JPS623603A - Position detecting system for linear mark - Google Patents

Abstract

PURPOSE:To detect the position of a bilateral linear mark by adjusting biases and gains to equalize position-output signal characteristics of right and left photoelectric transducers, amplifiers, and the whole of an optical system. CONSTITUTION:This system consists of an optical system 16 which focuses forms the images of light beams irradiated to linear marks 13 and 15 on band- shaped materials 12 and 14 like films on two photoelectric transducers 17 and 18, amplifiers 20 and 21 which amplify output electrical signals of transducers 17 and 18, an operational amplifier 26 for subtraction which amplifies a signal proportional to the difference between output signals of amplifiers 20 and 21. The light from a light source 10 is irradiated to linear marks 13 and 15, and the light of their light and darkness is image formed on transducers 17 and 18 by the optical system 16, and the outputs are amplified by amplifiers 20 and 21. One or both biases of them are adjusted by means 24 and 25 so that the output signals of them are equal to each other in the minimum output state, and one or both biases of them are adjusted by means 22 and 23 so that they are the same signal in the maximum output state. The position signal of a linear mark image 19 having a bilateral characteristic is set to zero to make the position error of zero.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an improvement in a detection method for detecting the center position of a linear mark drawn on a strip material such as film or paper, and in particular,
It relates to a method that can obtain predetermined position detection characteristics even if there are manufacturing or characteristic differences or variations in the dimensions, sensitivity, amplifier gain, optical system, etc. of the photoelectric conversion element. The present invention is used in the manufacturing technology industry for center position detectors for shaped marks.

(Prior Art) As a detector for detecting the center position of a linear mark on a strip material such as film or paper, conventionally, for example, an amplifier that amplifies the output of two photoelectric conversion elements, Some devices include a device detection function that includes a differential amplifier that amplifies the difference between the outputs of two amplifiers.

In such conventional detectors, the balance can be adjusted so that the differential amplifier output becomes zero when the center of the linear mark is at the center position of the two photoelectric conversion elements, and the magnitude of the output signal relative to the position can be adjusted. The configuration is such that the gain of the differential amplifier can be adjusted so that the difference can be adjusted.

(Problems to be Solved by the Invention) In the conventional detector described above, for example, if there are manufacturing or characteristic variations in the dimensions, sensitivity, amplifier gain, optical system, etc. of the photoelectric conversion element, Even if the position output signal becomes zero at the center position, the maximum value, gain, etc. of the position detection signals on the right side and left side of the center will not be the same, resulting in asymmetric characteristics. Therefore, we screen photoelectric conversion elements and amplifiers so that their characteristic variations are below the allowable value.
It is necessary to install the optical system with high precision.

In addition, each time the film material, color, or linear mark color is changed, the detector user must readjust the bias and gain adjustments, which is very inconvenient for the user. The need for adjustment technicians is required.

In order to solve the above-mentioned problems, the present invention makes the position-output signal characteristics of the right and left photoelectric conversion elements, amplifiers, and entire optical system the same by bias adjustment and gain adjustment, thereby making linear marks with left-right symmetrical characteristics. The purpose of this invention is to provide a position detection method.

(Means for Solving the Problems) The linear mark position detection method according to the present invention has the following features.

(1) Light rays irradiated onto a linear mark drawn on a strip material such as film or paper form images of bright and dark rays that pass through or are reflected on two photoelectric conversion elements. In a linear mark position detector equipped with an optical system, an amplifier that amplifies the output electrical signal of each photoelectric conversion element, and a differential amplifier that amplifies a signal proportional to the difference between the output signals of those amplifiers, each photoelectric conversion element is a first means having a function of adjusting the bias of one or both of the amplifiers so that the amplitude of the output signals of both amplifiers is the same in the minimum output state of the amplifier connected to the conversion element; and the maximum output of the amplifier. The second means has a function of adjusting the gain of one or both of the amplifiers so that the magnitudes of the output signals of both amplifiers are the same in the state.

(2) An optical system that images bright and dark light rays that are transmitted or reflected by a light beam irradiated onto a linear mark drawn on a strip material such as film or paper onto two photoelectric conversion elements;
In a linear mark position detector equipped with an amplifier that amplifies the output electrical signal of each photoelectric conversion element, and a differential amplifier that amplifies a signal proportional to the difference between the output signals of those amplifiers, each photoelectric conversion element is a first means having a function of adjusting the bias of one or both of the amplifiers so that the magnitude of the output signal of both amplifiers is the same in the minimum output state of the connected amplifier; a second means having a function of adjusting the gain of one or both so that the magnitude of the output signal of the amplifier is the same;
2 so that the magnitude of the output signal of the differential amplifier becomes minimum or zero when it is located at the center of the photoelectric conversion elements.
and third means having a function of adjusting the balance of the output signals of the respective amplifiers.

