JPH07324946A - Movement-amount detection apparatus - Google Patents

Abstract

PURPOSE:To provide a movement-amount detection apparatus in which the interval between a magnescale and a magnetic sensor is set surely even when the magnetization pitch of the magnescale is very small, which can obtain a stable position signal and whose structure is simple. CONSTITUTION:A magnetic encoder detects the movement amount of a stage 1 which is installed so as to be freely movable with reference to a fixation stand 10. The magnetic encoder is provided with a magnet 6 which is installed on the stage 1 and in which a magnescale 7 at a very small pitch has been magnetized and with a magnetic sensor 8 which is installed on the side of the fixation stand 10 in such a way that its detection face is energized to the magnet 6. A fluororesin film in a uniform thickness is baked and painted on the face of the magnescale 7 for the magnet 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving amount detecting device, and more particularly, to a moving amount detecting device for detecting the moving amount of a moving member provided movably with respect to a fixed member.

[0002]

2. Description of the Related Art As a device for detecting the amount of movement of a moving member, a magnetic encoder disclosed in Japanese Patent Laid-Open No. 62-157522 discloses a magnetic scale magnetized at a fine pitch on the surface and the movement of the magnetic scale. A magnetic encoder using a magnetic sensor for detecting a magnetic field, wherein the distance between the magnetic scale and the magnetic sensor is set by a flexible thin film body.

Usually, in this type of magnetic encoder,
The distance between the magnetic scale and the magnetic sensor is appropriately set to about half the magnetizing pitch distance of the magnetic scale. For example, when the magnetic pitch of the magnetic scale is 100 μm or less, in the above-mentioned conventional magnetic encoder, the thickness of the thin film body is 50 μm or less, which is very thin. And, by sandwiching this very thin thin film body, the distance between the magnetic scale and the magnetic sensor is maintained, and
The flexibility of the thin film body is used to urge the magnetic sensor to the magnetic scale.

In the magnetic encoder disclosed in Japanese Utility Model Laid-Open No. 2-97617, a magnetic sensor is incorporated in a holder made of metal or resin, and a protruding protrusion of the holder is brought into contact with a magnetic scale to make it magnetic. It has a structure in which a space is provided between the sensor and the magnetic scale.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The magnetic encoder disclosed in Japanese Patent No. 57522 has the following problems. First, holding the magnetic sensor becomes uncertain because the thin film body is very thin. Also, when the sensor installation is completed at the time of assembly, the magnetic sensor or the thin film body only lightly touches other members,
Problems such as deformation, bending, and cracking of the thin film body have occurred.

Further, by utilizing the flexibility of the thin film body,
Due to the structure in which the magnetic sensor is brought into contact with the magnetic scale, sufficient pressing cannot be obtained when the thin film body becomes very thin, and the magnetic sensor and the thin film body do not reliably adhere to the magnetic scale. Therefore, there is a problem that a reliable signal cannot be obtained and a position detection error occurs. In addition, since the thin film body is made of synthetic resin film, its durability against environmental changes such as temperature change is weak, and the thin synthetic resin film may be deformed under high temperature conditions, and the synthetic resin film may be deformed under low temperature conditions. There are problems that the film is cured and the contact state is changed, and the film is easily cracked.

Regarding the magnetic encoder disclosed in the above-mentioned Japanese Utility Model Laid-Open No. 2-97617, normally, in this type of magnetic encoder, the allowable range of the interval between the magnetic scale and the magnetic sensor is about ± 10% of the interval. For example, in the case of a minute one having an interval of about 50 μm (micron), the allowable range is 5 μm, which is very narrow.

In the above magnetic encoder, the following three factors are involved in determining the distance between the magnetic scale and the magnetic sensor. That is, the three factors of the accuracy of the thickness of the magnetic sensor, the dimensional accuracy from the bonding surface of the magnetic scale to the tip of the holder protrusion, and the accuracy of the thickness of the adhesive when bonding the magnetic scale and the holder are related. There is.

