JPH0245038Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the rotation angle of a drafting head, which is part of a device for electronically displaying the rotation angle of a drafting head on a universal parallel ruler.

Conventionally, in order to eliminate errors when an operator reads the rotation angle of the drafting head on a universal parallel ruler, the rotation angle is detected by optical means, and the detected signal is processed by an electronic circuit and displayed digitally. A device for detecting the rotation angle of a drafting head is known. The rotation angle detection device for the drawing head includes a rotation angle detector consisting of a light emitting element and a light receiving element, and two parallel slit plates.

One of the two slit plates has a large number of slits formed in a circular shape with a constant pitch, and the other slit plate has a number of slits formed with the same pitch as the above slits. It has a book slit.

The other slit plate is
The slit plate is configured to rotate around the center of one of the slit plates, and a rotation angle detector is provided in a fixed position on the other slit plate. In the rotation angle detector, the distance between the light emitting element and the light receiving element is fixed, and two slit plates are positioned between the light emitting element and the light receiving element. Since the light from the light emitting element is not parallel, if the position of one of the slit plates changes, the intensity of the light entering the light emitting element will change accordingly.
An accurate sinusoidal waveform angle detection signal cannot be obtained depending on the degree of overlap of the slits in the two slit plates.

An object of the present invention is to provide a rotation angle detection device for a drafting head that can obtain an accurate sinusoidal waveform angle detection signal. The present invention was proposed to achieve the above object, and consists of a main slit disk made of a thin magnetic material and having a large number of slits arranged in an annular manner around the periphery, and at least one pair of a light emitting element and a light receiving element. an angle detector; a holder for holding each element of the angle detector so that they can be placed facing each other across the slit of the main slit disk; and a magnet that is arranged in a portion facing the slitting machine of the holder holding the one element and having magnetic permeability to maintain a constant distance between the main slitting machine and the one element. It is characterized by having a spacer.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 4. Drafting head 1
is connected via a connecting member 2 to a vertical rail that is movable left and right on the drawing board along a horizontal rail attached to the upper edge of the drawing board (not shown).
The drafting head 1 is movable across the drawing board along the longitudinal rails above the drawing board. At the upper end of the drafting head 1, a knob 3 is rigidly connected to the upper end of a rotating main shaft (not shown). The lower end portion of the rotating main shaft is fixed to the drafting head board 4.
The drafting head board 4 has scale attachment parts (not shown) extending perpendicularly to each other, and a straight scale (not shown) is removably attached to the scale attachment parts.

An index lever knob 5 is provided protruding from the side surface of the knob 3. This index lever knob 5 forms part of an index mechanism that fixes the drafting head board 4 at fixed angles to a protractor 7 that is fixed to a non-rotating moving shaft 6.

The rotation angle of the drafting head 1 (that is, the rotation angle of the drafting head board 4) is stored inside the drafting head 1.
A drafting head rotation angle detection device 8 is incorporated to detect the rotation angle of the drawing head. The construction of the rotation angle detection device 8 of this drafting head is as follows. That is, a main slitting machine 9 made of a stainless steel plate shown in FIG. 2 is fixed to the moving shaft 6. As shown in FIG. This main slit plate 9
may be made of a magnetic material, and preferably has elasticity. As can be seen from FIG. 2, the main slitting machine 9 is equivalent to two semicircular plates made of stainless steel plates having different diameters joined at a diameter 10. Diameter 10 is the zero position of protractor 7 and 180
The main slitting machine 9 is fixed to the moving shaft 6 so as to match the diameter passing through the vertical position.

A second code pattern 12 is formed at the outermost portion of the main slitting machine 9, and this second code pattern 1
A first code pattern 11 is formed on the inner peripheral side of 2.

The first code pattern 11 is composed of a total of 360 slits 13 formed in parallel in the circumferential direction with a pitch of 1 degree.

The second code pattern 12 is formed on the outer circumferential side of the first code pattern 11, and is in a concentric relationship with the first code pattern 11. The second code pattern 12 functions to allow light to pass through on one side 9a and to block light on the other side 9b, with the diameter 10 of the main slitting machine 9 as an axis of symmetry.

