JP2003149046A - Pyroelectric sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high sensitivity, and simplify the insulation structure of conductor patterns, FETs, and terminals by shielding transmission to a pyroelectric element side of infrared rays as a disturbance light emitted to a base by a light shielding portion. SOLUTION: Since the light shielding portion 18 is formed inside the base 14 made of insulating material, transmission to the pyroelectric element 12 side of infrared rays emitted to the external surface 14b of the base 14 can be blocked. Since the base 14 is made of the insulating material, conductor pattern 34 can be formed on the internal surface 14a of the base 14 directly, and an FET 40, etc., can be mounted on this internal surface 14a directly. Besides, insulation of terminals 28, 30 can be performed with this base 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric sensor, and more particularly to a pyroelectric sensor in which, for example, infrared rays radiated on the outer surface of a base are blocked by a light-shielding portion from passing through to the pyroelectric element side.

[0002]

2. Description of the Related Art An example of a conventional pyroelectric sensor is shown in FIG. The pyroelectric sensor 1 includes a base 2 made of iron, kovar, or the like. The base 2 is provided with lead pins 3 penetrating therethrough.
The base 2 and the base 2 are insulated from each other by the insulating glass portion 4. An insulating plate 5 made of ceramics is placed on the upper surface of the base 2, and the pyroelectric element 6, FET (field effect transistor) 7a, resistor 7b, etc. are provided on the upper surface of the insulating plate 5. . These pyroelectric elements 6 etc.
It is electrically connected via a bonding wire 7c or the like. A sealing body 8 is fixed to the base 2 so as to hermetically seal the pyroelectric element 6 and the like. In the sealing body 8,
An opening 8a is formed, and an infrared transmitting portion 8b is attached to this opening 8a.

According to the pyroelectric sensor 1, infrared rays transmitted through the infrared transmitting portion 8b and applied to the pyroelectric sensor 1 can be detected with high sensitivity. That is, since the base 2 and the sealing body 8 are formed of an infrared ray shielding material such as iron or Kovar, infrared rays as ambient light hardly pass through the base 2 and the like. Therefore, the infrared ray transmitted through the infrared ray transmitting portion 8b is applied to the pyroelectric sensor 1, and the infrared ray can be detected with high sensitivity.

[0004]

In the conventional pyroelectric sensor 1 shown in FIG. 5, the base 2 is made of metal such as iron so that infrared rays as ambient light do not pass through the base 2 and enter the pyroelectric element 6. However, if a conductive material is used as the material of the base 2 as described above, the base 2 and the FET 7a are formed.
It is necessary to provide the insulating plate 5 on the base 2 in order to insulate the same from the like. Further, it is necessary to insulate the base 2 and the lead pin 3 from each other by the insulating glass portion 4. It is desired that the work of providing the insulating plate 5 and the insulating glass portion 4 be omitted.

Therefore, it is conceivable to form the base 2 with an insulating material such as ceramics. In this case, the infrared rays transmitted through the base 2 are irradiated to the pyroelectric element 6, and the infrared rays are increased. There is a problem that it cannot be detected with sensitivity.

Therefore, a main object of the present invention is to provide a pyroelectric sensor in which high sensitivity can be obtained by blocking transmission of infrared rays as disturbance light radiated to the base to the pyroelectric element side by a light shielding portion. It is to be.

[0007]

SUMMARY OF THE INVENTION The present invention provides a pyroelectric sensor in which a pyroelectric element is arranged on a base, and a lid body is provided which is combined with the base to seal the pyroelectric element. The pyroelectric sensor is characterized in that it is provided with a light-shielding portion that blocks infrared rays that enter the pyroelectric element through the base.

[0008]

According to the present invention, it is possible to prevent the infrared rays, which are the ambient light radiated to the outer surface of the base, from entering the pyroelectric element through the base by the light shielding portion formed on the base. As a result, it is possible to prevent the sensitivity of the pyroelectric sensor based on infrared rays as the ambient light from being lowered.

Further, since the infrared rays radiated to the outer surface of the base can be blocked by the light-shielding portion, the base can be enlarged in the direction of expanding the area of the inner surface of the base without lowering the sensitivity of the pyroelectric sensor. You can Accordingly, a space for mounting, for example, a conductor pattern and a transistor electrically connected to the conductor pattern on the inner surface of the base can be secured. In this case, for example, by providing the light shielding portion inside the base, the conductor pattern can be directly formed on the inner surface of the base, and the transistor or the like can be directly mounted on the inner surface.

