JPH0623971A - Device for measuring sheet length - Google Patents

Abstract

PURPOSE: To measure the length of sheets in a printing press by a method wherein a control device connected to a running sensor includes a calculation circuit for pulses of a rotation signal generator which are taken into the device between side edges of a leading edge signal and a trailing edge signal and the length of sheets being fed can be sensed by means of a noncontact means. CONSTITUTION: A rotation signal generator 7 generates pulses 11, e.g. pulses of 4096 every one revolution. And a target value 12 for the leading edge of a sheet 1 and a target value 13 for the trailing edge of the sheet 1 stored in a control device 9 are connected with signals 14, 15 of two sensors 10 respectively, whereby the length (1) of the sheet is obtained. In an embodiment, the length (1) has an expansion of an increment 11 over 3476 of the generator 7. In this case, in the target length of sheet, two increments 11 or length Δ1 lacks. In this case, the sheet is cut to extremely short length, and hence a corresponding impression cylinder is contaminated or in the case of a perfecting press, the sheet cannot be transferred any longer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a sheet length when a sheet is conveyed through a printing machine, and all constituent units used for conveying the sheet. For example, it relates to a type in which a paper feeding and discharging device, a printing mechanism and a folding machine are connected to each other via a closed gear train.

[0002]

From EP-A-0 0095 647 is known a device for monitoring the sheet transport in a sheet feeder of a printing press, in which case the sheet entering via an optoelectronic sensor. The leading edge and corners of the are controlled.

Furthermore, a detection disk is provided with a detection switch which is synchronized with the rotary movement of the printing press. The correct position of the sheet is controlled by means of a control device connected to the sensor and the detection switch, in which case it is checked whether the sheet occupies the sensor's response range between two detection times.

Depending on the result of the check, the control device issues an error warning or signal to the machine control device.

Disadvantageously, in this case, the device is provided only in the area of the paper feeder and cannot carry out dimensional control of the sheets.

German Patent Publication No. 383631
From the specification No. 0, there is known a device for controlling the switching process in a printing machine, in which the switching process is an incremental signal generator for the rotational angle of the printing machine, an optical device as a reflection photoelectric box provided on the turning drum. The release is related to the signal of the switch of the active sensor and the detection disk.

In one embodiment of this device, the turning of the deflecting drum relative to the storage drum by an angle related to the printing sheet length in order to switch the printing machine to double-sided printing,
It is detected by calculating the signal of the incremental signal generator between the two switching edges of the switch of the detection disc.

The disadvantage of this solution is that the optical sensor is aimed at the edge of the turning drum and at the same time is not provided for detecting the sheet length.

Federal Republic of Germany Utility Model No. 770043
The sheet-fed control device known from the specification No. 0 has a scanning element which is arranged inside the cylinder in the gripper edge. This device only controls the exact position of the gripping edge of the sheet, not the exact sheet length.

Furthermore, with the scanning device oriented towards the leading and trailing edges of the sheet, whether the sheet is located within the detection range of the scanning device at a defined time or in a defined time range. A solution for detecting is disclosed.

German Patent Publication No. 372027
No. 2, the scanning device signal is related to the signal for the angular position of the cylinder.

Japanese Patent Application Publication No. 1-306224
In document 7, the sheet signal of the scanning device is related to the signal produced by scanning the metal surface of the cylinder.

In this way, the leading edge of the sheet is the target of the impression cylinder.
It is checked whether it lies within a predefined rotation angle range in relation to the rotation angle position.

The disadvantage of this solution is that only the position and / or the change of position of the sheet relative to the angular position of the printing machine can be detected by the device, but the sheet length It is that the evaluation of cannot be performed.

Furthermore, German Patent Publication No. 341
In the folding machine for folding a sheet disclosed in the 1742 specification, the sheet length of the sheet flowing into the folding machine is detected by a measuring roller.

The measuring roller rolls into contact with the sheet and cooperates with a pulse signal generator whose output signal is calculated and supplied to a control circuit. For this purpose, the pulses emitted by the measuring roller between the leading and trailing edge signal edges of the sheet are calculated.

Disadvantageously, in this case, the accuracy is related to the sheet thickness and the sheet speed, and the measurement is only made at one point over the sheet width.

[0018]

SUMMARY OF THE INVENTION The object of the present invention is to measure the sheet length inside the printing press so that the length of the sheet fed by the contactless means can be detected. Is to improve the device.

[0019]

SUMMARY OF THE INVENTION According to the invention, the above-mentioned object is achieved in that the contactlessly operated sheet-travel sensor is arranged in a fixed position in the printing machine at a defined monitoring point. The sheet running sensor is directed toward the leading edge and the trailing edge of the sheet, a signal generator is provided for detecting the rotation angle of the printing press, and the control unit controls the sheet running sensor and the rotation signal. Solved by having the control device connected to the generator and having a calculating circuit for the pulses of the rotary signal generator incorporated in the control device between the leading and trailing signal side edges. Was done.

[0020]

The sensor detects the leading edge and the trailing edge of the sheet on each sheet and relates them to the appropriate machine angle. The angle difference between the leading edge and the trailing edge is directly proportional to the sheet length.