If the magnetic pitch of the magnetic scale is wide and the distance between the magnetic scale and the magnetic sensor is wide, all of these factors are within the allowable range. However, in the case where the magnetic pitch of the magnetic scale is narrow, and the distance between the magnetic scale and the magnetic sensor is narrow, it is difficult to keep the distance within the allowable range because of the dimensional accuracy of the holder in the structure of the conventional device. However, there is a possibility that a problem may occur such that the output of the signal becomes small or no output is obtained.

The present invention has been made to solve the above-mentioned problems, and even when the magnetizing pitch of the magnetic scale is extremely small, the magnetic scale and the magnetic sensor can be reliably spaced and stable. It is an object of the present invention to provide a movement amount detection device that can obtain a specified position signal.

[0011]

A movement amount detecting device of the present invention is a movement amount detecting device for detecting a movement amount of a moving member movably provided with respect to a fixed member,
A magnet provided with either the fixed member or the moving member and magnetized with a fine-pitch magnetic scale, and the other of the fixed member and the moving member has a detection surface biased against the magnet. And a magnetic sensor provided so as to provide a film having a uniform film thickness on at least one of the magnetic scale surface of the magnet and the detection surface of the magnetic sensor. The magnet on which the magnetic scale is magnetized and the magnetic sensor are in contact with each other via the coating film having the uniform film thickness and slide to detect the amount of movement.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Before giving a detailed description of an embodiment of the present invention, an outline of the embodiment will be described. In the magnetic encoder that is the movement amount detection device of the embodiment of the present invention, the surface of the magnetic scale or the sensor surface of the magnetic sensor is coated with a uniform thickness to ensure the magnetic scale and the magnetic sensor. The distance is set so that a stable position signal can be obtained.

The above coating treatment can be performed with a thickness of several tens of microns, and the variation in thickness is very small. Therefore, the magnetic scale or the magnetic sensor is subjected to coating treatment and both are energized. When they are brought into contact with each other, the distance between the magnetic scale and the magnetic sensor can be surely made to be equal to the thickness of the coating, and the variation in the thickness of the coating is small, so that a stable signal can be output.

Since the above-mentioned structure is adopted, it is only the thickness of the coating that determines the distance between the magnetic scale and the magnetic sensor, and the dimensional error of a plurality of parts, which has been a problem in the past, and the adhesive. It is possible to minimize the effect on output due to variations in thickness. In addition, since it is a film that is completely adhered to the surface of the magnetic scale or the surface of the magnetic sensor, the distance between the magnetic scale and the magnetic sensor may be changed by some external force, or the energized state may change due to temperature changes. Absent.

Therefore, according to the magnetic encoder of the embodiment of the present invention, the distance between the magnetic scale and the magnetic sensor can be made very accurately constant, especially when the distance between the magnetic scale and the magnetic sensor is smaller than 50 microns. It can be maintained and a stable position signal can be obtained.

FIG. 1 is a diagram showing the periphery of a stage of a robot which is movable in two axial directions to which a magnetic encoder which is a movement amount detecting apparatus according to a first embodiment of the present invention is applied. The stage 1 which is a moving member of the robot is movable in the left-right direction in FIG. 1, and is mounted on a fixed base 10 which is a fixed member via a roller 2 fixed on the stage 1 side.

The motor 3 is a drive source for moving the stage 1. When the male feed screw 4 fixed to the output shaft of the motor 3 rotates, the motor 3 is screwed into the feed screw 4 and the lower part of the stage 1 is rotated. Female screw 5 fixed to stage 1
Move to the left and right with.

The magnetic encoder of this embodiment is a device for detecting the amount of movement of the stage 1, and is mainly composed of a magnet 6 magnetized with a magnetic scale 7 and a magnetic sensor 8 as will be described later. It The magnet 6 is a magnet having a fine pitch magnetic scale 7 fixed on the stage 1 magnetized in the longitudinal direction, and is fixed in a state in which the longitudinal direction is aligned with the moving direction of the stage 1.

The magnetic sensor 8 is made of a glass substrate on which a magnetoresistive element is vapor-deposited, and its detection surface is in contact with the magnet 6 by the urging force of a spring (not shown). Further, the magnetic sensor 8 has a flexible substrate 8a fixed from its end and connected to a predetermined electric circuit. The magnetic sensor 8 is fixed on the fixed base 10 side and does not move together with the stage 1.