(Function) The function of the present invention will be explained. (See Figure 1) Light source 1
The linear mark 2 is irradiated with more light.

The bright and dark light rays of the linear mark are transmitted by the optical (lens) system 3.
Images are formed on photoelectric conversion elements 4 and 5.

The outputs of photoelectric conversion elements 4 and 5 are input to amplifiers 6 and 7, respectively. Even if the outputs of the amplifiers 6 and 7 are the same linear mark or the same strip material on which it is drawn, the outputs of the amplifiers 6 and 7 may be affected by the deviation of the optical axis of the lens system, the size of the photoelectric conversion element, the difference in sensitivity, the amplifier Usually, they are not the same due to differences in the amplification degree. Therefore, amplifiers 6 and 7
One or both of the biases are adjusted so that the output signals are the same in the minimum output state, and the gain of one or both is adjusted so that the output signals are the same in the maximum output state. Note that when the center of the linear mark is focused on the center position of the photoelectric conversion element, the balance is adjusted by the adjustment means 8 so that the magnitude of the output signal of the differential amplifier 9 becomes zero.

Also, for example, if the position output voltage does not become zero even though the linear mark image is at the center position of the photoelectric conversion element due to deterioration of the sensitivity of the photoelectric conversion element or changes in the characteristics of the amplifier and operational amplifier. Even in this case, the output voltage can be made zero by the input balance adjustment means of the operational amplifier (see FIG. 5).

(Example) The present invention will be described in detail below based on the drawings.

FIG. 1 is a block diagram showing the overall configuration of the present invention.

In the figure, 1 is a light source, 2 is a linear mark, 3 is a lens system that images light rays according to the brightness of the linear mark onto two photoelectric conversion elements 4 and 5, and 6 and 7 are output in the minimum output state. A means for adjusting the bias of one or both so that the magnitude of the signal is the same, and a means for adjusting the gain of one or both so that the magnitude of the output signal is the same in the maximum output state. An amplifier 8 having means for adjusting the balance so that when the imaging position of the linear mark is at the center of the two photoelectric conversion elements 4 and 5, the magnitude of the output signal of the subtraction operational amplifier 9 becomes zero. This is a possible means.

FIG. 2 is a block diagram of one embodiment of the present invention.

In the figure, 10 is a light source, for example, a light bulb having a linear coiled filament. 11 is a lens system, 12
1 is a strip material such as a film, and 13 is a linear mark drawn on it.

Note that although it is customary that the strip material 12 is transparent and the linear mark 13 is opaque, the opposite may be the case.

Furthermore, when it is difficult for the light beam to pass through, the refraction of the light beam irradiated onto the linear mark 15 drawn on the strip material 14 such as film or paper is utilized.

Reference numeral 16 denotes a lens system, through which light reaches two sets of photoelectric conversion elements 17 and 18. 19 is a linear mark imaged on the photoelectric conversion elements 17 and 18. The photoelectric conversion cables 17 and 18 convert the received light into electrical signals depending on the amount of light received, and the electrical signals are provided to amplifiers 20 and 21. 22 and 23 are examples of gain adjustment means for the amplifiers 20 and 21, 24 and 25 are examples of bias adjustment means for the amplifiers 20 and 21, and 26 is an operational amplifier for subtraction.

In the above configuration, the light beam emitted from the linear light source 10 is focused onto the strip material 12 or 14 by the lens system 11.

At this time, if the strip material 12 is transparent, the focal point of the opaque linear mark 13 drawn on its surface is focused by the lens system 16 onto the photoelectric conversion elements 17 and 18 on a contrasting linear mark image 19. tied as vice versa,
In the case of a contrasting linear mark 15 drawn on the surface of an opaque strip material 14, an image of the mark 15 created by light beams reflected from the strip material 14 and the linear mark 15 is transferred to a photoelectric conversion element by a lens system 16. A linear mark image 19 is formed on 17 and 18 .

The photoelectric conversion elements 17 and 18 each convert the amount of incident light into an electric signal proportional to the amount of incident light, which is converted into normal voltages ER and E by amplifiers 20 and 21, respectively.

Therefore, when the linear mark images 19 are present on these photoelectric conversion elements 17 and 18, the amount of incident light is reduced by that amount.

This amount of change changes depending on the position of the linear marks 13 and 15.

