JP3004858B2 - Absolute measurement encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoder for absolute measurement having a function of outputting a reference position signal for adjusting an origin position and a data communication function of monitoring an internal state.

[0002]

2. Description of the Related Art Conventionally, for example, a capacitance type absolute measuring encoder used as a length measuring machine, a goniometer or the like has been known. Some types of absolute measurement encoders have a data input / output function for maintenance or setting of internal constants. There is also a device having a function of generating a reference position signal for changing the absolute origin position and the counting direction.

[0003]

As described above, as the function of the encoder for absolute measurement increases and the amount of information to be output increases, the number of signal lines increases accordingly. On the other hand, as devices become smaller, the proportion occupied by signal line connection portions increases, and efficient use of signal lines is required. The present invention has been made in view of such circumstances, and has as its object to provide an absolute measurement encoder that can reduce the size of a device by efficiently using signal lines.

[0004]

The present invention provides a reference position signal generating means for outputting a reference position signal for adjusting the origin position, and a two-phase square signal for outputting a two-phase square wave signal for determining a moving direction. An absolute measurement encoder having a wave signal output means, a data input means for monitoring an internal state, and a data output means, wherein one of a reference position signal output line and a two-phase square wave signal output line is connected to a data output terminal. A signal line serving as a common signal line, and switching means for selectively switching and connecting one of the output terminal of the data output means and the output terminal of the reference position signal generating means to the common signal line in accordance with an operation mode. It is characterized by:

The absolute measuring encoder according to the present invention also has a main scale and a pickup in which electrodes of a predetermined pattern are formed and moved relative to each other, and detects a different capacitance depending on their facing position to detect the absolute displacement. Capacitance type absolute displacement detecting means for detecting,
Data input means for receiving serial data from the outside in order to monitor the state of the absolute displacement detecting means, data processing means for performing data processing such as state check based on the input data, and serial data Data output means, and photoelectric detection means that is formed integrally with the absolute displacement detection means and photoelectrically detects a reference position pattern on the scale and pickup,
A reference position signal generating means for processing an output of the photoelectric detecting means to output a reference position signal; and selecting one of an output terminal of the reference position signal generating means and an output terminal of the data output means according to an operation mode. Switching means connected to the common signal line.

The absolute measuring encoder according to the present invention also has a main scale and a pickup in which electrodes of a predetermined pattern are formed and moved relative to each other, and detects a different capacitance depending on their facing position to detect the absolute displacement. Capacitance type absolute displacement detecting means for detecting,
Data input means for receiving serial data from the outside in order to monitor the state of the absolute displacement detecting means, data processing means for performing data processing such as state check based on the input data, and serial data Data output means, and photoelectric detection means which is formed integrally with the absolute displacement detection means and outputs a two-phase square wave signal for photoelectrically detecting a pattern on the scale to determine a moving direction, A reference position signal generating unit that processes an output of the photoelectric detection unit and an output of the absolute displacement detection unit to output a reference position signal; and one of output terminals of the two-phase square wave signal according to an operation mode. Switching means for selecting one of the output terminals of the data output means and connecting to a common signal line.

[0007]

According to the present invention, the data output signal line is used as one of the reference position signal output line or the two-phase square wave signal line and the common signal line, and is used by switching between the normal operation mode and the data input / output mode. Like that. The reference position signal line and the two-phase square wave signal line are used to output necessary signals during normal use of the encoder, while the data output signal line is used when inputting and outputting data to monitor the internal state. These are shared only,
The number of signal lines can be reduced by selectively using them according to the use state of the device.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a linear encoder for absolute measurement according to an embodiment of the present invention, and FIG. 2 shows the configuration of the detector main body. The detector main body is composed of a main scale 1 and a pickup (slider) 2 in which electrodes of a predetermined pattern are arranged and formed and move relative to each other. A transmission electrode 5 and a reception electrode 6 having a predetermined pattern are formed on the pickup 2 respectively. On the main scale 1, a first transmission electrode 3 having a predetermined pattern and a second transmission electrode 4 electrically connected to the first transmission electrode 3 are formed.

The transmission electrode 5 on the pickup 2 and the first transmission electrode 3 on the main scale 1 are in different capacitive coupling states depending on the relative positions of the pickup 2 and the main scale 1. 4 and the receiving electrode 6 on the pickup 2 are capacitively coupled. By supplying a predetermined drive signal to the transmission electrode 5 and processing the signal detected from the reception electrode 6 by the detection circuit 11, the absolute displacement is determined from the magnitude of the capacitive coupling determined by the relative position of the main scale 1 and the pickup 2. The amount (position) can be detected. The principle of the capacitance type displacement measurement is described in, for example, Japanese Patent Application No. 2-132434 or Japanese Patent Application No. 2-169654 filed by the present applicant.

