JPS63118613A - Absolute encoder - Google Patents

Abstract

PURPOSE:To obtain a low-price encoder which leads out a multirotational absolute position signal by incorporating a battery, storing detection position information in an incremental type mechanism at all times, and outputting it in parallel. CONSTITUTION:A chargeable secondary battery 15 supplies electric power to a control substrate 40 which controls the reading of a magnetic head 10 at all times. When a motor 65 is powered on, operating electric power is supplied to the substrate 40 through an interface cable 41 and the substrate 40 operates principally therewith. At the same time, electric power is supplied to the battery 15 as well and a charging current is supplied thereto when the voltage of the battery 15 is low. Then, when the motor 65 is powered off, the operating electric power is not supplied 41 any more and circuits on the substrate 40 are powered on by the battery 15. Consequently, even when the power source of a driving source is turned off, the storage contents are maintained and even if a rotary disk 20 rotates in the period, the rotational position information is updated continuously, so the invariably accurate absolute position information on the rotary disk 20 is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an absolute encoder that is used by being directly assembled to a drive shaft of a servo motor or the like.

[Prior art and its problems] In recent years, with the development of robots and automatic machines, encoders (position code generators), which are rotational or linear position detection devices, have been widely used to control them, and the types of encoders have also increased. There is a wide variety.

Conventionally, positioning of the servo mechanism, especially the rotating part, was done using
Incremental type encoders are mainly used because of their simple structure and low price.

However, recently there has been an increasing demand for absolute type encoders. The reason for this is that, for example, when controlling the position of a robot, the home position is first detected,
It is necessary to operate based on this (if an incremental type is used, this operation is required every time the power is turned on again), but if there is an error in the initialization process of this home position detection, the subsequent Since this error will be included in the operation, this initialization work is extremely nerve-wracking and troublesome work. If this is an absolute type, once this setting is made, work can be started immediately regardless of whether the power is turned on or off, as long as there is no change in the work content, and there is no need for troublesome initialization processing.

However, with regard to this absolute type, there is an increasing demand for a type that can detect not only the conventional absolute position in one rotation but also in multiple rotations.

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide an absolute encoder that is inexpensive and capable of extracting multi-rotation absolute position signals. As one means for achieving this objective, this embodiment has the following configuration.

That is, an absolute encoder is connected to a drive shaft rotationally driven by a drive means to detect the amount of rotation of the drive shaft, and includes a rotary disk storing position information that rotates according to the rotation of the drive shaft; A reading means for reading storage position information of the rotating disk as a serial signal, a counting output means for counting and holding the read information of the reading means and outputting it as parallel information, and supplying operating power to the counting output means and the reading means. Equipped with a battery.

[Function] In the above configuration, an inexpensive and simple-structured absolute encoder can be provided by incorporating a power supply, constantly storing detected position information in an incremental type mechanism, and reducing the number of parallel output configurations.

[Example] Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the positional relationship between a rotating disk and a magnetic head in one embodiment of the present invention.

In the figure, 10 is a magnetic head constituted by the writable/readable M/R element of this embodiment, 20 is a rotating disk, and 30
is a drive shaft that rotates in accordance with the amount of movement of the controlled object.

A magnetic head 10 is disposed on a circumferential surface of a predetermined radius of the rotating disk 20 or at a position facing the circumferential surface, and at least the upper circumferential surface of a predetermined radius facing the magnetic head 10 has a high coercive force. It is coated with a magnetic material.

A schematic cross-sectional view of an encoder incorporating this magnetic head 10 and rotating disk 20 is shown in FIG.

Reference numeral 15 in FIG. 2 is a rechargeable secondary battery, which constantly supplies power to a control board 40 that performs read control for the magnetic head 10 and the like. 20 is the rotating disk shown in FIG. 1, 30 is a drive shaft that supports and rotates the rotating disk 20 at its center of rotation, 40 is a control board, 41 is an interface cable, 51 is a protective cover that protects the control board 40, 52.5
3 is a main body support base rotatably supporting the drive shaft 30;
and the main base of the main body.

Further, 52a and 53a are bearings into which the drive shaft 30 is fitted, and which rotatably support the rotary shaft on the main body support base 52 and the main body main base 53; A ring-shaped sponge-like elastic body is pressed into contact with the elastic body, 55 is a back plate that supports the elastic body 54, 58 is a protective cover for the secondary battery 15, 60 is a joint part, 65 is a motor, and 66 is a drive shaft of the motor 6°5. be.

In this embodiment, when the motor 65 is powered on, the control board 40 is connected via the interface cable 41.
Operating power is supplied to the control board 40, and the control board 40 is mainly operated by this power. At the same time, this power is also supplied to the battery 15, and when the battery 15 is being discharged, a charging current is supplied thereto. When the power to the motor 65 is turned off, the operating power supplied via the interface cable 41 is no longer supplied, and from now on, power is supplied from the battery 15 to each circuit on the control board 40, which will be described later. be done.

