JPS5851603B2 - Installation status confirmation device for position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position detection device, for example, a device for checking the installation state of a linear encoder in a digital tomb device by identifying the generation state of a zero signal for detecting an origin signal.

2. Description of the Related Art Digital length measuring devices mainly used for measuring length and positioning stages of machine tools include absolute type and incremental type linear encoders.

In recent years, in order to perform the functions of displaying absolute position information of the absolute method and displaying movement distance information from an arbitrary position to a fixed position of the incremental method in one device, the digital incremental method with an origin signal has been developed. Length measuring devices have been developed and are now in use.

In order to detect the origin signal, a scale for detecting the origin signal is attached to the pulse scale of the linear encoder.
A zero signal for detecting the origin signal is created by providing a window corresponding to the scale for detecting the origin signal on the index scale, or by combining a limit switch for detecting the origin signal with the pulse scale independently of the index scale. has been done.

This origin signal is a main count signal created from two main count signals whose phases are 1/4 pitch different and have the same period, a zero signal for detecting the origin signal, and two main count signals, as obtained by a well-known encoder. This is a signal obtained by ANDing a pulse train with twice the frequency of the signal.

In the creation of the zero signal for detecting the origin signal described above, in the former case, the pulse scale and index scale are
In the latter case, if the pulse scale and limit switch are not installed in the specified relationship on the machine tool, etc.
If the zero signal for detecting the origin signal is too long, too short, or biased to one side with respect to the origin signal, and it is installed in a predetermined relationship, the origin can be detected at a constant length without being biased to one side. Zero signal for signal detection is generated.

That is, in any case, the state in which the zero signal for detecting the origin signal is generated changes depending on how the encoder is attached to the machine tool or the like.

The following is an example of a linear encoder that has a scale for detecting the origin signal in the pulse scale and a window corresponding to the scale for detecting the origin signal in the index scale to create a zero signal for detecting the origin signal. Identification of the generation state of the detection zero signal will be explained based on the drawings.

FIG. 1 is a schematic diagram of a well-known incremental type linear encoder.

Reference numeral 1 denotes a pulse scale, in which a main scale section 1m and an origin detection scale section 1z are formed with bright and dark striped lines of about 10 .mu.m.

There is an index scale 4 at a position facing the pulse scale 1 and separated by a small distance, and it has two windows 4a and 4 having scales at the same pitch as the main scale part 1m.
b, and the scales of these two windows 4a and 4b have a phase difference of ]/4 pitch.

Also, index scale 4 includes pulse scale 1.
There is an origin detection window 4z at a position opposite to the origin signal detection scale section 1z.

Light emitting diodes 6a, 6b, 6z and light receiving elements 5a, 5b, 5z are fixed at positions corresponding to the windows 4a, 4b, 4z, respectively, so as to sandwich the pulse scale 1 and index scale 4, as shown in FIG. ing.

Only the pulse scale 1 is movable because it is attached to a machine stage (not shown), and the index scale 4°, the light emitting diode $ap6bp6z, and the light receiving element 5a
t5 b p 5 z is fixed to the machine body (not shown) and cannot be moved.

When the pulse scale 1 and index scale 4 are moved relatively, the main count signal 10a shown in the upper part of FIG.
, 10b are generated from the light-receiving elements 5a and sb, respectively, and by displaying these numbers, the relative movement amount of both scales can be read.

The main counting signals 10a and 10b are converted into rectangular wave signals 11a and 1, respectively.
1b, and create a pulse train 12 having twice the frequency of the signals 10a, 10b at the rising and falling edges of the signals 11a, 11b, and convert the pulse train 12 into 12a,
One cycle consists of four pulses 12a, 12b, and 12b.

Also, if scales 1 and 4 of one car are moved relatively,
The origin detection zero signal 10z is generated from the light receiving element 5z in the waveform shown in the upper part of FIG. 2, and the signal 1'lZ is obtained by shaping this into a rectangular wave. Specifically, the origin signal described above is Signal 11z and signal 11a are used as gate signals, and as shown in FIG.
Pulse 1 during the ON state of signal 112 and signal 11a
It is 2bO.

Now, before the linear encoder is mechanically attached, the pulse scale 1 and the index scale 4 are adjusted to a predetermined relationship in advance, and at that time, the origin signal / zoyless 12bO is placed in the center of the zero signal 11z for origin signal detection.
Suppose that we are in a state where we have obtained

However, when the linear encoder is actually attached to the machine body, pulse scale 1 and index scale 4 are
If there is not a predetermined relationship between A state where the origin signal pulse 12bO does not enter the detection zero signal 11z, or even if it does, an unstable state occurs in which it appears at the edge.

Therefore, the origin signal is not included. A slight shock could cause the origin signal to no longer be generated.

