JPH0321915B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying apparatus that can selectively project an original having a negative image and an original having a positive image onto a photoreceptor to always obtain a copy having a positive image. .

Conventionally, microfilm printers that use microfilm originals and copying machines that use reflective originals such as documents have been available as standalone products, but the two products were expensive and inconvenient.

In view of this, an apparatus combining a microfilm printer and an electrophotographic copying machine has been proposed. When copying a reflective original, such a device projects the reflected light from the original with a positive image onto a photoreceptor, and develops the electrostatic latent image formed on the photoreceptor using a regular developing method to create a positive image. When copying a microfilm original with a negative image, the transmitted light of the microfilm is projected onto a photoreceptor, and the electrostatic latent image formed on the photoreceptor is developed using a so-called reversal development method to create a positive image. I am trying to make copies with images.

In a normal developing method, for example, an electrophotographic photoreceptor is charged to a polarity different from that of a developing toner, and development is performed by applying the toner to an electrostatic latent image on the photoreceptor. On the other hand, in the reversal development method, a photoconductor is charged to the same polarity as the developing toner, and development is performed by applying the toner to the photoconductor.

In the above-mentioned type of device, if the photoconductor is larger than the projection original, it is possible to copy without using a reflective original cover during exposure, or to copy thick reflective originals such as books even if a cover is used. This creates an area on the photoconductor (periphery of the photoconductor) that corresponds to the surrounding area of the reflective original, where no light is projected.
A black frame is formed around the periphery of the photoreceptor. Furthermore, when copying a microfilm with a negative image, the peripheral edge of the negative image on the microfilm is generally transparent. ) creates an area onto which light is projected, forming a black frame around the periphery of the photoreceptor. Therefore, no matter which original is used, a black frame is formed around the photoreceptor that has formed the positive copy image, which is very unsightly.
There was a problem that lowered the commercial value of copies.

Therefore, in Japanese Patent Application Laid-Open No. 47-4483, a mask with an aperture of a certain size is placed in the image projection optical path,
When copying a negative image, the optical path at the periphery of the negative image is blocked by a mask, and when copying a positive image, the photoreceptor corresponding to the periphery of the positive image is exposed to prevent black edges from forming at the periphery of the copied image. However, there was a problem in that it was not possible to erase unnecessary images in any arbitrary area of both negative images and positive images before copying.

The present invention provides a copying apparatus that solves the above problems. The present invention will be explained below with reference to the drawings.

The drawing shows an electrophotographic copying apparatus according to an embodiment of the present invention. Reference numeral 1 indicates a microfilm projection unit, and inside the dark box 2 there are a reflecting mirror 3, a lamp 4, a microfilm 5 having a negative image, and a first projection lens 6.
is disposed, and a Fresnel lens 7 is disposed at the lower opening of the dark box 2. As shown in FIG. 2A, the microfilm 5 is transparent around the frame f having a negative image. Shaded areas indicate opaque areas. The lamp 4 is turned on when exposing the microfilm. The dark box 2 is rotatable about a shaft 8 between a position 2' shown by a broken line and a position shown by a solid line, and is placed at the position shown by a solid line when an image on a microfilm is to be copied. When the dark box 2 is placed at the solid line position, the Fresnel lens 7 is placed in close contact with the transparent plate 10 provided at the copying position 9. The image of the microfilm 5 is formed on the Fresnel lens 7 by the first projection lens 6, and the image formed on the Fresnel lens 7 is exposed by the second projection lens 11 on which the photosensitive paper S is placed. It is imaged at position 12. 1
Reference numeral 5 indicates a copying section, in which photosensitive paper (electrofax paper) S fed into the copying section 15 by a paper feed mechanism 16 is uniformly charged to a predetermined polarity by a charger 17, and then transferred to a belt 18. is carried to the exposure position 12 and stopped there. At this time, when the dark box 2 is placed at the solid line position, the lamp 4 is lit, and the transmitted light of the micro film 5 is transmitted through the projection lenses 6 and 11.
The exposure position 12 is then reached, and the image of the microfilm is formed on the photosensitive paper S. After the exposure, the photosensitive paper is conveyed again by the belt 18 to the developing device 19, where it is immersed in a developer and the electrostatic latent image is visualized by a reversal development method. Next, the photosensitive paper is heated and fixed while passing through a fixing device 20 and is discharged onto a discharge tray 21 .

