JPH07174582A - Encoder for absolute measurement - Google Patents

Abstract

PURPOSE:To provide an encoder for absolute measurement, which can miniaturize the apparatus by the efficient utilization of a signal line. CONSTITUTION:The encoder for absolute measurement is provided with a reference-position-signal generation circuit 17 which outputs a reference-position signal for adjusting an original point position and a data input circuit 14, a data processing circuit 13 and a data output circuit 16 which monitor an internal state. In the encoder for absolute measurement, a data-output signal line and a reference-position-signal output line are formed as a common signal line 21, a data communication state is judged by an output judgment circuit 15, and, according to its judged result, the output terminal of the data output circuit 16 and the output terminal of the reference-position-signal generation circuit 1 7 are changed over and connected to the common signal line 21 by a changeover circuit 18.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, for example, a capacitance type absolute encoder used as a length measuring machine, an angle measuring machine, etc. is known. Some encoders of this type for absolute measurement have a data input / output function for maintenance and internal constant setting. Further, there is 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, when the function of the absolute measurement encoder increases and the amount of information to be output increases, the number of signal lines also increases accordingly. On the other hand, as the downsizing of devices progresses, the proportion occupied by the signal line connection portion increases, and efficient use of the signal line is required. The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide an absolute measurement encoder capable of downsizing the device by efficiently using the signal line.

[0004]

According to the present invention, a reference position signal generating means for outputting a reference position signal for adjusting an origin position and a two-phase square wave 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 and a data output means for monitoring an internal state, and a reference position signal output line, a two-phase square wave signal output line, and a data output. A signal line is used as a common signal line, and there is a switching unit that selectively switches and connects either the output terminal of the data output unit or the output terminal of the reference position signal generation unit to the common signal line according to the operation mode. It is characterized by that.

The encoder for absolute measurement according to the present invention also has a main scale and a pickup, each of which has a predetermined pattern of electrodes arranged in an array and moves relative to each other. The absolute displacement is detected by detecting different electrostatic capacitances depending on their facing positions. Capacitance type absolute displacement detection means for detecting,
Data input means for receiving serial data from the outside in order to monitor the state of the absolute displacement detection means, data processing means for performing data processing such as status check based on the input data, and data processing results as serial data. A data output means for outputting as, and a photoelectric detection means integrally formed with the absolute displacement detection means for photoelectrically detecting the reference position pattern on the scale and the pickup,
Reference position signal generating means for processing the output of the photoelectric detecting means and outputting a reference position signal, and selecting either the output terminal of the reference position signal generating means or the output terminal of the data output means according to the operation mode. And a switching means connected to the common signal line.

The encoder for absolute measurement according to the present invention also has a main scale and a pickup, each of which has a predetermined pattern of electrodes arranged in an array and moves relative to each other. The absolute displacement is detected by detecting different electrostatic capacitances depending on their facing positions. Capacitance type absolute displacement detection means for detecting,
Data input means for receiving serial data from the outside in order to monitor the state of the absolute displacement detection means, data processing means for performing data processing such as status check based on the input data, and data processing results as serial data. Data output means for outputting as a two-phase square wave signal for photoelectrically detecting the pattern on the scale and determining a moving direction, the photoelectric detection means being integrally formed with the absolute displacement detection means. One of the reference position signal generating means for processing the output of the photoelectric detecting means and the output of the absolute displacement detecting means to output a reference position signal, and one of the output terminals of the two-phase square wave signal according to the operation mode. And a switching means for selecting one of the output terminals of the data output means and connecting it to a common signal line.

[0007]

According to the present invention, the data output signal line is used as the reference position signal output line or one of the two-phase square wave signal lines and the common signal line, and these are used by switching between the normal operation mode and the data input / output mode. I am trying. 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 data is input / output to monitor the internal state. As these are shared only,
The number of signal lines can be reduced by properly using the device according to the usage 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 an absolute measurement linear encoder according to an embodiment of the present invention, and FIG. 2 shows the configuration of the detector main body. The main body of the detector is composed of a main scale 1 and a pickup (slider) 2 each of which has a predetermined pattern of electrodes arranged and moves relative to each other. A transmission electrode 5 and a reception electrode 6 each having a predetermined pattern are formed on the pickup 2. 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, and the second transmission electrode on the main scale 1 is different. 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 size of the capacitive coupling determined by the relative position of the main scale 1 and the pickup 2. 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 by the present applicant.

A photoelectric type position detector used for generating a reference position signal is integrally formed with such an electrostatic capacitance type absolute displacement detector main body. That is, the 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 it are provided on the slit plate 7. A reference position pattern is formed on the main scale 1 and the pickup 2, the diffused light from the light emitting diode 8 is applied to this, and 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 in order to obtain a sine wave signal having a predetermined pitch as the scale moves, excluding the influence of the nonuniformity of the gap between the scale 1 and the pickup 2 and the influence of temperature fluctuation. ing. It is the photoelectric detection circuit 12 that outputs the two-phase square wave signal for determining the scale moving direction by processing the output signals of these light receiving diodes 91-94, and the position reference signal Y is generated from the output. It is the reference position signal generation circuit 17 that does. The principle of this photoelectric position detection is disclosed in
Since it is the same as that described in No. 187413, detailed description will be omitted.

