JP2003028643A - Electrode forming method for columnar piezoelectric vibrator and vibrator for piezoelectric vibration gyroscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a columnar piezoelectric vibrator comprising strip-like electrodes all of which have uniform thickness, and to provide a piezoelectric vibration gyroscope using the columnar piezoelectric vibrator reduced in the irregularity of characteristics, especially in the irregularity of transmission characteristics. SOLUTION: The electrodes of the columnar piezoelectric vibrator are formed by a screen printing method, and a plurality of strip-like patterns vertical to a printing direction are formed on a screen. The thickness of the emulsion at the portion on the surface of the screen excepting the insides of two straight lines, which respectively pass two outermost points in both directions of the printing patterns in the direction (widthwise direction) vertical to the printing direction among portions on the surface of the screen positioned on the side of a printing advance direction from the terminal lines of the finally printed strip-like pattern and the extention lines thereof, is made larger than that of the emulsion of other part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical piezoelectric vibrator and a method of forming electrodes thereof, and more particularly to a method suitable for forming electrodes of a vibrator for a piezoelectric vibration gyro.

[0002]

2. Description of the Related Art Piezoelectric ceramics have been applied to various fields, and a piezoelectric vibrating gyro using a cylindrical piezoelectric vibrator is an example thereof. As an angular velocity sensor, video, camera shake correction, ship, automobile, etc. It is used in fields such as attitude control devices for devices mounted on moving bodies, navigation systems for automobiles, and the like.

7A and 7B show an example of a schematic structure of a piezoelectric vibrator used in a piezoelectric vibrating gyro. FIG. 7A is a perspective view of the piezoelectric vibrator 40, and FIG. 7B is a piezoelectric vibrator. 40
It is sectional drawing in the center part. This piezoelectric vibrator 40
Is formed by forming electrodes on a cylindrical piezoelectric ceramic 41. Seven strip-shaped electrodes 42 to 48 are formed on the outer peripheral surface of the piezoelectric ceramic 41 at equiangular intervals and at positions parallel to the length direction. In these seven strip electrodes, 42
And 43, 43 and 44, 44 and 45, 45 and 46, 46 and 47, 46 and 47, 47 and 48 are all equiangularly arranged and, as shown in FIG. It is located parallel to the longitudinal direction.

Of these strip-shaped electrodes 42 to 48, every other strip-shaped electrode 42, 44, 4 is positioned along the circumference.
Reference numerals 6 and 48 are earth band electrodes, and both ends thereof are ring-shaped earth connection electrodes 49 as shown in FIG. 7A.
a, 49b. The strip electrode 45 is also called a drive terminal, and the remaining two strip electrodes 4 are
3, 47 are also called detection terminals.

Conventionally, a curved screen printing method has been used as a method for forming these strip electrodes 42 to 48. FIG. 2 shows a schematic view of a screen used for forming a conventional electrode. FIG. 2 (a) is a top view of FIG.
2B is a cross-sectional view taken along the line BB ′ of FIG. 2A.

A commonly used screen 30 comprises a frame 11, a mesh 12 and an emulsion 13. The mesh 12 is fixed to the frame 11 while maintaining a certain tension. The emulsion 13 is formed on one side of the mesh 12 with a constant thickness. The print pattern 14 is formed by removing the emulsion by etching or the like corresponding to the portion having the same shape as the electrode formed on the piezoelectric ceramics 41.

FIG. 4 shows a process flow of a conventional electrode forming method using a screen. 4 (a) to 4
(F) is a figure explaining six processes from step 4a to step 4f. Further, each drawing is composed of a side view and a front view which are arranged side by side. here,
22 is a squeegee, 23 is a conductive paste, and 24 is a vibrator receiving stage.

First, the squeegee 22 is pressed from the non-formed surface side of the emulsion 30 of the screen 30 in front of the print pattern 14 with a pressure on the screen 30, and the piezoelectric ceramic 41 is pressed against the emulsion 13 of the screen 30. They are in contact (step 4a). The situation is shown in FIG.

When the screen is started to move horizontally from this state, the piezoelectric ceramic 41 is moved to the screen 30 by the frictional force between the screen 30 and the piezoelectric ceramic 41.
The rotation starts in synchronization with (step 4b). The situation is shown in FIG.

