JPH08259043A - Paper break detection mechanism - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] The present invention relates to a paper break detection mechanism in a cut paper printing apparatus such as a printer, a copying machine, and a facsimile. The object of the present invention is to keep a printed paper folded. It is to prevent abnormalities such as missing prints and missing characters by reporting abnormalities when discharged or when printed on folded paper and discharged. When a pair of sheet break detection sensors 21 and 22 are provided at positions where both ends of the sheet pass near the stacker 16 and the difference between the times when the sheet 23 reaches the sheet break detection sensors 21 and 22 is longer than a predetermined time. It is determined that the leading edge of the sheet is folded, and if the difference between the times when the sheet 23 passes the sheet folding detection sensors 21 and 22 is longer than a predetermined time, it is determined that the trailing edge of the sheet is folded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet breakage detecting mechanism in a cut sheet printing apparatus such as a printer, a copying machine and a facsimile.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing an example of a cut sheet printing apparatus. The outline of the operation will be described below with reference to FIG. The surface of the photosensitive drum 14 is uniformly charged by the charger 11, and when a print signal decomposed into dot data is transmitted from the host device, the laser beam scans the surface of the photosensitive drum 14 to form an electrostatic latent image. To be done. The electrostatic latent image is carried to the position of the developing device 12, is developed by the mag roll 13 and becomes a toner image, and the toner image is carried toward the transfer device 6.

On the other hand, in response to a print signal from a host device, an electrostatic latent image is formed on the surface of the photosensitive drum 14, and at the same time, the paper on which the image is to be printed is picked by the hopper 1 by the rotation of the pick belt 2. It The paper picked by the hopper 1 is conveyed to the deceleration registration belt 4 by the registration conveyance belt 3. The deceleration registration belt 4 gradually lowers its rotation speed and finally stops to stop the sheet immediately before the photosensitive drum 14, and corrects the deviation of the sheet in the laser beam scanning direction. The deceleration registration belt 4 is adjusted in timing so that the toner image on the photosensitive drum 14 is transferred to a predetermined position on the paper.
Is rotated, and the paper is sent out from the deceleration registration belt 4 to the pinch roll 5. The pinch roll 5 sends the paper to the front of the transfer device 6 at the same speed as the peripheral speed of the photosensitive drum 14, and the transfer device 6 transfers the toner image to the paper.

The paper on which the toner image has been transferred has its accumulated charge reduced by AC corona discharge of the peeling device 7, is peeled off from the photosensitive drum 14, and is heated to a high temperature by the conveyor belt 8. The toner image is conveyed to the backup roll 9, and the toner image is fixed on the sheet by heat and pressure. The fixed sheets are sequentially sent to the stacker 16.

A sheet detecting sensor A17 and a sheet detecting sensor B1 are provided in the sheet conveying path from the hopper 1 to the stacker 16.
8. The paper detection sensor C19 and the paper detection sensor D20 are mounted, and when the arrival time of the paper between the sensors is longer than the specified value and when the detection time of one paper is long in each sensor is monitored. , Paper jams, etc. are detected.

[0006]

In the conventional cut sheet printing apparatus, when the paper arrival time between the sensors is longer than the specified value by the paper detection sensor mounted in the paper conveyance path, for example, the sensor A When the time from the detection of the sheet to the detection of the sheet by the sensor B is longer than the specified value, and when the passage time of one sheet in each sensor is longer than the specified value, the monitoring is performed and Although a detection signal is sent to the control device to report paper jams, device abnormalities, etc., monitoring is not performed when the paper arrival time or paper passage time is shorter than the specified value. Therefore, there is a problem in that even if the printed paper is folded in the middle or printed on the folded paper, the paper is ejected as it is and the printing ends normally.

Therefore, an object of the present invention is to report an abnormality when a printed sheet is ejected while folded or is printed on a folded sheet and is ejected, thereby preventing a serious obstacle such as missing print or missing characters. Especially.

[0008]

The above object is to provide a pair of paper break detection sensors at a position where both ends of the paper pass on a paper transport path in a paper break detection mechanism for a cut paper, and the paper is the above-mentioned paper break detection sensor. If the difference in the time to reach is longer than the predetermined time, it is determined that the leading edge of the sheet is folded, and if the difference in the time when the sheet passes the sheet folding detection sensor is longer than the predetermined time, it is determined that the trailing edge of the sheet is folded. It is achieved by

[0009]

According to the above construction, the pair of sheet breakage detection sensors can detect the leading edge and trailing edge of the sheet, and prevent the folded sheet from being discharged as it is.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing a procedure for detecting a sheet fold according to the present invention, FIG. 2 is a side view showing a peripheral portion of a sheet fold detection sensor, FIG. 3 is a plan view of FIG. 2, and FIGS. 4, 5 and 6 are sheets. It is a timing chart of a fold detection. 4 and 5
1 (High level) in FIG. 6 indicates that there is a signal.
Note that the same members as those of the conventional technique are denoted by the same reference numerals, and thus the description thereof will be omitted. In the present embodiment, the sheet breakage detection sensor 21, near the sheet detection sensor D20 closest to the stacker 16,
22 was provided. The sheet breakage detection sensors 21 and 22 are located downstream of the sheet detection sensor D20 in the sheet traveling direction,
Place them slightly inward from the lines on both sides of the paper. The operation will be described below.

