Tuning-fork type crystal vibrator and frequency adjustment method

Abstract

To provide a tuning-fork type crystal vibrator which simplifies a manufacture process of the tuning-fork type crystal vibrator, secures weight of a metal film and further prevents blurring from being residual in an edge part of a vibration arm after frequency adjustment.SOLUTION: A tuning-fork type crystal vibrator 10 comprises: a base; a vibration arm 13 which extends from the base and of which the cross section is rectangular; and a first metal film 15a for frequency adjustment which is deposited on at least a principal surface 16 of the vibration arm 13. An irradiation mark of a laser beam 4 irradiating the vibration arm 13 is formed on the first metal film 15a. The first metal film 15a is deposited over an entire region of one face in a width direction, a first irradiation mark 18a is formed in a one-side end portion 19 of at least the first metal film 15a in the width direction and formed over a second metal film 15b which is deposited on an outer side face 17a of the vibration arm adjacent to the one-side end portion 19.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a tuning fork type crystal resonator having a structure for realizing miniaturization and high accuracy, and a method for adjusting the frequency of the same. [Background technology]

[0002] A tuning fork type vibrator is a vibrator manufactured to vibrate at a constant frequency. For this reason, it is necessary to fine-tune the frequency by changing the physical parameters of the vibrator. Conventionally, as one of the methods for changing the physical parameters of the vibrator, a method of reducing the mass of the metal film formed on the tuning fork type vibrator is known. This is because the vibration frequency of the tuning fork increases by reducing the mass of the metal film. For example, as shown in FIG. 8(a), frequency adjustment by reducing the mass of the metal film is performed by irradiating a metal film 3 formed on the tip of the vibrating arm 2 of a tuning fork type crystal vibrator 1 with a laser beam 4 to melt and remove a part of the metal film 3, as shown in FIG. 8(b). When an irradiation mark 7 is formed on the metal film 3 by irradiation with the laser beam 4, metal slag 3' melted by the laser beam 4 may adhere in a slug-like form to the boundary between the irradiation mark 7 and the metal film 3, as shown in FIG. 8(b). In particular, in the conventional frequency adjustment method, the laser light 4 is swept from the inside to the outside in the width direction of the vibrating arm 2, so that there is a risk that burrs 5 are left as slug-like metal slag along the edge 6 of the vibrating arm 2 in the width direction. The burrs 5 may fall off the vibrating arm 2 during use of the tuning fork type crystal unit 1. When the burrs 5 come off, the mass of the vibrating arm 2 becomes lighter, and the vibration frequency of the tuning fork type crystal unit 1 changes. For this reason, the tuning fork type crystal unit described in Patent Document 1 prevents burrs from remaining on the edge of the vibrating arm by forming a metal film for frequency adjustment on the surface of the vibrating arm on the inside away from the outer periphery of the vibrating arm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-332872 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the tuning fork type quartz crystal unit disclosed in the above Patent Document 1, a new process such as positioning adjustment of the metal film is required to form the metal film for frequency adjustment on the inside away from the outer periphery of the vibrating arm. Also, as described above, the frequency of the tuning fork is adjusted by removing the metal film to reduce the mass of the vibrator. However, due to the recent trend of miniaturizing parts, the vibrator also tends to become smaller. In the case of a miniaturized quartz crystal unit, the surface area of ​​the vibrating arm is narrow, so the weight of the metal film is small, and there is a problem that the frequency adjustment margin is reduced. In the case of the tuning fork type quartz crystal unit disclosed in Patent Document 1, when the metal film is formed on the inside away from the outer periphery of the vibrating arm, the frequency adjustment margin is further reduced.

[0005] The present invention has been made in consideration of the above circumstances, and provides a tuning fork-type quartz crystal resonator and a frequency adjustment method in which no burrs remain on the edge of the vibrating arm after frequency adjustment, even when a metal film for frequency adjustment on the surface of the vibrating arm is formed over the entire width. [Means for solving the problem]

[0006] The tuning-fork-type quartz crystal resonator of the present invention comprises a base, a vibrating arm having a rectangular cross section extending from the base, and a first metal film for frequency adjustment formed on at least one surface of the vibrating arm, and in the tuning-fork-type quartz crystal resonator in which irradiation marks of laser light irradiated to the vibrating arm are formed on the first metal film, the first metal film is formed over the entire width of the one surface, and the irradiation marks are formed at least on one side end of the first metal film in the width direction, and are also formed over a second metal film formed on one side of the vibrating arm adjacent to the one side end.

