JPH07239203A - Linear encoder and detection head and storage media constituting it and electronic equipment with it - Google Patents

Abstract

PURPOSE:To increase output and stabilize characteristics with a simple configuration by spanning a band-like storage media, with its one side formed with a detection pattern, under a specified tension, so that an opposite part of a detection element of detection head slides on the other surface of storage media. CONSTITUTION:A band-like recording media (scale part) 1 is constituted with a non-magnetic face 1d and magnetic face 1c on which a position detection pattern is formed. The both ends 1a and 1b of the media 1 are fixed with holing members 2-1 and 2-2, so that tension F is given. A detection head 3 is provided with a magnet-resistance effect element 4 and a slider 5, and moves along a straight line X away from a holing extension line A of the media 1 by distance L. Thus, the media 1 is always energized toward a base pedestal 5a for tension. The shape of sliding part 5c of the slider 5 is formed flat so that the part facing an element 4 is away from it by the same distance, thus, constant gap is held at always between the element 4 and the magnetic face 1c. Increase in output and stabilization in characteristic are thus obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear encoder, and more particularly to a linear encoder suitable for use in an electronic device such as a serial type recording device for moving a carriage carrying a head for recording. Is.

[0002]

2. Description of the Related Art As an example of a conventional linear encoder (hereinafter referred to as an encoder), there is a magnetic encoder used in a recording device as disclosed in Japanese Patent Laid-Open No. 4-339670. This encoder is Fe-Cr-C
o A magnet is used as a rod and a magnetic pole pattern is formed on the surface to form a scale portion (magnetic medium). While maintaining a constant gap between the scale portion and the head for detecting the magnetic pole pattern, the entire outer peripheral surface of the rod-shaped magnetic medium is used. The structure is provided with a slider that slides as a guide part.

Another structure is disclosed in Japanese Patent Laid-Open No. 62-11.
Like an encoder disclosed in 2012, using a magnetic tape for audio or video as a magnetic medium,
A method has also been proposed in which the detection head and the magnetic medium face each other in a plane.

[0004]

However, in the case of the former encoder, since the detection head is plate-shaped and the magnetic medium is rod-shaped, the gap between the detection head and the magnetic medium is determined by the proximity of the two members. It is the smallest, and gradually increases as it gets away from this point. Therefore, the spacing loss also becomes large, and only about half of the output can be obtained as compared with the case where the plate-shaped recording medium and the plate-shaped detection head are arranged to face each other.

Further, considering the manufacture of an elongated magnetic medium material having a diameter of about 1 mm, it is the current situation that expensive Fe-Cu-Co magnets have to be used because they are limited to magnets that can be pulled out. Although this magnet can be pulled out, it has a problem that the manufacturing process is complicated and long.
Furthermore, since the holding force is as small as 600 Oe, the magnetic pole pattern is easily erased, and the reading error of the detection head is likely to occur.

Further, since the magnetic tape is used in the latter type of encoder, the durability of the magnetic medium becomes a problem in addition to maintaining the gap between the detection head and the magnetic medium. Generally, in order to keep the gap constant, a method is used in which the head to be detected and the magnetic layer of the magnetic medium are brought into contact with each other and slid. In such a case, the magnetic layer is scraped by an organic material such as a magnetic tape, the scraped powder causes an error, and finally the magnetic layer peels off, making detection impossible.

In view of the above problems, it is an object of the present invention to provide a linear encoder which has a simple structure and maintains a constant gap between the detection head and the scale portion.

Further, it is an object of the present invention to provide a detection head for forming this linear encoder and a recording medium.

It is another object of the present invention to provide an electronic device equipped with the above linear encoder.

[0010]

SUMMARY OF THE INVENTION In order to solve the problems conventionally encountered and to achieve the above object, the linear encoder according to the present invention has a detection pattern formed on one surface and can be stretched by a predetermined tension. A strip-shaped scale portion, and a detection head that holds a detection element that detects the detection pattern, and that has a sliding portion that slides on the other surface of the scale portion is formed at a facing portion of the detection element. Composed.

Further, the sliding portion is formed with a flat portion and an inclined portion continuous with the flat portion. A recess is formed in the flat portion, and the inclined portion is formed at an angle larger than an incident angle of the stretched scale portion to the detection head.

Further, the sliding portion is provided with a guide portion for regulating and guiding the position of the scale portion in the width direction.

Further, the detection head according to the present invention holds a detection element for detecting a detection pattern, and is formed by forming a flat portion and an inclined portion continuous with the flat portion at a portion facing the detection element. It

Further, the detection head is composed of polyphenylene sulfide.

A recess is formed in the flat portion.

Further, the recording medium according to the present invention comprises a belt-shaped non-magnetic base material, a magnetic layer formed on one surface of the base material, and a magnetic layer non-formed portion having a predetermined width at an end portion in the width direction. Is formed and formed.

Further, the non-magnetic base material is composed of polyethylene terephthalate.

A position detection pattern is formed on the magnetic layer.

Further, the electronic apparatus according to the present invention holds a band-shaped scale portion having a detection pattern formed on one surface and both ends of the scale portion so as to stretch the belt-shaped scale portion with a predetermined tension. Two holding parts, and a detection head that holds a detection element that detects the detection pattern, and a sliding part that slides on the other surface of the scale part is formed in a facing part of the detection element, The detection head is
While being engaged with the scale portion, the scale portion is provided so as to be movable at a position separated from the virtual straight line connecting the two holding portions by a predetermined distance.

Further, the recording head and a carriage for moving the recording head are provided, and the detection head is provided on the carriage.

Further, the sliding portion is formed by forming a flat portion and an inclined portion continuous with the flat portion. Further, a recess is formed in the flat portion. The inclined portion is formed at an angle larger than the angle of incidence of the stretched scale portion on the detection head.

Further, the sliding portion is provided with a guide portion for regulating and guiding the position of the scale portion in the width direction. Further, the detection head is arranged such that the guide portion is on the lower side in the vertical direction.

[0023]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining the outline of the embodiment of the present invention. Recording medium as a scale unit (hereinafter,
Both ends 1a and 1b of the medium 1 are holding members 2-1 and 2-
They are respectively fixed by 2, and both ends 1a and 1b are applied with tension F and fixed to a machine (not shown). The detection head 3 includes a magnetoresistive effect element (hereinafter, MR element) 4 and a slider 5 that holds the MR element 4 from the magnetic surface 1c of the medium 1 with a constant gap. The slider 5 is composed of a base 5a and an element holder 5b. The base 5a is provided with a sliding portion 5c that contacts and slides on the non-magnetic surface 1d side of the medium 1. Element holder 5b
Is attached to the base 5a so as to hold the MR element 4 with a constant gap from the magnetic surface 1c.

Further, the detection head 3 moves on a straight line X indicated by an alternate long and short dash line which is separated from the holding extension line A of the medium 1 by a distance L in a right angle direction. Therefore, the medium 1 is the base 5
It is always urged in the direction of a and is in a bowed state. In this embodiment, the non-magnetic base material of the medium 1 is polyester, and a lubricating layer such as Teflon or Si is formed on the surface on the non-magnetic surface (sliding surface) side to improve slidability. . Also,
The slider 5 is made of a polyphenylene sulfide (PPS) material containing carbon in this embodiment because it is excellent in accuracy and wear resistance and is effectively made of a material that is not charged with static electricity. Further, in the present embodiment, the sliding portion 5c of the slider 5 is formed in a planar shape so that the portion facing the MR element 4 is equidistant from the MR element 4.
The magnetic surface 1c of the medium 1 holds a constant gap to stabilize the output. In addition, the MR element 4 of the sliding portion 5c
The medium 1 is formed with slopes on both sides that are larger than the incident angle of the medium 1 on the slider 5.
Are in contact with the corners 5e of the slider 5 so as not to wear.

In this embodiment, such an encoder was used by being attached to a recording device as shown in FIG.

In FIG. 2, a carriage 11 shown by a one-dot chain line has a recording head 12 of an ink jet system or the like mounted thereon and is slidably provided on a guide bar 13.
It is guided so as to reciprocate by a drive shaft 14 having a spiral groove formed on its outer peripheral surface. That is, the carriage 11 has an engagement portion (not shown) that engages with the spiral groove of the drive shaft 14, and when the drive shaft 14 is rotationally driven by a carriage drive motor as drive means (not shown), the engagement is performed. The part moves along the spiral groove of the drive shaft 4, and the carriage 11 moves.

The carriage 11 reciprocates along the platen 15 as shown by the double-headed arrow, and the recording head 12 is driven during this movement, with respect to the recording sheet 16 wound on the outer peripheral surface of the platen 15. To eject ink drops,
The dots D are recorded at a predetermined pitch P. Then, images or characters are recorded in a dot matrix pattern.

On the other hand, there is provided an encoder which detects the position of the carriage 11 and generates a synchronizing signal, which is composed of the medium 1 as the magnetic scale portion and the detection head 3 described above.

In the medium (magnetic scale portion) 1, N poles and S poles are alternately magnetized to have opposite polarities along the length direction at a pitch corresponding to the pitch P of the dots D. For the sake of convenience, the pitch P of the dots D, that is, the pitch of the magnetization is shown to be much larger than it actually is, and the actual pitch is 100 μm or less. Then, as shown in FIG. 1, the medium 1 is stretched while being held in the shape of an arch, and the holding members 2-1 and 2-2 are held.
(FIG. 1) is fixed to a main body frame of a recording device (not shown). This state will be described in more detail with reference to FIG.

In this embodiment, the length of the medium 1 is 400
mm and the holding member 2-1 and 2-2 at both ends of the medium 1
A tension F of 700 gf is applied to the detection head 3 and L =
It is set to be 0.5 mm so that a restoring force to the holding extension line A side of the medium 1 acts on the base 5a side of the slider 5. The larger the tension F and the position L of the detection head 3 from the holding extension line A, the easier the base 5a and the medium 1 are in close contact with each other, and the magnetic surface 1
Although the gap between c and the MR element 4 is stable, if the tension F is too large, the frictional resistance increases when the detection head 3 moves to the end portion of the medium 1, and the driving power for driving the detection head 3 is increased. Since it increases, it is necessary to apply an appropriate tension.

By carrying out the above-described embodiment, the gap between the MR element 4 and the magnetic surface 1c of the medium 1 can be kept constant at 30 μm, and the output is also increased by about twice as much as when the medium is a round bar. , The characteristics were stable. Further, in the durability test, no error occurred even after 2 million reciprocations, and the initial characteristics could be retained.

Further, the detection head 3 according to the magnetic field of the medium 1
The output signal of the (MR element 4) is the flexible printed board 1
9 and the flexible cable 20 to the control circuit board 21 of the recording apparatus, and the position of the carriage 11 is detected by the output signal of the detection head 3 in the control circuit. For such an encoder,
This will be described in more detail below.

As the medium 1 (FIGS. 1 and 2) to be the scale portion, a pre-bed card material having a large coercive force and good durability was used. This card material is widely used in the world and is easy to obtain. The non-magnetic substrate is made of polyester, more specifically polyethylene terephthalate (PET), and has a thickness of about 200 μm.
The non-magnetic surface 1d contacting the sliding portion 5c of the slider 5 shown in FIG. 1 has a Si-based coating material of about 3 μm.
Is coated with a thickness of. On the magnetic surface 1c side, Ba ferrite (particle size: 2 to 3 μm) is mixed as a magnetic layer with a urethane resin having high heat resistance and is coated to a thickness of about 15 μm. The magnetic substance has a coercive force of 2750 Oe and is oriented in the longitudinal direction of the medium 1. On the surface,
The non-magnetic surface 1d is coated with a Si-based coating material of the same type as the coating material with a thickness of about 3 μm.

More specifically, the slider 5 has a shape as shown in FIG. Here, FIG. 3A is a cross-sectional view of the slider 5, and FIG. 3B is AA in FIG.
A cross-sectional view and FIG. 3C show a BB cross-sectional view in FIG. In these figures, the medium 1 is shown by hatching, and the MR element 4 is shown by a chain line. The portion 4b protruding from the MR element 4 slider 5
Is an electrode forming portion for connecting the flexible printed board 19 (FIG. 2).

