GB2132816A

GB2132816A - Quartz oscillators

Info

Publication number: GB2132816A
Application number: GB08236584A
Authority: GB
Inventors: Tung Kung-Chao
Original assignee: KUNG CHAO TUNG
Current assignee: KUNG CHAO TUNG
Priority date: 1982-12-23
Filing date: 1982-12-23
Publication date: 1984-07-11
Also published as: GB2132816B

Abstract

In a quartz oscillator and method of making the same, a quartz oscillator has a glass housing (4) and a glass cover portion (2) bonded together so as to enclose the quartz member (1), with a pair of electrical leads (21) connected to the quartz member and projecting through the cover. The bonding is carried out in a vacuum chamber and a pump is employed to remove air from the glass housing. The bonding may be by gluing, infra-red thermal welding or laser thermal welding, to form a hermetic seal. The assembly may be conducted on a large scale by inverting a plurality of housings into a support. The end of the quartz member, or of the electrical leads, may be glued to the inside of the end of the glass housing. <IMAGE>

Description

SPECIFICATION Quartz oscillators This invention relates to quartz oscillators.

The cost of material for conventional quartz oscillators is rather high. The basic costs for the materials of the metal can and the glass base often take up 50% of the total cost. Also, the material needs to withstand a considerable force from vacuum techniques during production and a distortion of the material and leakage are liable to take place in the products. Therefore, the wastage of unusable oscillators is rather high.

An object of the invention is to overcome these drawbacks.

According to this invention I propose a quartz oscillator comprising a glass housing containing a quartz member and a pair of electrical leads connected to the quartz member and having a glass cover located across an open end of the glass housing and bonded to the housing, so as to enclose the quartz member in the housing with one end of the leads projecting through the cover.

I also propose a method of assembling a quartz oscillator comprising soldering a pair of electrical leads to a quartz member, aligning the connected leads and quartz member in a glass housing, locating the leads in a glass cover portion located across the open end of the glass housing, bonding the housing and cover together so as to enclose the quartz member in the hosing, and either before or after the bonding placing the housing in a vacuum chamber wherein a pump is employed to substantially remove the air from the housing.

Embodiments of this invention are described by way of example, with reference to the drawings, in which: Figure 1 is a view through part of a conventional quartz oscillator; Figure 2 is an exploded view of a new quartz oscillator in the present invention; Figure 3 shows apparatus for use in assembling quartz oscillators according to the invention; Figure 4 is a view through part of an assembled quartz oscillator o the present invention; Figure 5 is a view through part of another embodiment of a quartz oscillator according to this invention; Figure 6 shows an infrared thermal welding apparatus for use in this invention with part re moved for illustration of the invention; Figure 7 is a sectional view of the new quartz oscillator in the present invention connected with infrared thermal apparatus; and Figure 8 shows a quartz oscillator of the present invention connected with laser thermal apparatus.

A conventional quartz oscillator has a member (1), which creates oscillations upon electrical stimulation. The power supply required for the oscillation is connected via a lead (21) to a pair of electrodes (11) on the quartz member. Since the air has a damping effect, the quartz member. Since the air has a damping effect, the quartz member (1 ) must be housed in a vacuum. A glass cover portion (2) is hermetically sealed in the base of a housing can (3) to prevent air from entering into the quartz oscillator.

The quartz oscillator is assembled as follows. The quartz blank (1) and glass portion are fixed between the two lead (21). Then each electrode (11) and lead (21 are soldered together to form a soldered pad (22) and to have the electrodes (11) connected electrically with the two leads (21). The lead (21) fixes the quartz blank in place and is then fastened together with the glass bead (2). The glass bead (2) and quartz blank (1) are put inside a vacuum pump chamber and a metal can (3) is placed over the bead and fixed by means of pressure. The inner diameter of the-metal can (3) is equal to the outer diameter of the glass bead (2) and so the metal can (3) has to be expanded a small amount under a considerably high pressure before being fitted over the glass bead (2) tightly.

Upon the metal can (3) and the glass bead (2) being pressed together imperfections may be formed by virtue of for instance, deviation of position, the precision of the contact surface, and the insufficiently smooth surface may result in twisted holes. Thus, the quartz container is liable to have air leaks or the quartz blank (1) may deform the metal can (3), so that it becomes damaged. The oscillators are usually mass produced and so the loss rate is rather high.

In this invention a glass housing is employed with the glass bead (2) and these may be fitted together by means of gluing or thermal welding.

Referring to Figure 2, there is shown a quartz oscillator of the present invention, which is assembled by gluing. First a forked quartz blank (1) is inserted upside-down, and the electrode (11) and the leads (21) are soldered together to form a soldered pad (22) for electrical correction. The leads (21) fix the quartz blank (1) in place, and are attached by gluing to one another.

In Figure 3 there is shown a tray (5), having an aray of small holes in which oscillators may be housed for assembly. A tubular glass housing (4) is inverted and located in each hole and a glass cover is inserted into the housing with a glass blank (1). Now the quartz blank (1) initially glued to the inside of the housing (4) at the closed end of the housing (41) as shown in Figure 4. Through the transparent glass tube (4), the quartz blank (1) is inspected to see whether it is positioned in the centre. After the glued point "a" (41) is cured some glue is applied between the glass tube (4) and the external edge of the glass bead (2) at the open end of the housing, circular in cross section. Before the glue at the opening is cured, the apparatus is placed inside a vacuum chamber (6) to pump out the air.During pumping out the air, the glue at the glued opening of the housing between the glass tube (4) and the glass bead (2) must not have become cured completely so that the air in the glass tube (4) may be withdrawn from the housing between the glass bead and housing. Upon the air in the glass tube (4) being removed as much as possible, the glued circular seam (b) will be almost cured so that the glass tube (4) and the glass bead (2) are sealed together hermetically. When the glued circular seam "b" (42) has set the vacuum chamber means (6) is operated to apply air pressure to the sealing to improve the sealing. The tray can then be removed and the aray of oscillators is ready.