[0007] Furthermore, in the frequency adjustment method for a tuning-fork type quartz crystal resonator of the present invention, in which a laser beam irradiation mark is formed on a metal film formed over the entire width direction of at least one surface of a vibrating arm, the frequency adjustment method adjusts the frequency, and includes a first step of sweeping a laser beam from the outside of one end of the vibrating arm in the width direction toward the inside of the vibrating arm, to form a first irradiation mark from one end of the metal film in the width direction to a predetermined inner position. Effect of the Invention

[0008] According to the tuning-fork-type quartz crystal resonator of the present invention, the irradiation marks of the laser light are formed on one side end of the first metal film in the width direction, and also extend across the second metal film formed on one side of the vibrating arm adjacent to the one side end, thereby preventing the occurrence of burrs near the edge portion in the width direction of the vibrating arm, including the one side end of the first metal film.

[0009] According to the frequency adjustment method of the tuning fork type quartz crystal unit of the present invention, by sweeping the laser light from the outside to the inside of one end of the width direction of the vibrating arm, the irradiation mark is formed on one end of the width direction of the first metal film and is also formed over the second metal film formed on one side of the vibrating arm adjacent to the one end, so that the generation of burrs can be prevented near the edge of the vibrating arm including the one end of the first metal film. Furthermore, according to the frequency adjustment method of the present invention, the frequency adjustment is performed on the metal film formed over the entire width direction of one side of the vibrating arm, so that the positioning adjustment process for limiting the deposition area of ​​the metal film is not required, and the manufacturing process of the tuning fork type quartz crystal unit can be simplified. Also, since the area where the metal film is formed is widened, the frequency adjustment margin can be increased. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view of a tuning-fork type crystal resonator according to an embodiment of the present invention. [Diagram 2]2(a) is an enlarged view of an irradiation mark when a laser beam is swept from the outside to the inside of the vibrating arm of a first metal film formed on the vibrating arm of the tuning-fork type quartz crystal resonator according to the above embodiment, and FIG. 2(b) is a cross-sectional view taken along line II-II in FIG. 2(a). [Diagram 3] 4 is a cross-sectional view showing a state in which laser light is irradiated from a rear surface of the vibrating arm through the base material to the first metal film according to the embodiment. FIG. [Figure 4] 5A to 5C are process diagrams illustrating a method for adjusting the frequency of the tuning-fork crystal resonator according to the embodiment. [Diagram 5] FIG. 2 is a plan view illustrating a first metal film after frequency adjustment in the tuning-fork type crystal resonator according to the embodiment. [Figure 6] (a) is a scanning microscope photograph of the plane of a vibrating arm showing irradiation marks formed by a conventional frequency adjustment method, and (b) is a scanning microscope photograph of the plane of a vibrating arm showing irradiation marks formed by the frequency adjustment method of the present invention. [Figure 7] 6(a) is a scanning microscope photograph of the side surface of the vibrating arm portion shown in FIG. 6(a), and (b) is a scanning microscope photograph of the side surface of the vibrating arm portion shown in FIG. 6(b). [Figure 8] FIG. 1A is a plan view of a tuning fork type crystal resonator having a metal film for adjusting frequency at the tip of the vibrating arm, and FIG. 1B is a perspective view for explaining a method for removing the metal film of a conventional tuning fork type crystal resonator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The tuning fork type crystal resonator of the present invention will be described below based on each embodiment with reference to the drawings. Note that the drawings are schematic representations of the tuning fork type crystal resonator, the components of the tuning fork type crystal resonator, and the peripheral components of the tuning fork type crystal resonator, and the actual dimensions and dimensional ratios of these do not necessarily match the dimensions and dimensional ratios shown in the drawings. Also, unless otherwise specified, for convenience, directions such as up and down are expressed based on the orientation of the tuning fork type crystal resonator shown in Figure 1. Duplicate descriptions will be omitted as appropriate, and the same symbols may be given to the same components.