[0010]

According to the present invention, it is possible to block the incidence of infrared rays as ambient light radiated on the outer surface of the base through the base to the pyroelectric element by the light shielding portion.
A highly sensitive pyroelectric sensor can be provided. And
Since the base itself is made of an insulating material, it is not necessary to provide the insulating plate 5 on the base in order to insulate the base from the FET and the like as in the conventional case. Further, it is not necessary to insulate the base and the terminal from each other by the insulating glass portion 4. Therefore, the insulation structure between the terminal and the FET and the base can be simplified, and the manufacturing cost can be reduced and the quality of the insulation property of the terminal can be improved as compared with the related art.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pyroelectric sensor of the present invention will be described with reference to FIGS. A pyroelectric sensor 10 of this embodiment shown in FIG. 1 has a pyroelectric element 12 inside, a base 14 and a lid 1.
6, which is hermetically sealed and is mounted on a substrate (not shown) for use. FIG. 1 shows a pyroelectric sensor 10.
FIG. 2 is a plan view of the pyroelectric sensor 10 to which the lid 16 is not attached.

As shown in FIGS. 1 and 2, the base 14 is a disk-shaped member having a diameter of about 7.0 mm and a thickness of about 2.3 mm. The material of the base 14 is, for example, glass having an insulating property and containing ceramics, and its main composition is borosilicate glass mixed with alumina, zirconia, or the like. Also, inside the base 14,
A light shielding unit 18 is provided.

As shown in FIG. 1, the light shielding portion 18 is a disk-shaped member having the same diameter as the base 14 and a thickness of about 0.1 mm. The light shielding portion 18 is sandwiched inside the base 14 in a state of being parallel to the plate surface of the base 14, and is fixed to the base 14. In this way, the light shielding portion 18 is formed over the entire base 14.
The light shielding portion 18 is formed of a metal such as nickel alloy, kovar, iron, or the like that shields infrared rays and electromagnetic noise, that is, an infrared ray shielding material. A lid supporting portion 20 is provided on the outer peripheral surface of the base 14 so as to surround the outer peripheral edge of the light shielding portion 18.

In the method of manufacturing the base 14 provided with the light shielding portion 18, for example, the inner surface side member and the outer surface side member of the base 14 are molded beforehand. Then, the disc-shaped light-shielding portion 18 is sandwiched between the two disc-shaped inner surface side members and the outer surface side member, and is fitted into the lid support portion 20. Next, the inner surface side member and the outer surface side member fitted in the lid support portion 20 are heated to melt and then cooled to solidify, whereby the base 14 is completed. The light-shielding portion 18 is provided inside the base 14 manufactured in this manner, and the base 14 and the light-shielding portion 1 are provided.
The outer peripheral surface of 8 adheres closely to the inner peripheral surface of the lid supporting portion 20,
The outer peripheral surface of 4 is fixed to the inner peripheral surface of the lid supporting portion 20.

As shown in FIGS. 1 and 2, the lid supporting portion 20 is a cylindrical portion 2 which is tightly joined to the outer peripheral surface of the base 14.
It has 0a. At the lower edge of the tubular portion 20a,
An annular flange 20b is formed in a direction projecting outward, and an annular coupling portion 20c is formed in a direction projecting inward at the upper end peripheral edge of the tubular portion 20a. Then, the holding portion 2 is provided at one predetermined position on the inner edge of the coupling portion 20c.
2 is formed integrally with this lid support portion 20. The holding portion 22 is for holding the pyroelectric element 12 together with a holding portion 24 which will be described later, and is formed by bending an upper end portion of a plate-like body into an L shape. The two holding portions 22 and 24 are
It is arranged parallel to the vertical direction. Both ends of the pyroelectric element 12 are fixed to the upper end portion, and the pyroelectric element 12 is supported in this state. The connecting portion 20c is for strengthening the connecting force between the lid supporting portion 20 and the base 14. The inner peripheral surface of the tubular portion 20a of the lid supporting portion 20 is in contact with the outer peripheral edge of the light shielding portion 18 over the entire circumference. Further, the contact surface between the inner peripheral surface of the lid supporting portion 20 and the outer peripheral surface of the base 14 is hermetically sealed.

The pyroelectric element 12 produces a sensor output according to the amount of infrared rays emitted by utilizing the pyroelectric effect. That is, the pyroelectric element 12 has spontaneous polarization, and surface charges are constantly generated, but in the steady state in the atmosphere, the pyroelectric element 12 is electrically neutralized by being combined with the charges in the atmosphere. When the pyroelectric element 12 is irradiated with infrared rays,
The temperature of the pyroelectric element 12 rises, and along with this, the charge state of the surface also breaks and the neutral state changes. At this time, the amount of infrared irradiation is measured by detecting the charges generated on the surface.
The pyroelectric element 12 is a pyroelectric material such as Pb (T
iZr) O3, PbTiO3, or another ceramic material.

