JPS6232403B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an optical position detection device that detects the relative position or amount of movement of a scale plate having a row of patterns and an image sensor consisting of a large number of light receiving elements. It is related to.

Although many devices have been known that measure length and the like based on distance traveled, there are very few devices that can do this simply and with high precision. For example, magnetic linear scales that utilize magnetism have been put into practical use, but they may not be available in some cases.

The object of the present invention is, for example, to
The object of the present invention is to provide an optical position detection device that can optically easily and accurately detect the position and amount of movement by using a light receiving element such as a couple device (charge-coupled device). a photoelectric image sensor in which elements are arranged; a scale plate in which optically distinguishable patterns having arbitrary shapes are arranged in rows at arbitrary intervals less than or equal to the effective length of the image sensor; A light source for projecting the pattern of the scale plate onto an image sensor, and a signal from the image sensor corresponding to the combination of the shape and spacing of the pattern of the scale plate, and the shape and/or the shape of the pattern stored in advance. It is composed of an arithmetic circuit that calculates the position of the image sensor based on the interval, and allows the pattern row direction of the scale plate and the arrangement direction of the image sensor's light receiving elements to be relatively movable in parallel, and the image sensor relative to the scale plate can be moved in parallel. It is characterized by detecting a specific position or amount of movement.

The present invention will be explained in detail below based on illustrated embodiments.

Here, the pattern of any shape referred to in the scale plate of the present invention includes cases where the shapes of each pattern are all the same in terms of dimensions such as height and width, or cases where the patterns are made of two or more different shapes, What is interval?
If the spacing between patterns is all the same,
Or, it includes cases where the distance is composed of two or more different distances.

FIGS. 1 and 2 show an image sensor 1 composed of a CCD used in the present invention, and in the case of FIG. A large number of light receiving elements 2 are arranged one-dimensionally, and in FIG. 2, n similar light receiving elements 2 are arranged two-dimensionally horizontally and vertically n'. These light-receiving elements 2 are individually independent light-sensing elements, and the effective length of the image sensor 1 is LO=n・w in the lateral direction in the image sensor 1 shown in FIG.
In the image sensor 1 shown in the figure, LO=n・
w, and LO′=n′・w′ in the vertical direction.

FIG. 3 shows a scale plate 3 used in combination with the image sensor 1. On this scale plate 3, a pattern 4i of an arbitrary width Wi wider than the size of the light receiving element 2 is placed at the center of each pattern 4. The centers are arranged at arbitrary intervals Li (μm). In the embodiment shown in FIG. 3, these patterns 4i are assumed to have different heights. When this scale plate 3 is used as a light transmission type, the pattern 4 must be a slit that transmits light, but when it is used as a light reflection type, the pattern 4 has a light reflectance that is different from other parts. Just make it different.

The image sensor 1 and the scale plate 3 are arranged as shown in FIG. 4 and used for measurement as a light transmission type, or arranged as shown in FIG. 5 and used as a light reflection type for measurement. In either case, the image sensor 1 and the light source 5 are connected to the connecting member 6
It is fixed integrally with the dial plate 3, and is movable parallel to and relative to the row direction of the patterns 4i on the scale plate 3. Note that if the light source 5 is long in the direction in which the patterns 4 are arranged, the light source 5 does not have to move together with the image sensor 1.

In the light transmission type optical system shown in FIG.
As shown in the block diagram of FIG.
will be projected. Output signals output from each light receiving element 2 of this image sensor 1 are input to an arithmetic circuit 10. The arithmetic circuit 10 includes, for example, a signal preprocessing circuit 11 for shaping a waveform, and a position calculation circuit 12 for calculating the position of the image sensor 1 based on the output thereof.
and an indicator 13 that indicates the amount of movement of the image sensor 1 as required. Furthermore,
A control circuit 14 is connected to the position calculation circuit 12 and generates a signal for controlling the position, for example, based on the output signal thereof. Note that signal processing is basically the same even in the case of the light reflection type optical system shown in FIG.

In the present invention, by selecting the shape and spacing of the pattern 4, detection of the position or amount of movement can be realized in some cases.