[0012] A typical manufacturing method for tuning fork type quartz crystal units is the chemical (wet) etching method. In this manufacturing method, a protective metal such as gold is formed on a quartz crystal wafer of several inches square or a circle by deposition or sputtering, a photosensitive resist is applied from above, and exposure and development are performed using an exposure mask with a pattern of the tuning fork outline, and the protective metal is patterned. The wafer is then immersed in a container filled with a liquid such as hydrofluoric acid or acidic ammonium fluoride, which erodes and dissolves the protective metal and areas other than those masked by the resist film, thereby forming the outline of the vibrator. Electrodes and metal films for frequency adjustment are deposited on the surface of the quartz crystal piece formed by the etching method.

[0013] After the above process, a part of the metal film for frequency adjustment formed on the tip of the crystal unit is removed by a laser to adjust the frequency of the crystal unit. The tuning fork crystal unit plays an important role as a clock signal source in electronic devices. The clock signal is a signal necessary to synchronize the operation of each circuit in the electronic device, and an accurate frequency is required. If the frequency is inaccurate, for example, in the case of a circuit operating at a high frequency, the period of the clock signal will be short, and the circuit may not operate correctly. Also, in the case of a circuit operating at a low frequency, the period will be long, and the operation may become slow. For this reason, the frequency adjustment process of the tuning fork crystal unit is a very important process that directly affects the performance of the electronic device.

[0014] As shown in FIG. 1, the tuning fork-type quartz crystal vibrator 10 comprises a base 11 to which a terminal electrode (not shown) is connected, and a pair of left and right vibrating arms 13, 14 having a rectangular cross section extending from the base 11, and a metal film 15 is formed on the tip portions of the vibrating arms 13, 14.

[0015] The vibrating arms 13 and 14 use the piezoelectric effect to convert an external force into an electrical signal. Taking the vibrating arm 13 as an example, the vibrating arm 13 has a structure in which a metal electrode 12 is added to the surface of a quartz crystal substrate. When an electrical signal is applied to the vibrating arm 13 from the outside, the quartz crystal vibrating arm 13 vibrates, generating an electric charge in the metal electrode 12. This electric charge is transmitted to an external circuit (not shown) via the metal electrode 12 and is output as an electrical signal. Because the electric charge changes periodically, it is possible to generate a signal at a constant frequency.

[0016] Specifically, the metal film 15 is a thin film formed by vapor deposition of gold. Gold is placed in a vacuum and heated using a heat source to vaporize the gold, which is then vaporized onto the quartz vibrating arms 13. For this reason, the metal film 15, which is a thin gold film, is formed over the entire surface of the tip of the vibrating arms 13. In addition, in the tuning fork type quartz crystal unit 10, the top surface having the largest surface area is referred to as the main surface 16. In addition, of the two side surfaces that intersect at right angles with the main surface 16, the surface that contacts the outside of the U-shape of the tuning fork type quartz crystal unit 10 is referred to as the outer side surface 17a, and the surface that contacts the inside of the U-shape is referred to as the inner side surface 17b.

[0017] 2(a) and (b), the metal film 15 includes a first metal film 15a formed on the main surface 16, a second metal film 15b formed on the outer side surface 17a, and a third metal film 15c formed on the inner side surface 17b. A fourth metal film 15d is also formed on the rear surface of the vibrating arm portion 13 facing the first metal film 15a. The thickness of the first metal film 15a is set to about 0.05 μm to 3 μm in this embodiment.

[0018] At least one of the metal films 15 can be increased in weight as a metal film for frequency adjustment. In this embodiment, the first metal film 15a formed on the main surface 16 is formed thicker than the other metal films as a metal film for frequency adjustment, and the weight is increased. The first metal film 15a is formed over the entire width of the main surface 16. The first metal film 15a is formed from one edge portion 13a to the other edge portion 13b in the width direction of the main surface 16, and covers the main surface 16 without any gaps in the width direction. Therefore, the manufacturing process is simplified compared to the case where the metal film is partially formed in the width direction of the main surface 16. In addition, by forming the first metal film 15a without any gaps in the width direction of the main surface 16, the weight of gold to be evaporated can be increased compared to the case where the metal film is partially formed. The edge portion refers to the corner portion where the main surface 16 intersects with the outer side surface 17a or the inner side surface 17b.