Further, as shown in FIGS. 1 and 3, three elongated plate-shaped terminals 26, 28 and 30 penetrate the base 14 in the vertical direction. Each of the terminals 26, 28 and 30 is fixed to the base 14 in a state where the contact surface with the base 14 is hermetically sealed. This base 14
Since the material is glass, the airtightness of the contact portion with each terminal 26 can be reliably maintained. The terminals 26, 28 and 30 are arranged at a predetermined interval, and the upper ends of the two terminals 26, 28 are formed on the inner surface (upper surface) 14 a of the base 14. The conductive patterns 32 and 34 are electrically connected.
Then, as shown in FIG. 2, the upper end portion of the remaining one terminal 30 is electrically connected to the coupling portion 20c of the lid supporting portion 20.

That is, one electrode of the pyroelectric element 12 shown in FIG. 2 is electrically connected to the terminal 30 via the right holding portion 22 and the coupling portion 20c (lid supporting portion 20). This terminal 30 is a ground terminal. And the pyroelectric element 1
The other electrode of 2 is electrically connected to the conductor pattern 36 via the holding portion 24 on the left side. This holding portion 24 is
The lower end is embedded and fixed in the base 14,
The conductor pattern 36 is formed on the inner surface 14 a of the base 14.

Further, each of the three terminals 26, 28 and 3 is
0 is inserted into each of the three terminal insertion holes 38 formed in the light shielding portion 18, and is arranged at a distance from the inner peripheral edge of each terminal insertion hole 38. Therefore, each terminal 26, 2
8 and 30 and the light shielding portion 18 are electrically insulated. The base 14 is interposed between the inner peripheral edge of each terminal insertion hole 38 of the light shielding portion 18 and each of the terminals 26, 28 and 30.

As shown in FIGS. 1 and 2, conductor patterns (conductor patterns are schematically shown in FIG. 2) 32, 34 on the inner surface 14a of the base 14.
And 36 are formed, and FETs (field effect transistors) 40, 40, resistors (not shown) and the like are also mounted on the inner surface 14a. These pyroelectric elements 12,
FETs 40, 40, resistors and terminals 26, 28, 30
Are holding portions 22, 24, conductor patterns 32, 34, 36
And electrically connected via a bonding wire (not shown). The FETs 40 and 40 and the resistor form a signal processing circuit that performs signal processing of the sensor output generated by the pyroelectric element 12. The FET 40 is for amplifying the sensor output, and the resistor is the pyroelectric element 1
This is for stabilizing the sensor output of No. 2.

The lid 16 has a circular shape in plan view which is substantially the same as the outer contour shape of the lid supporting portion 20, and has a cup shape which opens downward. An annular collar-shaped portion 16a is formed on the lower opening edge of the lid body 16 in a direction projecting outward. The lid 16 has a lower surface of a flange portion 16a of the lid 16 so as to cover the pyroelectric element 12 and resistance.
Resistance welding (electric welding) is performed on the upper surface of the collar-shaped portion 20b of the lid supporting portion 20. Then, as shown in FIG.
For example, a circular opening 16b is formed in the upper wall, and the infrared transmitting portion 42 is attached to the opening 16b. The infrared ray transmitting portion 42 is a transparent plate-like member formed of a conventionally known infrared ray transmitting material such as silicon, and hermetically seals the opening 16b.

The lid 16 has an inner surface 14 of the base 14.
In order to hermetically seal the pyroelectric element 12 mounted on a, the resistance, etc., and to prevent infrared rays as disturbance light radiated to the outer surface of the lid 16 from transmitting to the inner pyroelectric element 12 side. belongs to. However, the pyroelectric sensor 10 is irradiated with the infrared rays that have passed through the infrared transmitting section 42, and the infrared rays can be detected with high sensitivity.

The material of the lid 16 is an infrared ray shielding material such as nickel silver (Cu-Ni-Zn alloy). The material of the lid support portion 20 is a conductive material having an infrared ray shielding function such as nickel silver (Cu-Ni-Zn alloy). The material of the terminal is, for example, Kovar (Fe-Ni-Co alloy), and the material of the conductor pattern is, for example, nickel, gold or silver, both of which are conductive materials.

According to the pyroelectric sensor 10 shown in FIG. 1, the infrared rays as the disturbance light radiated to the outer surface 14b of the base 14 pass through the base 14 and enter the pyroelectric element 12 on the inside. It can be blocked by the formed light blocking portion 18. As a result, it is possible to prevent the sensitivity of the pyroelectric sensor 10 from decreasing due to the infrared rays as the ambient light.

