JPH0476111B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an exposure device for a copying machine.
More specifically, the present invention relates to an exposure device for a copying machine whose purpose is to detect the size of a document and to erase a black band-like latent image on a double-page spread that occurs in a thick document such as a book.

[Prior Art] Copying machines are generally equipped with a platen cover that is pivoted at one end. During copying operations, this platen cover blocks strong light from the copying machine from directly entering the operator's eyes. ing. However, when copying a thick document such as a book, the platen cover cannot cover it, and the strong light from the copying machine will shine directly into the operator's eyes, making the copying process painful. Ta. Further, in the slit exposure type copying machine, there is a problem in that the area where the original is not placed has a black border. Therefore, conventionally, as shown in FIGS. 7 and 8, the platen a
Two vertical and horizontal winding rolls b and c are installed below and on the opposite side of the original document placement reference edge, and one end of each of the sheet-like light shielding members d and e is wound onto each of these rolls b and c. An exposure device has been developed in which the other ends of these light-shielding members d and e are stretched so as to be pulled out in the reference direction by means of knobs g and h provided outside the main body f of the copying machine. When copying a document i using this exposure device, place the document i on a platen a as shown in FIG. Parts d, e
By pulling out the copy paper, it was possible to always align the portion of the document i to be copied at a fixed position on the copy paper.

[Problems to be Solved by the Invention] However, in the conventional exposure apparatus, it is troublesome to set up the light-shielding film, and when copying a thick original such as a book, the double-page spread of the book is placed on the platen. As a result, a black band latent image is generated, and this black band latent image is transferred directly to the copy paper. Therefore, a solution to this problem is currently desired.

[Means for Solving the Problems] The present invention has been made with the intention of solving the above-mentioned problems. In a copying machine comprising an optical system having an illumination light source, an imaging lens, etc., and a photoreceptor on which an electrostatic latent image is formed by the optical system, a light shielding film is movably disposed below the platen. In addition to establishing
A document size detection sensor is installed on the light-shielding film, and the light-shielding film is moved prior to the copying process to pre-scan the document with the sensor; A light source for erasing a black band latent image is provided at a position close to the process, and this erasing light source is configured to be able to emit light selectively based on a signal from the sensor. To provide an exposure device for a copying machine, characterized in that the position and width of a double-page spread are detected by a sensor, and the light emission timing and light emission time of the erasing light source are controlled based on the detection signal. It is.

[Effect] The above technical means works as follows.

When you start copying after setting the original,
As the light-shielding film moves, the document size detection sensor detects the document size and sends a signal to the light-shielding film moving means, so the light-shielding film is positioned at a predetermined position and the portion of the document that should be copied is always copied. You can align it to the correct position on the paper. In addition, when copying thick originals such as books, the original size detection sensor detects the position and width of the double-page spread of the book, and transmits the signal to the light source for erasing the black band latent image. By emitting light from the light source at a predetermined time for a predetermined period of time, the black band latent image exposed on the photoreceptor can be erased.

[Example] Examples of the present invention will be described in detail below based on the drawings.

FIG. 1 shows a schematic perspective view of an exposure apparatus of the present invention, and FIG. 2 shows a schematic side view thereof. It is installed in a copying machine whose main parts are composed of an optical system 5 having an image lens 3, etc., and a photoreceptor, that is, a photoreceptor belt 4, on which an electrostatic latent image is formed by the optical system 5, and its structure is as follows. A light-shielding film 6 is movably disposed on the lower surface of the platen 1 by a motor 7 that can rotate in forward and reverse directions as a moving means, and a light-shielding film 6 is installed on the light-shielding film 6 and placed on the platen 1. A document size detection sensor 8 that detects the size of the document A, and a black belt sensor that selectively emits light upon receiving a signal from the sensor 8 and is disposed near the exposed portion of the photosensitive belt 4 on the next process side. and an image erasing light source 9.

