JPH0310945B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects the image density from a detected member after completion of fixing, and controls each part of the copying machine so that the image density is appropriate based on the obtained signal. Regarding equipment.

In most conventional electronic copying machines, image density is detected from a toner image formed on a photoreceptor, and each part of the copying machine is controlled based on the obtained signal so that the image density is appropriate. However, in this control method, the density of the unfixed toner image is measured and the image density is controlled accordingly. However, since the unfixed toner is thermally deformed during fixing, its reflectance, that is, the density is Even if the amount of unfixed toner is controlled, it is not necessarily possible to ideally control the toner density after fixing.

This invention was made with the aim of improving this problem, and involves detecting the image density from the detected member after fixing, and controlling each part of the copying machine so that the image density is appropriate based on the obtained signal. It is an object of the present invention to provide a copy density control device for an electronic copying machine.

An embodiment of the present invention will be described in detail below with reference to the drawings. In the figure, reference numeral 1 denotes the main body of an electronic copying machine, which has a document placement table 2 on the top.A document 3 placed on the document placement table 2 is irradiated by a light source 4, and the reflected light is transmitted to an optical system 5. An electrostatic latent image is formed on the photoreceptor 6 by being guided to the surface of the photoreceptor 6, and at the same time, a target 7 placed near the original platen 2 is also exposed, and a non-image on the photoreceptor 6 is exposed. A target image 7a is formed in the area. The latent image of the document 3 and the target image 7a are developed into a toner image by a developing device 8 installed near the photoreceptor 1, and then transferred onto a paper 9 fed from a paper feeding device (not shown). When the target image 7a is
The image is transferred to the detected member 10, which is provided so as to move in parallel with the image. The member to be detected 10 is a sheet of paper 9
For example, a roll paper of the same quality as the paper 9 is fed to the photoreceptor 6 by the feed roller 11 at the same time as the paper 9 is fed, and the target image 7a is formed at intervals as shown in FIG. At the same time, the detected member 10 having the target image 7a transferred thereto is conveyed together with the paper 9 to a fixing device 12. The fixing device 12 is configured to simultaneously fix the toner image on the paper 9 and the target image 7a on the detected member 10 by means of a heating roller 12a and a pressure roller 12b. Further, behind the fixing device 12, an image density detector 13 is installed above the member to be detected 10, and the image density detector 13 detects the image density of the target image 7a as an electrical signal. At the same time, the obtained signals are input to a control circuit (not shown) of the copying machine main body 1, and thereby control various parts of the copying machine main body 1, such as the exposure amount, the bias potential of the developing device 8, the amount of charge of the transfer device 14, and the like. The fixing temperature of the fixing device 12 and the like are controlled so that an appropriate image density is achieved.

In the above embodiment, the detected member 10 was a roll paper, but as shown in FIG.
A may be made of a material that can be easily peeled off, such as polyester resin, and may be formed into an endless shape, and after the image density is detected, it is peeled off with a blade 15 in preparation for the next copying.

As described in detail above, this invention detects the image density after fixing from the detected member and controls each part of the copying machine, such as the exposure amount, developing bias, and charge amount, so that the target image can be detected. The best level of control can be expected in devices that use this technology to control each part of the copying machine body, and since a detection member separate from the copy paper is provided, a small and waste-free detection member can be used. Moreover, since this detected member can be guided by multiple rollers, there is less risk of trouble occurring around the photoreceptor or fixing device, and the position of the image density detector etc. within the copying machine body can be adjusted. It also has the advantage of being flexible. In addition, if a blank copy is made before copying the original, the image density is automatically adjusted, so that a copy with an appropriate image density can be obtained from the first copy.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which FIG. 1 is an overall schematic side view, FIG. 2 is a plan view thereof, and FIG. 3 is a plan view of a detected member on which a target image is fixed.
FIG. 4 is an explanatory diagram of another embodiment. 1 is a main body of the copying machine, 3 is a document, 6 is a photoreceptor, 9 is paper, 10 is a member to be detected, and 12 is a fixing device.

Claims (1)

[Claims] 1 A transfer and fixing process in which a latent image of a document exposed on a photoreceptor is developed into a toner image by a developing device and then transferred to paper, and the toner image transferred to the paper is fixed to the paper by a fixing device. A toner image formed on the non-image area of the photoconductor is transferred to the detection member, which is fixed by a fixing device together with the paper, and a detection member that runs parallel to the paper is provided in between. A copy density control device for an electronic copying machine, which controls each part of the copying machine main body to have an appropriate image density based on the image density after fixing detected by a detection member.