A raw original such as a general document or a drawing, that is, a reflective original having a positive image is placed on the transparent plate 8 .
At this time, the dark box 2 is placed at the broken line position 2'. The reflective original placed at the copying position 9 is illuminated by the lamp 25, and the light beam reflected from the reflective original passes through the second projection lens 11 and reaches the exposure position 12, where an image of the reflective original is formed on the photosensitive paper S. This electrostatic latent image on the photosensitive paper is visualized by a regular developing method. The lamp 25 is turned on only when exposing a reflective original. Note that when feeding the photosensitive paper S to the copying section 15, the charger 1
7, the charging polarity is switched depending on the type of original to be copied. That is, the charger 17 charges the photosensitive paper to a polarity different from the polarity of the developing toner in the developer 19 when copying a reflective original with a positive image, and the developer 19 charges the photosensitive paper with a polarity different from the polarity of the developing toner in the developer 19 when copying a microfilm original with a negative image. Charge the photosensitive paper to the same polarity as the developing toner.

Reference numeral 30 denotes a light-shielding plate that can be moved in and out of the projection optical path. Each light-shielding plate 30 is connected to an external operating knob 32 via a coupling mechanism 31, and its position can be adjusted by operating the operating knob. ing. To display the relative position of a light shielding plate to the outside so that the position of the light shielding plate moved by the operation of a knob can be seen from the outside. Note that the light shielding plates 30 are arranged on each of the four sides of the exposure position 12.

The light shielding plate 30 is placed close to the surface of the belt 18, and is moved parallel to the surface of the belt 18 by operating a knob 32. It is inserted into the projection optical path and positioned to close the optical path at the periphery of the projected image.

33 is a detector that detects the position of the light shielding plate 30;
It is made of microfilm and turns on when the light shielding plate 30 is inserted into the optical path, generating a logic "1" signal. On the side of the light shielding plate 30 facing the belt 18, a light emitting body 35 is arranged, in which a light emitting element made of electroluminescence is laminated between a pair of transparent electrodes. The light emitter 35 moves integrally with the light shielding plate 30. The light emitting element of this light emitter 35 emits light when a voltage is applied between the pair of transparent electrodes, and does not emit light when the applied voltage is cut off.

40 is a shooting button, and 41 is a shutter-reflecting plate that can be moved in and out of the projection optical path.Normally, it is placed at the solid line position to block the optical path, and when the projected image is to be exposed onto photosensitive paper S, it is rotated to the broken line position 41'. , open the optical path. 42 is a photoelectric conversion element that receives reflected light from the reflecting plate 41 placed at the solid line position through a lens 43, and is used as a detector that receives image light and detects the negative or positive polarity of the image. When the photographing button 40 is operated, the photosensitive paper S is sent to the exposure position 12, and when the photosensitive paper is placed at the exposure position, the reflective plate 41
moves to the broken line position 41' and the projected image is exposed to the photosensitive paper, and after the exposure is completed, the reflecting plate 41 moves to the original solid line position.

A phototransistor, a photodiode, a solar cell, or the like is used as the photoelectric conversion element 42, and this photoelectric conversion element outputs a voltage signal corresponding to the amount of light received. The larger the light receiving area of the photoelectric conversion element is, the better.
It may be configured to obtain the average voltage of the output signal of each photoelectric conversion element.

FIG. 3 shows a polarity detection circuit, in which 51 is an amplifier circuit that amplifies the output voltage of the photoelectric conversion element 42;
52 is a first reference signal generator that generates a first reference voltage signal; 53 is a first comparison circuit that compares the first reference signal with the output signal of the photoelectric conversion element; 1 outputs a logic "1" signal when the signal is higher than that of the reference signal. 54 is the first
A second reference signal generator generates a second reference voltage signal having a lower voltage than the reference voltage signal; 55 is a second comparison circuit that compares the second reference signal with the output signal of the photoelectric conversion element; The voltage of the signal is the second
When the signal is lower than that of the reference signal, a logic "1" signal is output. In other words, if the amount of light input to the photoelectric conversion element 42 is larger than the reference value, it is determined that the microfilm has a positive image, and a "1" signal is output from the comparator circuit 53. If the amount of light input to the photoelectric conversion element 42 is smaller than the reference value, the microfilm has a negative image. It is determined that it is a film, and the comparator circuit 55 outputs a "1" signal. 56, 57,
58 and 59 are AND gates, 60 and 61 are inverters, 62 is a charging polarity changeover switch that is switched by the output signals of AND gates 56 and 57, and 6
3 is the charger 1 according to the switching of the changeover switch 62.
7 is a high voltage generation source that applies a high voltage of positive polarity or negative polarity; 64 is a display; 65 is a voltage supply circuit;
66 is a pair of electrodes of the light emitter 35. 1st above
The reference voltage and the second reference voltage are set according to the type of photoelectric conversion element 42 and the base density of the original,
Each reference voltage is configured to be manually adjustable.