The second code pattern 12 forms part of a means for determining whether the drafting head 1 is rotated clockwise or counterclockwise.

As shown in FIG.
It is supported so as to move on the code pattern 11 along the main slitting machine 9.

As shown in FIG.
4 sets of slits 1 with book slit 15 as 1 set
Five groups are formed. An interval is set between each group of slits 15 to produce a phase difference of 90 degrees in the phase of the output signal.

In FIG. 2, a first angle detector 16, a third angle detector 18, a second angle detector 17, and a fourth angle detector 19 are arranged in order from the upper end to the lower end of the instruction slit plate 14. Angle detector 16, 17,
18 and 19 are arranged in such a positional relationship that they sandwich the main slitting machine 9 from the front and back sides of the main slitting machine 9, respectively.

The angle detectors 16, 17, 18 and 19 each include a light emitting element and a light emitting diode 1 as light emitting elements.
6a, 17a, 18a and 19a, and phototransistors 16b, 17b, 18 as light receiving elements.
b and 19b are built-in.

A rotation direction detector 20 is arranged at a position facing the instruction slit plate 14. This rotational direction detector 20 also includes angle detectors 16, 17, 18 and 19.
It has the same configuration as the light emitting diode 20
A and a phototransistor 20b are built in.

As shown in FIG. 4, light emitting diodes 16a,
The phototransistors 17a, 18a and 19a and the phototransistors 16b, 17b, 18b and 19b are fitted into a plastic holder 21 having a U-shaped cross section. Phototransistor 16b, 17b, 18b
and a block-shaped permanent magnet 22 adjacent to 19b.
is embedded in the holder 21.

An instruction slit plate 14 is fixed to the upper inner wall surface 21a of the holder 21, and a permanent magnet 22 is disposed between the instruction slit plate 14 and the main slit plate 9.
A spacer 23 is inserted in opposition to the holder 21, and the spacer 23 is fixed to the holder 21. The spacer 23 may have an apparent magnetic permeability depending on its configuration.

The main slit disk 9 is attracted by the permanent magnet 22 and is always in contact with the back side 23a of the spacer 23, so the slits 13 of the main slit disk 9 are connected to the light emitting diodes 16a, 17a, 18a and 19a and the phototransistors 16b and 17b. , 18b and 1
9b, and for this reason accurate sinusoidal signals of the rotation of angle detectors 16, 17, 18 and 19 are transmitted from these angle detectors 16, 17, 18 and 19. Emitted.

In the above embodiment, the permanent magnet was embedded in a plastic holder, but in another embodiment, the holder holding the angle detectors 16, 17, 18, and 19 is molded with a plastic magnet and the phototransistor is mounted. Only the side may be magnetized.

As described above, according to the present invention, the main slit disk made of magnetic material is rotated while being attracted to one element side by the magnet and always maintaining a constant distance from the one element by the spacer. ,
It is possible to obtain a more accurate sinusoidal waveform angle detection signal than with conventional rotation angle detection devices.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway sectional view of the drafting head.
Figure 2 is a plan view of two slit plates, and the third
This figure is a sectional view of a rotation angle detection device for a drafting head according to the present invention, and FIG. 4 is a partially enlarged sectional view of the rotation angle detection device for a drafting head. 1...Drawing head, 8...Drawing head rotation angle detection device, 9...Main slitting machine, 16, 17,
18 and 19... angle detector, 21... holder,
22...Magnet, 23...Spacer.

Claims (1)

[Claims for Utility Model Registration] A main slit disk made of a thin magnetic material and having a large number of slits arranged in an annular shape around its periphery; an angle detector comprising at least one pair of a light emitting element and a light receiving element; a holder for holding each element so that they can be placed facing each other across the slit of the main slit disk; a magnet that attracts a peripheral portion of the main slit disk toward one of the elements; A rotation angle detection device for a drafting head, comprising a magnetically permeable spacer placed on a portion of a holding holder facing the slitting machine to maintain a constant distance between the main slitting machine and the one element. .