The light shielding film 6 has a winding roll 1 whose one end is attached to a shaft 10 rotated by a motor 7.
1, and an edge member 12 having a crank-shaped cross section is attached to the other end. This edge member 12
One end of a cable 13 such as a wire is connected to both ends of the cable 13, and this cable 13 is connected to a transmission wheel 1 such as a pulley mounted on a driven shaft 14 facing the shaft 10.
5, and the other end is wound around a drive-side transmission wheel 16 mounted on the shaft 10.
Therefore, when the motor 7 rotates clockwise in the figure, the shaft 10 and the transmission wheels 16 and 15
rotates, and along with this, the cables 13 move and the light shielding film 6 moves in the opening direction. Conversely, when the motor 7 rotates counterclockwise, the light shielding film 6 similarly moves in the closing direction. In this case, the means for moving the light shielding film 6 does not necessarily have to be a motor 7 capable of forward and reverse rotation;
A motor may be connected to each of the driven shafts 14 and one of the motors may be selectively driven.

Further, the document size detection sensor 8 is constituted by, for example, a light reflection type sensor, and is installed on the horizontal portion 12a of the edge member 12. This sensor 8 detects the size of the document A, and after detecting the document size by a control circuit (not shown), overtravels within a predetermined distance range (for example, 20 to 50 mm), and within the range exceeding this distance, the document A
If not detected, a stop signal is sent to the motor 7, and a new document A is sent after overtravel.
If it detects this, it will move further. Therefore, the detection of the double-page spread of the document A by the sensor 8 is set so that the distance range X of this overtravel is at least larger than the distance (width) D of the double-page spread, as shown in FIGS. 4c and e. and after the start of its overtravel (in other words,
This is done by utilizing the fact that the sensor 8 newly detects the document A and moves it further without stopping within the predetermined overtravel distance range X). That is, the sensor 8 detects the overtravel start point and the new document detection point, and detects these points at the leading edge and trailing edge of the double-page spread of the document A (i.e.,
This is done by performing detection processing as an information source for the position and width of the double-page spread.

On the other hand, the black band latent image erasing light source 9 is located at the bottom of a channel-shaped case 17 that opens toward the photoreceptor belt 4 side and is arranged in the width direction of the photoreceptor belt 4, as shown in FIG. 3, for example. It is composed of a plurality of light emitting diodes etc. arranged at appropriate intervals on a printed circuit board 18 arranged on the
The light emitting device selectively emits light upon receiving a signal from the sensor 8, and emits light at a predetermined time and for a predetermined period of time. In this case, the black band latent image erasing light source 9 does not necessarily have to be a light emitting diode, but may be a light source such as a fluorescent light. Alternatively, the photosensitive belt 4 side may be irradiated through the photosensitive belt 4 side.

Next, the operating mode of the exposure apparatus of the present invention will be explained.

First, when copying a thick document A such as a book, as shown in FIG. 4 a to f and FIG.
When the operation switch (not shown) is turned on in the pre-operation state shown in FIG. The presence of document A is detected. Then, as shown in b and c of the figure, when the sensor 8 reaches the double-page spread of the document A, it starts overtravelling, detects the presence of the document A again within a predetermined distance range X of the overtravel, and continues moving further. . At this time, the overtravel start point detected by sensor 8 and the re-detection point of the document are detected as the leading edge and trailing edge of the double-page spread of document A (i.e., the position and width of the double-page spread), and the control circuit is memorized. After that, the edge of the document A is further detected by the sensor 8 (see d in the same figure), and as shown in e in the same figure, it overtravels by a predetermined distance When no new document is detected within the range, a stop signal is sent to the motor 7 to stop the movement, and then the document is fed back to the edge position again, and the detection of the document size is completed. A normal copying operation is performed in conjunction with this operation, and an electrostatic latent image is formed on the photosensitive belt 4, and a formed latent image is also formed on the copy paper B supplied to the photosensitive belt 4. At this time, a latent image of a black band C corresponding to the double-page spread of the original A is formed on the copy paper B, but it is detected by the sensor 8 when the copy paper B passes through the black band latent image erasing light source 9. The black band C is erased by the light emitted from the black band latent image erasing light source 9 based on the light emission timing corresponding to the position of the double-page spread (see FIG. 5). In this case, the light emitting time of the black band latent image erasing light source 9 is set based on the width of the double-page spread detected by the sensor 8 in advance and the moving speed of the photosensitive belt 4.