The material of the slider 5 is SiO ₂ filler for the purpose of improving wear resistance, and polyphenylene sulfide (PPS) to which carbon for slidability and charge removal is added. And this slider 5
As described above, the portion of the sliding portion 5c facing the MR element 4 is formed in a flat shape so as to be equidistant from the MR element 4, and the magnetic surface of the MR element 4 and the medium 1 is formed. 1 and 1 maintain a constant gap to stabilize the output.
Further, both sides of the portion facing the MR element 4 are formed with inclined surfaces larger than the incident angle of the medium 1 on the slider 5, so that the medium 1 does not slide on the corners of the slider 5 and wear. Has been done. In this embodiment, in order to make this effect more reliable, both sides of the portion facing the MR element 4 are formed in an arcuate cross section as shown in FIG. If is small,
It is also possible to form a plane having a small inclination angle with respect to the flat portion of the sliding portion 5c.

In addition, the recess 5 is formed in the substantially central portion of the sliding portion 5c.
d is formed to have a depth similar to the thickness of the medium 1. This is because the sliding portion 5c of the MR element 4, particularly the facing sliding portion 5c of the sensing pattern portion 4a, has a concave shape, and abrasion powder is contained between the sliding portion 5c of the slider 5 and the non-magnetic surface 1d of the medium 1. Even at this time, the abrasion powder is allowed to enter the concave portion 5d, and M
The gap between the sensing pattern portion 4a of the R element 4 and the magnetic surface 1c of the medium 1 is kept constant. In addition, medium 1
As shown in FIG. 3A, both ends of the concave portion 5d in the width direction are formed in an opening shape, and the abrasion powder entering the concave portion 5d can be discharged to the outside of the slider 5.

As shown in FIG. 3 (c), the base 5a
Are guide parts 5e, 5 that regulate the movement of the medium 1 in the width direction.
f is formed. The goals of this guide include: On the magnetic surface 1c side of the medium 1, a north pole and a south pole are alternately magnetized in a straight line over the entire width of the magnetic surface (magnetic layer) at a pitch of 70 μm and perpendicular to the longitudinal direction of the medium 1. On the other hand, the sensing pattern portion 4a of the MR element 4 is also 70 μm.
When the azimuth angle is the intersection angle between the magnetized line of the medium 1 and the line of the sensing pattern portion 4a, the azimuth angle is 0. If it is not close, the output will decrease. Therefore, the azimuth loss can be prevented by pressing the medium 1 against the guide portions 5e, 5e close to the sensing pattern portion 4a so that the guides at both ends align the magnetizing lines in the direction perpendicular to the longitudinal direction of the magnetic medium. It is possible. Since the surface of the medium 1 is arranged parallel to the vertical direction, it is preferable to arrange the slider 5 so that the guide portion 5e is on the lower side in the vertical direction. Also, MR
As shown in FIGS. 3B and 3C, the element 4 is adhesively held by the element holder 5b, and the element holder 5b is adhesively fixed to the base 5a with the guide portions 5e, 5f as a reference. As a result, the gap between the medium 1 and the MR element 4 can be maintained accurately.

When the slider 5 moves, the end of the medium 1 comes into contact with the guide portion 5e (5f), so that the magnetic layer comes into contact with the slider 5 to a slight extent. In order to prevent the contact between the magnetic layer and the slider 5, the magnetic body 1 may be configured as follows.

4 (a) and 4 (b) and FIG. 4 (c),
FIG. 3D is a diagram showing an example of such a magnetic body. 4 (a) and 4 (c) are top views of the respective examples.
(B) and FIG.4 (d) have shown sectional drawing of each example. In the example shown in FIGS. 4A and 4B, the magnetic layer is applied on the entire surface of the non-magnetic PET material, and the medium 32 to be the scale portion is formed by pressing from the magnetic layer side. Is. The medium 32 has the inclined surfaces 35 at both ends on the magnetic layer side of the base material 34 including the magnetic layer 33 due to the influence of the cutting angle of the cutting edge of the press machine. As a result, the end surfaces 32a and 32b of the magnetic material that are in contact with the guide portions 5e and 5f of the slider 5 are only the base material 34, and peeling of the magnetic layer 33 can be avoided.