The relationship between the position of this linear mark, the output voltage of each photoelectric conversion element, and the position detection voltage will be explained with reference to FIG.

In FIG. 3(A), PDR and PD[ are the right and left photoelectric conversion elements, H is the height of the element, W is the width, and G is the spacing between them. I is an image of a linear line on the photoelectric conversion element, and L is its width.

The outputs of photoelectric conversion elements PDR and PD are amplified by amplifiers A and A[, respectively, and voltages E and E
, is output as . These voltages are applied to differential amplifier A
, the following equation is calculated and the output Eo is obtained as the position detection voltage. That is, Eo=k (E, -ER)
・・・−(1) Here, k = amplification degree In this case, the center position d of the linear line L and the amplifier AR
The characteristics of the output voltages ER and E of and A are shown in Figure 3 (
Shown in B). In FIG. 3B, when the center of the linear line LI is at d[1, the right end of the linear line with the width coincides with the left end of the left photoelectric conversion element PD. d
When dL1, the amount of light incident on the photoelectric conversion element PD1 has a maximum value, so the output voltage E of the amplifier A has the value shown in FIG. 3(B). The value of dLl is d=
d, 1=-(W+(G+1)/2)...(2) Next, increase the center position of the linear line by d=, dL2°d[1+=-CW+(GL) /2) ・・・・・・(3
), the amount of light incident on the photoelectric conversion element PD becomes the minimum value, so the output voltage E of the amplifier AL becomes the value B in FIG. 3(B).

This value remains constant during d12≦d≦d[3.

d is a case where the right end of the linear line 1 and the right end of the photoelectric conversion element [3 PD] coincide. Therefore, dL3
-d[2+WL-L=-(G+L)/2...(4)
Moreover, in the case of displacement d = d14, photoelectric conversion element P
The right end of D[ and the left end of linear line L1 coincide, and the output to the amplifier becomes the maximum value, which is the same as A. That is, dL4=(GL)/2 ・・・・・・(
5) In the above manner, the output voltage E[ of the amplifier A is obtained as shown in FIG. 3(B).

In exactly the same way, amplifier A is also used for the right photoelectric conversion element.
The characteristic of the output voltage ER of R is obtained as shown in FIG. 3(B).

However, as shown in the figure, the maximum value and minimum value of the output voltage are not necessarily the same. This is because there are differences or variations in manufacturing or characteristics of the dimensions and sensitivity of the light-receiving element, the gain lens system of the amplifier, etc.

Regarding the displacement of the center part, the following relationship exists when the dimensions H, W, G, and [ of the photoelectric conversion element and the linear line are determined.

・°・dR2'R1""L4 'L3=,L
(7) Next, the output voltage E of the operational amplifier 26. is determined by equation (1). Therefore, the characteristics with respect to the displacement d are as shown in FIG. 3(C). As a result, when d=◯, E□-#O. Also, Eo=
The displacement that becomes ○ becomes d=do≠O.

This property causes an inconvenience when attempting to control the positioning at the center of a linear line because it becomes impossible to position the center.

To improve this, since the relationship expressed by equation (7) exists, the output voltages ER and E of the amplifiers AR and Δ may be adjusted so that the minimum and maximum values thereof are the same. That is, the output voltage ER of amplifiers AR and A,
and E are axially symmetrical as shown in FIG. 4(A). Therefore, the position output voltage E. is as shown in the same figure (B), which is an ideal characteristic symmetrical to the origin.

An embodiment of the above principle is shown in FIG. 2, in which the minimum adjustment means are bias adjustment resistors 24 and 25 of amplifiers 20 and 21. Further, the maximum value adjustment means is the gain adjustment resistor 22 of the amplifiers 20 and 21.
and 23.

The adjustment method is such that the width of the linear image is L>>W with respect to the photoelectric conversion element width W, and the amplifier output voltages ER and E are set to the same minimum value or the same predetermined value by the bias adjustment means 24 and 25. Adjust so that Further, the photoelectric conversion element is brought into a fully irradiated state, and the amplifier output voltages ER and EL are adjusted by the gain adjustment means 22 and 23 so that they become the same maximum value or the same predetermined value. In this case, setting both the maximum value and the minimum value to predetermined values can be achieved by repeating the bias adjustment and gain adjustment described above.

By the above adjustment, ideal characteristics as shown in FIG. 4 can be obtained. However, for example, as time passes after the product is delivered, the sensitivity of the photoelectric conversion elements 17 and 18 deteriorates, and the amplifier 20
．． 21 and the operational amplifier 26, the position output voltage Eo may not become zero even when the linear mark image is at the center of the photoelectric conversion element. In such a case, as shown in FIG. 5, the output voltage E is adjusted by the input balance adjusting means 27 of the operational amplifier 26. can be made zero.