Then, the speed of the screen is kept constant at the speed V ₀ (step 4c). The situation is shown in FIG.

While maintaining this speed V ₀ , the squeegee 22
When the paste passes over the printed pattern 14, the conductive paste 2
3 is scraped out through the mesh 12, applied on the circumference of the piezoelectric ceramics 41, and sequentially formed from the strip electrode 42 (step 4d). The situation is shown in FIG.

Then, the screen decelerates from the middle (step 4e). The situation is shown in FIG.

At the same time as the last printed strip electrode 48 is formed, the screen stops (step 4f). The situation is shown in FIG.

FIG. 6 is a diagram showing the relationship between the printing speed and the screen position in this conventional method. In the case of the curved surface printing method using such a screen, if the screen 30 is moved more than necessary, the piezoelectric ceramics 41 continue to rotate, and in that case, the electrode formed first comes into contact with the emulsion 13. Will end up.

Generally, the conductive paste used for screen printing is made so as not to dry at room temperature in order to improve workability and reproducibility. Therefore, when the non-dried electrode comes into contact with the emulsion, the electrode formed first is bleeding and cannot be clearly formed. In order to avoid this, FIG.
As shown in FIG. 6, the screen is stopped at the same time when the strip electrode 48 to be printed last is formed, that is, the piezoelectric ceramics 41 is prevented from rotating more than once after the electrode application, and the strip electrodes 42 to 48 already formed are removed. Without blurring
I try to keep it clear.

[0016]

However, in the above-described method, as is clear from FIG. 6, only the last printed strip electrode 48 is printed at a slower speed than the other strip electrodes. As a result, there is a problem that the thickness of the strip electrode 48 becomes thin. This is the piezoelectric vibrator 40
However, there is a problem in that the yield of the piezoelectric vibrator gyro deteriorates as it is.

The present invention has been made to solve the above problems, and enables the production of a cylindrical piezoelectric vibrator in which all the strip electrodes have a uniform thickness, and the dispersion of the characteristics of the piezoelectric vibrator, particularly the transmission characteristics. Therefore, it is an object of the present invention to reduce the dispersion of the above and to improve the yield of the piezoelectric vibrating gyroscope using this piezoelectric vibrator.

[0018]

In order to solve the above problems, the following means are used in the present invention.

That is, in the method of forming an electrode of a cylindrical piezoelectric vibrator having a shape in which an electrode is provided on the side surface of a cylinder, the electrode formation is performed by a screen printing method, and the screen surface used at this time is substantially parallel to the printing direction. A print pattern composed of a plurality of vertical strip-shaped patterns is formed. Of the strip-shaped patterns, the end line of the strip-shaped pattern to be printed last and the end line in the direction perpendicular to the printing direction (width Direction) and a portion on the screen surface located on the side of the printing direction with respect to the boundary line formed by extending the printing pattern in both the directions perpendicular to the printing direction (width direction). The thickness of the emulsion on the part on the screen surface outside the two straight lines passing through the two outermost points and parallel to the printing direction is set to be smaller than the thickness of the emulsion on the other parts on the screen surface. It may be printed using a thick and screen.

In the method for forming the electrode of the cylindrical piezoelectric vibrator, it is preferable to print using a screen in which the difference in the thickness of the emulsion between the portion where the emulsion is thickly formed and the other portion is larger than the printing thickness. .

In the method of forming the electrode of the cylindrical piezoelectric vibrator, it is preferable that the electrode of the cylindrical piezoelectric vibrator is formed by printing using a screen having a taper on a portion where the emulsion is thickly formed.

Further, in the method of forming the electrode of the cylindrical piezoelectric vibrator, it is preferable that the electrode of the cylindrical piezoelectric vibrator is formed by printing at a constant speed at least when the squeegee passes over the print pattern.

A cylindrical piezoelectric vibrating gyroscope vibrator may be manufactured by the method of forming an electrode of the cylindrical piezoelectric vibrator.

[0024]

In the present invention, the electrodes of the cylindrical piezoelectric vibrator are formed by the screen printing method. A plurality of strip-shaped patterns that are mainly perpendicular to the printing direction are formed on this screen, and the screen surface that is located on the print advancing direction side with respect to the end line of the strip-shaped pattern to be printed last and its extension line. Of the upper part, the outermost 2 in both directions of the print pattern in the direction perpendicular to the print direction (width direction)
The thickness of the emulsion in the portion on the screen surface excluding the inside of the two lines passing through the points and parallel to the printing direction is formed thicker than the other portions. As a result, in the final step of printing, both ends of the piezoelectric ceramic ride on the thick emulsion portion, and the printing surface of the piezoelectric ceramic moves away from the screen surface.

Further, by making the difference in the thickness of the emulsion between the portion where the emulsion is made thicker and the other portion larger than the printing thickness, the emulsion is prevented from coming into contact with the undried electrode.

Further, by using a screen having a taper in a portion where the emulsion is thickly formed, it is possible to keep the rotation of the piezoelectric ceramic smooth in a place where the thickness of the emulsion changes.

By printing at a constant speed at least when the squeegee passes over the print pattern,
It is possible to provide a piezoelectric vibrator in which all the strip electrodes have a uniform thickness. As a result, it is possible to reduce variations in the characteristics of the piezoelectric vibrator and contribute to an improvement in the manufacturing yield of the piezoelectric vibrating gyro, which is one of the applications of piezoelectric ceramics.

[0028]

Embodiments of the present invention will be described by taking the case of a piezoelectric vibrating gyro as an example.

FIG. 1 is a diagram showing the structure of a screen on which an electrode pattern of a vibrator for a piezoelectric vibrating gyroscope used in the electrode forming method of the present invention is formed. FIG. 1 (a) is a top view thereof, and FIG. 1 (b) is A-A 'of FIG. 1 (a).
It is sectional drawing by the cut surface shown by.

The screen 10 used in the present invention comprises a frame 11, a mesh 12 and an emulsion 13. The material of the mesh 12 is made of stainless steel, and is fixedly adhered to the frame 11 with a constant tension. The emulsion 13 is formed on one side of the mesh 12 with a thickness of 15 μm.

The print pattern 14 is formed by removing the emulsion by etching corresponding to the portion having the same shape as the strip electrode formed on the piezoelectric ceramics 41.

The outermost two points 18a and 18b of the print pattern 14 in the direction perpendicular to the printing direction are provided from the portion on the traveling direction side of the printing direction with respect to the end line 17 of the printing pattern and its extension lines 19a and 19b. Part 1 inside two lines 20a and 20b that pass through and are parallel to the printing direction
Emulsion thickness of parts 15a and 15b excluding 6 is 100 μm
And is thicker than 15 μm which is the emulsion thickness of other portions.

The thick emulsions 15a and 15b are provided with tapers 21a and 21b, respectively. Further, the thickness of the emulsions 15a and 15b needs to be larger than the printing thickness of the electrodes printed on the piezoelectric ceramics 41, but the printing speed, taper shape, etc.
It depends on several factors.

FIG. 3 shows a process flow of the electrode forming method according to the present invention. 3 (a) to 3 (g) are diagrams for explaining seven processes from step 3a to step 3g. Further, each drawing is composed of a side view and a front view which are arranged side by side.

Step 3 shown in FIGS. 3 (a) to 3 (d)
The steps from a to step 3d proceed in the same manner as the conventional method shown in FIGS. 4 (a) to 4 (d).

However, in the present invention, as shown in FIG. 3 (e), the strip-shaped electrode 48 is printed in the same manner as other strip-shaped electrodes without deceleration until the strip-shaped electrode 48 to be printed last is formed. Printed at speed V ₀ . (Step 4
e). This is shown in FIG. 3 (e).

After that, the screen continues to move, and the piezoelectric ceramics 41 on which the strip electrodes are not formed rides on the emulsions 15a and 15b which are thickly formed at both ends, and the screen starts decelerating. (Step 3f).
This is shown in FIG. 3 (f).

Finally, the screen stops and printing ends. (Step 3g). The situation is shown in Fig. 3 (g).
Is shown in.

At this time, the emulsion 16 and the emulsion 15a or 15
Due to the difference in thickness of b, the undried electrode does not come into contact with emulsion 16. Further, because of the taper 21, the piezoelectric ceramics 41 can smoothly rotate even at a point where the thickness of the emulsion changes.

FIG. 5 is a diagram showing the printing speed for seven strip electrodes. The horizontal axis shows the screen position,
Also, the part where the electrode pattern exists is displayed at the same time,
Printing speed is shown on the vertical axis. As shown in FIG. 5, by using the printing method (electrode forming method) of the present invention, it becomes possible to print all the strip electrodes at the same speed.

FIG. 8 is a diagram showing the thickness of the strip electrode of the piezoelectric vibrator formed by the method of the present invention and the conventional method. The thickness is shown as an average value of 45 pieces. The dimensions of the piezoelectric ceramics are 2 mm in diameter and 14 in length.
mm, the strip electrodes are 42, 43, 44, 45, 4
It is printed in the order of 6, 47 and 48.

As can be seen from FIG. 8, in the method of the present invention, all the electrodes are formed to have an average thickness of about 8.5 μm, while in the conventional method, the strip electrode to be printed last is printed. It is understood that only 48 has an average value of about 5 μm, which is thinner than the other strip electrodes. this is,
This is because, as shown in FIGS. 5 and 6, a difference in thickness occurs due to a difference in printing speed.

FIG. 9 is a diagram showing the distribution of transmission characteristics of the piezoelectric vibrating gyroscope electrode formed by the method of the present invention and the conventional method. Here, the transmission characteristic means that when a voltage is applied to the driving strip electrode 45, the two detection strip electrodes 43 are formed.
And 47, the smaller the difference between the two output voltages (hereinafter referred to as ΔV), the more symmetrically the strip electrodes are formed.

In FIG. 9, 20 mV is applied to the driving strip electrode 45.
Δ when the voltages output from the detection strip electrodes 43 and 47 are respectively amplified 50 times when the AC voltage is applied.
V was shown.

The piezoelectric vibrator manufactured by the method of the present invention is
Since the electrodes are formed uniformly, ΔV is distributed within ± 10 mV with 0 mV as the center. On the other hand, in the piezoelectric vibrator printed by the conventional method, since only the strip electrode 48 is thinly printed, the symmetry of the electrode is broken, and ΔV
Is 0 to -50 mV, and the central value is -25 m
It has become V and has deviated from 0 mV.

FIG. 10 shows a perspective view of the piezoelectric vibrating gyro. The piezoelectric vibration gyro 50 includes a resin molded circuit board (hereinafter referred to as MID) 51, support rubbers 52a and 52.
b, lead wires 53a to 53d, and a case 54.

In this piezoelectric vibrating gyro 50, first, the support rubbers 52a and 52b, the MID 51, and the support rubber 52 are provided.
The a and 52b and the piezoelectric vibrator 40 are bonded and fixed with a silicone adhesive. Next, each strip electrode on the piezoelectric vibrator 40 and MI
The D51 is electrically connected by soldering the lead wires 53a to 53d, and then the case 54 is covered to assemble.

The piezoelectric vibrating gyro 50 then enters the process of adjusting sensitivity and offset voltage.

Table 1 shows the yield in the adjustment process of the piezoelectric vibrating gyro assembled by using the piezoelectric vibrator in which electrodes are formed by the present invention and the conventional method.

[0050]

[Table 1]

The yield in the adjustment process is related to the transmission characteristic of the piezoelectric vibrator, that is, ΔV. If ΔV is large,
The sensitivity cannot be adjusted to the designed sensitivity, or the offset voltage cannot be adjusted to a small value. Therefore, as shown in FIG. 9, in the conventional method, the center value of ΔV is 0 mV.
The yield is 55% because the distribution is deviated from the distribution, whereas in the method of the present invention, ΔV is centered at 0 mV and the variation is small, so that the yield can be adjusted at 100%. .

By the way, in the above-mentioned embodiment, the example of the piezoelectric vibrating gyro has been described. However, in the electrode forming method of the cylindrical piezoelectric vibrator having a shape in which the electrode is generally on the side surface of the cylindrical column, the thickness of a plurality of electrodes is constant. It is effective to reduce the characteristic variation, and the electrode forming method of the present invention can be applied as the means.

[0053]

As described above, according to the present invention, it is possible to manufacture a cylindrical piezoelectric vibrator in which all electrodes have a uniform thickness, and as a result, variations in characteristics of the piezoelectric vibrator are improved, The yield of the piezoelectric vibrating gyro could be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a screen used in an electrode forming method of the present invention. FIG. 1A is a top view of FIG.
FIG. 1B is a cross-sectional view taken along the line AA ′ in FIG.