In addition to the pure length measurement, via the control device,
Various adjustment processes relating to the sheet length can be carried out, such as automatic adjustment of the turning device, monitoring of the sheet transport during turning and control of the powder usage time.

Furthermore, it is possible to monitor the contamination of the impression cylinder by means of a sheet length measurement, in which case, for example, diagonally cut sheets or very short cut sheets, Sheets whose trailing edge lies within the print image area are detected.

In this case, the ink is transferred from the blanket cylinder to the corresponding impression cylinder and is absorbed by the back side of the next sheet. This sheet is waste and the corresponding impression cylinder must be washed.

The input of the position of the printed image can be carried out, if necessary, by manually detecting the preconditioning data of the disc scanner or by using the registration data.

If the trailing edge of an individual sheet lies between the printing start and the appropriate printed image, the dampening medium is transferred to the corresponding impression cylinder, which has a similar disadvantageous effect. .

If two sheet running sensors juxtaposed to one another are used to detect the sheet length, it is also possible to detect the leading edge or the trailing edge, which is preferably bevelled. The obliquely cut leading edge or trailing edge can also be detected when using the sheet traveling sensors provided alternately on the driving side and the operating side for each printing mechanism.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows an apparatus for measuring the sheet length when the sheet is conveyed through the printing machine 2. The printing machine 2 has, in addition to the paper feeding device 3 and the paper discharging device 4, five printing mechanisms 5 each having a cylinder 6 used for conveying sheets. All component units used for transporting are connected to each other by a gear transmission (not shown).

The rotation angle of the printing press is detected by an incremental rotation signal generator 7, which is connected to a drive 8 and to a control unit 9.

Furthermore, a large number of optoelectronic sensors 10 are stationary along the conveying path of the sheet 1 and the printing machine 2 is provided.
Incorporated therein, the sensors 10 are each connected to a control unit 9.

Next, the work format of the apparatus will be described with reference to FIGS. 2 and 3.

The rotation signal generator 7 is, for example, 409 for each rotation.
6 pulses 11 are generated. The setpoint value 12 for the leading edge of the sheet 1 and the setpoint value 13 for the trailing edge of the sheet 1, which are stored in the control unit 9, are coupled to the signals 14, 15 of the two sensors 10. A sheet length 1 is obtained.

In the exemplary embodiment, the sheet length l has a spread of increments 11 over 3476 of the rotation signal generator 7, in this case two increments 11 or a length Δl at the target sheet length. Is running out.

In this case, the sheet 1 is cut very short, so that the corresponding impression cylinder becomes contaminated or, in the case of double-sided printing, the sheet 1 cannot be conveyed further.

The system diagram shown in FIG. 3 shows the signal flow when measuring the sheet length. The control device 9 is supplied with signals from the rotation signal generator 7 and the sensor 10. The pulses of the rotation signal generator 7 are calculated in the calculator 16 in relation to the edge signal side edges 14, 15.

An average value is formed in the average value forming machine 17 from the sheet length l of a large number of sheets 1, and a reference value 18 is obtained from this average value. The sheet length l of the sheets whose length difference Δl exceeds a predetermined value is not used for forming the average value. In the comparator 19, the reference value for each sheet 1 is compared with the actual value of the sheet length l.

In the output section, the control device 9 controls the paper feeding device 3 when there is an unacceptable difference between the reference value and the actual value.
A signal is generated in the adjusting member 21 or a warning signal in the output device 20 for the subsequent transport of the sheet in the direction of the sheet discharge device 4.

[Brief description of drawings]

FIG. 1 is a schematic view of a sheet length measuring device.

FIG. 2 is a pulse diagram for measuring sheet length.

FIG. 3 is a systematic diagram for measuring sheet length.

[Explanation of symbols]

 1 Sheet 2 Printing Machine 3 Paper Feeding Device 4 Paper Ejecting Device 5 Printing Mechanism 6 Body 7 Rotation Signal Generator 8 Driving Device 9 Control Device 10 Sensor 11 Pulse 12,13 Target Value 14,15 Signal 16 Computer 17 Average Value Formation Machine 18 Reference value 19 Comparator 20 Output machine l Sheet length Δl Length difference

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ud Brasius, Federal Republic of Germany Reimen Eschenweg 7

Claims (1)

[Claims] 1. A device for measuring a sheet length when a sheet is conveyed through a printing press, wherein constituent units used for conveying are connected to each other via a gear transmission. A contactless-acting sheet-fed type, in which a sheet-length-related control device is provided for the drive of the printing press and for the number of adjusting elements. A paper running sensor (10) is arranged in a fixed position in the printing machine (2) at a defined monitoring point, in which case the paper running sensor is directed towards the leading edge and the trailing edge of the sheet (1). In addition, a signal generator (7) for detecting the rotation angle (2) of the printing machine is provided, and the control device (9) includes a sheet traveling sensor (10) and a rotation signal generator (7). ), And the control device (9) controls between the leading edge signal side edge and the trailing edge signal side edge. Device for measuring sheet length, characterized in that it has a calculation circuit for the pulses of the rotation signal generator (7) incorporated in the device (9).