JPH02114121A - Reflection type optical encoder plate - Google Patents

Abstract

PURPOSE:To achieve a stability of an operation of a focus servo along with a larger freedom of designing by providing a focus servo track for a focus servo without a small pit at a central part of an encoder track. CONSTITUTION:In a rotary encoder disc 1, circular arc small pits 4 with a pit width W smaller than the diameter of a light spot 40 of a laser light beam are arranged in groups to form one pit unit 3. Pit units 3 each comprising the groups of the small pits are arranged in a ring alternately with a land sections 5 in plurality at an angle alpha of opening at an equal interval to form an encoder track 2. Then, at the central part of the encoder track 2, focus servo tracks 6 are formed in a ring with no small pits 4 for a part where a light spot 40F for a focus servo is irradiated. The diameter-wise width of the focus servo track 6 exceeds a range in which the light spot 40F is irradiated with the rotation of the rotary encoder disc 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical encoder plate used in an optical encoder device that detects rotational or linear speed or position using a semiconductor laser beam.

(Prior Art) In recent years, optical encoder devices such as optical rotary encoder devices have been widely used. This optical rotary encoder device optically detects the rotational speed and position of the drive shaft of the object to be measured by directly connecting the input shaft of the device to the drive shaft of the object to be measured.

This optical rotary encoder device includes a transmission type that detects slits and pits by changes in transmitted light due to rotation of a rotary encoder disk with slits and pits, and a transmission type that detects slits and pits by changes in transmitted light due to the rotation of a rotary encoder disk with slits and pits. There is a reflective type that detects these slits and pits based on changes in reflected light.

This reflection type optical rotary encoder device has slits or pits (four parts or convex parts) cut on the surface of a rotary encoder disc using a manufacturing method for optical discs, compact discs, etc. in a predetermined direction in the circumferential direction of the disc. Encoder tracks arranged in a ring pattern are read by a laser reader by converting changes in the intensity of reflected laser beams into electrical signals.

FIG. 5 is a configuration diagram showing a first example of a conventional rotary encoder disk used in a reflective optical rotary encoder device, in which (A) is a plan view and (B) is a partial view. The enlarged plan view is an enlarged cross-sectional view taken along the Z-Z line in the figure (B).

In the figure, a rotary encoder disk 1 of a first conventional example is shown.
1 is made of transparent plastic, such as polycarbonate resin, and has four or convex pits 13 formed in a ring shape on one surface at equal intervals with an opening angle α, manufactured by a method for manufacturing compact discs, etc. Disc-shaped substrate 11a
A reflective film 11b is formed on the surface of the substrate 11a on which the pits 13 are formed by vapor deposition or sputtering of a metal such as aluminum, and a protective film made of an ultraviolet curing resin or the like is laminated in close contact with the reflective film 11b. Membrane 11c
It becomes more. In the following description, including other examples, an example will be described in which the pit 13 is a convex portion with respect to the land portion 15 which is a flat portion other than the pit 13 when viewed from the substrate 11a side.

The length of the pit 13 in the radial direction is determined by the following: A light spot (A) 40A, a light spot (F) 40F, a light spot When reading with (B) 40B, it is sufficiently longer than the length between both ends of the optical spots (A) 40A and (B) 40B, and the height is optically approximately the wavelength λ of this laser beam. It is formed to be equivalent to 1/4. Also, this pit 1 on the same circumference
The width P of 3 and the width Q of the land portion 15 between the pits are equal.
(P-Q), this pit width P and the land portion width Q between the pits are this light spot (A) 40A.

The diameters are approximately equal to those of (F) 40F and (B) 40B. Then, the uneven pattern of the encoder track 12 in which the pits 13 and the land portions 15 between the pis and the dots are arranged alternately in a ring shape is read by a laser reading device to be described later. Further, 7 is the center hole.

The rotary encoder disk 11 of the first conventional example configured as described above is used by being incorporated into a reflective optical rotary encoder device.

FIG. 6 is a schematic configuration diagram showing an example of a reflective optical rotary encoder device using a rotary encoder disk according to an embodiment of the present invention and a conventional example.