FIG. 2 is a diagram showing a schematic view of a screen used for forming a conventional electrode. 2 (a) is a top view thereof, FIG. 2 (b).
2A is a cross-sectional view taken along the line BB ′ of FIG.

FIG. 3 is a diagram showing a process flow of an electrode forming method of the present invention. FIGS. 3A to 3G are views for explaining seven processes from step 3a to step 3g.

FIG. 4 is a diagram showing a process flow of an electrode forming method using a screen according to a conventional method. 4 (a) to 4 (f)
FIG. 6 is a diagram illustrating the six processes of steps 4a to 4f.

FIG. 5 is a diagram showing printing speeds for seven strip electrodes in the electrode forming method of the present invention.

FIG. 6 is a diagram showing a relationship between a printing speed and a screen position in a conventional electrode forming method.

FIG. 7 is a diagram showing a schematic structure of a piezoelectric vibrator used in a piezoelectric vibrating gyro. FIG. 7A is a perspective view of FIG.
(B) is sectional drawing in the center part.

FIG. 8 is a diagram showing the thickness of a strip electrode of a piezoelectric vibrator printed by the present invention and a conventional electrode forming method.

FIG. 9 is a diagram showing a distribution of transmission characteristics of a piezoelectric vibrator printed by the present invention and a conventional electrode forming method.

FIG. 10 is a perspective view showing a piezoelectric vibrating gyro.

[Explanation of symbols]

10 screen 11 frame 12 mesh 13, 16 emulsion 14 of normal thickness print pattern 15a, 15b thickly formed emulsion 17 end line 18a, 18b of print pattern outermost part of print pattern in a direction perpendicular to the print direction Points 19a, 19b Extension lines 20a, 20b of the end line of the print pattern A line 21 passing through the outermost point of the print pattern in a direction perpendicular to the print direction and parallel to the print direction 21 Taper 22 Squeegee 23 Conductive paste 24 Transducer receiving stage 30 Screen 40 Piezoelectric oscillator 41 Piezoelectric ceramics 42 Earth strip electrodes 43, 47 Detection strip electrodes (detection terminals) 44, 46, 48 Earth strip electrodes 45 Drive strip electrodes (drive terminals) 49a, 49b Ground connection electrode 50 Piezoelectric vibration gyro 51 MID (resin molded circuit board) 52a, 52b Support rubbers 53a to 53d Lead wire 54 Case

Claims (5)

[Claims] 1. A method for forming an electrode of a cylindrical piezoelectric vibrator having a shape in which an electrode is provided on a side surface of a cylinder, wherein the electrode formation is performed by a screen printing method, and a screen surface used at this time is mainly formed in a printing direction. A print pattern composed of a plurality of strip-shaped patterns perpendicular to is formed. The end line of the strip-shaped pattern to be printed last among the strip-shaped patterns and the end line is extended in a direction perpendicular to the printing direction. Printing that passes through the two outermost points in both directions of the print pattern in the direction perpendicular to the printing direction, which is a portion on the screen surface that is located on the side of the printing direction in relation to the boundary line created by The thickness of the emulsion in the portion on the screen surface located outside the two straight lines parallel to the direction is made thicker than the thickness of the emulsion in other portions on the screen surface. A method for forming an electrode of a cylindrical piezoelectric vibrator, which comprises printing using lean. 2. A screen according to claim 1, wherein the difference in the thickness of the emulsion between the portion where the emulsion is thickly formed and the other portion is larger than the printing thickness. A method for forming an electrode of a cylindrical piezoelectric vibrator, which is characterized in that printing is performed using. 3. The method for forming an electrode of a cylindrical piezoelectric vibrator according to claim 1, wherein printing is performed by using a screen having a taper on a portion where the emulsion is thickly formed. Method for forming electrodes. 4. The method for forming an electrode of a cylindrical piezoelectric vibrator according to claim 1, wherein printing is performed at a constant speed at least when the squeegee passes over the print pattern. Electrode forming method for cylindrical piezoelectric vibrator. 5. A vibrator for a piezoelectric vibration gyro, wherein electrodes are formed by using the electrode forming method for a cylindrical piezoelectric vibrator according to any one of claims 1 to 4.