[0019] As shown in FIG. 2(b), the frequency adjustment is performed by irradiating the laser light 4 from the back side of the vibrating arm 13 and melting and removing the first metal film 15a formed on the main surface 16. At that time, the laser light 4 is swept in the A direction parallel to the main surface 16 from the outside to the inside of the outer side surface 17a of the vibrating arm 13, so that a first irradiation mark 18a is formed on one edge portion 13a of the main surface 16 of the vibrating arm 13. On the other hand, the laser light 4 is swept in the B direction parallel to the main surface 16 from the outside to the inside of the inner side surface 17b of the vibrating arm 13, so that a second irradiation mark 18b is formed on the other edge portion 13b of the main surface 16 of the vibrating arm 13. In addition, by irradiating the laser light 4 from the back side of the vibrating arm 13, irradiation marks are also formed on the edges 13a' and 13b' of the back surface corresponding to the edges 13a and 13b of the main surface 16. In this way, by reducing the mass of the first metal film 15a, it is possible to shift the frequency of the vibrating arm 13 and the vibrating arm 14 into the target frequency range. As described above, by increasing the deposition area of ​​the first metal film 15a and the weight of the gold to be deposited, the frequency adjustment margin is increased.

[0020] Approximately circular irradiation marks 18a and 18b are formed on the first metal film 15a irradiated with the laser light 4. When the laser light 4 is swept while being continuously irradiated in the width direction of the vibrating arm 13, the irradiation marks 18a and 18b are formed in the shape of elongated holes (see FIG. 4). The irradiation marks 18a and 18b refer to the exposed surface of the base material (quartz crystal) that is formed after the metal film is melted and removed by the laser light 4.

[0021] In this embodiment, as shown in FIG. 2(a), a first irradiation mark 18a is formed from one side end 19 of the first metal film 15a formed on the main surface 16 of the vibrating arm 13 to the upper end 21 of the second metal film 15b formed on the outer surface 17a. That is, since the first irradiation mark 18a is formed on the edge portion 13a of the main surface 16, the melted and removed metal slag does not remain as a burr on the edge portion 13a. Similarly, since the second irradiation mark 18b similar to the above is formed from the other side end 20 of the first metal film 15a to the upper end 22 of the third metal film 15c formed on the inner surface 17b, the other edge portion 13b also does not have a burr of metal slag, similar to the edge portion 13a.

[0022] Generally, at the boundary between the irradiation mark and the metal film formed after the laser light is irradiated, the metal slag melted by the laser light may become slag and adhere. In this embodiment, as described later, when the laser light 4 is irradiated, it is swept from the outside to the inside in the width direction of the vibrating arm 13. That is, since the laser light 4 is swept from the edge portion 13a of the vibrating arm 13 to the inside, the milk crown-like molten slag 30 (see FIG. 3) formed by melting the metal film is not easily generated at one side end 19 of the first metal film 15a including the edge portion 13a, and the first irradiation mark 18a is formed. In addition, this first irradiation mark 18a is formed from the edge portion 13a to the upper end 21 of the second metal film 15b continuing from the edge portion 13a. Therefore, slag due to the irradiation mark is not easily generated near the edge portion 13a, and the generation of burrs at the edge portion 13a can be suppressed. As a result, no burrs caused by molten slag fall off from the vibrating arm portion 13 during use of the tuning fork type crystal vibrator, so that fluctuations in frequency can be prevented and stability in quality is ensured.

[0023] On the other hand, the second irradiation mark 18b is formed on the other end 20 in the width direction of the first metal film 15a, and is also formed across the upper end 22 of the inner surface 17b of the vibrating arm adjacent to the other end 20. The other end 20 in the width direction refers to an area having a certain area close to the inner surface 17b of the main surface 16. In this way, the irradiation marks 18a, 18b are formed on both the edge portions 13a and 13b of the vibrating arm 13, exposing the surface of the base material.

