JPH0729459Y2 - Photoelectric encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a photoelectric encoder for detecting a moving position of a moving body using a semiconductor light receiving device in which a plurality of light receiving elements are integrated.

[Prior Art] An optical system of a conventional general photoelectric encoder used for detecting a moving position of a moving body is composed of four main parts of a light source, a moving slit plate, a fixed slit plate and a light receiving element. Basically, it has a structure that includes a fixed slit plate. Therefore, in order to obtain a highly accurate detection signal with this type of encoder, it is necessary to suppress variations in the above-mentioned components and relative positioning errors as much as possible. Moreover, the light-receiving surface of the light-receiving element facing the light-shielding portion of the fixed slit plate essentially has no opportunity to receive light, and it cannot be said that the light-receiving area is effectively used.

Therefore, as a configuration in which the fixed slit plate is deleted, an encoder as schematically shown in FIG. 3 is considered.

In FIG. 3, on a single N-type semiconductor substrate 4, adjacent ones have a phase difference of 90 ° in electrical angle A.
In order to generate encoder signals of each phase of B ..., a plurality of light receiving elements 5a to 5d having the same shape and the same characteristics are arranged in close proximity at equal intervals, and the element width t1 of each light receiving element and the distance between the elements are set. The total width with the interval t2 is set to be approximately 1/2 of the width t3 of the slit 6a of the moving slit plate 6 facing each other. FIG. 4A is a plan view showing the outline of the semiconductor light receiving device in the encoder shown in FIG.

In FIG. 4 (A), dummy light receiving elements 5e which are not used as encoder light receiving elements are arranged at the left and right ends of the light receiving element group 5 including a plurality of sets of light receiving elements 5a to 5d. The function of the dummy light receiving element 5e will be described with reference to FIG. In FIG. 5, the phase A light receiving element 5a is in the fully open state, the phase light receiving element 5c is in the fully closed state, and the B and phase light receiving elements 5b and 5d are in the half open state. Normally, at the end of each light receiving element of an integrated light receiving element, the mixing of a photocurrent signal from an adjacent element is essentially an unavoidable problem.

This is because the diffusion current component due to the minority carriers 11 generated by the light irradiation diffuses to the adjacent light receiving element through the depletion layer 12. However, in the case of an encoder that performs waveform processing of the differential current of the encoder signals of the A, B, and respective phases, the adjacent light receiving element becomes another channel, so even in the state of FIG. On the other hand, the photocurrent signal is not mixed in, the difference current is hardly reduced, and an encoder signal with a very good S / N ratio can be obtained. Further, the diffused currents generated at both ends of the A-phase light receiving element 5a are uniformly mixed into the B-phase light receiving element 5b and the dummy light receiving element 5e in the half-opened state. There is almost no effect on the mutual phase difference between the signal waveforms. For this reason, in the light receiving element which does not have the light receiving element adjacent on one side, the light receiving elements on both sides take in more diffusion current than the light receiving elements adjacent to each other, which causes variations in light receiving sensitivity. As a result, the dummy light receiving elements are formed at the left and right ends of the light receiving element group 5 in FIG. 4 (A).
5e is arranged.

Next, the operation of the photoelectric encoder having the above semiconductor light receiving device will be described with reference to FIGS. 6 (A) and 6 (B). Symbols t1, t2, t3, ... T8 in the figure indicate the time when the moving slit plate 6 sequentially moves in the same direction at a constant speed, and after time t8, it is repeated from time t1. , Omitted here. When the moving slit plate 6 sequentially moves from time t1 to time t8, as shown in FIG. 6 (B), from the light receiving elements 5a and 5c of phase A and phase 5, adverse effects due to mixing of photocurrent signals from other adjacent channels are adversely affected. 180 ° phase-shifted, clean trapezoidal waveform encoder signals 13a, 13b are obtained, and the B-phase and phase-phase light-receiving elements 5b, 5d
Also, from the encoder signals of A and phase, encoder signals 13c and 13d with a phase difference of 90 degrees can be obtained respectively,
By using the waveform processing circuits 15a and 15b as shown in FIG. 7, high-accuracy rectangular wave encoder signals 14a and 14b can be obtained.
Can be obtained.