The rotary encoder disk 11 of the first conventional example has an input shaft 30 that is pivotally supported in the center hole 7 by a bearing (not shown).
It is fixed to and rotates as a unit.

This human power shaft 30 is directly connected to a drive shaft (not shown) of the object to be measured, and is rotationally driven thereby. Then, the laser reading device 31 reads the uneven pattern formed by the pits 13 of the encoder track 12 and the land portions 15 between the pits, thereby detecting the rotational speed and position of the drive shaft.

That is, this laser reading device 31 includes a semiconductor laser oscillator 32, a grating polarizing plate 33, and a collimating lens 3.
4. Polarizing beam splitter 35. 1/4 wavelength plate 36, objective lens 37, cylindrical lens 38, photodiode 39
It is composed of etc.

A laser beam from this semiconductor laser oscillator 32 is divided into three beams by this grating polarizing plate 33. The light spot (F) 40F formed by the central beam among these three beams is used for focus servo, which will be described later.
B) 40B is used for reading the encoder track 12. These three beams are connected to the collimating lens 34, the polarizing beam splitter 35.1/4
Light spots (A) 40A and (F) 40F pass through the wavelength plate 36 and the objective lens 37 and are placed on the encoder track 12 of the rotary encoder disk 11.

(B) Irradiated as 40B. These three light spots (A), (F), and (B) are collectively referred to as a light spot 40. These three beams reflected on the surface of the reflective film 11b of the rotary encoder disk 11 are reflected by the objective lens 3.
7. Passes through the 1/4 wavelength plate 36, and because it passes through this 1/4 wavelength plate 36 twice has a 90° phase difference from the incident light, it passes without being reflected by the polarizing beam splitter 35,
The photodiode 39 passes through the cylindrical lens 38.
The signal is converted into an electrical signal and output as a signal via the amplifier 42.

Here, since the height of the pit 13 is optically approximately 1/4 of the wavelength λ of the laser beam as described above, the reflection when the light spot 40 irradiates the boundary part of the pit 13 The light reflected from the top of the pit 13 and the light reflected from the land portion 15 are (1/4 wavelength)X2
Because of the difference in optical path length between the two, they interfere with each other and are diffracted, resulting in a decrease in intensity.

FIG. 7 is an explanatory diagram showing the relationship among the optical spot, encoder track, and signal output waveform in the device of FIG. 6 incorporating the rotary encoder disk of FIG.
) is the optical spot (A), (B) is the cross section of the encoder track, (C) is the signal output waveform due to the optical spot (A), and (D) is the signal output waveform due to the optical spot (B). It is.

As shown in the figure, when the encoder track 12 rotates in the direction shown by the arrow, the light spot (A) 4
A phase signal which is a signal output of waveform C by 0A, and B which is a signal output of waveform d by the optical spot (B) 40B.
A phase signal is obtained.

Here, the grating polarizing plate 33 is rotated so that the phase difference between the waveform C of the A-phase signal and the waveform d of the B-phase signal is an electrical angle of 90°, as shown in FIG. 5(B). Thus, the light spots (A) 40^ and (B) 40B are rotated by a mechanical angle β-2 in the rotation direction. As mentioned above,
The pit width P and the land width Q between the pits on the same circumference are the light spots (A) 40A and (B) 4
Since it is approximately equal to the diameter of 0B, the waveforms C and d of the A-phase and B-phase signals have the same duty ratio of polarity change.

Next, in the reflective optical rotary encoder device, the human power shaft 30 of the rotary encoder disk 11
A so-called focus servo that causes the focal point of the optical spot 40 of the laser beam to follow the plate surface of the disk 11 will be described in response to surface runout due to mounting accuracy.

FIG. 8 is an explanatory diagram of the focus servo in an example of a reflective optical rotary encoder device, in which (A) is when the plate surface is too close, and (B) is when the plate surface is at the correct focal position. , the same figure (C) shows the case where the board surface is too far away.

