JPH0674917U - Evaluation device for digital incremental encoder - Google Patents

Abstract

(57) [Abstract] [Purpose] To generate a much larger number of pulses from the sinusoidal voltage obtained in the encoder than that corresponding to the zero-pass region. Arrangements for extracting two sinusoidal voltages related to stroke or angle, and devices 21, 22, 3 for converting both sinusoidal voltages into four continuous sinusoidal voltages by rectification or inversion. And a device 4 for electrically synthesizing a linear portion of the sine wave voltage in the zero-pass region into a periodic triangular wave voltage, and using a change in the digital value derived from the obtained triangular wave voltage as an incremental encoder pulse. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 According to the present invention, two sine wave voltages having a phase difference of 90 degrees in electrical angle and having the same amplitude and the same period and related to the stroke or the angle can be taken out from the output terminal. The present invention relates to an evaluation device for a digital incremental encoder, which can be converted into a number of pulses which is proportional to a progressed stroke or an angle and in which a voltage derived from a sine wave voltage can be converted into a digital value.

[0002]

[Prior art]

 The above-mentioned incremental encoder can be configured as a linear system or a rotary system, and operates in principle, for example, photoelectrically or magnetically. All of these systems have in common that the sinusoidal voltage zero crossings or couplings are evaluated and used to simulate strokes. Magnetic type digital encoders are described in, for example, the magazine "Siemens-Zeit schrift" 1960, pages 669 to 671, and optical type encoders are described in, for example, the magazine "Siemens Components" 19 (1981), Nos. 1 and 12. ~ Page 13

It is often desirable to increase the resolution of such encoders, that is, to increase the number of certain pulses emitted per advanced stroke or angle.

[0004]

[Problems to be solved by the device]

 It is an object of the present invention to provide an evaluation device which can generate a much larger number of pulses from the raw signal of an encoder in a relatively simple manner than would correspond to the original zero crossing of a sinusoidal voltage.

[0005]

[Means for Solving the Problems]

 To achieve the above object, according to the present invention, a device for extracting two sinusoidal voltages having a phase difference of 90 electrical degrees from each other and having the same amplitude and the same period, which are related to a stroke or an angle, A device that converts both sinusoidal voltages into four continuous sinusoidal voltages by rectification or inversion, and a linear triangular part related to the stroke or angle in the region of zero passage of these sinusoidal voltages. A device for electrically synthesizing the voltage is used, and the change in the digital value derived from the obtained triangular wave voltage is used as the incremental encoder pulse.

In this way, it is possible to obtain a temporary encoder line number that is sufficiently higher than the conventional mechanical encoder line number, and on the one hand it is based on quantization and on the other hand the absolute value is determined within one period of the sine wave. It is based on the fact that it is possible to obtain 8 branches for evaluation by forming.

[0007]

【Example】

 The present invention will now be described in more detail with reference to the drawings.

In FIG. 1, an optical incremental encoder 1 includes a pulse disc 11 and scanning devices 12 and 13 attached thereto. From the output terminals of these scanning devices 12 and 13, a voltage represented by sin x or cos x (see FIG. 2a) can be taken out according to the movement. These raw signals have a phase difference of 90 degrees in electrical angle with each other, and have substantially sinusoidal waveforms. Both signals have a changing portion that rises almost linearly in the range of passing through the zero point (approximately −45 degrees to +45 degrees), which is due in part to the characteristics of the sine function and This is due to the configuration of the encoder itself, especially the optical encoder. The deviation between the sinusoid and the straight line can optionally be corrected by a non-linear conversion element, eg an analog-to-digital converter with non-linear characteristics.

Therefore, a triangular wave raw signal having a gradient proportional to the frequency is formed from the amphibian signals sin x and cos x having a phase difference of 90 degrees in electrical angle. The formation of this triangular wave can be easily realized as follows. That is, first, the absolute value of both voltages sin x and cos x (FIG. 2b) is formed, and the smaller of both voltage values is used. By doing so, in the period T of the rotation angle, the triangular wave voltage u _D shown by the broken line having the individual branches A1 to A8 is obtained.