This absolute measurement encoder has a function of exchanging serial data with an external terminal for checking the internal state and setting internal constants. Therefore, as shown in FIG. 1, the serial data input circuit 14 whose input terminal is connected to the data input signal line 20 and the data processing circuit 1 which performs predetermined data processing based on the input data.
3, and a serial data output circuit 1 for outputting the processing result
Have six. The output of the data processing circuit 13 is also provided with a data output determination circuit 15 that determines whether or not it is necessary to output serial data. This data input / output function is not usually used by the user, but is used for maintenance and inspection and for setting internal constants before shipment.

The output terminal of the data output circuit 16 and the output terminal of the reference position signal generation circuit 17 are selected by the switching circuit 18 controlled by the output determination circuit 15 and connected to the common signal line 21. The common signal line 21 serves as a data output signal line and a reference position output signal line. 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 the information of the photoelectric detection circuit 12. Specifically, as these serial data information, each position data of the capacitance type detection circuit 11 and the photoelectric detection circuit 12, or position data obtained by combining these, self-diagnosis result of each detection circuit, and the data processing circuit 13 itself. It also includes self-diagnosis results.

With such a configuration, in the normal operation mode in which the length measuring machine is normally used, for example, the switching circuit 1
The contact point of 8 is switched so 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 the 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 a predetermined process. At this time, the output determination circuit 15 determines that the data input / output process is being performed and controls the switching circuit 18. As a result, the switching circuit 18 automatically switches the contact 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 the serial output data is output to the common signal line 21. To be done.

An algorithm for controlling the switching circuit 18 by the output judging circuit 15 is as shown in FIG. 3, for example. When the power is turned on, the switching circuit 18 enters the normal operation mode (BC connection) for generating the 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 a normal operation in which serial data communication is not performed, the reference position signal is output as described above.
When the serial data communication is performed, the switching circuit 18 determines the serial data communication mode (AC) depending on the determination result.
Connection) (S13). When the serial data communication is completed (S14), the normal operation mode is automatically switched (S15).

In the above operation mode switching control, for example, a communication end command is added to serial data from the terminal,
A control flow as shown in FIG. 4 may be used. When the power is turned on, the switching circuit 18 enters the normal operation mode (BC connection) for generating the reference position signal (S21). Then, the communication end command is detected (S22), and if the command is not detected and the serial data communication is judged (S2).
4) Then, the switching circuit 18 becomes the serial data communication mode (AC connection) according to the determination result (S25), and the serial data is transmitted (S26). Step S22
When the communication end command is detected at, the detection result switches to the normal operation mode (S23).

FIG. 5 shows the configuration of another embodiment of the present invention.
Parts corresponding to those in FIG. 1 are assigned the same reference numerals as those in FIG. 1 and detailed description thereof 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, and the capacitive detection circuit 11 obtains the upper digit and the photoelectric detection circuit 12 obtains the lower digit, and the reference position signal generating circuit 17 synthesizes these. Shows the 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 it to the common signal line 24, and the rest of the square wave signal X1 remains unchanged. The signal is output to the square wave signal output line 25. Also in this embodiment, the effect of miniaturizing the encoder by sharing the signal line can be obtained as in the previous embodiment.

[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 drawings]

FIG. 1 shows the configuration of an absolute displacement measuring encoder 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 same 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]

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 ... Capacitive 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 generating circuit, 18 ... Switching circuit, 20 ... Data input signal line, 21, 24 ... Common signal lines.

Claims (3)

[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 outputting means for outputting a two-phase square wave signal for determining a moving direction, and an internal state. In an absolute measurement encoder having a data input means and a data output means for monitoring, the reference position signal output line, one of the two-phase square wave signal output lines and the data output signal line are used as a common signal line. , For absolute measurement, having switching means for selecting either the output terminal of the data output means or the output terminal of the reference position signal generating means according to the operation mode and switching and connecting to the common signal line Encoder. 2. A capacitance type electrostatic capacitance type which has a main scale and a pickup, each of which has a predetermined pattern of electrodes arranged and moves relative to each other, and which detects an absolute displacement by detecting a different capacitance depending on the facing position of the main scale and the pickup. An absolute displacement detection means, a data input means for receiving serial data from the outside to monitor the state of the absolute displacement detection means, and a data processing means for performing data processing such as state check based on the input data, Data output means for outputting the 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; Reference position signal generating means for processing the output of the means and outputting a reference position signal, and An encoder for absolute measurement, comprising: an output terminal of the reference position signal generating means and a switching means for selecting one of the output terminals of the data output means and connecting to the common signal line. 3. A capacitance type electrostatic discharger, which has a main scale and a pickup, each of which has a predetermined pattern of electrodes arranged in an array and moves relative to each other, and which 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, and data processing means for performing data processing such as state check based on the input data, A data output means for outputting the data processing result as serial data, and a two-phase square wave signal integrally formed with the absolute displacement detection means for photoelectrically detecting the pattern on the scale and determining the moving direction. Photoelectric detection means, and outputs the reference position signal by processing the output of the photoelectric detection means and the output of the absolute displacement detection means. A reference position signal generating means and a switching means for selecting either one of the output terminals of the two-phase square wave signal or the output terminal of the data output means according to the operation mode and connecting to the common signal line. An encoder for absolute measurement characterized by having.