In addition, when copying a normal document A', as shown in FIGS. 6a and 6b, when the operation switch is turned ON in the state shown in FIG. The light shielding film 6 is driven to move in the opening direction, and the sensor 8 detects the edge of the document A' (see FIG. 4B). Thereafter, the light shielding film 6 stops after overtravelling within a predetermined range, and is fed back to the document edge position by the reverse rotation of the motor 7 or the like (see c and d in the same figure). and,
A normal copying operation is performed, but at this time the black band latent image erasing light source 9 does not emit light and the copy paper B is not irradiated.

In the above embodiment, the case where the light shielding film 6 moves toward one side of the platen 1 has been described, but in reality, the light shielding film 6 also moves in a direction perpendicular to this direction.
The copy portions matching the sizes of originals A and A' are set by arranging them and performing similar operations.

[Effects of the Invention] As described above, according to the exposure apparatus of the present invention, a light-shielding film is movably disposed below the platen, and a sensor for detecting the document size is installed on the light-shielding film. Prior to the copying process, the light shielding film is moved and the original is preliminarily scanned by the sensor, and a light source for erasing a black band latent image is arranged at a position close to the exposure area of the photoreceptor for the next process. In addition, the erasing light source is configured to be capable of selectively emitting light based on a signal from the sensor, and when copying a document with a double-page spread, the sensor detects the position and width of the double-page spread. Since the light emitting timing and light emitting time of the erasing light source are controlled by signals, the following effects can be obtained.

1. A copy portion that matches the original size can be easily set on the platen without requiring complicated operations, so copying efficiency can be improved.

2. Even in the case of thick originals such as books, the black band latent image area corresponding to the double-page spread area can be erased, so that copying performance can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of an exposure apparatus of the present invention, FIG. 2 is a schematic side view thereof, and FIG. 3 is a cross-sectional perspective view showing an example of a light source for erasing a black band latent image in the present invention.
4a to 4f are schematic side views showing the operating mode of the exposure apparatus of the present invention, FIG. 5 is a schematic side view showing the operating mode of the light source for erasing black band latent images, and FIGS. 6 a to d are the schematic side views showing the operating mode of the exposure apparatus of the present invention. FIG. 7 is a perspective view showing the entire conventional exposure device, and FIG. 8 is a perspective view showing the main parts thereof. Explanation of symbols, 1... Platen, 2... Light source for illumination, 3... Imaging lens, 4... Photosensitive belt (photoreceptor), 5... Optical system, 6... Light shielding film, 7... Motor, 8 ...Original size detection sensor, 9...
Light source for erasing black band latent images.

Claims (1)

[Claims] 1. In a copying machine that is equipped with an optical system having an illumination light source, an imaging lens, etc. below a platen on which a document is placed, and a photoreceptor on which an electrostatic latent image is formed by this optical system, A light-shielding film is movably disposed below the platen, and a sensor for detecting the size of the original is installed on the light-shielding film, and the light-shielding film is moved and the original is pre-scanned by the sensor prior to the copying process. A light source for erasing a black band latent image is disposed at a position close to the exposed portion of the photoreceptor for the next process, and the light source for erasing can selectively emit light based on a signal from the sensor. When copying a document having a double-page spread, the sensor is configured to detect the position and width of the double-page spread, and use this detection signal to control the emission timing and duration of the erasing light source. An exposure device for a copying machine characterized by: