JPH0614907U - Length measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an optical length measuring device capable of changing a position of an origin serving as a reference of a processing position. [Structure] A scale 10 mounted inside a casing 13 is provided with a measuring scale 11 and a plurality of origin marks 12. The detection head 18 that moves relative to the scale 10 is provided with an origin detection slit 20, a measurement slit 22, and photoelectric conversion elements 21, 23 and 24. A magnet 17 is set outside the casing 13 at a position corresponding to each origin mark 12 so that the N and S poles sandwich each mark. The magnet 17 selects an arbitrary origin. The detection head 18 is provided with N and S pole Hall elements 25 and 26 for detecting the N and S poles of this magnet. When the scale 10 is moved to the right with respect to the detection head 18, from the AND of the right feed signal obtained from the photoelectric conversion elements 23 and 24, the origin mark signal, and the latch signal of the output of the S pole Hall element, The origin signal indicating is obtained.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical length measuring device, and more particularly to a length measuring device capable of arbitrarily changing a position of an origin serving as a position detection reference at a plurality of predetermined positions.

[0002]

[Prior art]

 A length measuring device is attached to a machining table or the like of a machine tool, for example, to read a relative movement amount of the machining table with respect to a tool. An example of this length measuring device is an optical length measuring device.

In general, an optical length measuring device is composed of a scale unit directly attached to a machine tool and the like, a counter unit for obtaining an actual movement amount based on a detection signal from the scale unit, and displaying it. Has been done.

As shown in the schematic view of FIG. 4, the scale unit A has a scale body 1 made of a glass plate or the like, and a detection head 2 that moves relative to the scale body 1. Further, the scale body 1 is provided with stripe-shaped scales 1a made of a metal film formed by vapor deposition of Cr or the like and by etching. In addition, the scale body 1 is provided with an origin mark 1b at a predetermined position above the scale.

The detection head 2 is provided with the light source 3 on one side and the slits 4 and 5 and the photoelectric conversion elements 6 and 7 on the other side of the scale body 1. The slit 4 corresponds to the origin mark 1b, and the light from the light source 3 which has passed through the slit 4 and the origin mark 1b is received by the photoelectric conversion element 6. The slit 5 corresponds to the scale 1a of the scale body A, and the photoelectric conversion elements 7a and 7b correspond to positions where the phases of the moire fringes generated by the slit 5 and the scale 1a are shifted by 90 °. Is provided. Then, based on the received signals from the two photoelectric conversion elements 7a and 7b, the moving direction and the moving amount of the detection head 2 with respect to the scale body 1 can be obtained.

Next, a method of obtaining an origin serving as a machining reference will be described with reference to FIGS. FIG. 5 is a view schematically showing the origin mark 1b formed on the scale body 1 and the slit 4 of the detection head 2. FIG. 6 is a graph showing changes in the amount of light received by the photoelectric conversion element 6.

As shown in FIG. 5, the origin mark 1b and the slit 4 are patterned so as to have a negative / positive relationship. When the detection head 2 moves relative to the scale body 1, the origin mark 1b moves relative to the slit 4 and the weight of both patterns changes. The amount of light received by the photoelectric conversion element 6 changes according to the movement of the origin mark 1b.

As shown in FIG. 6, the amount of light received by the photoelectric conversion element 6 produces a minimum peak waveform when the lattice portion of the slit 4 completely overlaps the gap portion of the origin mark 1b, and the peak value becomes equal to the reference value and the peak value. The hold circuit obtains a pulse-shaped origin output waveform from this peak waveform. The falling edge of the origin output waveform is used as the origin signal by a counter unit (not shown).

[0009]

[Problems to be solved by the device]

 By the way, the origin mark 1b may be provided at the central portion of the scale body 1 or at the end portion thereof depending on the purpose of use of the length measuring device according to the type of machining of the machine tool and the convenience of the user. The positions are different. In the conventional method, since the origin mark 1b is directly formed on the scale body 1 and the slit 4 is also directly formed on the detection head, the origin position cannot be changed after the scale body 1 is formed. . Therefore, the user must specify the origin position before purchasing the length measuring device. On the other hand, the manufacturer has to manufacture various types of length measuring devices that differ only in the origin position according to the user's specification, which poses a manufacturing problem that mass production is not possible. There is also a problem in that it is complicated in terms of management.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a length measuring device capable of changing the position of an original point serving as a reference of a processing position.