Therefore, when installing a linear encoder on a machine, it is important to identify the generation state of the zero signal for home signal detection in order to know whether the installation conditions of the pulse scale and index scale are in the specified relationship. be.

Since the zero signal for detecting the origin signal is placed at one point within the effective length of the pulse scale 1 or at intervals of, for example, 5QI31, the signal is only output momentarily and sporadically.

Even if it is observed with an oscilloscope or the like, it cannot be seen as a continuous signal, so it has been difficult to observe the waveform of the momentary signal 11z.

Furthermore, a memory type oscilloscope that can store the instantaneous waveform of the signal 11z for a long time is actually used, but this is very expensive.

The above has a scale 1z for detecting the origin signal and a window 4z corresponding to it, and uses not only an encoder that creates a zero signal for detecting the origin signal, but also a combination of a pulse scale and a limit switch independently of the index scale. The same thing can be said when creating a zero signal for detecting the origin signal.

An object of the present invention is to provide an apparatus that can inexpensively and reliably identify the generation state of a zero signal for origin signal detection without observing the waveform with an oscilloscope or the like.

In the following, in order to create a zero signal for detecting the origin signal, the present invention will be implemented using a linear encoder having a scale for detecting the origin signal in the pulse scale and a window corresponding to the scale for detecting the origin signal in the index scale. An example will be explained in detail based on the diagram.

A first example will be described.

In FIG. 3a, 13 is an up/down counter to which a pulse train 12 as shown in the lower part of FIG. 4 is input.

Counting is done.

As described above, the gate circuit 17 detects the zero signal 11z for detecting the origin signal and the signal 11b while the signal 11a is in the ON state.
A specific pulse 1 whose rising edge is extracted as a gate signal
2bO is set as the origin signal.

When the origin signal 12bO generated from the gate circuit 17 enters the up/down counter 13, it resets the counter 13 to zero, and from the zero reset position 1tR1, the counter 13
counts the pulse train 12 and sends the pulse count value to the storage circuit 14.

Thereafter, when the zero signal 11z for detecting the origin reaches its falling position s2, the memory circuit 14 uses the pulse generated from the falling detection circuit 16 at the moment of the falling of the zero signal 11z for detecting the origin, and the memory circuit 14 registers the counter 13. Memorize the count value.

That is, from the zero reset position R1 to the falling position S2
The count value of the counter 13 up to this point is stored in the storage circuit 14.

This is displayed on the light emitting diode numeric display element 15.

At this time, the rising position S1 of the zero signal for origin signal detection
The length from to the falling position S2 is set in advance to a length that counts the four pulse intervals of the pulse train 12.

Specifically, in this embodiment, from pulse 12b to pulse 12
a, 12b, 12a.

The length from the rising position s1 to the falling position S2 of the zero signal 11z for detecting the origin signal is determined as the length of the four intervals between the five pulses 12b.

In FIG. 4, the pulse of the origin signal 12bO resets the counter 13 to zero at the zero reset position R1 where it occurs.

When feeding pulse scale 1 in ten directions, signal 1
If the count value of the counter 13 is stored at the falling position S2 of 1z, the value will be O or +1. Or +
2 or +3. Or it becomes +4.

Similarly, if you perform the same operation when feeding in the - (minus) direction, the counted values will be 01-1, -2, -3, etc. -4.

Here, it must be avoided that two or more origin signals 12bO are included in the origin signal detection zero signal 11z used as a gate signal.

To do this, the above situation can be avoided if the on-state time of the zero signal 11z for home signal detection is 1.5 times or less and 0.5 times or more the period of the main count signals 11a and Ilb. It is.

For example, the effective existence range of the falling edge of the zero signal 11z for detecting the origin signal is set to be between the pulses 12a and 12a when the zero signal 11z for detecting the origin signal is being fed in ten directions, and the held count value is +1 or +2. In this case, it can be determined that the generation state of the zero signal 11z for detecting the origin signal is not too long, too short, or biased to one side with respect to the origin signal 12bO, that is, it is a stable state.

However, 0. Alternatively, if a value other than +1 or +2, such as +3, is stored and displayed, the generation state of the zero signal for home signal detection is too long or too short, or it is biased to one side with respect to the home signal 12bO. In other words, it can be said that it is in an unstable state.

As described above, according to this embodiment, the zero signal for detecting the origin signal can be generated by simply adding a memory circuit, a fall detection circuit, and a gate circuit to the function of the counting circuit, without using a memory display type oscilloscope. The occurrence state can be reliably identified.

Next, a second embodiment will be explained based on FIG.

As shown in FIG. 3, the second embodiment uses means instead of the memory circuit 14 used in the first embodiment to identify the generation state of the zero signal for detecting the origin signal.