[0024] In this embodiment, the first irradiation mark 18a formed on one side end 19 of the vibrating arm 13 and the second irradiation mark 18b formed on the other side end 20 are formed on the same line. That is, the first metal film 15a is removed symmetrically on the left and right with respect to the center line CL in the longitudinal direction of the vibrating arm 13. If the weight balance is different between the left and right in the vibrating arm 13, the vibration center of the vibrating arm 13 may be shifted. By removing the first metal film 15a symmetrically on the left and right of the vibrating arm 13, it is possible to give the vibrating arm 13 equal vibration characteristics on the left and right.

[0025] The irradiation marks 18a, 18b may be formed across the width of the first metal film 15a between one end 19 and the other end 20. The irradiation marks 18a, 18b may be formed in a plurality of rows in a direction perpendicular to the width of the first metal film 15a. By forming the irradiation marks 18a, 18b in a plurality of rows, it is possible to remove a large amount of the first metal film 15a. This allows the frequency of the tuning fork crystal resonator 10 to approach the target frequency in a short time. The irradiation marks 18a, 18b may be formed in succession such that each of the irradiation marks formed by the laser irradiation overlaps with the adjacent irradiation marks, or may be formed in succession with a gap between the adjacent irradiation marks.

[0026] Next, a method for adjusting the frequency of the tuning fork type crystal unit 10 will be described. As shown in FIG. 3, the tuning fork type crystal unit 10 is arranged so that the first metal film 15a is on the lower surface side. The laser light 4 is irradiated to the vibrating arms 13 and 14 from the back surface side facing the first metal film 15a through the base material. This is to prevent the re-adhesion of the metal that was once evaporated by melting the first metal film 15a due to the irradiation of the laser light 4.

[0027] In Fig. 4, the steps of adjusting the frequency while forming irradiation marks on the first metal film 15 formed on the main surface 16 of the vibrating arms 13, 14 are shown by symbols a to r. A shows the state before the vibrating arms 13, 14 are irradiated with laser light, and b to r show the process in which the first irradiation marks 18a and the second irradiation marks 18b are gradually formed larger on the first metal film 15a by repeating the first and second steps. In particular, b to o show the steps of forming the first spot row 31 by connecting the first irradiation marks 18a and the second irradiation marks 18b on the same line, and p to r show the initial step of forming the second spot row 32 at a position adjacent to the first spot row 31.

[0028] The first step includes a step of sweeping the laser light 4 from the outside of the outer end 23 in the width direction of the vibrating arm 13 to a predetermined position toward the inside of the vibrating arm 13 to form a first irradiation mark 18a, as shown in b, f, j, m, and p, and a step of moving the laser light 4 from the vibrating arm 13 to the vibrating arm 14 and sweeping the laser light 4 from the outside of the inner end 24 in the width direction of the vibrating arm 14 to the inside of the vibrating arm 14 to a predetermined position, as shown in c, g, k, o, and q. As shown in FIG. 4d, the first irradiation mark 18a of the same size is formed on the vibrating arm 13 and the vibrating arm 14 by the first step.

[0029] On the other hand, the second step includes a step of sweeping the laser light 4 from the outside of the outer end 25 of the vibrating arm 14 in the width direction toward the inside of the vibrating arm 14 to a predetermined position to form a second irradiation mark 18b, as shown in d, h, l, and r, and a step of moving the laser light 4 from the vibrating arm 14 to the vibrating arm 13 and sweeping the laser light 4 from the outside of the inner end 26 of the vibrating arm 13 in the width direction toward the inside of the vibrating arm 13 to a predetermined position as shown in e, i, and n. As shown by the symbol f in FIG. 4, the second irradiation mark 18b of the same size is formed on the vibrating arm 13 and the vibrating arm 14 by the second step. Note that the second irradiation mark 18b is the same size as the first irradiation mark 18a formed on the vibrating arm 13 and the vibrating arm 14 by the first step.