Further, since the fixed slit plate is not necessary, it is easy to position each component, and since there is no portion where light is blocked by the fixed slit plate, the light receiving area of the encoder light receiving element is effectively used, etc. It has many excellent advantages.

[Problems to be Solved by the Invention] By the way, when it is desired to arbitrarily change the resolution of encoder position detection to some extent, in a conventional general photoelectric encoder including a fixed slit plate, a movable slit plate and a fixed slit plate are used. It was dealt with by changing each slit width. However, when it is attempted to change the resolution with the photoelectric encoder having the above-described semiconductor light receiving device that does not include the fixed slit plate, the slit width of the moving slit plate 6 is changed and at the same time, the light receiving width of the light receiving elements 5a to 5e is changed. I have to do it. Also, with this kind of encoder,
From each of the light receiving elements 5a to 5e shown in FIG.
Since the leader line 8 leading to the position is formed by P-type diffusion, there is a problem that the resolution change must be dealt with by changing the impurity diffusion process. For example, in order to obtain an encoder having half the resolution of the light receiving device shown in FIG. 4A, as shown in FIG. The leader line 8 will have to be changed. Therefore, it is necessary to go through an individual impurity diffusion step for each desired resolution setting. In particular, when the light receiving element and the waveform processing circuit are integrated on one chip by the bipolar monolithic IC process, the impurity diffusion process exists after the P-type diffusion. This is not easy because it has the drawbacks of complicated work-in-process slice management, long manufacturing time, and high manufacturing cost.

The object of the present invention is to use a semiconductor light receiving device without having to perform an individual impurity diffusion process for each desired resolution setting, which is advantageous in terms of manufacturing time, management of photomasks, etc. An object is to provide a photoelectric encoder that can obtain different resolutions.

[Means for Solving Problems] In order to achieve the above-mentioned object, the present invention, as shown in FIGS. 1 (B) to (D) and FIG. 2 (B) of the embodiment, A plurality of light receiving elements for generating at least A phase, B phase, phase and phase encoder signals are formed on the light source, the slit plate 6, and the semiconductor substrate 4, and lead lines are connected to the light receiving elements. And a semiconductor light receiving device 20,
Photoelectric type that generates a periodic signal according to the relative moving speed between the slit plate 6 and the semiconductor light receiving device 20 by applying light from a light source to a light receiving element through a slit 6a formed in the slit plate 6 Intended for encoders. In such a photoelectric encoder, according to the present invention, a plurality of basic light receiving elements 1 having the same shape are arranged on a semiconductor substrate 4 in a row at a predetermined interval in the moving direction. And at least A
Phase, B phase, phase and light receiving elements for generating phase encoder signals are configured by connecting a predetermined number of adjacent basic light receiving elements 1 selected according to the resolution in parallel with conductive material wiring (2a to 2d). In addition, the lead wire is also composed of conductive material wiring (2a to 2d).

[Advantage of the Invention] In the present invention, a predetermined number of adjacent basic light receiving elements 1 are connected in parallel to form a light receiving element for generating encoder signals of at least A phase, B phase, phase and phase, and connecting the lead wires. The resolution of the encoder can be easily changed by changing the pattern of the conductive material wirings 2a to 2e. In other words, according to the present invention, the conductive material is different from the conventional photoelectric encoder in which the light receiving element having the width dimension necessary to obtain the desired resolution and the lead wire corresponding to the width must be formed by the impurity diffusion process. By changing the wiring pattern, a photoelectric encoder with a desired resolution can be easily obtained. When manufacturing the photoelectric encoder of the present invention, after a certain impurity diffusion process is completed, the contact 3 of the basic light receiving element 1 is formed, and then a wafer having aluminum for internal wiring deposited on the entire surface of the wafer is used. Therefore, there is an advantage that the resolution change can be dealt with in a very short throughput time and, at the same time, it is more advantageous in manufacturing than the conventional one in terms of photomask management, diffusion in-process slice management and the like. Further, when the light receiving element and the waveform processing circuit are integrated on one chip in the bipolar monolithic IC process, this difference becomes particularly large.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

1 (B) to 1 (D) show a semiconductor light receiving device and a movable slit plate of an embodiment of a photoelectric encoder according to the present invention. Note that FIG. 1A is a reference diagram for facilitating the understanding of the present invention.