The above explanation is based on the case where the output voltages ER and E[ of the amplifiers 20 and 21 reach the maximum value when the photoelectric conversion cables 17 and 18 are irradiated. You may also want to apply a different bias voltage from the beginning to ensure the same level of accuracy. Additionally, the color of the strip material may be darker than the linear mark.

In such a case, the bias is adjusted so that the output voltage of the operational amplifier 26 is minimized, and when the photoelectric conversion cable 17.18 is in a light-shielded state, the output voltage E8, E of the amplifier 20.21 is
, becomes the maximum value, the gain of the amplifiers 20 and 21 will be adjusted.

Normally, when a photoelectric conversion element, amplifier, optical system, etc. are simply combined, the minimum and maximum values of the output voltage of the left and right amplifiers are different, so even if the center of the linear mark coincides with the center of the photoelectric conversion element, the position The detected voltage does not become zero, causing an error in the center position.

Therefore, as described above, by adjusting the minimum value of the position voltage to the same value by adjusting the bias of the amplifier and adjusting the maximum value to the same value by adjusting the gain, it is possible in principle to make the center position error zero. Also, by adjusting the input balance of the operational amplifier, changes over time in the center position can be corrected.

(Effects of the Invention) As explained above, according to the present invention, even if there are variations in dimensions and sensitivity of photoelectric conversion elements, variations in characteristics of amplifiers, variations in gain, optical axis deviation of optical system, etc., the same or predetermined By adjusting the bias and gain of the amplifier so that the minimum and maximum values of are obtained, the position signal of the linear mark image can be made zero, and the position error can be made zero. Furthermore, if a center position error occurs due to aging, it can be corrected by adjusting the input balance of the operational amplifier.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of the present invention, FIG. 2 is a configuration diagram of an embodiment of the present invention, FIGS. 3 and 4 are characteristic diagrams showing the operation of the present invention, and FIG. FIG. 2 is a configuration diagram showing a main part of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Light source, 2... Linear mark, 3... Optical (lens) system, 4 and 5... Photoelectric conversion element, 6
and 7...bias adjustment and gain adjustment amplifier, 8...subtraction operational amplifier, 10...light source, 1
DESCRIPTION OF SYMBOLS 1... Optical (lens) system, 12 and 14... Strip material, 13 and 15... Linear mark, 16...
Optical (lens) system, 17 and 18... Photoelectric conversion element, 19... Linear mark image, 20 and 21...
- Amplifier, 22 and 23...gain adjustment means, 2
4 and 25...bias adjustment means, 26...subtraction operational amplifier, 27...balance adjustment means. Patent applicant: Toyo Kikai Co., Ltd. Figure 7 Figure 2

Claims (2)

[Claims] (1) An optical system that images bright and dark light beams that are transmitted or reflected by a light beam irradiated onto a linear mark drawn on a strip material such as film or paper onto two photoelectric conversion elements;
In a linear mark position detector equipped with an amplifier that amplifies the output electrical signal of each photoelectric conversion element, and a differential amplifier that amplifies a signal proportional to the difference between the output signals of those amplifiers, each photoelectric conversion element is a first means having a function of adjusting the bias of one or both of the amplifiers so that the magnitude of the output signal of both amplifiers is the same in the minimum output state of the connected amplifier; A method for detecting the position of a linear mark, comprising second means having a function of adjusting the gain of one or both of the amplifiers so that the magnitudes of the output signals of the amplifiers are the same. (2) An optical system that images bright and dark light rays that are transmitted or reflected by a light beam irradiated onto a linear mark drawn on a strip material such as film or paper onto two photoelectric conversion elements;
In a linear mark position detector equipped with an amplifier that amplifies the output electrical signal of each photoelectric conversion element, and a differential amplifier that amplifies a signal proportional to the difference between the output signals of those amplifiers, each photoelectric conversion element is a first means having a function of adjusting the bias of one or both of the amplifiers so that the magnitude of the output signal of both amplifiers is the same in the minimum output state of the connected amplifier; a second means having a function of adjusting the gain of one or both so that the magnitude of the output signal of the amplifier is the same;
2 so that the magnitude of the output signal of the differential amplifier becomes minimum or zero when it is located at the center of the photoelectric conversion elements.
1. A method for detecting the position of a linear mark, comprising: third means having a function of adjusting the balance of the output signals of the plurality of amplifiers.