JPS6221935Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a contact type encoder for a measuring instrument, and particularly to a contact type encoder for a measuring instrument that is suitable for small measuring instruments that are battery-driven with low current consumption.

2. Description of the Related Art Encoders that detect the mechanical displacement of a probe as an electrical digital signal are well known, and are applied in various measurement fields as length measuring machines, position detectors, and the like. This type of encoder electrically detects the length of the object to be measured as a scale or other displacement amount, and the electrical detection means include electromagnetic type,
Various types of encoders are known, such as electrostatic type and photoelectric type. In particular, photoelectric conversion type encoders are used as micrometers, calipers, coordinate measuring machines, etc. due to their advantages such as miniaturization and high-precision measurement. It has been widely put into practical use.

However, conventional devices of this type have the drawbacks of being relatively expensive and consuming a relatively large amount of current. In particular, batteries are used as a drive source for recent compact length measuring machines and other equipment, and for this reason, there is a demand for low current consumption and long life spans. The digital displacement detection device has the advantage that its electrical processing is formed from a C-MOS circuit, and the current consumption in these electrical processing circuits is extremely small. In photoelectric devices, a light emitting device for photoelectric conversion, such as a light emitting diode, consumes a large amount of current, resulting in a problem that the overall current consumption increases.

In contrast to the non-contact type encoders mentioned above, contact type encoders have been known that detect electrical digital signals from opening/closing operations by contacting contacts, and can electrically detect mechanical displacement with a simple structure. It has the advantage of being highly accurate and has been put to practical use in certain fields, but it has only been used as a positioning mechanism that does not require precision or as a rotational position detection device for large drive mechanisms. Its use was not considered at all, especially in length measuring machines that require small size and high precision. In other words, this type of contact type had fundamental drawbacks such as low contact reliability, extremely unstable contact state, and extremely easy contact state change after long-term use. It was considered impossible to use it in length measuring machines, etc., where poor contact directly causes errors.

However, this device has the advantage that it can convert mechanical displacement into electrical digital pulses only by applying voltage, and basically does not require current consumption. We focused on the application of this method to a small length measuring machine that can be driven by a battery with low current consumption by combining it with a voltage type element such as a C-MOS transistor.

However, with such a contact encoder,
There is a drawback that various noises are mixed into the input voltage that changes as the detection contact opens and closes, and as a result, the accuracy and reliability of the measuring device are significantly impaired. This type of noise is mainly caused by the surface condition of the contacts, such as dirt, the presence of high resistance parts, and other surface deterioration due to long-term use, and it has been impossible to completely prevent the incorporation of these noises.

FIG. 1 shows a schematic configuration of the above-mentioned contact type encoder, which includes a group of slit contacts 10 and 12 made up of a plurality of conductors arranged at a predetermined interval, and a measuring probe connected to the group of slit contacts 10 and 12. A sliding contact 14 that moves in the AB direction in response to mechanical displacement is provided, a battery 18 serving as a DC power source is connected to the sliding contact 14 via a resistor 16, and the slit contact group 1
A detection voltage is applied between 0 and 12 and the sliding contact 14. Both slit contact groups 10 and 12 can be formed, for example, from slit electrodes formed by vapor deposition on the side surface of a disk, or from linear slit electrode groups, and the sliding contact 14
can be formed from a brush contact that rotates or moves linearly in conjunction with the probe. Therefore, as the sliding contact 14 moves in the direction of the arrow AB, the opening/closing operation between the slit contact 10 or 12 and the sliding contact 14 causes the sliding contact 14 to be removed from the terminals 20 and 22.
A digital signal corresponding to the amount of movement can be detected. By arranging the slit contact groups 10 and 12 with a predetermined phase difference, 90 degrees in FIG. It becomes possible to obtain a square wave signal.

However, as described above, when the detection contact is formed from the simple slit contacts 10, 12 and the brush contact 14, noise due to disturbances enters the terminals 20, 22, and especially in the critical state of opening/closing of the detection contact, the contact It is known that incomplete contact causes non-negligible noise, and
The figure shows a state in which disturbance noise or critical noise occurs before and after a predetermined measurement signal, that is, region T. Therefore, in the conventional apparatus, these noises, particularly noises caused by poor contact between the contacts, cause counting errors in digital measurement signals and the like, resulting in a drawback that the accuracy of the measuring instrument is significantly reduced.

The present invention was devised in view of the above-mentioned conventional problems, and its purpose is to provide an improved contact type encoder for measuring instruments that can effectively eliminate noise caused by contact failure. .