A photoelectric position detector used for generating a reference position signal is integrally formed with such a capacitance type absolute displacement detector main body. That is, a slit plate 7 is integrally attached to the pickup 2, and one light emitting diode 8 serving as a point light source and four light receiving diodes 91 to 94 surrounding the slit plate 7 are provided on the slit plate 7. A reference position pattern is formed on the main scale 1 and the pickup 2, and the diffused light from the light emitting diode 8 is applied to the reference position pattern. The modulated reflected light is detected by the four light receiving diodes 91 to 94. .

The four light receiving diodes 91 to 94 are provided to obtain a sine wave signal of a predetermined pitch as the scale moves, excluding the influence of unevenness of the gap between the scale 1 and the pickup 2 and the effect of temperature fluctuation. ing. It is the photoelectric detection circuit 12 that processes the output signals of the light receiving diodes 91 to 94 and outputs a two-phase square wave signal for determining the scale moving direction, and generates the position reference signal Y from the output. The reference position signal generation circuit 17 performs this operation. The principle of this photoelectric position detection is described in, for example,
This is the same as that described in Japanese Patent No. 187413, and the detailed description is omitted.

The absolute measuring encoder has a function of transmitting and receiving serial data to and from an external terminal for checking an internal state and setting an internal constant. For this purpose, as shown in FIG. 1, a serial data input circuit 14 whose input terminal is connected to a data input signal line 20, a data processing circuit 1 for performing predetermined data processing based on input data
3, and a serial data output circuit 1 for outputting a processing result
6. The output of the data processing circuit 13 is also provided with a data output determination circuit 15 for determining whether serial data output is necessary. This data input / output function is not normally used by the user, but is used for maintenance and inspection and setting internal constants before shipment.

An output terminal of the data output circuit 16 and an output terminal of the reference position signal generation circuit 17 are selected by a switching circuit 18 controlled by an output determination circuit 15 and connected to a common signal line 21. The common signal line 21 is a data output signal line and a reference position output signal line. Further, the two-phase square wave signals X0 and X1 used to determine the moving direction obtained from the data of the photoelectric detection circuit 12 are output from the two-phase square wave signal output line 22, respectively. The information output as serial data may include information of the photoelectric detection circuit 12 in some cases. More specifically, as the serial data information, position data of the capacitance detection circuit 11 and the photoelectric detection circuit 12 or position data obtained by combining them, the self-diagnosis result of each detection circuit, and the data processing circuit 13 itself Self-diagnosis results are also included.

In such a configuration, for example, in a normal operation mode in which the device is normally used as a length measuring device, the switching circuit 1
In 8, the contacts are switched such that the terminal C connected to the common signal line 21 is connected to the terminal B on the reference position signal generation circuit 17 side, and the reference position signal is output to the common signal line 21. In a data input / output mode in which serial data is input / output for checking the internal state, serial data is input from the outside, and the data processing circuit 13 performs predetermined processing. At this time, the output determination circuit 15 determines that data input / output processing is being performed, and controls the switching circuit 18. Thereby, the switching circuit 18 automatically switches the contacts so that the terminal C connected to the common signal line 21 is connected to the terminal A on the reference serial data output circuit 16 side, and outputs the serial output data to the common signal line 21. Is done.

An algorithm for controlling the switching circuit 18 by the output determination circuit 15 is, for example, as shown in FIG. When the power is turned on, the switching circuit 18 enters a normal operation mode (BC connection) for generating a reference position signal (S1).
1). Then, the output determination circuit 15 determines whether or not to perform serial data communication based on, for example, serial data input from the outside or a data request signal included therein (S12). In the normal operation without performing the serial data communication, the reference position signal is output as described above.
When performing the serial data communication, the switching circuit 18 determines the serial data communication mode (A-C
Connection) (S13). When the serial data communication ends (S14), the mode is automatically switched to the normal operation mode (S15).

The above operation mode switching control is performed, for example, by adding a communication end command to serial data from a terminal,
A control flow as shown in FIG. When the power is turned on, the switching circuit 18 enters a normal operation mode (BC connection) in which a reference position signal is generated (S21). Then, a communication end command is detected (S22). When the command is not detected and serial data communication is determined (S2).
4), the switching circuit 18 enters the serial data communication mode (AC connection) according to the determination result (S25), and serial data transmission is performed (S26). Step S22
When the communication end command is detected in step S23, the mode is switched to the normal operation mode based on the detection result (S23).