In the above configuration, when the output voltage of the photoelectric conversion element 42 that receives the transmitted light of the microfilm 5 or the reflected light of the reflective original is higher than the first reference voltage,
That is, when a reflective original is placed at the copying position 9, the AND gate 56 opens and outputs a positive signal, and this positive signal switches the polarity switch 62, causing the high voltage source 63 to pass through the charger 17 to the developer. A high voltage having a polarity different from that of the developed toner is applied, whereby the copy paper S is charged to a polarity different from that of the toner. Note that the changeover switch 62 is configured to be changed over when the photographing button 40 is operated.

When the reflective original is placed at the copying position, if the size of the reflective original is smaller than the effective copying area, that is, the photosensitive paper S, operate the operation knob 32 to close the light shielding plate 30.
is inserted into the optical path, and a light shielding plate is installed so that the light path corresponding to the area surrounded by the edge of the projected image on the photosensitive paper S and the edge of the photosensitive paper is closed by the light shielding plate 30. Position.

When the light shielding plate 30 is inserted into the optical path, the output signal of the light shielding plate detector 33 opens the AND gate 59, and the output signal of the AND gate causes the voltage supply circuit 65 to connect the pair of electrodes of the light emitter 35. A voltage is applied to 66, and the light emitter 35 emits light. Therefore, during image exposure, the portion of the photosensitive paper corresponding to the optical path closed by the light-shielding plate 30 is uniformly exposed to the light from the light emitter, and if the original has a positive image, it is developed using the regular developing method. This exposed portion of the photoreceptor (where no charge is present) is not developed. If a microfilm S' with a positive image shown in Fig. 2B is used instead of a reflective original, the optical path of the opaque area around the frame f' of the microfilm 5' will be blocked from light in the same way as with the reflective original. A plate may be inserted and the portion of the photosensitive paper corresponding to the opaque portion may be illuminated by the light emitter 35.

The above-mentioned light-shielding plate can also be used to prevent copying of a search mark provided on the side of an image, a frame number, or a part of the image, and can erase these parts without developing them.

Next, when the output voltage of the photoelectric conversion element 42 is lower than the second reference voltage, that is, when the microfilm 5 with a negative image is projected onto the copying position 9, the AND gate 57 opens and outputs a negative signal, and this negative The polarity changeover switch 62 is switched in response to the signal, and a high voltage having the same polarity as the developed toner in the developing device is applied from the high voltage source 63 to the charger 17, whereby the copy paper S is charged to the same polarity as the toner. Ru.

When the image on the microfilm 5 is projected onto the copying position, if the size of the projected image is smaller than the effective copying area, that is, the photosensitive paper S, operate the operation knob 32 to insert the light-shielding plate 30 into the optical path. The optical path corresponding to the transparent part around the film frame is closed with a light shielding plate. At this time, since the AND gate 56 is closed, no voltage is applied to the light emitter electrode 66, and the light emitter 35 does not emit light. Therefore, during image exposure, the portion of the photosensitive paper corresponding to the optical path closed by the light shielding plate 30 is not exposed, and in the case of a negative image, this unexposed portion of the photosensitive paper is developed by the reversal development method. (there is a charge) is not developed.

Further, when the output voltage of the photoelectric conversion element 42 is lower than the first reference voltage and higher than the second reference voltage, the AND gate 58 is opened, and the output signal of the AND gate lights up the display 64, and the image is recorded on the document. Inform the user that it is difficult to judge the negative or positive of

This occurs when a special image such as a photograph is recorded on the original, especially when using a microfilm original, but in such cases, the user must distinguish the polarity of the image on the original. The changeover switch 62 is changed over manually. In general, microfilm has a high gamma value, so it is mostly used for drawings.
Originals such as documents are recorded, and it is not suitable for recording originals such as photographs. Therefore, for most microfilms, even if the difference between the first reference voltage and the second reference voltage is increased, the polarity of the image on the microfilm can be determined automatically and reliably.