FIG. 2 is a cross-sectional view around the magnet 6a and the magnetic sensor 8 as seen from the moving direction of the stage 1. On the surface of the magnet 6a to which the magnetic scale 7 is magnetized, a fluororesin coating film 9 having a uniform film thickness is baked and coated with a uniform thickness. The detection surface 8b of the magnetic sensor 8 is in contact with the upper surface thereof. The baking-applied fluororesin coating 9 has a very small coefficient of friction on the surface, and therefore is excellent in sliding with other members and is also excellent in durability. Further, since it is a non-magnetic material, it does not adversely affect the magnetic field of the magnetic scale.

The operation of driving the stage of the robot constructed as described above and detecting the amount of movement thereof will be explained. When the motor 3 is driven to move the stage 1, the stage is fixed on the stage 1. The magnet 6 also moves with the stage 1, and the magnetic sensor 8 and the magnetic scale 7
The contact surface of the magnet 6 magnetized by is relatively slid,
The output of the sensor 8 detects the amount of movement of the stage 1.

At the time of detecting the amount of movement, the distance between the detection surface of the magnetic sensor 8 and the magnet surface is set to an appropriate value depending on the thickness of the fluororesin coating film 9. It is possible to prevent the distance between the detection surface of the magnetic sensor and the magnetic scale from deviating from the design value due to integration of variations in dimensions, variations in adhesive thickness, and the like. In addition, there is no problem with uncertainties in holding the sensor, reliability deterioration due to temperature change, etc., which has occurred in the method of securing a gap by sandwiching the thin film body applied to the conventional device, and stable as the output of the magnetic sensor. You get what you did. Further, the structure of the magnetic encoder itself is also advantageous in terms of cost because it is a simple structure in which the surface of the magnet 6 is simply coated with the fluororesin film 9 by baking.

Next, an interchangeable lens barrel of a camera to which a magnetic encoder, which is a movement amount detecting device according to a second embodiment of the present invention, is applied will be described. FIG. 3 shows an interchangeable lens barrel of the camera. This interchangeable lens barrel has a built-in focusing drive mechanism that determines whether the camera body is in focus or not, and when it is out of focus, calculates the amount of lens extension until focus is achieved. , The lens is moved to the in-focus position while detecting the position of the lens. The lens barrel has a magnetic encoder that is a mechanism for detecting the lens extension position.

The structure of the lens barrel will be described. A cam ring 22, which is a moving member, is rotatably fitted to the outer periphery of a fixed frame 21, which is a fixed member. A movable frame 23 is fitted on the inner periphery of the fixed frame 21 so as to be movable in the optical axis O direction. The fixed frame 21 is formed with a straight cam groove 2la, and the cam ring 22 is formed with an oblique cam groove 22a. A roller 24 is inserted perpendicularly to the optical axis O through both cam grooves 21a and 22a, a roller shaft 25 is inserted therein, and is screwed and fixed to the moving frame 23. A lens frame 27 is fixedly fitted inside the moving frame 23 with a screw, and the lens 2 is attached to the lens frame 27.
8 are supported.

A ring-shaped plastic magnet 29 is fixedly adhered to the rear end of the cam ring 22. The plastic magnet 29 is made of nylon (polyamide resin) 12 and magnetic powder, and a magnetic scale 30 having a fine pitch is magnetized in the circumferential direction on the outer peripheral surface thereof.

The pitch of the magnetic scale 30 is 84 μm (microns) in the magnetic encoder of this embodiment.
The N and S poles are alternately magnetized as shown in FIG. Further, on the surface of the plastic magnet 29 on which the magnetic scale 30 is magnetized, a fluororesin film 31 is baked and coated with a uniform film thickness over the entire circumference (see FIG. 10). The fluororesin coating 31 has a very small coefficient of friction on the surface, and is excellent in sliding with other members.
It also has excellent durability. Further, since it is a non-magnetic material, it does not adversely affect the magnetic field of the magnetic scale 30. The film thickness of the fluororesin coating 31 is about 20 μm.
However, it is baked and coated with an accuracy of plus or minus 5 μm.

