JPS6220849Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic copying machine, and particularly to an improvement in a structure for automatically selecting a recording paper size.

Recently, the performance of electronic copying machines has been significantly improved, and various operations have been automated.

Although it is being promoted to automatically identify the size of the original and select and feed the recording paper accordingly, various problems have prevented this from being fully put into practical use at this stage. That is, for this purpose, the size of the document must be detected optically. In this case, there is no problem if the white background of the document and the reflectance of the document cover are approximately the same, but
If the reflectance of the document and the document cover are different, it is impossible to determine which brightness is detected or which reference should be used to set the exposure amount. In other words, since the measured brightness of the document surface includes both the document and the document cover, there is an inconvenience that the document size cannot be detected unless such a distinction is made.

First, in order to simply distinguish between the document and the document cover, it is possible to optically detect the document and the document cover by basically making their reflectances different. However, in this case, since various originals are used, the reflectance is not constant, and it is necessary to set the reflectance of the original cover. However, if the reflectance of the document cover is set appropriately, the amount of light reflected from the photoreceptor decreases, resulting in darkened edges of the copied electrophotograph, resulting in an unclear image. For this reason, automation of exposure is difficult to implement, and the reliability of detecting the document size is low.

The present invention was developed in view of the above circumstances, and its purpose is to provide an electronic copying device that can very easily detect the size of a document and automatically select the corresponding recording paper. It is.

An embodiment of the present invention will be described below based on the drawings. First of all, even if some of the light reflected by the document cover to which the photoconductor is not sensitive disappears, the above-mentioned problems will not occur, so the spectral reflectance of the document cover should be made as close to the reflectance of the photoconductor as possible. This makes it possible to prevent adverse effects on the photoreceptor due to changes in the reflectance of the document cover.

For example, a photoreceptor in which the photoconductive layer is made of selenium has sensitivity on the short wavelength side of 0.6 μm or less, as shown by the solid line in FIG. Therefore, for example, a document cover having a spectral reflectance as shown by the solid line may be used. The material used for this document cover is, for example, polyvinyl chloride, unsaturated polyester, polyurethane, silicone resin, or the like. Furthermore, the following colorants are selected depending on the matching with these materials. That is, the blues include ultramarine, cobalt blue, copper phthalocyanine blue, and oil blue. Chrome green as green, copper phthalocyanine green, cadmium red as red,
They are Marqueury Red and Pyrazon Red. Note that two or more of these colorants can also be mixed to adjust the color.

Further, the spectral reflectance of a generally used white original is shown by a solid line. In this way, the original exhibits substantially uniform reflection characteristics from the visible region to the near infrared region.

The present invention is applied to an electronic copying machine as shown in FIG. 2 using a photoreceptor, a document cover, and a document having such characteristics. That is, 11 is a casing, and a document mounting table 12, which will be described later, is provided on the top of the casing. A photoreceptor 13 is rotatably supported within the housing 11.
Along this peripheral wall, a charging device 14, a developing device 15,
A transfer device 16 and a cleaning device 17 are arranged. Also, on one side of the housing 11, there are a plurality of cassettes 18, each containing recording sheets 9a and 9b of different sizes.
19 are placed. The recording sheets 9a and 9b are fed from cassettes 18 and 19 as paper feed rollers 18a and 18b rotate, respectively, and a paper feed device 20 is constituted by these sheets. The paper feed device 20, the transfer device 16, and the paper discharge tray 21 attached to the other side of the housing 11 are connected to a conveyance path 22.
are connected. A fixing device 23 is opposed to the conveyance path 22 between the transfer device 16 and the paper discharge tray 21 .

