JP2734166B2 - 1-track type absolute encoder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a one-track absolute encoder capable of detecting an absolute position.

[Conventional technology]

Encoders detect the amount of movement and the movement angle and speed obtained based on this, and are classified into absolute encoders that can detect the absolute position within the movement range and incremental encoders that can simply detect the movement amount or movement angle. Is done.

In any case, the encoder is configured as follows: (1) Two minimum reading units having different physical properties such as a reflectance, a transmittance, a polarization state, a magnetic property, and a magnetization direction are represented by binary numbers 0 and 1. When represented by a code, a code plate formed by arranging a predetermined pattern consisting of a sequence of 0 and 1 on one track;
(2) It is divided into a sensor head that detects 0 and 1 separately.

In addition, a mechanical drive mechanism for relatively translating the code plate and the head is sometimes required.

The code plate has a long plate shape (tracks along a straight line ... linear encoder), a disk shape (tracks along a circumference ... rotary encoder), a cylindrical shape (along the outer peripheral surface of the cylinder). There is a track ... Rotary encoder).

Recently, a one-track type absolute encoder whose absolute position is known by only one track has been proposed.
No. -175211 and Japanese Utility Model Application Laid-Open No. 60-152916).

The code plate of this one-track type absolute encoder has a special pattern consisting of a sequence of 0s and 1s. For example, in an incremental encoder, 0s and 1s may simply be alternately arranged on one track, but a special pattern has a special permutation.

A special pattern used for such a one-track type absolute encoder code plate is called a "one-track type absolute pattern".

For example, in the case where 01 and two codes are arranged (the total number of codes is 2 ⁿ : n = 1st), if the head detects 0, the head becomes 0
, And if 1 is detected, it is known that the head is now at the 1 position, and the absolute position is eventually detected. Therefore, 01 is the lowest “1 track type absolute pattern”.

Similarly, when n = second order (the total number of codes is 2 ⁿ = 4),
0011 is an example of the “one-track absolute pattern”.

This will be described below. In the case of the linear encoder, when the left sensor of the n = 2 sensors reaches the position of the right end (tail), a signal is not detected by the left sensor, so that the left end (head) is used. Since it is necessary to add one code from, a pattern of 00110 is considered. For a rotary encoder,
No need to add.

In the case of n = 2 order, a head in which n = 2 sensors capable of detecting n = 2 consecutive codes are arranged in the moving direction is used, and this is moved one code at a time from the left. When n = 2 codes are read simultaneously, they are detected in the order of 00, 01, 11, and 10. Since these four code pairs are all different, the absolute position of the head in any one of the four positions is determined. Is detected.

Therefore, it will be understood that 0011 is an example of the “one-track absolute pattern”.

In such “one-track absolute pattern”, a full-period sequence (the total number of codes is indicated by 2 ⁿ )
, A group called M-sequence, and another group. Further, the full-period sequence includes a group called extended M-sequence in which one "0" is added before the M-sequence. It is.

Note that if it is possible to use a shorter period, a part of the entire periodic sequence can be used in practice.

By the way, in this one-track type absolute encoder, the number of sensors is required to be equal to the number of bits n. Considering the practical number of bits n = 10 or more (1024 or more in number of pulses), the sensor is arranged in the longitudinal direction of the track. Forming a sensor line (sensor array) aligned in a row, the signal lines (wirings) from the sensors are enormous in number, and the encoder and the embedded device (for example,
(Robots, machine tools, numerically controlled machines), the number of wirings between them is enormous, and the finishing is poor.

Therefore, as a prior art, it has been proposed to convert absolute position information (code information) detected in parallel by a sensor array into a serial signal by a parallel-to-serial conversion circuit and output the serial signal (Japanese Patent Application No. Hei. No. 288029, FIG. 3 and FIG. 2 of the present application).

According to this, at least one output line from the encoder is required.

[Problems to be solved by the invention]

However, since the output (detected signal) from each sensor is output in a serial manner, (1) whether the sensor array is correctly arranged, whether the sensor head is correctly assembled, the interval between the sensor and the code plate is correct, etc. Inspection,
(2) When performing phase adjustment (timing adjustment to detect when a sensor comes in the middle of the minimum reading unit), adjustment for outputting a correct waveform, and other adjustments, which serial signal is output from which sensor There is a problem that it is difficult to determine whether the inspection or adjustment work is difficult.

[Means for solving the problem]

The number m of sensors required for this inspection and adjustment may be much smaller than the number n of sensors in the sensor array, and usually only 2 to 4 sensors are required. The workability is the best at both ends of the sensor array.

Therefore, in the present invention, the sensor head is provided with an inspection or adjustment exposure terminal that is electrically connected to each of the limited m sensors (preferably, sensors at both ends of the sensor row).

[Action]

Since there is an exposed terminal, if conduction is made from here during inspection or adjustment, the output of the corresponding sensor can be easily obtained in parallel.

(Example of the present invention)

 Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of an absolute encoder according to the embodiment.

In Figure 1, the code plate 1, a track 1A, the sensor head 2, the sensor S _1, S _2, S _3, S _4, the parallel - serial converter circuit 3, those described in the conventional example, respectively similar configuration and function Having.

Sensor S ₁ to S ₄ are arranged in a row constitute a sensor column.

The absolute position information (code signal) detected in parallel by the sensors S _{1 to} S ₄ is converted to serial by the parallel-serial conversion circuit 3 and output from the output line 3 b to the built-in device.

From m = 2 sensors S ₁ and S ₄ at both ends of the sensor row,
Another wiring extends and is electrically connected to the exposed terminals 5a and 5b.

Thus, the outputs of the sensors S ₁ , S ₄ can be taken directly from the terminals 5a, 5b and their signals can be read directly.

〔The invention's effect〕

As described above, according to the present invention, when converting the absolute position detected in parallel to serial and outputting the serial position, for a small number of sensors in the sensor array, exposed terminals that are directly conductive are provided, so that inspection and inspection can be performed. Adjustment work has become easier.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an absolute encoder according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a schematic configuration of an absolute encoder according to the prior art. [Description of Signs of Main Parts] 1... Code plate 2... Sensor head 3... Parallel-serial conversion circuit 1A... Absolute pattern S ₁ , S ₂ , S ₃ , S _4. Plug-in devices 5a, 5b ... exposed terminals

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yuji Yamazaki 471 Nagaodaicho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Nikon Yokohama Works (56) References JP-A-1-311221 (JP, A) JP-A-2 JP-A-3-150414 (JP, A) JP-A-1-79199 (JP, U) JP-A-1-179273 (JP, U)

Claims (2)

(57) [Claims] 1. A code plate having a one-track absolute pattern formed of a predetermined sequence of 0s and 1s when two minimum reading units having different physical properties are represented by binary codes of numbers 0 and 1. A one-track-type absolute encoder comprising a sensor head having a sensor array comprising a predetermined number of bits of sensors capable of distinguishing between 0 and 1 and capable of distinguishing between 0 and 1; Or a first output terminal for sequentially selecting and outputting the sensor array in accordance with the adjustment work; and m second output terminals for constantly outputting m specific bits in the sensor array. A one-track type absolute encoder provided on a sensor head. 2. The one-track type absolute encoder according to claim 1, wherein said m is 2, and said two sensors are located at both ends of said sensor row.