In this embodiment, the pulse train 12 is input to the up/down counter 13 via the gate circuit 18 and counted.

The rising and falling signals of the zero signal 11Z for detecting the origin signal are taken out by the rising and falling detection circuit 20,
Set-reset flip-flop circuit 19 is set.

Using the flip-flop circuit 19, the gate circuit 18 inputs the pulse train 12 to the up/down counter 13 only during a certain period from the rise to the fall of the zero signal 11z for detecting the origin signal.

The origin signal 12bO also resets the up/down counter 13 to zero when it occurs.

When the pulse scale 1 is moved in the child direction, the up/down counter 13 counts the pulse train 12 from the zero reset position R1 to the falling position S2 of the zero signal 11z for home signal detection, holds the value, and displays the light emitting diode number. If the display element 15 is used to display the image, the same effects as in the first embodiment can be obtained in this embodiment as well.

In the above embodiments, the present invention is explained using a linear encoder having a scale for detecting the origin signal in the pulse scale and a window corresponding to the scale for detecting the origin signal in the index scale. Alternatively, the present invention can also be applied to a linear encoder in which a limit switch is combined with a pulse scale to create a zero signal for detecting the origin signal.

Furthermore, although the present invention has been described in the above embodiments only with respect to a photoelectric encoder, it goes without saying that the present invention can also be applied to a magnetic encoder.

As described above, according to the present invention, it is possible to inexpensively and reliably identify the generation state of the zero signal for detecting the origin signal without observing it with an oscilloscope or the like. This will be extremely easy to confirm.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a well-known incremental type linear encoder, and Fig. 2 shows two main count signal origin detection zero signals related to the device shown in Fig. 1, a signal obtained by shaping these three signals into a rectangular wave, and a main count signal. FIG. 3 is a block diagram showing two embodiments of the present invention. FIG. Figure 4 shows two main count signals shaped into rectangular waves related to the device in Figure 3, a zero signal for origin detection also shaped into a square wave, a pulse train with twice the frequency of the main count signal, an origin signal, etc. FIG. Explanation of symbols of main parts, pulse scale...1
, Main scale part...1m, Index scale...4, Two windows on the index scale.
...4a.

Claims (1)

[Claims] 1. An output that has a pulse scale and an index scale opposed to the scale, and outputs two main count signals whose phases differ by 1/4 pitch according to the relative movement amount of both scales. inputting the device and the two main counting signals;
a pulse generation circuit that outputs pulses having twice the frequency of those pulses; and a zero signal for detecting the origin signal having a pulse width corresponding to a predetermined number of pulses output from the pulse generation circuit at a predetermined position of the relative movement. and a circuit that receives the two main count signals and the zero signal and generates an origin signal at a position approximately in the middle of the pulse width of the zero signal. In the installation state confirmation device, a counting device is provided to count the pulses output by the pulse generation circuit during the time from when the origin signal is input until the zero signal disappears, and the number of pulses counted by the counting device is provided. An installation state confirmation device characterized by being provided with a display device that displays. 2. In the device according to claim 1. The circuit that generates the origin signal extracts the zero signal for origin signal detection and the rising edge of the other main count signal while one of the two main count signals is on as a gate signal, sets it as the origin signal, and generates it. A verification device characterized in that the counting device has an up/down counter, and the up/down counter is reset to zero when an origin signal generated from the gate circuit enters the counter. 3. In the device according to claim 2. The counting device further includes a memory circuit and a falling detection circuit that generates a pulse when the zero signal for detecting the origin signal reaches a falling position, and the memory circuit is configured to detect the falling edge from the zero reset position. A confirmation device characterized in that the count value of the pulse from the pulse generating circuit by the up/down counter up to the time when the pulse is generated from the falling detection circuit is stored by the pulse from the falling detection circuit. 4. In the device according to claim 2, the counting device further includes a rising and falling detection circuit for detecting rising and falling signals for detecting the origin signal, and a set set by this detection circuit. It has a reset flip-flop circuit, and a gate circuit that inputs the pulse from the pulse generation circuit to the counter only during a certain period from the rise to the fall of the zero signal for detecting the origin signal using the flip-flop circuit. A confirmation device characterized in that the down counter counts the pulses from the pulse generation circuit from the zero reset position to the falling position of the zero signal for detecting the origin signal and holds the counted value. 5. In the device according to any one of claims 1 to 4, the zero signal generation circuit for detecting the origin signal includes the pulse scale provided with the scale for detecting the origin signal, and the scale for detecting the origin signal. and the index scale provided with a corresponding window. 6. In the device according to any one of claims 1 to 5, the signal generation time of the zero signal for origin signal detection is 1.5 times or less and o, 5 times or more the period of the main count signal. A confirmation device characterized by: