an example with reference to the accompanying drawings. In FIG. 141, which schematically shows each well-known process, it has been omitted since it is not directly related to the present invention. 1 is a fixed document table made of glass installed on a part of the upper surface of the device frame (not shown); 2 is a document holding cover c that is connected with a hinge or the like so that it can be opened and closed with respect to the machine frame; ), 3 indicates the translucent liangnan to be copied. Reference numeral 4 denotes a light source for exposing the original (hereinafter simply referred to as the @ light source), which is oriented so that the emitted light can come into contact with the original table (or original surface) at an acute angle α, as shown in FIG. ing.

5, 6.7.8, and L are scanning optical systems provided below the document table, and specifically, the light source 4 for exposure.
A first reflecting mirror 5 that receives reflected light from the original 3 due to the change in direction and changes its direction, a second reflecting mirror 6 that is spaced apart from the first reflecting mirror and has a parallel trap, and the @2 reflecting mirror. A third reflecting mirror 7 and a fourth reflecting mirror 8 are attached so as to form an approximately square shape, and an imaging lens L is provided between the third reflecting mirror and the fourth reflecting mirror. In the embodiment shown in FIG. 1, the first reflecting mirror 5 integrally moves back and forth parallel to the document table l at a speed V while maintaining the relationship shown in the figure with the exposure light source 4 and the light-shielding film S formed thereon. It is structured like a vine. Further, lI2 and the third reflecting mirrors 6 and 7 are also integrally constructed, and are controlled by appropriate means so that they reciprocate in the same direction at a speed of 3 AV of the first reflecting mirror. D indicates a rotary drum having a known selenium-tellurium vapor deposited film or a binder type photosensitive layer on its surface. Reference numeral 9 denotes an illumination means attached to one side of the document table 2, that is, the platen on the side in contact with the document 3.
The leading edge (that is, the scanning start side by the exposure light source 4; the left edge in FIG. 1) and the trailing edge (in FIG. It has a large area that covers the right end). However, if the placement reference surface of the document placed on the document table is determined, only the portion corresponding to the leading edge and/or trailing edge depending on the desired document size is K.
An illumination means is provided, and during recording (copying) operations,
A trap control may be performed to energize the illumination means only at a predetermined time based on the output signal from an appropriate document size detection means, or if the device is equipped with a microcomputer, the document size or transfer Of course, it is possible to control so that the illumination means is energized only in necessary parts according to the silogram selected according to the size of the material.

If such control is applied, and the explanation is based on the embodiment shown in FIG. (see Figure 2), and therefore, the light emitted from the exposure light source is superimposed at the same time, slightly before it reaches the leading edge of the document. K to do it,
(See Figure 3) Control is essential.

The operating sequence of the embodiment configured as described above will now be described. Place the original 3 at a predetermined position on the original platen 1, and press the operation port on the operation panel (not shown) to turn on the exposure light source, and move it from the position shown in FIG. 1 to the right side at the same speed as the first reflecting mirror 5. Move.

Start exposure scanning. After a predetermined period of time, the illumination means is energized and the light emitted from the light source is superimposed immediately before or at the same time as reaching the leading edge of the document, and the light is exposed as shown in FIG. The slit S1 is guided onto the photosensitive drum D in a rotating state 11 via an optical system including the first reflecting mirror 5.

As is well known, a charge is applied to the photosensitive drum D in advance, and therefore, in other words, according to the luminous flux,
As shown by the diagonal lines in Figure 2, the charge on the photosensitive drum corresponding to the shadow area created by the relationship between the thickness of the original and the irradiation angle of the single-light source is dissipated, resulting in the development process. This eliminates unnecessary toner from adhering to the corresponding portions of the following sections.

Thereafter, the reflected light from the document is sequentially guided onto the photosensitive drum D through the mirror groups 5, 6, 7 and 8, which move in the same direction at a predetermined speed ratio to maintain the optical path length as described above.
Therefore, an electrostatic charge pattern corresponding to the original is continuously created on the photosensitive drum. When scanning of the document via the light source 4 and the optical system is completed, these movable members move back to the left so as to restore the positional relationship shown in FIG.