The portion of the photodiode 39 in FIG. 6 that receives the reflected light spot (F) 41F corresponding to the light spot (F) 40F caused by the central beam among the three beams is the eighth
As shown in the figure, it is a four-division photodiode 39F. The two diagonal outputs of the four-division photodiode 39F are combined and supplied to both input terminals of the differential amplifier 42F. And the same figure (B)
As shown in FIG.
Since 1F equally hits the four-division photodiode 39F, the output of the differential amplifier 42F becomes O, and the focus servo circuit (not shown) does not operate. The same figure (A
), (C), if the low-reflection encoder disk 11 is too close or too far away, the shape of the reflected light spot (F) 41F becomes an ellipse due to the cylindrical lens 38. As a result, this differential amplifier 4
A focus servo signal is output from 2F. In response to this focus servo signal, the focus servo circuit corrects the objective lens 37 to the correct focal position by driving a focus servo actuator (not shown). By the above operation, the optical spot 40 of the laser beam is adjusted so that it is always focused on the surface of the reflective film 11b of the rotary encoder disk 11.

Next, a method of outputting the human phase and B-phase signals will be described.

FIG. 9 is an explanatory diagram of a signal output section in an example of a reflective optical rotary encoder device.

Light spots (A) 40A and CB caused by beams on both sides of the three beams of the three photodiodes in FIG.
) 40B corresponding to reflected light spots (A) 41A and (
As shown in FIG. 9, the portion receiving B) 41B is two photodiodes 39A and 39B for the reflected light spots (A) 41A and (B) 41B. The portion receiving the reflected light spot (F) 41F is the four-division photodiode 39F as described above.

The outputs of these two photodiodes 39A and 39B are output as the aforementioned A-phase signal and B-phase signal via amplifiers 42A and 42B.

The first conventional row encoder disk 1 explained above
1, if the pit width P and the land width Q between the pits are increased according to the design specifications of the encoder track 12, the output waveforms are as shown in FIGS. 7(C) and 7(D).
The symmetrical waveform shown in Figure 2 becomes a distorted waveform.

FIG. 10 is an explanatory diagram of the device shown in FIG. 6 incorporating the row encoder disc shown in FIG. 5, when the pit width and the width of the land between pits are large; The cross section (B) in the same figure shows the signal output waveform.

As shown in FIG. 7(A), the width P of the pit 13-2 in this case and the width Q of the land portion 15-2 between the pits are the same as the light spot (A) 40A shown in FIG. 7(A). For example, the signal output waveform e is sufficiently larger than the diameter of Become. This distorted waveform has been reported to make waveform processing difficult when one pulse is divided into several times the number of pulses by electrical circuit processing to improve detection accuracy.

In order to solve the above problems, the following proposals have been made to obtain a large wave height difference and an appropriate waveform.

FIG. 11 is a configuration diagram showing a second example of a conventional rotary encoder disk used in a reflective optical rotary encoder device, where (A) is a partially enlarged plan view and (B) is a partially enlarged plan view.
is an enlarged sectional view taken along the line U-U in FIG.

As shown in the figure, in the second conventional low-resonance encoder disk 21, a plurality of arc-shaped small pits 24 with a pit width W smaller than the diameter of the optical spot 40 of the laser beam form a group. Two pit units 23 are formed. The pit unit 23 made up of this small pit group corresponds to the pit 13 in the first conventional example described above. In the example shown in FIG. 11, the pit width P and the land portion width Q between the pits explained in FIG.
Since this corresponds to the case where the diameter is sufficiently larger than the diameter of the pit unit 23, the opening angle α-2 between the pit units 23 is larger than the opening angle α between the pits 13.
A plurality of encoder tracks 22 are arranged in a ring shape at equal intervals.

The width W of the small pit 24 of this pit unit 23 is, for example, approximately 1/4 of the diameter of this light spot 40, and the width V of the land portion between these small pits is also the same.
The height of 4 is optically approximately 1/4 of the wavelength λ of the laser beam.
It is considerably formed. Also, this encoder track 2
The configuration other than the second concavo-convex pattern is the same as that of the first conventional example explained in FIG.

The rotary encoder disk 21 of the second conventional example having the above-mentioned configuration is incorporated and used in the above-mentioned reflective optical rotary encoder device shown in FIG.

The operation of this reflective optical low-reflection encoder device is as described above, but in this case, when the light spot 40 is on the pit unit 23, the reflected light is reflected from the top of the small pit 24. Since the light and the reflected light from the land portion 25 have a difference in optical path length of 1/2 wavelength, they interfere with each other and are diffracted, so that the light is attenuated.

FIG. 12 is a signal output waveform diagram of the device shown in FIG. 6 incorporating the rotary encoder disk shown in FIG.
) is the A-phase signal waveform, and (B) is the B-phase signal waveform.

As shown in the figure, the encoder track 22 is the eleventh
When rotated in the direction indicated by the arrow in the figure, the A phase signal which is the signal output by the light spot (A) 40A has a waveform f, and the B signal by the light spot (B) 40B
The phase signals have a waveform g, and both have the same duty ratio of polarity change.

Here, the waveform f of this human phase signal and the waveform g of this B phase signal
The darating polarizing plate 33 is rotated so that the phase difference between the light spots (A) 40A and (B) 40B is 90 degrees as shown in FIG. 11(A). It is rotated by a mechanical angle β-3 in the direction of rotation. Furthermore, if the width W of the small pit 24 and the width (2) of the land portion between the small pits are appropriately selected so as to increase the interference of the reflected light, the difference in wave height between the waveforms f and g becomes large. .

Note that the opening angle between the pit units 23 is α,
If the small pits 24 are formed to correspond to the pits 13 described above in FIG. 5, the signal output waveform in this case has a large difference in wave height and is of course sinusoidal.

(Problem to be Solved by the Invention) As described above, the signal output waveform of the reflective optical rotary encoder device incorporating the rotary encoder disk 11 of the first conventional example is determined by the pit width P and When the land portion width Q between the pits is increased, the difference in wave height is small and the waveform is distorted, so there is a problem that the degree of freedom in design is small.

In addition, in the reflection type optical rotary encoder device incorporating the rotary encoder disc 21 of the second conventional example, the operation of the focus servo by the light spot (F) 40F is controlled by the rotary encoder disc 21. When the rotation speed is several hundred rpm, the disturbance of the focus servo signal due to the small pit 24 is DC to 3kllz.
The frequency is higher than the servo band, so there is no effect. However, when the rotational speed of the disk 21 becomes small, the disturbance of the focus servo signal caused by the small pits 24 overlaps with the frequency region of this servo band, so there is a problem that the small pits 24 disturb the operation of the focus servo. What happened?

The present invention has been made with attention to the above points, and is applicable to a reflective optical rotary encoder device such as a reflective optical rotary encoder disc that greatly increases the degree of freedom in design and stabilizes the operation of a focus servo. The object of the present invention is to provide a reflective optical encoder plate for use in the present invention.

(Means for Solving the Problems) In the reflective optical encoder plate of the present invention, a plurality of pit units each consisting of a group of small pits are arranged in a predetermined pattern on an encoder plate that responds to the rotation or linear motion of an object to be measured. A reflective type that detects the rotational or linear speed or position of the object to be measured by forming an encoder track with a laser beam and converting changes in the intensity of the reflected laser beam into electrical signals and reading the encoder track using a laser reader. A reflective optical encoder plate used in an optical encoder device is configured to include a focus servo track for focus servo without the small pit formed in the center portion of the encoder track.

The reflective optical encoder plate of the present invention is the reflective optical encoder plate described above, and is configured such that a reference pit for generating a reference signal is formed at one location on the focus servo track.

(Example) The reflective optical encoder plate of the present invention has an encoder track in which pit units consisting of small pit groups and land portions are arranged alternately, and a light spot in which three beams of laser beams for reading are arranged is formed. A focus servo track without the small pits is formed in a portion irradiated with the central light spot (F) 40F for focus servo. In each of the embodiments, an example of a reflective optical rotary encoder disk will be described below, as in the case of the conventional example described above.

FIG. 1 is a configuration diagram showing an example of a rotary encoder disc used in a reflective optical rotary encoder device, which is a first embodiment of the reflective optical encoder plate of the present invention.
3A is a plan view, FIG. 1B is a partially enlarged plan view, and FIG.

As shown in the figure, the rotary encoder disk 1 according to the first embodiment of the present invention has the focus servo mounted at the center of the encoder track 22 of the rotary encoder disk 21 according to the second conventional example. A track 6 is formed. In this rotary encoder disk 1, a plurality of small arc-shaped pits 4 having a pit width W smaller than the diameter of the optical spot 40 of the laser beam are grouped together to form one pit unit 3. This pit unit 3 consisting of a group of small pits corresponds to the pit 13 in the first conventional example described above, and a plurality of pit units 3 are arranged in rings at equal intervals with the land portions 5 at an opening angle α. They are arranged in a shape to form an encoder track 2.

The width W of the small pits 4 of this pit unit 3 is, for example, approximately 1/4 of the diameter of the light spot 4o, the width of the land portion between these small pits is also the same, and the height of this small pit 4 is It is optically formed to correspond to approximately 1/4 of the wavelength λ of the laser beam. The radial length of this pit unit 3 is the light spot (A) formed by the three laser beams.
40A.

When reading with the light spot (F) 40F1 and the light spot (B) 40B, the length between the ends of the light spots (A) 40A and (B) 40B on both sides is also sufficiently long.
The width P of this pit unit 3 and the width Q of the land portion 5 between the pit units 3 on the same circumference are equal (P
-Q), this pit unit width P and the land portion width Q between the pit units are formed to be approximately equal to the diameter of this optical spot 4o.

In the center of the encoder track 2, a ring-shaped focus servo track 6 without the small pits 4 is formed in a portion irradiated with the focus servo light spot (F) 40F. The width of the focus servo track 6 in the radial direction is determined by the rotation of the rotary encoder disk 1, so that the light spot (F) 4
It is beyond the range where 0F is irradiated. Moreover, except for the concavo-convex pattern of the encoder track 2, the structure is the same as that of the second conventional example explained in FIG.

The rotary encoder disk 1 according to the first embodiment of the present invention having the above-described structure is incorporated into the reflective optical rotary encoder device described above in FIG. 6 for use.

The operation of this reflection type optical rotary encoder device is as described above, so the description thereof will be omitted. 4 is not present, the operation of the focus servo described above is not disturbed.

FIG. 2 is a signal output waveform diagram of the device shown in FIG. 6 incorporating the rotary encoder disc shown in FIG. It is.

As shown in the figure, when the encoder track 2 rotates in the direction indicated by the arrow in Figure 1, the light spot (
A) The A-phase signal, which is a signal output by 40A, has a waveform a
Therefore, the B-phase signal generated by the light spot (B) 40B has a waveform of 1, and both have the same duty ratio of polarity change.

Here, the grating polarizing plate 33 is rotated so that the positional difference between the waveform a of this A-phase signal and the waveform of this B-phase signal is 90'' electrical angle, and the polarizing plate 33 is rotated as shown in FIG. 1(B). As shown, the spots (A) 40A and (B) 40B are now rotated by a mechanical angle β in the rotation direction.The width W of the small pit 4 and the width V of the land portion between the small pits are
If selected appropriately to increase the interference of the reflected light mentioned above,
The difference in wave height between waveforms a and b becomes large.

Note that the opening angle between the pit units 3 is set to α-2, and this small pit 4 is defined as the small pit 24 described above in FIG.
If formed correspondingly, the signal output waveform in this case will be as shown in FIG. 12, and of course the operation of the focus servo described above will be stabilized.

Next, a second embodiment will be described in which a pit for generating a reference signal is formed on the focus servo track 6.

FIG. 3 is a configuration diagram showing an example of a rotary encoder disk used in a reflective optical rotary encoder device, which is a second embodiment of the reflective optical encoder plate of the present invention.
FIG. 5A is a plan view, and FIG. 2B is a partially enlarged plan view.

As shown in the figure, the rotary encoder disk 1-2 of the second embodiment of the present invention is located at the center of the encoder track 2 of the rotary encoder disk 1 of the first embodiment of the present invention. The formed focus servo track 6
In this example, a Me pit 8 for generating a basic signal is formed. That is, in this rotary encoder disk 1-2, a Z-phase signal for indicating a zero address is placed at one location on the circumference of a ring-shaped focus servo track 6-2 formed at the center of the encoder track 2-2. This reference pit 8 for generation is formed. The reference pit 8 is shown as an example constituted by a group of small pits similar to the small pit 4 in the pit unit 3 in FIG. 3, but it may be a single pit like the pit 13 in FIG. 5. . When the reference pit 8 is composed of a single pit, the pit width P is, for example, approximately 1/4 of the diameter of the optical spot (F) 40F. The structure other than the reference pit 8 is the same as that of the first embodiment of the present invention explained in FIG.

The rotary encoder disc 1-2 of the second embodiment of the present invention having the above-described structure is incorporated into the reflective optical rotary encoder device described above in FIG. 6 for use.

The operation of this reflective optical rotary encoder device is as described above, so it will be omitted, but in this case, the light spot (F
) 40F irradiates the reference pit 8, one pulse of the Z-phase signal, which is a reference signal, is output.

This Z-phase signal is output by, for example, adding the four outputs of the four-part photodiode 39F, and outputting the resultant signal through an amplifier (not shown).

Next, a third embodiment will be described in which a pit row for tracking servo is formed on the focus servo track 6.

FIG. 4 is a configuration diagram showing an example of a low-reflection encoder disk used in a reflection-type optical rotary encoder device, which is a third embodiment of the reflection-type optical encoder plate of the present invention.
3A is a plan view, FIG. 1B is a partially enlarged plan view, and FIG.

As shown in the figure, the rotary encoder disk 1-3 of the third embodiment of the present invention is located at the center portion of the encoder track 2 of the rotary encoder disk 1 of the first embodiment of the present invention. The formed focus servo track 6
In this embodiment, a tracking servo pit 9 for tracking servo is formed. That is, in this rotary encoder disk 1-3, a ring-shaped focus servo track 6 is formed in the center of the encoder track 2-3.
-3, this tracking servo pit 9, which is a ring-shaped pit row for tracking servo, is formed. This tracking servo pit 9 is located at the center of the focus servo track 6-3 in the radial direction.
The tracking servo pit 9 is formed concentrically with the pit unit 3 and the center hole 7, and the radial width of the tracking servo pit 9 is, for example, approximately 1/4 of the diameter of the light spot (F) 40F produced by the reading laser beam. The height is optically equivalent to approximately 1/8 of the wavelength λ of this laser beam. Also, other than this tracking servo pit 9,
The configuration is similar to that of the first embodiment of the present invention explained in FIG.

The rotary encoder disk 1-3 of the third embodiment of the present invention having the above-described structure is incorporated into the reflection type optical rotary encoder device described above in FIG. 6 for use.

The operation of this reflection type optical rotary encoder device is as described above, so the description thereof will be omitted, but in this case, the tracking servo track 9 is moved to the light spot (F ) 40F, this light spot (F) 40F
Tracking servo follows this tracking servo track 9 and corrects fluctuations in the output signal due to eccentricity of the disk 1-3, so-called tracking servo.

This tracking servo operation is performed, for example, as follows.

The four-division photodiode 39 receives the reflected light spot CF) 41F corresponding to the light spot (F) 40F.
The two outputs of F on the photodiode 41^ side are combined and sent to one input terminal of a differential amplifier (not shown), and the two outputs of the photodiode 41B side are combined and input to one input terminal of the differential amplifier (not shown). supplied to the other input terminal. and,
A change in the input signal fed to both input terminals of this differential amplifier according to the deviation of this optical spot (F) 40F from the tracking servo pit 9 is outputted as a tracking servo signal by this differential amplifier. be done. A tracking servo circuit (not shown) drives a tracking servo actuator (not shown) in response to this tracking servo signal, so that this light spot (
F) In 40F, the position of the tracking servo pit 9 in the radial direction is always corrected so that the tracking servo pit 9 always passes through the center.

