JPH0450689Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field of the Invention] The present invention relates to a copying device that can copy both information written on a board and a manuscript placed on a manuscript table.

[Prior art]

Conventionally, in devices that make it possible to copy information written on a board, the board reading method generally uses a plane scanning method using a CCD sensor as a solid-state image sensor, and the recording method generally uses a thermal recording method. This type of digital method not only makes it impossible to copy written information on a blackboard onto plain paper;
Since the recording speed is low, it takes time to copy a large number of sheets, and the resulting recording density is about 6 dots/mm.

Therefore, a method of recording information written on a board using an electrophotographic method has recently been proposed. This type of method includes a method in which information written on a board is directly imaged on a belt or drum-shaped photoreceptor of a conventional electrophotographic copying machine, and is copied onto a plain paper transfer material using a known electrophotographic process. The information written on the board is imaged once on a field lens installed on a manuscript table, and the image is formed on a photoreceptor through an optical system in an electrophotographic copying machine, and then transferred to a transfer material using a known process. There are ways to make copies.

Both methods can copy the original placed on the manuscript table and the information written on the board onto plain paper, and have improved recording density compared to conventional digital methods. When obtaining a single copy, after copying a board document once, if the transfer material obtained by the copying is used as a copy original to make a second copy, there is no wastage of time due to the copying speed.

However, in both of the above conventional techniques,
When copying a board document and copying a document placed on a document table (hereinafter referred to as "board copy mode" and "document surface copy mode," respectively) using the same copying device, it is extremely difficult to obtain proper images for both. It was difficult.

A specific example of the above problem will be described below with reference to the drawings.

FIG. 1 is a perspective view for explaining an example of a conventional example, and FIG. 2 is a side view of the same. In the figure, reference numeral 1 denotes a white to light-colored flexible board member such as a wide synthetic resin belt, which is stretched between rollers 2 and 3. The board is substantially flat in the vertical direction, and is movable by rotating rollers 2 and 3 in the direction of the arrow. At this time, information written on the board is scanned and projected onto a photoreceptor by an optical system to be described later. Desired information is written on the board of the member 1 using an appropriate writing instrument on the side shown at A, and the information written on the board is written on a lamp at a position B, which is the opposite side from A, by rotation of rollers 2 and 3. 4 and is scanned.

Reference numeral 5 denotes a copying process section, which has an electrophotographic photoreceptor 7 inside a box 6 that rotates in the direction of the arrow. A photosensitive charging device, a developing device, a transfer charging device, and a cleaning device are provided along the rotation path of the photoreceptor 7. On the other hand, there is a means for supplying a transfer material to the transfer charging device position, or a means for supplying a transfer material to the transfer material. A fixing device for fixing the toner image is also provided at a predetermined position.
Since these are well known, their explanation will be omitted.

A movable document table 8 is attached to the upper part of the box body 6. In the original copy mode, an original to be copied such as a document is placed on this original table 8, and the table 8 is placed on the member 1.
The document is scanned by moving forward in the direction of the arrow substantially perpendicular to the direction of movement. When scanning of the original is completed, the table 8 returns to the home position. When scanning a document,
An image of the document placed on the stand 8 is formed and exposed onto the photoreceptor 7 by an imaging optical system consisting of mirrors 9 and 11 and a lens 10 arranged inside the box 6. This exposure position is between the photosensitive charger and the developer. Note that the imaging optical system projects an image of the document portion located at position C, which is a fixed position with respect to the box body 6, onto the photoreceptor 7.

On the other hand, in the board copy mode, the field lens 12 is placed in contact with or close to the document table 8 at the C position. On the other hand, in the copy mode for the original placed on the original platen 8, the field lens 12 is retracted from the above position. That is, the field lens 12 includes members 1 to 4, and the first and second mirrors 1.
3, 14, and a board box 16 that houses the lens 15.
A retractable optical path cover 1 such as a bellows attached to the
In the board copying mode, it is lowered and placed at the upper position, and in the document copying mode, it is raised and moved away from the movement path of the table 8.