In order to form this triangular wave voltage u _D , the absolute value forming device is provided with two absolute value forming devices 21 and 22, and the absolute value forming devices 21 and 22 have absolute values at their output terminals. Outputs the voltage | sin x | and | cos x |. These two output voltages are compared with each other in the voltage discriminator 3, and only the smaller of the two voltages is evaluated each time. This means that, in this embodiment, the outputs of the absolute value generators 21 and 22 are selected and led via the switch 31 or 32 controlled by the voltage discriminator 3. Thus, the triangular wave signal u _D is input to the analog / digital converter 4. This analog-to-digital converter 4 operates as an instantaneous value encoder and forms a corresponding digital value from a given voltage. This quantized triangular wave signal produced at the output of the analog-to-digital converter 4 is monitored by the evaluation logic 5 for changes. The pulse V or R is given to the bidirectional counter 6 each time the quantization unit is changed, depending on the sign direction. Therefore, the count content of the counter 6 corresponds to the actual value of the position. The evaluation logic circuit 5 is controlled by the voltage discriminator 3 and the voltages sin x, cos x via the conductor 33 in order to form the pulses in a sign-related manner. The count content of the bidirectional counter 6 can be given to the intermediate register and the display 7, and is used for higher-order control in some cases.

The above-mentioned device can also be used for measuring the rotation speed and the speed, in which case the change in the count content of the bidirectional counter 6 is obtained within a certain scanning time, and is used as a measure of the speed. Used.

As shown in FIG. 3, the triangular wave voltage can be formed from the voltages sin x and cos x and the voltage bars sin x and cos x, which are the voltages sin x and cos x, which are slightly different from the above method. In this case, first obtain the voltage u ₁ consisting of the larger of the two voltages cos x and bar sin x as indicated by the broken line, and similarly, as shown by the chain line, the larger of the two voltages sin x and bar cos x. The voltage u ₂ synthesized from is obtained. Next, when the smaller _{one of} the voltages u ₁ and u ₂ is selected, the periodic triangular wave voltage u _D can be obtained again.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a waveform diagram of an output sine wave voltage of an encoder and a triangular wave signal obtained from the sine wave voltage.

FIG. 3 is a waveform diagram of another method for obtaining a triangular wave signal.

[Explanation of symbols]

 1 Incremental encoder 11 Pulse disk 12, 13 Scanning device 21, 22 Absolute value generator 3 Voltage discriminator 4 Analog-digital converter 5 Evaluation logic circuit 6 Bidirectional counter 7 Display

Claims (4)

[Scope of utility model registration request] 1. A device for extracting two sine wave voltages having a phase difference of 90 degrees in electrical angle and having the same amplitude and the same period and related to a stroke or an angle, and by rectifying or inverting both sine wave voltages. A device for converting into four continuous sine wave voltages, and a device for electrically synthesizing a linear portion related to a stroke or an angle in a region of zero passage of these sine wave voltages into a periodic triangular wave voltage. A digital type incremental encoder evaluation device characterized in that a change in a digital value derived from the obtained triangular wave voltage is used as an incremental encoder pulse. 2. The evaluation device for a digital incremental encoder according to claim 1, further comprising a device for forming absolute values of both sinusoidal voltage and a device for comparing the absolute values. 3. The evaluation device for a digital incremental encoder according to claim 1, wherein a change in digital value between predetermined scanning points is used as a measure of speed or rotation speed. 4. The evaluation device according to claim 1, wherein an absolute value former connected to the encoder output terminal, a voltage discriminator attached to the absolute value former, and an absolute value former. An evaluation device for a digital incremental encoder, which comprises an analog-digital converter placed after the value forming device and a bidirectional counter controlled by the analog-digital converter.