A magnetic sensor head portion 40, on which a magnetic sensor is mounted, is fixed to the rear flange of the fixed frame 21. FIG. 5 shows an exploded perspective view of the magnetic sensor head portion 40. In the mounting magnetic sensor holder 32 of the magnetic sensor head portion 40, a positioning plate 34 for positioning the magnetic sensor 33 is attached by a fixing screw to a screw hole 32b of the holder.
It is fixed in.

The positioning plate 34 is made of metal or
The magnetic sensor 33 is made of a plate material such as plastic.
The positioning portion 34a for positioning the magnetic sensor 33 and the relief portion 34b for escaping the solder swell when the magnetic sensor 33 and the flexible printed circuit board 37 are soldered are formed by press working or molding. The magnetic sensor 33 to which the flexible printed circuit board 37 is soldered is inserted into the positioning portion 34a of the positioning plate 34.

A pressing coil spring 35 is inserted into the screw hole 32a provided in the magnetic sensor holder 32,
By tightening the coil spring fixing screw 36, the tip portion 36a of the fixing screw 36 is loosely fitted to the inner diameter side of the pressing coil panel 35, and the abutting portion 36 of the fixing screw 36.
b contacts the end of the coil spring 35. The contact part 3
Due to the urging force of the coil spring 35 pressed by 6b, the magnetic sensor 33 is moved to the plastic magnet 2 described above.
The magnetic sensor 33 is biased to the 9 side, and slidably contacts the fluororesin film 31 of the plastic magnet 29 through the epoxy protective film 33b on the surface thereof.

The magnetic sensor 33 has a detection surface in which a magnetoresistive element 33a is vapor-deposited on a ceramic substrate. FIG. 6A shows an enlarged surface of the magnetoresistive element detection surface of the magnetic sensor 33. It is a figure. The magnetoresistive element 33
An epoxy protective film 33b for protection is further formed on the surface of a. The epoxy protective film 33b has a film thickness of about 20 microns and is formed by screen printing. The four corners of the magnetic sensor 33 are chamfered by the through holes 33c.

FIG. 6B shows an enlarged view of the back surface of the magnetic sensor 33. As described above, the four corners of the magnetic sensor 33 are cut through holes 33c, which are used for soldering from the magnetoresistive element 33a on the front surface of FIG. 6A to the back surface of FIG. 6B. The pattern 33d is electrically connected. The flexible printed circuit board 37 is soldered to the back surface of the magnetic sensor 33.

FIG. 7 is a diagram showing a soldered state of the magnetic sensor 33 and the flexible printed board 37. Also,
FIG. 8 is a view on arrow D of FIG. 7. As shown in FIGS. 7 and 8, the through holes 33c at the four corners of the magnetic sensor 33 shown in FIG. 6B, the soldering pattern 33d on the rear surface thereof, and the conductive pattern 37a of the flexible printed circuit board 37. And become conductive by soldering and are fixed.

FIG. 9 is a view showing the state in which the magnetic sensor 33 is inserted and fitted in the positioning plate 34 as seen from the direction C in FIG. According to this figure, the positioning portion 34a is the magnetic sensor 3
It can be seen that the relief portion 34b is positioned on the side surface other than the through hole 33c and the escape portion 34b avoids the solder rising portion. If the width dimension of the positioning portion 34a is slightly press-fitted, the subsequent assembling work can be performed more smoothly. When the positioning plate 34 is a metal plate, the positioning 34a on the side where the magnetic sensor 33 is inserted is used.
The magnetic sensor 33 can be smoothly inserted by setting the edge of the above as the sagging side at the time of press working.

FIG. 10 is a view of the magnetic sensor head portion 40 viewed from the optical axis O direction. As shown in the figure, the magnetic sensor 33 is urged by the pressing coil panel 35, and is connected to the plastic magnet 29 via the epoxy protective film 33b on the sensor detection surface and the fluororesin coating 31 of the plastic magnet 29. Abut. Further, the front, rear, left and right directions of the magnetic sensor 33 are reliably positioned by the positioning plate 34.