In the example shown in FIGS. 4 (c) and 4 (d), a thermosensitive compression type magnetic tape (for example, a magnetic stripe of a bank card and a magnetic stripe is formed on the surface of a base material 43 made of a non-magnetic PET material formed in a tape shape. By attaching (equivalent) 44, the end face portions 42a and 42b of the medium 42 are the base material 42 only. Since the magnetic pattern is magnetized to the medium 42 after the magnetic tape 44 is attached, the end portion 4 of the medium 42 is
Since it is not necessary to regulate the parallelism of the magnetic tape 44 with respect to 2a and 42b so strictly, in the present embodiment, the magnetic tape 44 is attached to the tape-shaped base material 42. Cutting process and magnetic tape 4
By making the attaching process of 4 the same, the end portion 42 of the medium 42 is
The parallelism of the magnetic tape 44 with respect to a and 42b can be increased. In this case, the sensing pattern portion 4a of the MR element 4 can be formed small.

[0042]

As is apparent from the above description, the present invention has a simple structure and can keep the gap between the detection head and the scale unit constant, and the output is also higher than that when the medium is a round bar. It increased about 2 times, and the characteristics were stable.

In the durability test, no error occurred even after 2 million reciprocations, and the initial characteristics could be maintained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the outline of an embodiment of the present invention.

FIG. 2 is a diagram for explaining the outline of an embodiment in which the encoder of the present invention is attached to a recording device.

3A and 3B are views for explaining details of a detection head (slider), in which (a) is a cross-sectional view of the slider 5 and (b).
Shows a sectional view taken along line AA in (a), and (c) shows a sectional view taken along BB in (a).

4A, 4B, and 4C are views showing other examples of the medium, respectively.

[Explanation of symbols]

 1 recording medium (scale part) 2 holding part 3 detection head 4 MR element 5 slider 5c sliding part

Claims (18)

[Claims] 1. A belt-shaped scale portion having a detection pattern formed on one surface thereof and capable of being stretched by a predetermined tension, and a detection element for detecting the detection pattern, the scale portion being provided at an opposing portion of the detection element. A linear encoder comprising: a detection head formed with a sliding portion that slides on the other surface of the portion. 2. The linear encoder according to claim 1, wherein the sliding portion is formed with a flat portion and an inclined portion continuous with the flat portion. 3. The linear encoder according to claim 2, wherein a recess is formed in the flat portion. 4. The linear encoder according to claim 2, wherein the inclined portion is formed at an angle larger than an incident angle of the stretched scale portion to the detection head. 5. The linear encoder according to claim 1, wherein the sliding portion is provided with a guide portion that regulates and guides the position of the scale portion in the width direction. 6. A detection head, which holds a detection element for detecting a detection pattern, and has a flat portion and an inclined portion continuous with the flat portion, which is formed in a portion facing the detection element. 7. The detection head according to claim 6,
A detection head comprising polyphenylene sulfide. 8. The detection head according to claim 6, wherein a recess is formed in the flat portion. 9. A band-shaped non-magnetic base material, a magnetic layer formed on one surface of the base material, and a magnetic layer non-formed portion having a predetermined width formed at an end in the width direction. Recording medium. 10. The recording medium according to claim 9, wherein the non-magnetic base material is polyethylene terephthalate. 11. The recording medium according to claim 10, wherein a position detection pattern is formed on the magnetic layer. 12. A belt-shaped scale portion having a detection pattern formed on one surface, two holding portions for holding both ends of the scale portion so as to stretch the belt-shaped scale portion with a predetermined tension, A detection head that holds a detection element that detects a detection pattern, and a detection head in which a sliding portion that slides on the other surface of the scale portion is formed in a facing portion of the detection element, wherein the detection head is the An electronic device, wherein the electronic device is provided so as to be engaged with the scale portion and movable at a position separated from the virtual straight line connecting the two holding portions by a predetermined distance. 13. The electronic device according to claim 12, further comprising a recording head and a carriage that moves the recording head, and the detection head is provided on the carriage. 14. The sliding member according to claim 12,
An electronic device having a flat portion and an inclined portion continuous with the flat portion. 15. The electronic device according to claim 14, wherein a recess is formed in the flat portion. 16. The inclined portion according to claim 14,
An electronic device, characterized in that it is formed at an angle larger than the angle of incidence of the stretched scale portion on the detection head. 17. The electronic device according to claim 12, wherein the sliding portion is provided with a guide portion that regulates and guides the position of the scale portion in the width direction. 18. The electronic device according to claim 12, wherein the detection head is arranged such that the guide portion is on a lower side in the vertical direction.