JPS58101084A - Jam detector - Google Patents

Abstract

PURPOSE:To provide a titled detector which can effectively operate irrespective of the type and thickness of sheets by generating a jam detection output when the time difference between the signal formed upon movement of the sheet and the sheet feeding command signal exceeds the set value. CONSTITUTION:Part of the luminous flux of a light source 1 is passed through a feed hole 4, is converged via a recticle lens 5, and is focused to the special position of a photoelectric converter 6. A monostable multivibrator 8 and a monostable multivibrator 9 (time constant of T1) are triggered by the differentiated output of the mechanism for detecting focused flux. A sheet feed signal to a printer is set to a set signal of a monostable multivibrator 10 (for deciding the time constant T2 so that the maximum delay time from the reception of the sheet feed signal to the start of feeding the sheet is specified). After a sheet feed signal is received, the time T2 is elapsed, and the sheet feed does not occurs or one side feed occurs, thereby obtaining a sheet feed malfunction signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing device used in, for example, an electronic computer, and relates to a paper jam detection method that detects a paper jam using a signal related to the running of paper detected without touching the paper and a paper feed command signal to the printing device. It is related to equipment.

Conventionally, a paper jam detection mechanism is provided with a cover over a paper feed sprocket, and uses a microswitch or the like to detect that when the feed fall of the paper misaligns with the sprocket, the paper climbs over the sprocket and pushes up the cover. Therefore, in the case of thin paper, even if a jam occurs, the microswitch may not be activated, and in the case of thick or multi-part paper, the cover may be pushed up by the creases of the paper, etc. It was easy to cause malfunctions.

The present invention has been proposed in view of the disadvantages that conventional jam detection devices have, and its purpose is to provide a jam detection device that operates reliably regardless of the type and thickness of paper. It's there.

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a transparent perspective view of an embodiment of the present invention in which a feed hole image of continuous paper is projected onto a light receiving element. In FIG. 1, 2 is an outer box that houses a light source l and blocks external light, and 4 is a feed hole punched in the continuous paper. Further, 5 is a kamapoko lens that converts the feed hole image into a line image perpendicular to the running direction of the paper, and 6 is a conversion element that forms an output that changes electrically with fluctuations in the light receiving section. Further, 7 is a feed hole image created by the Kamapoko lens 5.

Next, the operation of the apparatus shown in FIG. 1 will be explained. light source l
After a part of the light beam passes through the feed hole 4 , it is converged by the Kamapoko lens 5 and focused on a specific part of the photoelectric conversion element 6 . When the paper is fed here, the image forming area on the photoelectric conversion element changes, so the output voltage of the photoelectric conversion element 6 changes.

Therefore, the movement of the paper is recognized electrically.

FIG. 2 is an example of a circuit diagram for processing electrical signals sent from the detection mechanism shown in FIG. 1 and paper feed signals sent to the printing device to detect paper feed abnormality. In addition, the first
Although a single detection mechanism is shown in the figure, it is actually installed in the left and right front feed holes, and left and right detection outputs are given to the circuit shown in FIG. Furthermore, the monostable multivibrator 8 and the monostable 9 in FIG. 2 have a time constant T1, and are triggered by the differential output of the detection mechanism shown in FIG. The time constant T1 is selected to compensate for the mounting accuracy of the detection mechanism and the drilling accuracy of the feedhole. The outputs of both monostable multivibrators 8 and 9 are combined by an AND gate Gl, and set/reset/
It becomes a reset input for flip-flop R5-FF. That is, when the paper does not move or when the feeding of either the left or right paper lags behind the other by more than the time determined by the time constant Tl, the reset signal is not generated. On the other hand, the paper feed signal to the printing device becomes the set signal for the monostable multivibrator 3 having the time constant T2 at the same time that the aforementioned set/reset flip-flop R3-'FF is set. The maximum delay time from the reception of the B1 signal to the start of paper feeding is determined. Here, the inverted output of monostable multivibrator 3 and the set-reset flip-flop R3
- By combining the outputs of FF with AND gate G2, a paper feed abnormality signal is generated if paper feed does not occur after a time determined by time constant T2 has elapsed after receiving the paper feed signal, or if one-sided feed occurs. can be obtained as the output of Antogame) G2.

As explained above, the present invention does not detect a jam itself but rather monitors the running of paper, so it has the effect of reliably detecting all paper troubles in a printing device.

[Brief explanation of the drawing]

FIG. 1 is a transparent perspective view of the main parts of an embodiment of a jam detection device according to the present invention, and FIG. FIG. Here, 1... Light source, 2... Outer box, 3... Continuous paper, 4... Feed hole, 5... Kamapoko lens, 6... Photoelectric element, 7... Feed hole image It is. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] It has a photoelectric conversion section for obtaining a signal formed by the movement of the paper, and a comparison section for comparing the time difference between the signal formed by the movement of the paper and the paper feed command signal, and the comparison section compares the time difference between the signal formed by the movement of the paper and the paper feed command signal. A jam detection device characterized in that a jam detection output is generated when the jam detection output is exceeded.