The magnetizing pitch of the magnetic scale 30 is 84 μm as described above. Normally, in the magnetic encoder of this type, the distance between the magnetic resistance element 33a surface of the magnetic sensor 33 and the magnetic scale 30 is small. , It should be set to about 50% of the above magnetizing pitch. In this case,
The interval is set to about 40 μm. In this embodiment, as shown in the sectional view of the contact portion between the magnetic sensor and the magnetic scale in FIG. 11, 20 μm of 40 μm is given by the epoxy film 33b screen-printed on the surface of the magnetic sensor 33,
The remaining 20 μm is provided by the fluororesin coating 31 baked on the surface of the plastic magnet 29.

Next, the operation of detecting the amount of extension of the lens by the magnetic encoder of the present embodiment constructed as described above will be explained. When the camera body side determines that the lens is out of focus and the lens extension amount up to the focus is calculated, the cam ring 2 is driven by a lens extension motor (not shown).
2 is rotationally driven. When the cam ring 22 rotates, the cam shaft 22 penetrates the cam groove 22a on the cam ring 22 and the straight cam groove 21a on the fixed frame 21, and the roller shaft 25 and the roller 24 fixed to the moving frame 23 move the straight cam groove 21a on the fixed frame 21.
Move along. This movement causes the moving frame 23 to move to the optical axis O.
It is paid out in the direction. Then, the lens frame 27 fixed to the inner circumference of the moving frame 3 and the lens 28 are also extended in the optical axis O direction (see FIG. 3).

At this time, due to the rotation of the cam ring 22, the plastic magnet 29 fixed to the rear end of the cam ring also rotates, and the magnetic scale 30 magnetized on its surface also rotates. At this time, the magnetic sensor head 40
Since the magnetic sensor 33 is biased toward the plastic magnet 29 by the pressing coil spring 35, the surface of the plastic magnet 29 is coated with the fluororesin film 31, and the fluororesin coating 31 is screen-printed on the surface of the magnetic sensor 33. The plastic magnet 29 rotates by sliding while abutting on the coating 33b.

During the rotating operation, the distance between the magnetic scale 30 magnetized on the plastic magnet 29 and the magnetic sensor 33 is always the film thickness of the fluorine resin coating 31 baked on the plastic magnet 29 and the magnetic sensor. Three
Epoxy resin coating 33 screen-printed on the surface of 3
Accurately maintained by the total thickness of b.

Then, a stable magnetic field change is always applied to the magnetoresistive element 33a, and the magnetoresistive element 3
The resistance value of 3a changes with the change of this magnetic field, and a stable electric signal can be obtained. This electric signal is sent to a predetermined arithmetic circuit via the flexible printed circuit board 37. Based on the highly accurate electric movement position signal obtained in this way, the lens 28 is extended by a predetermined amount until focusing and stops at the focusing position.

As described above, in the lens barrel having the built-in magnetic encoder of this embodiment, the dimension of a plurality of parts or the variation of the thickness of the adhesive, which has been a problem in the past. Does not deviate from the design value of the distance between the detection surface of the magnetic sensor and the magnetic scale caused by the integration of In addition, problems such as uncertainties in holding the sensor and a decrease in reliability due to temperature changes that occur in the case of a structure in which a conventional thin film body is sandwiched are eliminated.

Further, the relative movement between the magnetic sensor 33 and the plastic magnet 29 is given an appropriate biasing force between them by the pressing coil spring 35, and further through the epoxy resin coating 33b and the fluororesin coating 31. Since it slides, it slides stably with a minimum frictional force, and is driven in a preferable state in terms of wear resistance.

In the above lens barrel, when the inner diameter of the cam ring 22 and the outer diameter of the fixed frame 21 have a clearance for rotational sliding, the cam ring 2
Even if 2 moves slightly in the radial direction with respect to the fixed frame 21, the magnetic sensor 33 is always urged by the plastic magnet 29 by the urging force of the pressing coil spring 35, and stably abuts. Therefore, the magnetic sensor 33 and the magnetic scale 30 of the magnet 29 are always maintained at a constant interval.

When the cam ring 22 and the plastic magnet 29 rotate, some frictional force is generated in the circumferential direction between the fluororesin coating 31 and the epoxy resin coating 33b, but the magnetic sensor 33 is moved by the positioning plate 34. Since the magnetic sensor 33 is positioned, the magnetic sensor 33 does not shift in the circumferential direction due to the frictional force and output an erroneous signal.

FIG. 12 shows the magnetic encoder of the second embodiment.
FIG. 11 is a sectional view of a contact portion between a magnetic scale and a magnetic sensor portion in a modified example of the da. In this modification, a fluororesin coating 43e is applied by baking onto the upper surface of the epoxy resin coating 43b for protecting the magnetoresistive element on the magnetic sensor 43. On the other hand, the plastic magnet 29 is characterized by not being coated with a fluororesin film. The other structure is the same as that of the second embodiment.

In this modification, as shown in FIG. 12, both the epoxy resin film 43b and the fluororesin film 43e on the surface of the magnetic sensor 43 have a thickness of about 20 μm.
Thus, the distance between the magnetized surface of the magnetic scale 30 on the surface of the plastic magnet 29 and the detection surface of the magnetic sensor 43 is set to about 40 μm. This is suitable when the magnetizing pitch of the magnetic scale is around 80 microns, as in the case of the second embodiment.

FIG. 13 shows a magnetic sensor plate 48 at the previous stage of cutting as the magnetic sensor 43 unit in this modification.
FIG. In the manufacturing process of the magnetic sensor 43, the magnetoresistive element 43a is vapor-deposited on the ceramic substrate in the state of the magnetic sensor plate 48 which is an assembly of a plurality of magnetic sensors 43 at first as shown in FIG. The film 43b is screen-printed over the entire surface.

After that, the chips are cut into the chip shapes shown in FIGS. 6A and 6B. Prior to the cutting process, the magnetic sensor plates 48 are attached to the respective magnetic sensors 43. Then, the surface of the fluororesin film 43e is baked and coated at once. This is more advantageous in terms of workability and cost than painting after cutting.

At this time, since there is a soldering pattern on the back surface, the fluororesin coating 33e is prevented from adhering. Since the fluororesin film 33e is non-conductive, even if it adheres to the through hole 43c portion other than the solder pattern, the patterns are electrically connected,
Besides, it does not adversely affect the performance of the sensor.

As described above, the epoxy resin coating 43b of this modification is processed, and the fluororesin coating 4 is further applied to the upper surface.
When the magnetic sensor 43 obtained by baking and painting 3e is assembled to the magnetic head portion, and the sensor 43 of the magnetic head portion is urged and brought into contact with the plastic magnet 29 side as described above, if the cam ring 22 rotates. A stable electric position signal can be obtained. This variant has
This is suitable when a fluororesin coating or the like cannot be attached to the plastic magnet 29 side.

In the magnetic encoder of the second embodiment described above and its modification, both of the magnetic sensors 3 are used.
Although the magnetoresistive elements 3 and 43 are formed by vapor-depositing the magnetoresistive elements on the ceramic substrate, another substrate, for example, a glass substrate on which the magnetoresistive elements are vapor-deposited may be used as shown in the first embodiment. Absent. Further, the magnetic sensor itself may be a magnetic sensor utilizing the Hall effect.

Further, the material of the plastic magnet 29 is not limited to the above-mentioned nylon 12, but may be PPS (polyphenylene sulfide resin) having a high heat resistance, a metal magnet, a magnetic tape, or a coating of a magnetic material. May be. Also, the shape of these magnets is related to the movement of the cam ring, but it is not limited to a ring shape, but may be an arc shape if necessary, and a linear plate shape, rotation and rectilinear motion. It may have a spiral shape corresponding to the inclusion.

In the present embodiment, the cam ring 22 as the moving member performs only the rotational movement with respect to the fixed frame, but in addition to the moving member performing the linear movement, the linear movement and the rotational movement. Also, the magnetic encoder of the present invention is applicable, and in those cases, the shape of the corresponding plastic magnet 29 is selected as described above.