For example, if the intervals Li of the patterns on the scale plate 3 are all equal and the width Wi of the patterns is arbitrary, the position and width Wi of each pattern 4i (i=
1, 2, 3, ...) are stored in advance in the position calculation circuit 12, and first, before the image sensor 1 moves, the position calculation circuit 12 calculates a certain pattern based on the output signal of the image sensor 1. 4a and calculate the center position of its width Wa. At this time, a reference point is determined so that the p-th light receiving element 2p on the image sensor 1 becomes the center of the pattern 4a.
Next, this image sensor 1 moves and pattern 4
If the center of the pattern 4a is at the q-th light receiving element 2q of the image sensor 1 when passing m pieces of ...(1), and this equation (1) can be calculated by the position calculation circuit 12. Note that this movement can be obtained by a similar calculation even in the opposite direction. If the pattern interval Li is determined so that the image sensor 1 can completely sense two adjacent patterns 4 at the same time, no matter where the image sensor 1 is located on the scale plate 3, the image sensor 1
It is possible to calculate the position of

Furthermore, even if the width Wi and pattern interval Li of the pattern 4 of the scale plate 3 are different as shown in FIG. , It can be found as However, in this case, the position and width Wi of pattern 4, and the pattern interval Li (i=
The values 1, 2, . . . ) need to be stored in advance in the position calculation circuit 12 as in the previous case.

Image sensor 1 length LO and pattern spacing
Due to resolution limitations arising from the relationship between Li and width Wi,
With the above-mentioned means, the length of the scale plate 3 may be insufficient. The application example shown in FIG. 8 is a scale plate 3 to deal with such a case, and the entire scale is divided into several blocks Bk, and different pattern widths W are used for different blocks B. . Also, the pattern interval within the same block Bk
Lk are different from each other, and the pattern intervals Lk at corresponding positions between each block Bk are equal.
At this time, if the position of the pattern 4k, the relationship between the width Wk and the block Bk, and the pattern interval Lk are stored in the position calculation circuit 12, the position of the image sensor 1 can be determined.

FIG. 9 shows an example of application of the case described above, in which the scale plate 3 is divided into several blocks Bk, and the pattern interval within each block Bk is
Lk is kept constant, and different pattern intervals L are used for different blocks B. These relationships can be stored in the position calculation circuit 12 as in the case described above, and can be equivalent to using a long scale plate 3.

Several examples of combinations of pattern spacing L and width W used in the present invention have been described, but when the width W and spacing L of the pattern 4 are uniquely defined on the scale plate 3, The position of the image sensor 1 can be detected without predetermining a reference point, and naturally the moving distance of the image sensor 1 can be determined. Note that the shape of the pattern 4 is varied not only in width W but also in height. For example, if the two-dimensional image sensor 1 shown in FIG. 2 is used, even more combinations of spacing and shape are possible. Furthermore, regarding this two-dimensional image sensor 1, by using a scale plate with patterns arranged not only in the horizontal direction but also in the vertical direction, it is possible to determine the relative position or amount of movement of the image sensor 1 in the two-dimensional direction. can.

As explained above, the optical position detection device according to the present invention is capable of determining the relative position and amount of movement through simple arithmetic processing, and the measurement resolution can be set to the size of the light receiving element, resulting in measurement accuracy. It is also highly valuable in industry.

[Brief explanation of the drawing]

Fig. 1 is a plan view of an image sensor in which light-receiving elements are arranged one-dimensionally, Fig. 2 is a plan view of an image sensor in which light-receiving elements are arranged two-dimensionally, Fig. 3 is a front view of the scale plate, and Fig. 4 The figure shows a configuration diagram of an optical system in which a light source, scale plate, and image sensor are arranged in a light-transmissive manner.
Fig. 5 is a block diagram of an optical system in which a light source, a scale plate, and an image sensor are arranged in a light-reflection type, Fig. 6 is a block diagram showing a signal transmission system, Figs. 7, 8, and 9.
The figure is a front view of another embodiment of the scale plate. 1 is an image sensor, 2 is a light receiving element, 3 is a scale plate, 4 is a pattern, 5 is a light source, 10 is an arithmetic circuit, 11 is a signal preprocessing circuit, 12 is a position calculation circuit, 13 is an indicator, Wi is a pattern width dimension,
Li is the pattern spacing.

Claims (1)

[Scope of Claims] 1. A photoelectric image sensor in which a large number of light-receiving elements are arranged, and an optically distinguishable pattern having an arbitrary shape arranged in a row and having an arbitrary length smaller than the effective length of the image sensor. , a light source for projecting the pattern of the scale plate onto the image sensor, and a signal from the image sensor corresponding to the combination of the shape and spacing of the pattern of the scale plate. It consists of an arithmetic circuit that calculates the position of the image sensor based on the shape and/or spacing of the stored patterns, and the direction of the pattern rows on the scale plate and the arrangement direction of the light receiving elements of the image sensor are relatively parallel. An optical position detection device that is movable and detects the relative position or amount of movement of an image sensor with respect to a scale plate. 2. The optical position detecting device according to claim 1, wherein the pattern of the scale plate is divided into a plurality of blocks, and the shapes or intervals of the corresponding patterns are different between the blocks. 3. The optical position detection device according to claim 1, which projects the pattern of the scale plate onto the image sensor in a transparent manner. 4. The optical position detection device according to claim 1, which projects the pattern of the scale plate onto the image sensor in a light reflective manner.