[0011]

[Means for Solving the Problems]

 The length measuring apparatus of the present invention comprises a scale having a measuring scale formed thereon, a detection head which moves relative to the scale, a moire fringe formed on the detecting head together with the measuring scale of the scale. A measuring slit that occurs, a light source provided on the detection head, and a photoelectric conversion element provided on the detection head for detecting two or more phase signals from the moire fringes. In a length measuring device that detects relative displacement using two or more phase signals from the photoelectric conversion element, a plurality of origin marks formed on the scale and each origin mark provided on the detection head are detected. The origin detection means for outputting the origin mark signal and the origin mark of any origin mark so that magnetic poles with different polarities are arranged on both sides of each origin mark in the measuring direction. A magnet that can be freely set beside, a pair of Hall elements that are provided in the detection head and have different polarities that detect the magnetic field of the magnet and output a signal, and a signal from the Hall element that is latched and latched. A latch circuit that outputs a signal, a direction determination circuit that determines the length measurement direction from the phase signal from the photoelectric conversion element and outputs a direction determination signal, and the latch signal, the direction determination signal, and the origin mark signal. It has an origin determination circuit which takes AND and outputs an origin signal.

[0012]

[Action]

 The scale and the detection head are moved relative to each other. The origin detecting means successively detects a plurality of origin marks on the scale and outputs an origin mark signal. The photoelectric conversion element outputs two or more phase signals from the moire fringes generated from the measuring scale of the scale and the measuring slit of the detection head. The direction determination circuit outputs a direction determination signal in the length measuring direction from these phase signals. When the detection head reaches the specific origin mark specified by setting the magnet, the Hall element of the detection head outputs a signal. The latch circuit latches this signal and outputs a latch signal. Then, the origin determination circuit ANDs the origin mark signal, the direction determination signal and the latch signal and outputs an origin output signal indicating a specific origin mark.

[0013]

【Example】

 One embodiment will be described with reference to FIGS. A measuring scale 11 is formed on the scale 10 made of glass or the like. A plurality of origin marks 12 (to) are formed on the measuring scale 11 of the scale 10 at appropriate intervals. The scale 10 is fixed to the lower surface of the upper plate 14 of the casing 13 whose both ends and the lower surface are open.

A groove portion 15 is formed on the upper surface of the upper plate 14 of the casing 13 in the vicinity of the scale 10 and along the longitudinal direction of the scale 10. In the vicinity of the groove portion 15, displays 16 indicating the positions of the respective origin marks 12 formed on the scale 10 are formed. A permanent magnet 17 is installed in the groove 15. The permanent magnet 17 has a U-shape having a size such that the N pole and the S pole are arranged at positions on both sides of the origin mark 12, and by arranging the permanent magnet 17 in accordance with the display 16. , One of the multiple origin positions can be arbitrarily selected.

Inside the casing 13, a detection head 18 that moves relatively along the scale 10 is provided. The detection head 18 has a substantially U-shaped cross section sandwiching the scale 10, and an LED 19 as a light source is provided on one side.

An origin detection slit 20 corresponding to the origin mark 12 and a photoelectric conversion element 21 are provided as origin detection means on the other side of the detection head 18 opposite to the LED 19 with the scale 10 interposed therebetween. There is. On the other side, a measuring slit 22 corresponding to the measuring scale 11 and two photoelectric conversion elements 23, 24 are provided.

One photoelectric conversion element 21 detects a change in the light amount of the LED 19 due to the overlap of the origin mark 12 and the origin detection slit 20 and outputs an origin mark signal for each origin mark. The other two photoelectric conversion elements 23 and 24 detect the moire fringes generated by the measuring scale 11 and the measuring slit 22 with a phase difference of, for example, 90 ° and output them as an A-phase signal and a B-phase signal. To do.

An N-pole hall element 25 and an S-pole hall element 26 are provided on the LED 19 side of the detection head 18. These Hall elements 25 and 26 are located close to the groove 15 of the casing 13 in which the magnet 17 is set. That is, if the detection head 18 moves relative to the scale 10 and the casing 13, both Hall elements 25 and 26 detect one pole of the magnet 17 before the selected origin position. Output a signal. In the present embodiment, in FIG. 1, when the scale 10 moves to the right with respect to the detection head 18, the origin marks 12 that are sequentially detected are called, ... It was arranged so as to have a south pole.

Next, the configuration of a circuit for processing the signals from the photoelectric conversion elements 21, 23, 24 and both Hall elements 25, 26 will be described with reference to FIG. The direction determination circuit 30 receives the A-phase signal and the B-phase signal from the photoelectric conversion elements 23 and 24 and outputs a right feed signal or a left feed signal.

The signals from the S-pole Hall element 26 and the N-pole Hall element 25 are input to the latch circuits 31 and 32, respectively, and are output as latch signals. The latch circuits 31 and 32 are reset by the origin mark signal.

