JPH02277090A - Fixing device for electrophotographic printing device - Google Patents

Abstract

PURPOSE:To prevent an interrupted paper from discoloring by providing a photoelectric sensor which detects paper feeding holes, detecting abnormality in paper feeding by the comparing the output of the sensor with previously determined reference and stopping the exposure of a xenon lamp. CONSTITUTION:The photoelectric sensor constituted of a photoelectric switch 15 provided with a light emitting part and a light receiving part, and a light reflecting plate 16 is provided on the position of the paper feeding holes of the paper on the paper advancing side. A beam emitted from the light emitting part of a switch 15 is reflected by the reflecting plate 16. The resultant intense reflected beam is detected by the light receiving part to detect the paper feed holes, and its output is sent to control part 17. The control part 17 compares the period when the switch 15 is outputting the signal with the one under a normal condition. When the control part 17 recognizes any differences exceeding of a previously determined range, the control part 17 instantaneously stops both the light emission of the xenon lamp and printing operation. Thus, the interrupted paper can be surely prevented from discoloring caused by excess light emission.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fixing device for an electrophotographic printing device, and particularly to a fixing device for an electrophotographic printing device that fixes toner adhered to paper by flash exposure of a xenon lamp. Concerning vessels.

[Conventional technology]

FIG. 3 is a configuration diagram showing a general configuration example of an electrophotographic printing apparatus equipped with a fixing device using flash exposure from a xenon lamp. Unnecessary portions of the charge charged on the photoreceptor drum l by the main charger 2 are discharged by light irradiation from the light source 3λ, etc., and an electrostatic latent image is formed. This electrostatic latent image is developed by a developing device 4, and the toner attached to the photoreceptor drum 1 is transferred to a sheet of paper 9 by a transfer device 5.
4 is sent by the paper transport section 6 to a fixing device 11 having a xenon lamp 12, where it is heated and fixed.

A tension lever 10 and a feed roller 13 apply a constant tension to the paper 9 conveyed to the fixing device 11, and the sheet 9 is fed to the fixing device 11 in a predetermined state. Note that the toner remaining on the photosensitive drum 1 after the transfer is removed by a cleaning device 7, and the residual electric charge is removed by a static eliminator 8.

Conventionally used fixing devices do not particularly have a function of detecting abnormalities in the conveyance state of paper. Therefore, the fuser 11
Measures are taken to stop the xenon lamp 12 from emitting light by detecting an abnormality in the position of the tension lever 10 in front or in the rotational state of the feed roller 13 in the rear.

[Problem to be solved by the invention]

The conventional paper feed abnormality detection method described above does not directly detect abnormalities in paper feed to the fuser, so it may not be possible to respond accurately and quickly to abnormalities. The drawback was that it emitted light and heated the paper, causing it to discolor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device for an electrophotographic printing apparatus that has a function of directly detecting an abnormality in paper feeding and can prevent discoloration of paper.

[Means to solve the problem]

The fixing device of the electrophotographic printing device of the present invention is installed at a position through which the paper feed hole passes, in the fixing device of the electrophotographic printing device, which fixes toner adhered to the paper by flash exposure of a xenon lamp. The apparatus includes a photoelectric sensor that detects a paper feed hole, and a control unit that compares the output of the photoelectric sensor with a predetermined standard to detect an abnormality in paper feed and stops the exposure of the xenon lamp. .

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of essential parts of an embodiment of the present invention, and FIG. 2 is a block diagram of the embodiment of FIG. 1.

As shown in FIG. 1, a photoelectric switch 1 has a light emitting part and a light receiving part at a position where the paper feed hole passes through on the paper entry side.
5 and a reflective plate 16, the light emitted from the light emitting part of the photoelectric switch 15 is reflected by the reflective plate 16, and the strong reflected light is detected by the light receiving part to detect the feed hole of the paper, The output is sent to the control section 17 shown in FIG. The control unit 17 compares the duration of the output signal of the photoelectric switch 15 with the normal state, and if a difference exceeding a predetermined range is found, it immediately stops the xenon lamp 12 from emitting light and also stops the printing operation.

In the above embodiment, it was explained that the photoelectric switch 15 detects the sprocket hole using the strong reflected light from the reflection plate 16, but an absorbing plate is provided in place of the reflection plate 16, and the spout hole is detected by eliminating the reflected light. You may also do so. Further, the light emitting section and the light receiving section may be separately installed above and below the paper to form a photoelectric sensor, and the same effect can be obtained even if the photoelectric sensor is installed on the paper discharge side of the fixing device.

〔Effect of the invention〕

As explained above, the present invention has a function in the fuser unit that directly detects an abnormality in paper feeding and controls the light emission of the xenon lamp, so it is possible to reliably prevent paper that has stopped from discoloring due to excessive light emission. effective.

FIG. 2 is a block diagram of the embodiment shown in FIG. 1, and FIG. 3 is a configuration diagram showing a general configuration example of an electrophotographic printing apparatus.

■...Photosensitive drum, 2...Main charger, 3...Light source, 4...Developer, 5...
...Transfer device, 6...Paper transport section, 7...
... Cleaner, 8 ... Static eliminator, 9 ...
Paper, 10...Tension lever 11...
...Fuser, 12...Xenon lamp, 13
...Feed roller, 14...Toner, 15...Photoelectric switch, 16...Reflector, 17...Control unit.

Claims (1)

[Claims] In the fixing device of an electrophotographic printing device, which fixes toner adhered to paper by flash exposure from a xenon lamp, there is a photoelectric sensor that is installed at a position where the paper passes through the paper's paper perforation, and a photoelectric sensor that detects the paper's paper perforation. A fixing device for an electrophotographic printing apparatus, comprising: a control section that compares the output of the sensor with a predetermined standard to detect abnormality in paper feeding and stops exposure of the xenon lamp.