[0030] In this way, the frequency is adjusted while gradually increasing the size of the first irradiation mark 18a and the second irradiation mark 18b by repeating the first and second steps. As described above, the size of the irradiation mark formed in each step is the same for the vibrating arm 13 and the vibrating arm 14, and the size of the first irradiation mark 18a formed in the first step and the size of the second irradiation mark 18b formed in the second step are also the same in each of the vibrating arms 13 and 14. This is to maintain the weight balance between the vibrating arm 13 and the vibrating arm 14 after the frequency adjustment, and the left and right weight balance within each of the vibrating arms 13 and 14.

[0031] As described above, the laser light is swept from the outside to the inside of the width direction of each vibrating arm 13, 14, so that milk-crown-shaped molten scum 30 (see Figure 3), which tends to form in the sweep direction, does not form at the side ends of each vibrating arm 13, 14 in the width direction.

[0032] The irradiation marks 18a, 18b are formed continuously in the width direction of the vibrating arms 13, 14 such that adjacent irradiation spots of the laser light overlap each other. By overlapping adjacent irradiation spots, it is possible to prevent the metal film from remaining unmelted. In addition, by sweeping the laser light 4 at a pitch smaller than the diameter of the irradiation spot of the laser light, the amount of removal of the first metal film 15a is made finer, and the resolution of the frequency adjustment is improved.

[0033] FIG. 5 shows a state where the first spot row 31 to the fifth spot row 35 are provided on the first metal film 15a formed on the vibrating arm 13. Arrows A and B indicate the sweep direction of the laser light. As shown by arrow A, the first irradiation marks 18a of the first spot row 31 to the fifth spot row 35 are formed sequentially from one end 19 of the vibrating arm 13 toward the inside as the laser light 4 is swept from the outside to the inside in the width direction of the vibrating arm 13. On the other hand, as shown by arrow B, the second irradiation marks 18b of the first spot row 31 to the fifth spot row 35 are formed sequentially from the other end 20 of the vibrating arm 13 toward the inside as the laser light 4 is swept from the outside to the inside in the width direction of the vibrating arm 13.

[0034] As shown in FIG. 5, the first spot row 31 to the fourth spot row 34 are formed over the entire width of the vibrating arm 13 by repeating the first and second steps. The fifth spot row 35 shows a state where the sweep of the laser light 4 is terminated halfway in the width direction due to the completion of frequency adjustment. The first spot row 31 to the fifth spot row 35 are irradiated so that adjacent irradiation spots of the laser light overlap in the longitudinal direction of the vibrating arm 13. By overlapping adjacent irradiation spots with each other, it is possible to prevent the remaining melted metal slag. In addition, by setting the spot interval L to a pitch smaller than the spot diameter, it is possible to finely remove the first metal film 15a and improve the resolution of the frequency adjustment.

[0035] 6 and 7 are scanning microscope photographs comparing a case where irradiation marks 18 are formed on a metal film 15 formed on a pair of vibrating arms 13 and 14 by the frequency adjustment method of the present invention with a case where irradiation marks 18 are formed by a conventional frequency adjustment method. Fig. 6 is a front view of the vibrating arms 13 and 14, and Fig. 7 is a side view of the vibrating arm 13. In both figures, (a) is the conventional example, and (b) is the present invention.

[0036] In the conventional frequency adjustment method, the laser light is swept from the inside to the outside in the width direction of the vibrating arms 13 and 14. On the other hand, in the present invention, as described above, the laser light is swept from the outside to the inside in the width direction of the vibrating arms 13 and 14. In the conventional frequency adjustment method, as shown in FIG. 6(a), it can be seen that burrs 5 are formed on both ends in the width direction of the vibrating arms 13 and 14. Also, as shown in FIG. 7(a), it can be seen that the burrs 5 protrude from the main surface 16 of the vibrating arm 13, and the metal film 15 remains on the upper end 21 of the outer surface 17a. On the other hand, in the frequency adjustment method of the present invention, as shown in FIG. 6(b), there are almost no burrs on both ends 19 and 20 in the width direction of the vibrating arms 13 and 14. Also, as shown in FIG. 7(b), it can be seen that the metal film 15 does not remain on the upper end 21 of the outer surface 17a of the vibrating arm 13, and the irradiation mark extends to the side.