Further, the lid 16 has a pyroelectric element 1 in which infrared rays as disturbance light with which the outer surface of the lid 16 is irradiated are inside.
Since it is possible to block the transmission to the second side, the pyroelectric sensor 10 is irradiated with the infrared rays transmitted through the infrared transmission section 42, and as a result, the infrared rays can be detected with high sensitivity.

Infrared rays radiated to the outer surface 14b of the base 14 can be blocked by the light blocking portion 18, so that the area of the inner surface 14a of the base 14 can be increased without lowering the sensitivity of the pyroelectric sensor 10. Base 14
Can be increased. This allows the base 14
It is possible to secure a space for providing the conductor patterns 32, 34, 36, the FETs 40, 40 electrically connected to the conductor patterns 32, 34, 36, and a signal processing circuit such as a resistor on the inner surface 14a. Since the light-shielding portion 18 is provided inside the base 14, the conductor patterns 32, 34, 36 can be formed directly on the inner surface 14a of the base 14, and the FET 40 and the resistor, etc. can be directly formed on the inner surface 14a. Can be implemented.

As described above, since the base 14 itself is formed of the insulating material, it is not necessary to provide the insulating plate 5 on the base 14 in order to insulate the base 14 and the FET 40 from each other as in the conventional case. It is not necessary to insulate the base 14 and the terminals 26, 28, 30 from each other by the insulating glass portion 4. Therefore, the terminals 26 etc. and the FE
The insulating structure between the T40 and the base 14 can be simplified, the manufacturing cost can be reduced as compared with the conventional case, and the terminal 2 can be provided.
It is possible to improve the quality of the insulation properties such as 6.

Furthermore, since the base 14 is made of an insulating material, when the pyroelectric sensor 10 is soldered to a substrate (not shown), the base 14 and the terminals 26 and the like contact each other, and Even if 14 and a board-side conductor pattern (not shown) formed on the board are in contact with each other, a short circuit between them does not occur. Therefore, the short circuit failure can be eliminated.

However, in the above embodiment, as shown in FIG. 1, the light shielding portion 18 is provided inside the base 14. However, instead of this, the light shielding portion 18 is provided on the inner surface 1 of the base 14.
4a or the outer surface 14b may be provided. When the light-shielding portion 18 is provided on the inner surface 14a of the base 14, the light-shielding portion 18 includes the conductor pattern 32, the holding portion 22,
24, FETs 40, 40, and the resistor so as not to be electrically connected. Then, the light shielding portion 18 is attached to the base 14
When provided on the outer surface 14b of the
6 and the like are formed so as not to be electrically connected. Then, it is preferable that the light shielding portion 18 and the lid supporting portion 20 are in contact with each other. This is because infrared rays as ambient light are prevented from passing through the gap between the light shielding portion 18 and the lid supporting portion 20 to the inside of the pyroelectric element 12 side.

In the above embodiment, the base 14 is made of glass containing ceramics having an insulating property, but other materials having an insulating property may be used.

In the above embodiment, the surface mount type pyroelectric sensor 10 has been described as an example, but the pyroelectric sensor of the present invention can be applied to the discrete type.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a pyroelectric sensor of the present invention.

FIG. 2 is a plan view showing a pyroelectric sensor to which the lid body of FIG. 1 embodiment is not attached.

FIG. 3 is a bottom view showing the pyroelectric sensor of the embodiment of FIG.

FIG. 4 is a partial cross-sectional view of the pyroelectric sensor of FIG. 1 viewed from a side surface direction.

FIG. 5 is a vertical sectional view showing a conventional pyroelectric sensor.

[Explanation of symbols]

10 ... Pyroelectric sensor 12 ... Pyroelectric element 14 ... Base 14a ... Inner surface 14b ... outer surface 16… Lid 18 ... Shading section 20 ... Lid support 22, 24 ... Holding unit 26, 28, 30 ... Terminal 32, 34, 36 ... Conductor pattern 38 ... Terminal insertion hole 40 ... FET 42 ... Infrared transmitting part

Claims (4)

[Claims] 1. A pyroelectric sensor having a pyroelectric element disposed on a base, and a lid body which is coupled to the base to seal the pyroelectric element, wherein the base is made of an insulating material, and A pyroelectric sensor comprising a light-shielding portion that blocks infrared rays that enter the pyroelectric element through a base. 2. The pyroelectric sensor according to claim 1, wherein the light shielding portion is formed inside the base, and a conductor pattern is formed on an inner surface of the base. 3. The pyroelectric sensor according to claim 1, wherein the light shielding portion is formed over the entire base. 4. The pyroelectric sensor according to claim 1, wherein the material of the base is glass.