When the cut sheet printing apparatus starts the printing operation and the sheet 23 reaches the sheet detection sensor D20, the sheet non-passage detection timer starts. After the paper non-passage detection timer is started, the paper 2 is detected by the paper break detection sensors 21 and 22.
Watch for 3 to arrive. If the paper 23 has not reached the paper folding detection sensor 21 or 22 even after X (ms) has passed since the undetected timer was started,
The paper is considered to have been folded as indicated by the dotted line and the abnormal paper fold is reported. FIG. 4 shows a timing chart when a paper non-passage abnormality occurs.

On the other hand, after the paper non-passage detection timer starts, X
When the paper 23 reaches either one of the paper break detection sensors 21 or 22 within (ms), the paper non-passage check is ended, the paper break detection timer is started, and the break check of the leading end of the paper is started. If the paper 23 does not reach the remaining one of the paper break detection sensors 21 or 22 even after Y (ms) has elapsed since the paper break detection timer was started, the leading edge of the paper 23 is broken as shown by the one-dot chain line in FIG. It is considered that there is a paper fold abnormality. FIG. 5 shows a timing chart when the leading edge of the sheet is abnormally broken.

On the other hand, after the paper break detection timer is started, Y
If the detection of the paper 23 is completed within (ms), the paper 2
The paper break detection sensor 2 is finished after checking the tip break of 3
Monitor the passage of sheet 23 through 1 or 22. Either paper break detection sensor 21 or 22
When 3 is passed, the paper break detection timer is started to start checking the rear end of the paper. When the sheet 23 does not pass through the other remaining sensor of the sheet fold detection sensor 21 or 22 even if Z (ms) or more has elapsed after the sheet fold detection timer was started, the rear end of the sheet 23 is as shown by the chain double-dashed line in FIG. The paper is considered to be folded, and a paper fold abnormality is reported. FIG. 6 shows a timing chart when the trailing edge of the sheet is broken.

On the other hand, after the paper break detection timer starts, Z
If the sheet 23 passes through the remaining one of the sheet break detection sensors 21 or 22 within (ms), the sheet 23
Judge that there is no crease in the sheet, pass it normally, and monitor the next sheet.

The X (ms) indicates the paper non-passage detection monitoring time, and the Y (ms) and Z (ms) indicate the paper breakage detection monitoring time. As an example, in a high-speed cut paper laser beam printer, When the size is A4 size, X = 300 (ms) and Y = Z = 15 (ms) can be set.

Here, when the paper size is different, X (m
By changing s), Y (ms) and Z (ms)
Further, when there are a plurality of paper sizes, a paper folding detection sensor is provided at a position corresponding to the paper size, and a simple circuit can be added or changed to cope with the situation.

In the present embodiment, the sheet breakage detection sensor 21 is provided in the vicinity of the sheet detection sensor D20 closest to the stacker 16.
Since 22 is provided, it is possible to detect all the folds of the paper that have occurred on the paper transport path. The paper fold detection sensor may be provided in the vicinity of a paper detection sensor other than the above, or may be provided separately from the paper detection sensor at any place on the paper conveyance path. You may provide in pairs.

[0018]

According to the present invention, the addition of the paper break detection sensor, the simple change of the control circuit, and the change of the micro program cause the printed paper to be discharged when it is folded or printed on the broken paper. Since abnormalities are reported when discharged, it is possible to prevent serious problems such as missing prints and missing characters.

[Brief description of drawings]

FIG. 1 is a flowchart showing a procedure for detecting a sheet break according to the present invention.

FIG. 2 is a side view showing a peripheral portion of a paper fold detection sensor.

FIG. 3 is a plan view showing a peripheral portion of a paper fold detection sensor.

FIG. 4 is a timing chart in the case of a paper non-passage abnormality.

FIG. 5 is a timing chart when the leading edge of the paper is abnormal.

FIG. 6 is a timing chart when the trailing edge of the sheet is abnormally folded.

FIG. 7 is a configuration diagram illustrating an example of a cut sheet printing apparatus.

[Explanation of symbols]

Reference numeral 9 is a heat roll, 10 is a backup roll, 16 is a stacker, 20 is a sheet detection sensor D, 21 and 22 are sheet fold detection sensors, and 23 is a sheet.

Front page continued (72) Inventor Kiyomi Tsuchiya 1060 Takeda, Hitachinaka City, Ibaraki Prefecture, Hitachi Koki Co., Ltd. (72) Inventor Takashi Ebihara 1060 Takeda, Hitachinaka City, Ibaraki Hitachi Koki Co., Ltd.

Claims (2)

[Claims] 1. A paper break detection mechanism for a cut paper, wherein a pair of paper break detection sensors are provided at positions where both ends of the paper on the paper transport path pass, and a difference in time for the paper to reach the paper break detection sensor is predetermined. If the difference between the times when the paper passes through the paper folding detection sensor is longer than a predetermined time, it is judged that the paper is bent at the trailing edge of the paper. Detection mechanism. 2. The paper break detection mechanism according to claim 1, wherein the paper break detection sensor is provided in the vicinity of a paper discharge section.