Although the third embodiment of the present invention described above has been described in terms of the case where the tracking servo pit 9 is combined with the first embodiment of the present invention described above, the third embodiment of the present invention is combined with the tracking servo pit 9 in combination with the second embodiment of the present invention described above. Of course, a combination is also possible.

Further, in the description of the first to third embodiments described above, the case where the small pits 4 are arc-shaped has been described, but even if the small pits 4 are arranged in the radial direction, they do not form an angle with the radial direction. They may be arranged as follows.

Further, in the above description, the case where the pit unit 3 is formed on one side of the rotary encoder disc 1.1-2.1-3 has been described, but it may be formed on both sides.

Furthermore, although the above description has been made regarding a reflective optical rotary encoder disc that detects rotational motion of the object to be measured, it can also be applied to a reflective optical linear encoder disc that detects linear motion.

(Effects of the Invention) The reflective optical encoder plate of the present invention used in the reflective optical encoder device having the above configuration stabilizes the operation of the focus servo and provides a symmetrical output waveform. , the degree of freedom in designing a device using this increases, and a highly accurate device can be constructed.

Furthermore, since the reference signal can be obtained without providing a dedicated detection device, the cost of the device using this can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a rotary encoder disc used in a reflective optical rotary encoder device, which is a first embodiment of the reflective optical encoder plate of the present invention;
The figure is a signal output waveform diagram of the device shown in FIG. 6 incorporating the disc shown in FIG. 1, and FIG. 3 is a reflection type optical rotary encoder device which is a second embodiment of the reflection type optical encoder plate of the present invention. FIG. 4 is a configuration diagram showing an example of a low-reflection encoder disc used in the present invention.
A configuration diagram showing an example of a rotary encoder disk used in a reflective optical rotary encoder device which is an example of
Fig. 5 is a configuration diagram showing an example of T51 of a conventional rotary encoder disk used in a reflective optical rotary encoder device, and Fig. 6 shows a rotary encoder disk according to an embodiment of the present invention and a conventional example. 7 is an explanatory diagram showing the relationship between the light spot, encoder track, and signal output waveform in the device of FIG. 6 incorporating the disk of FIG. 5. , 8th
The figure is an explanatory diagram of the focus servo in the device shown in Fig. 6,
FIG. 9 is an explanatory diagram of the signal output section in the device of FIG. 6, and FIG. 10 is an explanation of the device of FIG. 6 incorporating the disk of FIG. 5 when the pit width and the land width between the pits are large. 11 is a configuration diagram showing a second example of a conventional rotary encoder disk used in a reflective optical rotary encoder device, and FIG. FIG. 3 is a signal output waveform diagram of the device. 1.1-2.1-3.11.21...Rotary encoder disk, 2.2-2.2-3.12.22...Encoder track, 3.23...Pit unit, 4・
...Small pit, 5,15.15-2.25...Land portion, 6.6-2.6-3...Focus servo track, 7...Center hole, 8...Reference pit, 9... Tracking servo pit, 31... Laser reading device,
40... light spot. Patent applicant: Japan Victor Co., Ltd. Representative: Kunio Kakiki l1 Figure 17m Y Flood

Claims (2)

[Claims] (1) Forming an encoder track in which a plurality of pit units each consisting of a group of small pits are arranged in a predetermined pattern on an encoder plate that responds to the rotation or linear motion of the object to be measured;
This encoder track is used in a reflective optical encoder device that detects the rotational or linear velocity or position of the object to be measured by converting the intensity changes of the reflected laser beam into electrical signals and reading them using a laser reader. A reflective optical encoder plate, characterized in that the reflective optical encoder plate includes a focus servo track for focus servo without the small pit formed in the center of the encoder track. (2) The reflective optical encoder plate according to claim 1, wherein a reference pit for generating a reference signal is formed at one location on the focus servo track.