Further, a fluororesin coating film and an epoxy resin film for providing a space between the surfaces of the magnetic sensors 33 and 43 and the surface of the plastic magnet 29 are also excellent in slidability and durability, As long as the magnetic sensor does not impair the performance of the magnetic sensor, such as magnetism and non-conductivity, various types can be applied to the magnetic encoder of the present invention. For example, a coating film of a thermosetting resin such as polyimide resin or phenol resin may be used.

When the magnetic pitch of the magnetic scale 30 is rough and the distance between the magnetic sensor detection surface and the magnetic scale is wide,
The coating layer for providing the gap may be formed by outsert molding the above epoxy resin or thermosetting resin on a metal magnet.

Regarding the film thickness, a proper film thickness may be taken according to the magnetizing pitch, and in some cases, multiple coatings may be applied. The biasing structure of the magnetic head portion is also constituted by, for example, a leaf spring instead of the pressing coil spring 35, or the magnetic sensor holder 32 and the positioning plate 34 are integrated.
Various modifications are possible.

(Supplementary Note) Based on the embodiment described above, it is possible to propose a movement amount detecting device having the following configuration. That is, (1) In a movement amount detection device that detects the movement amount of a moving member that is provided so as to be movable with respect to a fixed member, a magnetic scale with a fine pitch is provided on either one of the fixed member and the moving member. The magnetic scale of the magnet includes a magnetized magnet, and a magnetic sensor having a detection surface biased to the magnet on the other side of the fixed member and the moving member. A movement amount detecting device, wherein at least one of the surface and the detection surface of the magnetic sensor is subjected to a coating treatment with a uniform film thickness.

(2) In the above Supplementary Note (1), the moving member makes a rotational movement with respect to the fixed member. (3) In the above-mentioned supplementary note (1), the moving member moves linearly with respect to the fixed member. (4) In the above supplementary note (1), the moving member performs a combined motion of the rectilinear motion and the rotary motion with respect to the fixed member. (5) In the above supplementary note (1), the magnet is formed in a plate shape. (6) In the above supplementary note (1), the magnet is formed in a ring shape. (7) In the above supplementary note (1), the magnet is formed in an arc shape which is a part of the ring shape. (8) In the above supplementary note (1), the magnet is formed in a spiral shape.

(9) The above supplementary notes (1), (6),
In any one of (7) and (8), the fixed member and the movable member are formed in a tubular frame.

(10) In the above-mentioned Supplementary Note (9), the movable frame rotates about the axis with respect to the fixed member. (11) In Addition (9) above, the movable frame rotates in the axial direction with respect to the fixed member. (12) The above supplementary notes (9), (10), and (1
In any one of 1), the moving frame is fitted to the outer circumference or the inner circumference of the fixed member.

(13) In the above supplementary note (1), the magnetic sensor is a magnetoresistive element. (14) In the above supplementary note (1), the magnetic sensor is a Hall element. (15) In the above supplementary note (1), the magnetic sensor is a ceramic substrate or a glass substrate on which a magnetoresistive element is vapor-deposited. (16) In the above supplementary note (1), the magnetic sensor is a glass substrate on which a magnetoresistive element is vapor-deposited. (17) In the above Supplementary Note (1), the coated surface is non-conductive. (18) In the above Supplementary Note (1), the coated surface is non-magnetic. (19) In the above supplementary note (1), the coating treatment is performed using a material having low surface friction. (20) In the above supplementary note (1), the coating treatment is performed using a material having high wear resistance. (21) In the above supplementary note (1), the coated surface is applied to the magnet surface by baking coating. (22) In the above-mentioned supplementary note (1), the coated surface is formed on the surface of the magnet by molding. (23) In the above-mentioned supplementary note (1), the coating surface is formed of a thermosetting resin coating. (24) In the above Supplementary Note (1), the treated surface is formed of a fluororesin coating. (25) In the above Supplementary Note (1), the surface to be coated is formed with an epoxy resin coating. (26) In the above supplementary note (1), one of the magnetic scale surface of the magnet and the detection surface of the magnetic sensor is subjected to a multi-layer coating treatment with a uniform film thickness. (27) In Addition (1) above, the film-treated surface is a fluororesin film and is formed on the magnetic scale surface of the magnet. (28) In Addition (1) above, the coating surface is an epoxy resin coating and is formed on the detection surface of the magnetic sensor. (29) In the above-mentioned supplementary note (1), the coating surface is a fluororesin coating or an epoxy resin coating, both of which are formed on the detection surface of the magnetic sensor.