Also in the semiconductor light receiving device of the present embodiment, in accordance with the semiconductor light receiving device shown in FIG. 4, the same shape corresponding to encoder signals of A, B, ... A plurality of basic light-receiving elements 1 having the same characteristics are arranged in close proximity to each other.

In the present embodiment, the widths of the light receiving elements and the intervals between the light receiving elements of the A, B, ... Phases are set in correspondence with the maximum resolution that can be used by the encoder. This maximum resolution is due to photoresist mask alignment error, etching variation,
Also, it is determined in consideration of the light receiving sensitivity of the photodiode.

Further, in the present embodiment, most of the basic light-receiving elements 1 ... Or most of the light-receiving elements 1e except for a few light-receiving elements 1e at the end of the basic light-receiving element group 10 are provided in a predetermined number of adjacent [FIG. 2 pieces, 4 pieces in (C), 5 pieces in (D)] are connected in parallel by the conductive material wirings 2a to 2d, and a phase difference of 90 degrees is provided for each of the predetermined number of basic light receiving elements. A ・ B ・ ・
A semiconductor light receiving device 20 is configured as a light receiving element that generates an encoder signal for each phase.

Then, the movable slit plate 6 facing the semiconductor light receiving device 20.
The slit width is set to be approximately twice the total width of the element width and the element-to-element spacing of several basic light-receiving elements connected in parallel.

With the above configuration, a photoelectric encoder having a resolution that is a fraction of the maximum resolution is obtained.

Next, the procedure for setting the resolution in a wide range will be described with reference to FIG. 1 and the following table.

Each of the light receiving devices 20 shown in FIGS. 1 (A) to (D) has a resolution of 1000 P / R when the maximum resolution in the above table is, for example, 1000 P / R. , (B)
The product of 500P / R, the product of (C) is 250P / R, and the product of (D) is 200P / R. For example, in the case of FIG. 1B with a resolution of 500 P / R, two adjacent ones of the basic light receiving elements 1 ... Shown in FIG. .. Forming the encoder light receiving element for each phase. In the case of the resolution of 250 P / R in FIG. 1 (C), four adjacent basic light-receiving elements 1 ... Are sequentially connected in parallel to form encoder light-receiving elements for each phase A, B, ... . In the case of the resolution of 200P / P shown in Fig. 1 (D), five adjacent basic light-receiving elements 1 ... Are sequentially connected in parallel to form encoder light-receiving elements for each phase A, B ,. To do. The parallel connection in these cases is performed by aluminum wirings 2a to 2d through the contacts 3 provided at both ends of the basic light receiving element 1 in the longitudinal direction. In the case of such parallel connection, since the above-mentioned depletion layer is distributed between the basic light receiving elements, a diffusion current due to the minority carriers is generated, and this portion can also be regarded as a substantially effective light receiving area. Furthermore, a total of 19 kinds of resolutions can be obtained by changing the combination for all the different maximum resolutions in the above table, and thus the required resolution can be almost covered. Of course, it is clear that many combinations other than the above combinations are possible. Moreover, in the photoelectric encoder of the present invention, although the resolution in a very wide range can be set, the basic light receiving element group 10 has the semiconductor substrate 4
The surface area can be configured to be approximately the same as that of the conventional example shown in FIG.

In FIG. 1 (B), the three basic light receiving elements on both left and right sides of the basic light receiving element group 10 are dummy light receiving elements 1e that are not used as encoder light receiving elements. By connecting the dummy light receiving element 1e to the N-type semiconductor substrate by the aluminum wiring 2e, it is possible to solve the above-mentioned problem of mixing of the diffusion current. Further, it is not always necessary to use the three basic light-receiving elements on both the left and right ends as dummy light-receiving elements. One of the three basic light-receiving elements on the left and right ends is used as a dummy, and the remaining basic light-receiving elements are not used. The contacts of the light receiving element may be left idle.