On the other hand, as is well known, the transfer material (IA not shown) sent in synchronization with the recording operation passes through the transfer process while overlapping the image area on the photosensitive drum, and is transferred onto the photosensitive drum by the operation of the transfer means. retains the toner that is transferred from the toner. Thereafter, it is separated from the photosensitive drum by appropriate means, passed through a fixing process, and discharged outside the machine to be used as a recorded material. After passing through the transfer process, the toner remaining on the photosensitive drum is removed by an appropriate cleaning means in the form of a fur brush or blade, and the residual charge G on the photosensitive drum is removed by a corona discharge electrode using an AC voltage. It is neutralized by a static eliminating means such as the like, and preparation for the next recording operation is now completed.

As mentioned above, since the illumination means 9 eliminates the problem of shadows, it is possible to create a state in which the leading edge of the transfer material is skewed so that it protrudes beyond the leading edge of the image area formed on the photosensitive drum. Even if the size of the transfer material is larger than the size of the original,
For example, even if the document l#whale is positioned in the center, an image without excess toner adhering to the recording medium or transfer material can be obtained.

The above explanation is based on a 9-dimensional moving format electronic copy with a fixed manuscript table.
Although the X copying machine has been described as an example, the former can be made movable,
It goes without saying that the present invention can be applied even to devices in which the latter is in a fixed state, and in which the document table is fixed and the optical system is moved. Scan the original while keeping it fixed and horizontal.
It can also be applied to devices that form images. Furthermore, the present invention has a function as a device that uses the principles of electrophotography, for example, a copying device, and uses a CRT or the like on top of it!
Convert the air signal into an image and make a copy if necessary. Further, the present invention becomes more advantageous when combined with the following devices.

That is, by integrally providing a light receiving element at an appropriate location related to the source 4 for the source 4 in FIG. 1, and pressing the recording operation,
Once the illumination source light source is moved forward in a non-energized state, and when it reaches the vicinity of one end of the document (the trailing edge of the document), it emits light at 1j. , received light at [
,・Soσ゛) output for scanning of the optical system (I! light source)
II (corresponds to the original size), inputs it into the memory circuit, automatically selects the program installed in the micro combinator, and during the subsequent main scan,
This aims to eliminate unnecessary movements and ensure more accurate control than control by mechanical means such as microswitches.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing only the main parts of an embodiment of the present invention, FIG. 2 is an enlarged schematic diagram for explaining the shadows at the edge of a document that occur in a conventional electrostatic recording device, and FIG. 3 is an enlarged schematic diagram illustrating the application of the invention to remove the shadow appearance of FIG. 2; FIG. 1... Original table, 2... Original holding cover ~ 3...
Original, 4... Light source for exposing the original, 5, 6.7 and 8... 1st. $12, third and fourth reflecting mirrors, 9... illumination means D... recording body 1 L... imaging lens, B... slit. Agent Yoshimi Kuwabara 1 illustration

Claims (4)

[Claims] (1) A manuscript table for placing the manuscript to be copied;
Providing an illumination means for exposing the original, which is provided opposite to the original table;
Further, during operation, at least the light emitted from the document exposure light source is directed to the leading edge of the document and/or! ! By controlling the illumination means to be energized within approximately the same time period as the illumination device reaches the trailing edge of the document, the charge applied in advance on the recording medium corresponding to the edge gK of the document is extinguished. to remove the shadow WA (D appearance) caused by the thickness of the original.
An electrostatic recording device characterized by the following. (2) The electrostatic recording device according to claim 1, wherein the illumination means is electroluminescence. (3) A special feature characterized in that the illumination means described in Ir7I has a width that covers almost the entire surface of the document table! F## The electrostatic recording device according to the desired range item 1 or 2. (4) The document table is fixed, and the scanning optical system is configured to reciprocate in parallel with the document table, and is controlled to have a speed ratio of 2:1.
2. The electrostatic recording device according to claim 1, comprising a movable mirror.