Thus, the image of the board scanned at the B position is projected onto the field lens 12.
The optical system includes first and second mirrors 13 and 14, and a lens 15. The first mirror 13 is arranged in the vertical direction and reflects the light from the board illuminated by the lamp 4 laterally along the board, and the second mirror 14 reflects the light from the first mirror 13 onto the board. It is reflected downward along. The lens 15 receives the light from the second mirror 14 and forms an image of the board portion at position B onto the field lens 12. The image formed on the field lens 12 is transferred and imaged onto the photoreceptor 7 at the same position as in the original copying mode by the imaging optical system comprising the mirrors 9, 11 and the lens 10.

[Problem that the invention attempts to solve]

In such an apparatus, in order to obtain a proper image without fog in both the board copying mode and the document surface copying mode, the amount of exposure to the photoreceptor must be made equal in both modes.

However, in the board copying mode, the light transmission efficiency is considerably reduced because the light is once projected onto the original surface and then transferred and imaged onto the photoreceptor. In other words, in order to equalize the amount of exposure in both modes, it is necessary to increase the amount of light projected onto the document surface in the board copy mode. In other words, a load is placed on the illumination device and projection lens of the board projection optical system, which leads to increased power consumption, larger size of the device, and higher cost.

An object of the present invention is to provide a copying apparatus capable of copying both information written on a board and an original placed on a document table, which consumes less power without increasing the size of the apparatus, and which produces images that are suitable for both modes. The object of the present invention is to provide a board copying device that can obtain the following.

〔Example〕

The present invention is achieved by switching the value of the developing bias of the electrophotographic copying device, which is shared between the board copying mode and the original copying mode. In other words, for example, if the amount of exposure to the photoreceptor in the board copy mode is less than the exposure amount in the original copy mode, and if the board is copied with a developing bias that produces an appropriate image in the original copy mode, the exposure amount Due to the small amount of light, a fogging phenomenon occurs in the copied image, making it impossible to obtain a proper image.

Therefore, if the value of the developing bias in the board copy mode is set higher than the value of the developing bias in the document surface copying mode, it is possible to obtain a proper image without fogging in both cases.

In other words, by setting the value of the developing bias according to the exposure amount in the board copying mode and the original copying mode, and switching the developing bias according to the mode selection, it is possible to obtain a proper image in both modes.

In this embodiment, information written on a board is imaged once on a field lens provided on a document table, and the image is transferred and formed on a photoreceptor.
It goes without saying that the present invention can also be applied to cases where information written on a board as shown in the figure is directly imaged onto a photoreceptor.

Further, in the above embodiment, a case has been described in which the exposure amount in the board copy mode is lower than the exposure amount in the document side copy mode, but the opposite case also holds true. In that case, the value of the developing bias may be set lower in the board copy mode than in the document surface copy mode. In any case, it is sufficient to control the development bias by switching the value of the developing bias according to the exposure amount in both modes.

As shown in Fig. 4, the specific development bias switching configuration is as shown in FIG.
, and determine the voltage to be applied to the developing roller L of the developing device.

〔effect〕

As explained above, in a copying device that can copy both information written on a board and a document placed on a document table, the device can be easily configured by switching the developing bias according to the exposure amount in both modes. This makes it possible to create a recording device that can obtain appropriate images in both modes with low power consumption without increasing the size of the device.

[Brief explanation of the drawing]

Fig. 1 is a perspective view for explaining a conventional example, Fig. 2 is a perspective view for explaining a conventional example;
3 is a side view showing another embodiment, and FIG. 4 is a developing bias selection circuit diagram. In the figure, 1 is a board member, 8 is a manuscript table, and 9 is a board member.
10 is a lens, 11 is a mirror, 12 is a field lens, 13 is a first mirror, 14 is a second mirror, and 15 is an imaging lens.

Claims (1)

[Scope of claim for utility model registration] In the board copying mode, the optical image of the board
An image is formed by the imaging optical system, and this optical image is transferred and formed on the electrophotographic photoreceptor by the second imaging optical system.On the other hand, in the original copy mode, the image of the original placed on the original platen is An image is formed on the electrophotographic photoreceptor by the second imaging optical system, and the amount of exposure to the electrophotographic photoreceptor is different between the paperboard copy mode and the document surface copy mode. In an electrophotographic copying device that can also make copies, the developing bias of the electrophotographic copying device should be switched between when copying a board document in the above-mentioned board copying mode and when copying the original side in the above-mentioned original side copying mode. Characteristic electrophotographic copying device.