[0037] According to the above-mentioned frequency adjustment method of the tuning fork type crystal unit 10, the frequency is adjusted on the metal film formed over the entire width of one surface of the vibrating arm, so that the process of positioning adjustment for limiting the formation area of ​​the metal film is not required, and the manufacturing process of the tuning fork type crystal unit can be simplified. Also, since the formation area of ​​the metal film is widened, the frequency adjustment margin can be increased. Furthermore, since the laser light is swept from one outside of the vibrating arm in the width direction to the inside of the vibrating arm, it is possible to provide a tuning fork type crystal unit in which no burrs remain on the edge of the vibrating arm after the frequency adjustment. [Explanation of symbols]

[0038] 4. Laser light 10 Tuning fork crystal unit 11 Base 12 Metal electrode 13 Vibrating arm 13a Edge section 13b Edge section 14 Vibrating arm 15 Metal Film 15a First metal film 15b Second metal film 15c Third metal film 15d Fourth metal film 16 Main Surface 17a External surface 17b Inside surface 18a First irradiation mark 18b Second irradiation mark 19 One end 20 Other end 21 Upper end 22 Upper end 23 Outer edge 24 Inner end 25 Outer edge 26 Inner end 30 Milk crown-like molten slag 31 First Spot Row 32 Second Spot Row 33 3rd Spot Row 34 4th Spot Row 35 5th Spot Row A,B Laser light sweep direction CL center line L Spot Spacing

Claims

1. A base and A vibrating arm portion having a rectangular cross section extending from a base portion; a first metal film for frequency adjustment formed on at least one surface of the vibrating arm portion; In the tuning-fork type quartz crystal resonator, an irradiation mark of a laser beam irradiated to the vibrating arm portion is formed on the first metal film, The first metal film is formed over the entire width of the one surface, A tuning-fork-type quartz crystal vibrator in which the irradiation mark is formed at least on one side end of the first metal film in the width direction, and is also formed across a second metal film formed on one side of the vibrating arm portion adjacent to the one side end.

2. The tuning-fork type quartz crystal resonator according to claim 1, wherein the irradiation mark is also formed on the other end of the first metal film in the width direction, and is also formed across a third metal film formed on the other side of the vibrating arm portion adjacent to the other end.

3. 3. The tuning-fork type crystal resonator according to claim 2, wherein the irradiation mark is formed continuously from one end portion to the other end portion in the width direction of the first metal film.

4. 4. The tuning-fork type quartz crystal resonator according to claim 3, wherein irradiation marks formed continuously from one end portion of the first metal film to the other end portion of the first metal film in a width direction are provided in a plurality of rows in a direction perpendicular to the width direction of the first metal film.

5. A method for adjusting a frequency of a tuning fork type crystal unit, comprising the steps of: forming a laser beam irradiation mark on a metal film formed over an entire width direction of at least one surface of a vibrating arm; and adjusting the frequency of the tuning fork type crystal unit. A frequency adjustment method for a tuning-fork type quartz crystal resonator, comprising a first step of sweeping laser light from an outside of one end of the vibrating arm in the width direction toward the inside of the vibrating arm, to form a first irradiation mark from the one end of the metal film in the width direction to a predetermined inner position.

6. The method includes the first step and the second step, 6. The frequency adjustment method for a tuning-fork type quartz crystal resonator according to claim 5, wherein the second step comprises sweeping a laser beam from the outside of the other end of the vibrating arm in the width direction toward the inside of the vibrating arm, to form a second irradiation mark from the other end of the metal film in the width direction to a predetermined inner position.

7. 7. The method for adjusting a frequency of a tuning-fork type crystal resonator according to claim 6, wherein the second irradiation mark is formed on the same line as the first irradiation mark formed in the first step.

8. 7. The method for adjusting the frequency of a tuning-fork type crystal resonator according to claim 5, wherein the laser light is irradiated continuously in a width direction of the vibrating arm so that adjacent irradiation marks overlap each other.

9. 7. The frequency adjustment method for a tuning-fork type quartz crystal resonator according to claim 5, wherein the laser light is irradiated from the other surface side of the vibrating arm that faces the one surface of the vibrating arm, the other surface side being opposed to the one surface of the vibrating arm, onto a metal film formed over the entire width direction of at least one surface of the vibrating arm.

Images