Then, the origin mark signal output from the photoelectric conversion element 21, the latch signal of the S-pole Hall element 26, and the right feed signal are input to one AND circuit 33 as the origin determination circuit.

The origin mark signal, the latch signal of the N-pole Hall element 25, and the left feed signal are input to the other AND circuit 34.

The outputs of the AND circuits 33 and 34 are input to the OR circuit 35, and the output of the OR circuit 35 becomes the origin signal.

Next, the operation of the above configuration will be described with reference to the timing chart of FIG. As shown in FIG. 1, the magnet 17 selects the origin mark. (1) Rightward feeding The scale 10 is moved to the right with respect to the detection head 18. The origin mark signal is output in this order. When the S pole of the magnet 17 approaches the S pole Hall element 26 of the detection head 18, the S pole Hall element 26 outputs a signal during the origin mark signal. With this output, the latch circuit 31 outputs a latch signal. This latch signal is connected until the fall of the origin mark signal. During this time, the direction determination circuit 30 determines the moving direction of the scale 10 based on the A-phase and B-phase signals output from the photoelectric conversion elements 23 and 24, and outputs the right feed signal.

Then, the AND circuit 33 outputs the origin signal only when the origin mark signal is turned ON during rightward feeding during latching, and simultaneously releases the latch. When the origin mark is turned ON during latching due to left feed, this latch signal is turned OFF so that the origin signal is not output to prevent malfunction.

(2) Leftward feeding The scale 10 is moved to the left with respect to the detection head 18. The origin mark signal is output in this order. When the N pole of the magnet 17 approaches the N pole Hall element 25 of the detection head 18, the N pole Hall element 25 outputs a signal before the origin mark signal is output. With this output, the latch circuit 32 outputs a latch signal. Connect this latch signal to the falling edge of the origin mark signal. During this period, the direction determination circuit 30 determines the moving direction of the scale 10 based on the A-phase and B-phase signals output from the photoelectric conversion elements 23 and 24, and outputs the left feed signal.

Then, the AND circuit 34 outputs the origin signal only when the origin mark signal is turned ON by the left feed during latching, and simultaneously releases the latch. When the origin mark signal is turned on due to right feed during latching, this latch signal is turned off so that the origin signal is not output and malfunctions are prevented.

[0028]

[Effect of device]

 According to the present invention, a magnet is arranged at an arbitrary origin among a plurality of origin marks, and this is detected by the Hall element of the detection head. Therefore, according to the present invention, the position and the number of the origin in the length measuring device can be selected, and the origin position can be easily changed even after being attached to a machine or the like. For this reason, it is not necessary to increase the number of types of scale bodies, and one type can meet all the needs of users, simplifying the management and maintenance work.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment.

FIG. 2 is a block diagram showing a signal processing function in one embodiment.

FIG. 3 is a timing diagram of signals output during operation of one embodiment.

FIG. 4 is a perspective view of a conventional length measuring device.

FIG. 5 is a diagram showing a principle of origin detection in a conventional length measuring device.

FIG. 6 is a diagram showing a principle of origin detection in a conventional length measuring device.

[Explanation of symbols]

 10 scale 11 measuring scale 12 origin mark 17 permanent magnet (magnet) 18 detection head 19 LED as light source 20 origin detection slit as origin detection means 21 photoelectric conversion element as origin detection means 22 measurement slit 23, 24 photoelectric conversion Element 25 N-pole Hall element 26 S-pole Hall element 30 Direction determination circuit 31, 32 Latch circuit 33, 34 AND circuit as origin determination circuit

Claims (1)

[Scope of utility model registration request] 1. A scale on which a measuring scale is formed, a detection head which moves relative to the scale, and a measuring slit which is provided on the detecting head and produces moire fringes together with the measuring scale of the scale. And a photoelectric conversion element which is provided in the detection head and which detects two or more phase signals from the moire fringes and is provided in the detection head. The relative displacement between the scale and the detection head is In a length measuring device that detects using two or more phase signals from the photoelectric conversion element, a plurality of origin marks formed on the scale and the origin marks provided on the detection head are detected to detect the origin mark signal. It can be changed to any origin mark vicinity so that the origin detection means for outputting and the magnetic poles with different polarities are arranged on both sides of each origin mark in the length measuring direction. A pair of Hall elements having different polarities for detecting the magnetic field of the magnet and outputting a signal, and a latch for latching the signal from the Hall element and outputting a latch signal. A circuit, a direction determination circuit that determines the length measurement direction from the phase signal from the photoelectric conversion element and outputs a direction determination signal, A of the latch signal, the direction determination signal, and the origin mark signal.
A length measuring device having an origin determination circuit that outputs an origin signal by taking ND.