In order to achieve the above object, the present invention includes a slit contact made of a plurality of conductors arranged at regular intervals, and a brush contact that slides relative to the slit contact in conjunction with the mechanical displacement of a probe. and a power supply that applies a detection voltage between both contacts, the brush contact is composed of a plurality of electrically connected common brush contacts, and each bare brush contact is a group of minute contacts. and slit contacts are formed corresponding to different conductors along the relative sliding direction of the brush contacts, and the conductor width of the slit contacts is set narrower than the slit width, and any of the bare brush contacts It is characterized in that it outputs a detection signal when it comes into contact with the conductor of the slit contact.

Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 3 shows a schematic diagram of a preferred embodiment of the contact type encoder according to the present invention. Slit contact 1
0 is set. The brush contact 14 is moved relative to the slit contact 10.
However, the characteristic feature of the present invention is that the brush contact 14 consists of a plurality of bare brush contacts arranged corresponding to different slit contacts, and in the embodiment, three adjacent Three bare brush contacts 14a, 14b, and 14c are provided at equal intervals for each slit. And each elementary brush contact 14a, 14
As is clear from FIG. 3, b and 14c are composed of a group of minute contacts arranged in a direction substantially perpendicular to the relative sliding direction of the brush contacts, and are electrically connected in common to each other. When the brush contact contacts the conductor of the slit contact 10, a detection signal will be obtained from the detection contact.

The embodiment of the present invention has the above-mentioned configuration, and each bare brush contact 14a, 14b, 14c is connected in parallel in common, and each bare brush contact is provided corresponding to the slit contact 10, so that at least Either one bare brush contact is a slit contact 14
It becomes possible to obtain a detection signal when the remaining bare brush contacts come into contact with the slit contact 10, and even if the remaining bare brush contacts are in an irregular contact state with the slit contact 10, a desired detection signal can be extracted from the bare brush contacts that are in a normal contact state. This makes it possible to reliably prevent conventional counting errors caused by contact failure.

In the illustrated embodiment, each bare brush contact 14a, 1
4b and 14c are provided corresponding to adjacent slits, but in the present invention, the arrangement of each bare brush contact can be arbitrarily selected, and it is also possible to provide bare brush contacts separated by a plurality of slits. be.

Furthermore, in the present invention, a plurality of bare brush contacts are connected in parallel, and these bare brush contacts and slit contacts do not necessarily connect and disconnect at the same time. A situation occurs in which the contact time between the contact time of the bare brush contact that comes into contact with the contact 10 and the opening time of the last bare brush contact that leaves the slit contact 10, that is, the contact time, is slightly longer than before, and this causes the detection signal to decrease. The ratio between the "H" and "L" times, that is, the duty ratio of the detection pulse signal, may be slightly different from the conventional one. In this embodiment, in order to set the duty ratio of this detection pulse signal to a desired value, for example, 50%, it is preferable that the ratio of the conductor width A to the slit width B of the slit contact 10 is set to a value different from the conventional one. In the embodiment, the conductor width A is set slightly shorter than the slit width B in order to obtain a duty ratio of 50%.

As explained above, according to the present invention, it is possible to reliably prevent counting errors caused by poor contact between the brush contacts and the slit contacts by using a plurality of bare brush contacts that are made up of a group of minute contacts and are connected in parallel. . Moreover, since the conductor width of the slit contact is set narrower than the slit width, it is possible to prevent the deterioration of the duty ratio due to the brush contact being formed from multiple bare brush contacts, and the accuracy of the measuring instrument is and reliability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing one example of a contact encoder, FIG. 2 is a detection waveform diagram of the encoder of FIG. 1, and FIG. 3 is a preferred embodiment of the contact encoder for measuring instruments according to the present invention. FIG. 10...Slit contact, 14...Brush contact,
14a, 14b, 14c...Brush contact, 18
……power supply.

Claims (1)

[Claims for Utility Model Registration] A slit contact made of a plurality of conductors arranged at regular intervals, a brush contact that slides relative to the slit contact in conjunction with the mechanical displacement of a probe, and both. A power source that applies a detection voltage between the contacts, and a contact type encoder for a measuring instrument, wherein the brush contacts are composed of a plurality of electrically commonly connected bare brush contacts, and each bare brush contact is composed of a group of minute contacts. and slit contacts are formed corresponding to different conductors along the relative sliding direction of the brush contacts, and the conductor width of the slit contacts is set narrower than the slit width, and one of the bare brush contacts is A contact type encoder for measuring instruments that outputs a detection signal when it comes into contact with a conductor of a slit contact.