FIG. 5 shows the configuration of another embodiment of the present invention.
1 are given the same reference numerals as in FIG. 1 and detailed description is omitted. In the above embodiment, the case where the reference position code pattern is formed on the main scale 1 and the pickup 2 and the reference position signal Y is directly obtained from the output of the photoelectric detection circuit 12 has been described. In this embodiment, there is no special reference position code pattern, the upper digit is obtained by the capacitance detection circuit 11, the lower digit is obtained by the photoelectric detection circuit 12, and the reference position signal generation circuit 17 synthesizes these. Shows a case where the reference position signal Y is output.

In this embodiment, the reference position signal Y is
The signal is output to the reference position signal output line 23 without passing through the switching circuit. The switching circuit 18 switches between one of the two-phase square wave signals X0 and X1 obtained from the photoelectric detection circuit 12 and the serial data output and outputs the same to the common signal line 24, and the remaining square wave signal X1 remains unchanged. The signal is output to a square wave signal output line 25. According to this embodiment, similarly to the previous embodiment, the effect of reducing the size of the encoder by sharing the signal lines can be obtained.

[0019]

As described above, according to the present invention, the serial data output signal line and the reference position signal output line or 2
By sharing the phase square wave signal output line, the number of signal lines can be reduced, and the absolute measurement encoder can be downsized.

[Brief description of the drawings]

FIG. 1 shows a configuration of an encoder for measuring absolute displacement according to an embodiment of the present invention.

FIG. 2 shows a configuration of a detector main body of the embodiment.

FIG. 3 shows a mode switching control algorithm of the embodiment.

FIG. 4 shows another mode switching control algorithm.

FIG. 5 shows a configuration of an encoder for measuring absolute displacement according to another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main scale, 2 ... Pickup, 3 ... First transmission electrode, 4 ... Second transmission electrode, 5 ... Transmission electrode, 6 ... Reception electrode, 7 ... Slit plate, 8 ... Light emitting diode, 91-94
... Light receiving diode, 11 ... Capacitance type detection circuit, 12 ...
Photoelectric detection circuit, 13 data processing circuit, 14 data input circuit, 15 output determination circuit 15, 16 data output circuit, 17 reference position signal generation circuit, 18 switching circuit, 20 data input signal line, 21, 24 ... common signal lines.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-297817 (JP, A) JP-A-5-71985 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01D 5/00-5/62

Claims (3)

(57) [Claims] 1. A reference position signal generating means for outputting a reference position signal for adjusting an origin position, a two-phase square wave signal output means for outputting a two-phase square wave signal for determining a moving direction, and an internal state An absolute measurement encoder having a data input means and a data output means for monitoring a signal, wherein one of a reference position signal output line, a two-phase square wave signal output line and a data output signal line are used as a common signal line. A switching means for selecting one of an output terminal of the data output means and an output terminal of the reference position signal generating means in accordance with an operation mode and switching and connecting to the common signal line. Encoder. 2. An electrostatic capacitance type which has a main scale and a pickup in which electrodes of a predetermined pattern are formed and move relative to each other, and detects an absolute displacement by detecting different electrostatic capacitances depending on their facing positions. Absolute displacement detection means, data input means for receiving serial data from the outside to monitor the state of the absolute displacement detection means, data processing means for performing data processing such as state check based on the input data, Data output means for outputting a data processing result as serial data; photoelectric detection means integrally formed with the absolute displacement detection means for photoelectrically detecting a reference position pattern formed on the scale and the pickup; A reference position signal generating means for processing the output of the means and outputting a reference position signal; and Switching means for selecting one of the output terminal of the reference position signal generating means and the output terminal of the data output means and connecting to a common signal line. 3. An electrostatic capacitance type having a main scale and a pickup in which electrodes of a predetermined pattern are formed and moved relatively to each other, and detecting an absolute displacement by detecting different electrostatic capacitances depending on their opposing positions. Absolute displacement detection means, data input means for receiving serial data from the outside to monitor the state of the absolute displacement detection means, data processing means for performing data processing such as state check based on the input data, A data output means for outputting a data processing result as serial data; and a two-phase square wave signal integrally formed with the absolute displacement detection means for photoelectrically detecting a pattern on the scale to determine a moving direction. And a reference position signal by processing the output of the photoelectric detection unit and the output of the absolute displacement detection unit. Reference position signal generating means, and switching means for selecting one of the output terminals of the two-phase square wave signal and one of the output terminals of the data output means and connecting to a common signal line according to an operation mode. An encoder for absolute measurement, comprising: