JPH04169452A - Photoelectric transmission type paper edge position detecting method for sheet and web - Google Patents

Abstract

PURPOSE:To improve accuracy of detecting a paper edge position by providing further more a pair of equal light projecting/receiving elements for detecting a temperature in addition to a pair of light projecting/receiving elements used for detecting the edge position. CONSTITUTION:In arithmetic device groups 3, 5, 7, 9, arithmetic operation is performed by a signal of light receiving amount in accordance with a position of a detected object, placed between an optical lens group for the edge detection and projection/ reception of light projecting/receiving elements, to obtain output voltage in proportion to the edge position. In temperature correcting arithmetic device groups 4, 6, 8, 12, a change of peripheral temperature is supervised by a temperature detecting optical lens group and light projecting/receiving elements 2. A light emitting output by a change of the peripheral temperature is corrected to always hold an output signal in a fixed value. Quite the same to the temperature detecting optical lens group and the light projecting/receiving elements 2 is used for the edge detecting optical lens group and the light projecting/receiving elements 1 and also using the same to circuits 4, 6 for the arithmetic circuits 3, 5, so that even when peripheral temperature of the edge detecting position is changed, the edge position can be high accurately detected by contriving stabilization of a quantity of light.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention detects the edge position of a sheet or plate-like strip made of film, paper, rubber, cloth, metal, plastic, etc. To this end, the present invention relates to an improvement in a photoelectric transmission type edge position detection method for sheets and other strip-like objects constructed by combining at least one pair of light emitting and light receiving elements.

(Prior Art) Conventionally, as means for detecting the edge position of a running object in the form of a sheet or plate such as a running film, rubber, paper, or net, one light source is placed at the edge of the object. There are known methods and apparatuses for detecting the edge position of the strip by projecting the transmitted light onto a single light receiving element and using an output voltage proportional to the amount of light received.

As shown in Figure 1, this principle uses a light-emitting element a and a light-receiving element A, and the light beam leaving the light-emitting element A reaches the light-receiving element A, and the detected object A is blocked by the light beam. , the position of the edge of the detected object is detected by moving between the received light beams other than those blocked.

(Problem to be Solved by the Invention) However, in the case of this detection means, when the ambient temperature of the detection device used changes, the light emitting output in the case of the light emitting element and the short circuit current in the case of the light receiving element change, respectively, depending on the ambient temperature. It has the disadvantage that it changes due to the influence of the sensor, resulting in a change in the output that is similar to moving the object to be detected.

Up until now, temperature compensation has been performed by using a thermistor etc. in the light emission output circuit to suppress changes in the light emission output as much as possible even when the temperature changes, but since it is not a feedback loop control method, each element Due to large errors due to variations in the values and poor linearity, accurate edge detection and use at high temperatures were not possible.

The present invention was researched and developed in order to eliminate the above-mentioned drawbacks of the conventional detector, and when the ambient temperature of the detector changes, the detection signal of the conventional detector changes as if the object to be detected was moved. In view of the drawback that similar output changes are caused, the object of the present invention is to provide a photoelectric transmission type edge position detection method for sheets and similar belt-like objects that can eliminate this drawback.

(Means for solving the problem) As a means to solve the above problem and achieve the purpose,
In the present invention, in a photoelectric transmission type edge position detection method in which an infrared light emitting diode and a silicon photodiode are provided facing each other to detect the edge position of a sheet or a belt-like object in a transmission manner, at least one further pair is provided. Sheets and other sheets that use the same light-emitting element and light-receiving element to detect the edge position by providing a temperature compensation circuit so that the edge detection position does not shift even if the ambient temperature changes. We developed and adopted a photoelectric transmission method for detecting the position of the edge of a strip.

(Function) As described above, in the present invention, in addition to the pair of light emitting/receiving elements used for detecting the edge position, at least another pair of the same light emitting/receiving elements is provided for temperature detection. Even if the temperature changes, the light emitting output of the light emitting element and the short circuit current of the light receiving element are constantly monitored so that they remain constant, and the emitting element current is controlled by a temperature compensation circuit in the amplifier, such as an A-L-L-C circuit. It is possible to correct the output signal and keep the output signal constant at all times, which has the effect of improving the accuracy of detecting the position of the ear tip.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings. FIG. 2 shows a block diagram of the temperature compensation circuit used in the present invention, and in the same figure, 1 is an optical lens group for detecting the edge of an edge, and a light emitting and receiving element, which are designated by reference numerals 3.5.7.9. The arithmetic unit group performs calculations based on the signal of the amount of light received depending on the position of the object to be detected between the light emission and reception, and is configured to obtain an output voltage proportional to the edge position. 2 is an optical lens group for temperature detection and a light emitting/receiving element, numbered 4.6.8
．． It is configured to monitor changes in ambient temperature using a group of computing units called an A-L-L-C circuit for temperature correction shown at 12. With this configuration, the light emission output is corrected due to changes in ambient temperature, and the output signal is always kept constant.

Next, to explain the loop provided by the latter A-L-L-C circuit 2, when a voltage Va is applied from the reference power supply A to the input part of the integrator 8 in the arithmetic unit group,
This is done by controlling the current of the light emitting element in a loop including an integrator so that the voltage of V2 becomes Va=V2.

Here, if the ambient temperature changes to a higher side, the light emitting output of the light emitting element decreases, the short circuit current of the light receiving element increases (the amount of increase is very small compared to the decrease in the light emitting output), and The voltage at the two points changes in the direction of decreasing, but since the calculation is performed using the input of the integrator, the output voltage v3 of the integrator immediately changes to the higher side, increasing the light emission output, and
Correction is quickly performed until the two points have the same voltage as Va.

Here, the optical lens group and light emitting/receiving element for detecting the edge of the edge indicated by reference numeral 1 are exactly the same as the optical lens group and light emitting/receiving element for temperature detection indicated by reference numeral 2, and
The arithmetic circuit shown in is the same as the circuit shown in 4.6, so even if the temperature around the edge detection position changes, it can be regarded as ■a-■2LF-■1. As a result of stabilizing the amount of light, it has become possible to detect the position of the ear tip with high precision, unaffected by changes in ambient temperature.

In the figure, A is the object to be detected, the opening is the detector body, a is the light emitting element, e is the light receiving element, C is the lens, 1 is the light emitting/receiving element for detecting the edge of the ear (including the optical system lens), and 2 is the detector body. Light emitting/receiving element for temperature detection (including optical system lens), 3.4 is I/V converter, 5.6 is synchronous rectifier circuit, 7 is adder, 8 is integrator, 9
10 is an amplifier, 10 is a pulse oscillator, 11 is a switching transistor for pulse driving the light emitting element, 12 is a transistor for driving the light emitting element, and ASB is a reference power source.

Although the main embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. Of course, design changes are possible.

(Effects of the Invention) As described above, the present invention provides a photoelectric transmissive type selvage device in which an infrared light-emitting diode and a silicon stub diode are provided facing each other to detect the edge position of sheets and other strips in a transparent manner. In the edge position detection method, at least one more pair of the same light emitting element and light receiving element is used to detect the edge position by providing a temperature compensation circuit so that the edge detection position does not shift even if the ambient temperature changes. Since this method relates to a photoelectric transmission type edge position detection method for sheets and belt-like sheets characterized by
, L, L, and C circuits, it is possible to correct the light emitting output and obtain a constant edge detection output signal, thereby maintaining a good amount of detected light and determining the edge edge position of the strip with high precision. This has the great effect of achieving detection.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic diagram showing a light-shielded state of an object to be detected in a transmission type edge detection device, and FIG. 2 is an overall block diagram of the circuit.

Claims (1)

[Claims] In a photoelectric transmission edge position detection method in which an infrared light emitting diode and a silicon photodiode are provided facing each other to detect the edge position of sheets or other strips in a transmission manner, at least another pair of the same light emitting element and Photoelectric transmission of sheets and other strip-like materials, which uses a light receiving element to detect the edge position by installing a temperature compensation circuit so that the edge edge detection position does not shift even if the ambient temperature changes. Ear end position detection method.