In the present invention, the means for detecting the negative or positive polarity of an image is not limited to the above embodiment.

FIG. 4 shows another embodiment of the polarity detector, in which 142 is a detector having a photoelectric conversion element corresponding to the photoelectric conversion element 42 in FIG. 1, 143 is a reflective original illumination lamp, and 144 is a reflective shade. , 145 is the first
146 is a second mirror, 147 is a projection lens, 148 is an electrophotographic photosensitive drum having a photoconductive layer, and 149 is a shutter. detector 142,
Lamp 143, reflective shade 144 and first mirror 14
5 is integrally provided so as to be movable parallel to the transparent plate 10 at the same speed, and when the lamp 143 is turned on, the light from the lamp is reflected by the reflective original on the transparent plate 10 and hits the first mirror 145. The second mirror 146, which simultaneously moves in the same direction at half the speed of the first mirror, reverses the direction of the lens
47, and is projected onto a photosensitive drum 148 that rotates at a constant speed ratio with the first mirror 145.

When detecting the polarity of an image on a reflective original, at least the detector 142 and the lamp 14 are used before copying.
3 is moved with the lamp 143 turned on, and the detector 142 receives the reflected light from the reflective document scanning a predetermined area. At this time, it is moved at a slower speed than scanning for copy exposure. After completing the scan for polarity detection, the detector
The lamp 143 is returned to its original waiting position.

In addition, when detecting the polarity of a microfilm image, the detector 142 is turned off with the lamp 143 turned off.
is moved so that the detector 142 receives the image light transmitted through the microfilm. The output signal of detector 142 is sent to the detection circuit shown in FIG. 150
151 is a developing device, 152 is a transfer roller, and 153 is a cleaning device. Images on the reflective original and the microfilm are scanned onto the photosensitive drum by movement of the first and second mirrors.

FIG. 5 shows a light shielding material used in the copying apparatus shown in FIG.
It is disposed close to the exposure position of and is movably held on rails 156. The light shielding plate 155 is connected to a belt 159 stretched between pulleys 157 and 158, and is moved in the direction of arrow b by rotating an operating knob connected to the pulley 158, and is moved in and out of the projection optical path. Luminous body 1 similar to Fig. 1
60 is provided on the photosensitive drum side of the light shielding plate 155. In addition, although a light emitting element is used in the above embodiment, the light shielding plate has a reflective surface on the photoconductor side, the light from the lamp is projected onto this reflective surface, and the reflected light from the reflective surface is projected onto the photoconductor. Good too. Further, a light shielding plate may be placed near the copying position.

In the present invention, other known copying methods capable of regular development and reversal development can be applied as the copying method.

As described above, according to the present invention, an image in any area can be erased regardless of whether it is a negative image or a positive image, and furthermore, whether the image is negative or positive is automatically detected and the operation of the irradiation means is controlled. There is no risk of making a mistake when copying. In addition, since the light shielding member for erasing a positive image and the irradiation means for erasing a negative image are moved integrally, there is no need to provide a device to move them independently, and the structure of the device can be simplified. Furthermore, since the image erasing area can be adjusted by a common setting means, erasing work can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a copying machine showing one embodiment of the present invention, FIGS. 2A and B are front views of a film, FIG. 3 is a diagram showing a polarity detection circuit, and FIG. 4 is a diagram showing another embodiment. FIG. 5 is a perspective view showing another embodiment of the light shielding plate. 5... Micro film, 6, 11... Projection lens, 25... Lamp, 30... Light shielding plate, 35... Light emitter, 42... Photoelectric conversion element.

Claims (1)

[Claims] 1. An optical means for projecting a negative image or a positive image onto a charged photoreceptor; a light shielding member that is movable within and outside the image projection optical path and capable of adjusting the optical path blocking position; and an optical means that is integrated with the light shielding member. an irradiation means that is movable to the opposite side of the light-blocking surface of the light-blocking member and irradiates the surface of the photoconductor corresponding to the light path blocking position in a timely manner; means for setting an area to be erased;
A detection means for detecting a negative or positive image, and an operation of an irradiation means depending on whether the image is negative or positive detected by the detection means when a light shielding member is moved to block a light path corresponding to an area of the image to be erased. 1. A copying apparatus comprising: means for controlling.