The document mounting table 12 is designed as shown in FIG. That is, reference numeral 1 denotes a document table made of a transparent glass material, which is covered with a document cover 2 made of the above-mentioned material and having reflective properties. An original 3 having the above-mentioned reflection characteristics is interposed between the original table 1 and the original cover 2. A photocoupler 4, which is a detection element, is provided along the document table 12 so as to be able to move back and forth. The photocoupler 4 is made of, for example, GaP, GaAs,
A light-emitting diode such as GaAsP is easy to use because it can emit red or green light, but it is composed of a light-emitting element 4a, which may also be an incandescent lamp, and a light-receiving element 4b such as CdS, Se, SPD (silicon photodiode), etc. be done. Further, a filter having a desired spectral transmittance may be used in combination, if necessary. The wavelength sensitivity range of the photocoupler 4 is as shown by the solid line in FIG. 1, and the wavelength sensitivity range of the photocoupler 4 is such that the solid line indicating the reflection characteristics of the document cover 2 is not reflected. However, for the solid line representing the reflection characteristics of the original 3, it covers a sufficiently sensitive wavelength range.

When the print button 25 is pressed as shown in FIG. 5, the copying process control circuit 26 is activated and the photocoupler 4 constituting the document detection circuit moves forward to optically scan the document table 12. Then, as shown in FIG. 4, the signal output from the photocoupler 4 changes greatly between a certain part of the document 3 and the other part m.
As a result, it is possible to optically recognize the distinction between the third portion of the document and the second portion of the document cover. By extracting the area between and m as the density detection area of the original 3, necessary exposure control can be performed. The output duration of the photocoupler 4 is measured by a pulse counter, and as shown in FIG. 5, the size of the document 3 is detected from the detection time by the document size detection circuit 27, and compared with the detection circuit 28 of the recording paper size set in advance. Comparison and verification are performed in the verification circuit 29. And this circuit 2
9, a recording paper size selection signal is issued to the paper feeder drive circuit 30. On the other hand, the copying process control circuit 26 sends a signal to the paper feed timing control circuit 31, and when the AND is determined, the paper feed device drive circuit 30 rotates the paper feed roller 18a or 18b to produce the recording paper of the selected size. Pa or Pb will be supplied. Furthermore, if a desired size of recording paper is to be used regardless of the original size, it is sufficient to switch to the manual size selection circuit 32.

Note that the photocoupler 4 detects the size and density of the original 3 during forward movement, and exposes it during backward movement, and other devices perform predetermined operations.

Further, in the above embodiment, the photocoupler 4 is used for both identification of the document 3 and density detection, but the invention is not limited to this. Dedicated detection elements may be provided for each, and these processes can be performed using conventionally known methods. Various electronic processes are possible.

Furthermore, in the above embodiment, selenium was used as the photoconductor 13 used, but the invention is not limited to this, and other types of photoconductors may be used. By setting the spectral reflectance of and the wavelength used by the detection element,
The same effects as in the above embodiment can be obtained. Further, the number of detection elements is not limited, and if a plurality of detection elements are used, errors in measuring the density of the original can be reduced. Various other modifications and applications are possible within the scope of the gist of the present invention.

As explained above, according to the present invention, a document is covered with a document cover having a spectral reflectance corresponding to the spectral sensitivity wavelength range of an electrophotographic photoreceptor, and light in a wavelength region in which the spectral reflectance of the document cover is low is A detection element that detects the size of the original using the sensor is provided, and a paper feeder that feeds recording paper of a specified size according to the signal from this detection element is installed, making it possible to detect the original size with high accuracy. You can automatically switch and feed recording paper of the corresponding size.
This has the effect of significantly improving processing efficiency.

[Brief explanation of the drawing]

Fig. 1 is a reflection characteristic diagram for explaining the basic principle of the present invention, Fig. 2 is a schematic vertical cross-sectional view of an electronic copying machine showing an embodiment of the invention, and Fig. 3 is a diagram of its main parts. 4 is a signal output diagram, and FIG. 5 is an electrical block diagram. 3...Photoconductor, 2...Document cover, 3...Document, 4...Detection element (photocoupler), Pa, Pb
... Recording paper, 20 ... Paper feeding device.

Claims (1)

[Scope of utility model registration request] Cover the document with a document cover that has a spectral reflectance that corresponds to the spectral sensitivity wavelength range of the electrophotographic photoreceptor,
A detection element is provided that uses light in a wavelength range with low spectral reflectance of the original cover to identify the original and the original cover and detect the size of the original, and records a specified size according to the signal from this detection element. An electronic copying apparatus characterized by being provided with a paper feeding device that feeds recording paper of a plurality of sizes.