As described above, in this embodiment, the resolution is changed by changing the aluminum wirings 2a to 2d which connect the predetermined number of basic light receiving elements 1 adjacent to each other in parallel, which is completely different from that in the conventional semiconductor light receiving device. Therefore, it has excellent advantages as described below. That is, in the present embodiment, the impurity diffusion process used for forming the semiconductor light receiving device can be shared by encoders of various resolutions. This makes it possible to deal with various resolution settings in a very short throughput time, and at the same time, it is advantageous in manufacturing in terms of photomask management, diffusion in-process slice management, and the like.

Moreover, the advantage of the semiconductor light receiving device shown in FIG. 4 is utilized as it is, and the alignment of the encoder parts is easy,
It also has excellent advantages such as effective use of the light receiving surface of the basic light receiving element 1.

Next, another embodiment of the present invention will be described. Figure 2 (A) shows
2 is a diagram showing a configuration example of a semiconductor light receiving device and a movable slit plate of a photoelectric encoder that obtains a sinusoidal encoder signal previously filed by the present applicant. In the figure, the same parts as those in FIG. 1 (A) are designated by the same reference numerals. 10A
Is a first basic light receiving element group formed on the semiconductor substrate 4 in substantially the same manner as the light receiving device of FIG. 1 (A), and 10B has a predetermined phase relationship with the light receiving element group 10A.
It is a second basic light receiving element group arranged in parallel with the same configuration as. 16A on the slit plate 6 is the first basic light receiving element group 1
The first slit group facing 0A, 16B is the slit group 16A
Is a second slit group arranged in parallel with a predetermined phase relationship and facing the second basic light receiving element group 10B.

The semiconductor light receiving device 20 of FIG. 2 (B) includes two adjacent basic light receiving devices 1 in each of the basic light receiving device groups 10A and 10B arranged in the same manner as the light receiving device of FIG. 2 (A). , First
Similar to the one shown in FIG. 3B, aluminum wirings 2a to 2d are combined and connected in parallel. And the slit group 16
The slit widths of A and 16B are set to be approximately twice the total width of the element width and the inter-element spacing of the two basic light receiving elements 1 connected in parallel, like the slit width in FIG. 1 (B). ing.

In both of the devices shown in FIGS. 2A and 2B, the phase of the second slit group 16B with respect to the first slit group 16A is substantially sinusoidal than that of each of the light receiving element groups 10A and 10B due to the movement of the movable slit plate 6. Both light-receiving element groups so that a wavy light-receiving signal can be obtained
A predetermined phase relationship is set according to the phase relationship between 10A and 10B. When the device of FIG. 2 (A) is designed to support the maximum resolution, the device of FIG.
It outputs a sinusoidal encoder signal with a resolution of.

Although both the light receiving element groups 10A and 10B described above are arranged side by side on the same semiconductor substrate 4, they may be arranged on different semiconductor substrates and arranged side by side, and the present invention can be applied to this case as well. Of course.

In each of the above embodiments, the encoders A, B,
Although the case where the phase and the signal of the phase are generated has been described, a light receiving element used for generating other encoder signals, for example, a light receiving element used for generating the encoder C signal which is the reference signal of the encoder is configured. In this case, the present invention can be applied. Further, not only the light-receiving element that directly generates the encoder signal, but also the light-receiving element formed on the semiconductor light-receiving device for other purposes, for example, the bias light-receiving element may be configured by using the present invention. is there.

Further, in each of the above-mentioned embodiments, the semiconductor light receiving device using the N-type semiconductor substrate and common to the cathode is illustrated, but a semiconductor light receiving device using the P-type semiconductor substrate and common to the anode may be used, and the light receiving element for the encoder and the waveform processing may be used. The present invention can be applied to a semiconductor integrated circuit device in which a circuit is contained in one chip.

Further, although all the embodiments described above exemplify the photoelectric linear encoder, the present invention is not limited to this, and it goes without saying that the invention can be applied to a photoelectric rotary encoder.