The magnetic head 10 has a read head section 10a for two tracks.
, 10b. And on this rotating disk 20,
On the magnetic recording track arranged on the magnetic material surface of the surface facing the read head section 10a of the magnetic head 10, magnetic scales are written in advance at every certain angle α by a known method, and other The other magnetic recording tracks arranged on the magnetic material surface facing the read head section tab include a rotating disk 20.
A reference position signal (Z) indicating the reference position of rotation of is written.

A schematic circuit configuration of the control board 40 is shown in FIG.

In the figure, reference numerals 101 and 102 indicate the read head section 10a.

An amplifier circuit 103 amplifies the read signal from the read head unit 10b, which is amplified by the amplifier circuit 101,
This is a counter that counts the position information (signal A) of the fully rotating disk 20 that is sent serially, and outputs the counting results in parallel. Further, 104 to 111 are buffers.

The counter 103 may have any capacity depending on the resolution of the position information stored on the rotating disk 20.
It is only necessary to output unique parallel position information that corresponds one-to-one to each position information. Specifically, 0″11″, ---n
-1" and "n" parallel information is output, and the multi-values have a one-to-one correspondence with the position information writing position on the rotating disk 20.

Further, 115 is a D type flip-flop (F/F), which is set by the input of the reset switch 130, and is reset by the fall of the Z signal from the read head section 10b since the D terminal is at ground level. 116,11
7 is an AND circuit, and the AND circuit 116 is F/F 1
15 sets, and the AND circuit 117 is F/F.
115 is satisfied when in the reset state, and each outputs a pulse synchronized with the Z signal. 118 is a latch circuit that latches the counter 103 count value when the first two signals arrive after inputting the reset switch 130 as reference position information, and thereafter latches the counter 103 first every time a Z signal arrives. Preset to location information value. Thereby, by inputting the reset switch 130, the output position information can be set to "0" at any timing, and it is also possible to correct errors every rotation.

As mentioned above, power is constantly supplied to each of the above components (excluding buffers 109 to 111) from the secondary battery 15, and the stored contents are maintained even if the power of the drive source is turned off. Even when the plate 20 rotates, the rotational position information accompanying the rotation is constantly updated, and the correct absolute position information of the rotating disk 20 can always be output. For this reason, it is equipped with an incremental encoder mechanism, and the control circuit is only equipped with a power supply and a circuit that generates and constantly stores absolute position information of the rotating disk from the position information of the rotating disk, so it can be treated as an absolute encoder from the outside. be able to.

Furthermore, the control circuit of this embodiment includes a rotation number counter of 119, 1
It is equipped with a latch circuit 20 and a timer 121, and counts the number of Z signals that come from the timer 120 within a specified fixed period of time (for example, 1 minute), and calculates the time when the specified time has elapsed. The number of rotations of the rotary disk 20 can be output by latching the numerical value in the latch circuit 120 and outputting it to the outside via the buffers 109 to 111.

Further, when the specified time has elapsed, the rotation number counter 119 is reset and counts the number of Z signals within a certain period of time.

These circuits may have a configuration in which power is constantly supplied from the battery 15, or a configuration in which power is supplied only when power is supplied to the drive source.

As described above, the secondary battery 15 is in a charged state when power is supplied to the drive source, and is in a discharge state when the drive source is not powered on. However, this battery 15 is not limited to a secondary battery, and of course may be a primary battery. In this case, the supply/non-supply of power from the battery to each circuit is performed by a switch.

As explained above, according to this embodiment, even though the basic part of the encoder is an incremental type, it functions as an absolute type from the outside, and since it is electronic, the initial position of the output (“0” position) can be set arbitrarily, and the number of revolutions can also be output.

[Effects of the Invention] As explained above, according to the present invention, it is possible to provide an absolute encoder that is inexpensive and has a simple configuration.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the positional relationship between a rotating disk and a magnetic head in an embodiment of the present invention, Fig. 2 is a schematic cross-sectional view of the embodiment, and Fig. 3 is a control board circuit diagram of the embodiment. be. In the figure, 10...Magnetic head, 15...Secondary battery, 2
0... Rotating disk, 30... Drive shaft, 40... Control board, 41... Interface cable, 51.58
...protective cover, 52...body support base, 53.
...Main body main base, 54... Sponge-like elastic body,
55... Back plate, 65... Motor, 66...
...Motor drive shaft, 101.102...Amplification circuit, 1
03゜119...Counter, 104-111...Buffer, 115...Flip-flop, 116,11
7: AND circuit, 118, 120: latch circuit, 121: clock means.

Claims (2)

[Claims] (1) An absolute encoder connected to a drive shaft rotationally driven by a drive means to detect the amount of rotation of the drive shaft, and a rotary disk storing position information that rotates according to the rotation of the drive shaft; A reading means for reading storage position information of the rotating disk as a serial signal, a counting output means for counting and holding information read by the reading means and outputting it as parallel information, and supplying operating power to the counting output means and the reading means. An absolute encoder characterized by comprising a battery. (2) The absolute encoder according to claim 1, wherein the battery is a secondary battery, and is charged by an externally supplied operating power when the driving means is in operation.