[0061]

According to the movement amount detecting device of the present invention, at least one of the magnetic scale surface of the magnet and the detection surface of the magnetic sensor is coated with a uniform film thickness, and the magnetic scale of the magnet is inserted through the coating film. Since the surface and the detection surface of the magnetic sensor are brought into contact with each other, the detection surface of the magnetic sensor has been a problem in the past, and the detection surface of the magnetic sensor is calculated by integrating the dispersion of the dimensions of a plurality of parts or the dispersion of the thickness of the adhesive. The magnetic scale spacing does not deviate from the design value.

Further, it is possible to solve the problems such as uncertainness of sensor holding and the occurrence of an error due to temperature change in the case of a conventional device in which a thin film body is sandwiched in order to keep this interval constant. Then, the distance between the magnetic sensor and the magnetic scale is always kept constant, and a stable electric position signal can be output.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the periphery of a stage of a robot to which a magnetic encoder that is a movement amount detection device according to a first embodiment of the present invention is applied.

FIG. 2 is a cross-sectional view of a magnet and a magnetic sensor seen from the stage moving direction of the magnetic encoder of the first embodiment of FIG.

FIG. 3 is a perspective view of an interchangeable lens barrel of a camera to which a magnetic encoder that is a movement amount detecting device according to a second embodiment of the present invention is applied.

FIG. 4 is an enlarged view showing a magnetized state of a magnetic scale applied to the magnetic encoder of the second embodiment shown in FIG.

5 is an exploded perspective view of a magnetic sensor head portion applied to the magnetic encoder of the second embodiment of FIG.

6A and 6B are enlarged views of the front surface and the back surface of the detection surface of the magnetic sensor of the magnetic sensor head portion of FIG. 5, and FIG.
The front surface is shown, and FIG. 6B shows the back surface.

FIG. 7 is a diagram showing a soldered state of the magnetic sensor of the magnetic sensor head portion of FIG. 5 and the flexible printed board.

FIG. 8 is a view on arrow D of FIG. 7.

9 is a view of the magnetic sensor head portion of FIG. 5 in which a magnetic sensor is inserted and fitted into a positioning plate, as viewed from the direction C of FIG. 5;

10 is a view of the magnetic sensor head portion of FIG. 5 as viewed from the optical axis direction.

11 is a sectional view of the contact portion between the magnetic sensor and the magnetic scale in the magnetic encoder of the second embodiment of FIG.

FIG. 12 is a sectional view of a contact portion between a magnetic scale and a magnetic sensor portion in a modification of the magnetic encoder of the second embodiment shown in FIG.

FIG. 13 is a perspective view of a magnetic sensor plate before cutting the magnetic sensor in the magnetic encoder of the modified example of FIG. 12;

[Explanation of symbols]

 1 …………………… Stage (moving member) 6 ……………… Magnet 7,30 ……………… Magnetic scale 8,33 ……………… Magnetic sensor 9,31 ………… Fluororesin coating (coating) 10 …………………… Fixing stand (fixing member) 21 ………………… Fixing frame (fixing member) 22 …………………… Cam ring (moving member) 29 …… …………… Plastic magnet (magnet)

Claims (1)

[Claims] 1. A movement amount detection device for detecting a movement amount of a moving member provided movably with respect to a fixed member, wherein a magnetic scale having a fine pitch is provided on either one of the fixed member and the moving member. A magnetized magnet and a magnetic sensor having a detection surface biased to the magnet on the other side of the fixed member and the moving member, and a magnetic scale of the magnet. A movement amount detecting device, wherein at least one of the surface and the detection surface of the magnetic sensor is subjected to a coating treatment with a uniform film thickness.