[Effect of the Invention] As described above, according to the present invention, at least the A phase, the B phase,
Since a plurality of light receiving elements for generating the phase and phase encoder signals are configured by connecting a predetermined number of adjacent basic light receiving elements in parallel by conductive material wiring, and the leader line is also configured by conductive material wiring, A photoelectric encoder of arbitrary resolution can be easily obtained only by changing the pattern of the conductive material wiring with the semiconductor substrate being common. Therefore, according to the present invention, in comparison with the conventional photoelectric encoder that cannot obtain different resolution unless the width dimension of the light receiving element and the lead line are changed by the impurity diffusion process, according to the present invention, The manufacturing time can be shortened, the management burden of the photomask and the diffusion in-process slice can be reduced, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 (A) is a reference diagram for facilitating the understanding of the first embodiment of the present invention, and FIGS. 1 (B) to (D) respectively show the essential parts of the first embodiment of the present invention. 2A is a plan view showing the second embodiment of the present invention for easy understanding, and FIG. 2B is a main part of the second embodiment of the present invention. A plan view and FIG. 3 are sectional views showing a schematic configuration of a main part of a photoelectric encoder in which a fixed slit plate is omitted, FIG. 4 (A),
6B is a plan view showing an example of a semiconductor light receiving device of a conventional photoelectric encoder, FIG. 5 is a sectional view showing a state in which a diffused current is generated and mixed into an adjacent light receiving element, FIG. 6A, FIG. 7B is an explanatory diagram showing an outline of the operation of the photoelectric encoder shown in FIG. 3, and FIG. 7 is a block diagram of a signal processing circuit for waveform-processing a signal from the light receiving device. 1 ... Basic light receiving element, 10 ... Basic light receiving element group, 2a to 2e ...
… Aluminum wiring as conductive material wiring, 4… Semiconductor substrate,
6-moving slit plate, 10A-first basic light-receiving element group, 10B-second basic light-receiving element group, 16A-first slit group, 16B-second slit group, 20 --- Semiconductor light receiving device.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Keigo Kikuchi 1-15-1 Kitaotsuka, Toshima-ku, Tokyo Sanyo Denki Co., Ltd. (72) Yasushi Tanaka 1-14-1 Toranomon, Minato-ku, Tokyo Sanx Co., Ltd. (72) Inventor Kazuo Marushima 1-14-1 Toranomon, Minato-ku, Tokyo Sanx Co., Ltd. (56) Reference JP 47-21153 (JP, A) (JP, U) Actually opened 61-67511 (JP, U) Actually opened 61-52219 (JP, U) Actually opened 60-88279 (JP, U)

Claims (4)

[Scope of utility model registration request] 1. A light source, a slit plate, and a semiconductor substrate, at least a plurality of light receiving elements for generating encoder signals of A phase, B phase, and phase are formed, and lead lines are connected to the light receiving elements. And a semiconductor light receiving device formed by applying the light from the light source to the plurality of light receiving elements through a slit formed in the slit plate, thereby providing a relative position between the slit plate and the semiconductor light receiving device. In a photoelectric encoder that generates a periodic signal according to different moving speeds, a plurality of basic light receiving elements having the same shape are arranged on the semiconductor substrate at predetermined intervals in the moving direction, and the at least A phase , B phase, a plurality of light receiving elements for generating phase and phase encoder signals, a predetermined number of adjacent basic light receiving elements selected according to the resolution are arranged by conductive material wiring. Photoelectric shape encoder characterized by being composed by well conductive material wiring and the lead lines connected and configured. 2. The photoelectric encoder according to claim 1, wherein the plurality of basic light receiving elements are provided in a number corresponding to the maximum resolution of the encoder. 3. The semiconductor light receiving device according to claim 1, wherein a plurality of basic light receiving elements are arranged in a row on the semiconductor substrate as described above.
Of the first basic light receiving element group and the first basic light receiving element group are arranged side by side on the same or different semiconductor substrate as the first basic light receiving element group with a predetermined phase relationship with respect to the first basic light receiving element group. A second basic light receiving element group, and a predetermined number of the adjacent basic light receiving elements in each of the basic light receiving element groups are connected in parallel by conductive material wiring to form at least the A phase, the B phase, the phase and the phase. A plurality of light receiving elements for generating an encoder signal are configured, and the slit plate has a first slit group facing the first basic light receiving element group, and a predetermined slit group for the first slit group. The photoelectric encoder according to claim 1, further comprising a second slit group arranged in parallel with each other in a phase relationship and facing the second basic light receiving element group. 4. The photoelectric encoder according to claim 1 or 3, wherein an aluminum wiring is used as the conductive material wiring.