Referring to Figure 5, there is shown a view of part of another embodiment in the present invention using gluing in assembling the oscillator. A glass cover (2) installed with a forward vertical quartz blank (1) is glued together with a glass tube (4). The leads (21) are glued to the closed end of the glass tube (4) instead of the forked quartz blank. The procedure is otherwise the same as before. When the glue at the closed end "c" (43) is just about cured, the glass bead (2) and the glass tube (4) may be glued together at the open end of the tubular housing (4) by means of glued circular seam "b" (42). Thus may be automatically carried out in the tray(s) the tray is placed in a vacuum chamber means (6) to pump out the air so as to finish off the gluing between the glass bead (2) and the glass tube (4) as before.The leads and quartz blank may be soldered together in any desired manner before being housed, for example the quartz blank need not touch the closed end of the housing as in the first embodiment.

Referring to Figure 6, there is shown a quartz oscillator which is welded together by infrared heating. In Figure 8 there is shown an embodiment which is welded by means of laser heating. Before conducting these thermal welding processes, the quartz blank (1) is again first inverted in the glass housing. Then, the electrode (11) and the leads (21) are soldered together to form a soldered pad (22) so as to connect electrically the blank and leads and to facilitate the glass bead (2) with the quartz blank (1) attached to be welded to the glass tube by means of infrared or laser thermal welding. The reason for inverting installing the quartz blank (1) is to orient the soldered pad (22) away from the glass bead (2) so as to prevent the soldered pad (22) from being melted during the thermal welding.

The glass tubes (4) are each in a hole in a longitudinal channel in a support (7), as shown in Figures 6 and 7. The two lead (21) are then bent outwards and the glass bead (2) is inverted and placed in the glass tube (4). The ends of the leads (21) are rested on the top surface of the support (7).

Then, the quartz oscillators are put in a vacuum chamber means, and when the air is pumped out, infrared heating is operated for a given period of thermal welding time so as to meet the edge of the glass bead (2) and the glass tube (4) to hermatically seal them together. Then, the thermal energy source is cut off to allow the weld to set. In order to prevent the soldered pad (22) from being melted by heat, not only is the quartz blank (1) inverted, but also a cooling means is furnished.

Referring to Figure 8, there is shown a forked quartz member according to the present invention, being fitted by laser thermal welding. First, the glass tube (4) is placed on a turn table (8), and the glass bead (2) installed with quartz blank (1) is inverted and located in the glass tube (4). The bent over ends of the leads (21) are hung over the edge of a hole (82) of a supporting plate (81) that is disposed over the turn table (8). Then, the glass bead (2) is located in the glass tube (4), is placed into a vacuum chamber to pump out the air. When this has been substantially completed, the turn table (8) is started and the laser means (9) is turned on to transmit a laser beam of light directly towards the areas of the glass bead and the glass tube to be welded. These areas will be melted instantly and the housing and bead are rotated so that the laser beam melts the whole area of the tube around the glass bead.

Claims

1. A quartz oscillator comprising a glass housing containing a quartz member and a pair of electrical leads connected to the quartz member and having a glass cover located across an open end of the glass housing and bonded to the housing, so as to enclose the quartz member in the housing with one end of the leads projecting through the cover.

2. A quartz oscillator according to claim 1, wherein at least one of the other end of the leads to the end located in the cover and the quartz member is bonded to the inside of the housing at the other end of the housing to the cover.

3. A quartz oscillator according to claim 1 or 2, wherein the quartz member is forked.

4. A method of assembling a quartz oscillator comprising soldering a pair of electrical leads to a quartz member, aligning the connected leads and quartz member in a glass housing, locating the leads in a glass cover portion located across the open end of the glass housing, bonding the housing and cover together so as to enclose the quartz member in the housing, and either before or after the bonding placing the housing in a vacuum chamber wherein a pump is employed to substantially remove the air from the housing.

5. A method according to claim 4, further comprising bonding at least one of the quartz member and the other end of the leads to the end located in the cover to the inside of the housing at the other end of the housing to the cover.

6. A method according to claim 4 or 5, wherein the glass housing is inverted before the leads and quartz member are placed inside.

7. A method according to claim 4, 5 or 6, wherein when the cover and the housing are substantially bonded together, air is supplied so that the form bonding forms a hermetic seal.

8. A method according to any one of claims 4 to 7, which is carried out at the same time on an aray of oscillators in a support.

9. A method according to any one of claims 4 to 8, wherein the bonding is effected by gluing before removing the air from the housing.

10. A method according to any one of claims 4to 8, wherein the bonding is effected by infrared welding after removing the air from the housing.

11. A method according to any one of claims 4 to 8, wherein the bonding is effected by laser welding after removing the air from the housing.

12. A method according to claim 10 or 11, wherein the ends of the leads projecting from the cover are rested on a support during the welding.

13. A method according to claim 11, wherein the housing is angularly moved with respect to a stationary laser beam so as to effect bonding lineary round the entire periphery.

14. A quartz oscillator constructed and arranged substantially as herein described with reference to any of Figures 2 to 8.

15. A method of assembling a quartz oscillator, substantially as herein described with reference to any of Figures 2 to 8.