JP2603384Y2 - Pyroelectric infrared detector - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric infrared detector used in a human body detection system and the like, and more particularly to a pyroelectric infrared detector which minimizes the influence of external noise.

[0002]

2. Description of the Related Art As is well known, when a pyroelectric body receives infrared rays, it absorbs its thermal energy and causes a change in temperature, causing a change in spontaneous polarization and a charge on the surface. In this way, charge is induced on the surface in proportion to the minute temperature change,
This charge is detected as a current or a voltage by an external circuit. The pyroelectric infrared detector uses such a pyroelectric effect and is used for human body detection and the like.

FIG. 3 shows a configuration example of a conventional pyroelectric infrared detector.
It will be explained together. Three lead terminals 731, 732, and 733 protrude from the upper surface of the metal base 73, and three points of the printed wiring board 72 are supported on these lead terminals,
Further, circuit components 721 and 722 and supports 761 and 762 are mounted on the upper and lower surfaces of the substrate, and the pyroelectric element 71 is supported on the support. Then, a flat optical filter 75 is joined to a metal cap 74 having a light incident window, and these components are covered with the cap 74. The optical filter 75 has a non-insulating substrate made of a conductor or semiconductor such as a silicon wafer as a base,
A frequency-selective insulating film (not shown) for transmitting infrared light is formed on at least one of the front and rear surfaces,
Thereafter, it is obtained by cutting into a predetermined size and shape. Since the conductor or the semiconductor portion is exposed on the cut surface (that is, the side surface), the metal cap and the optical filter are electrically connected to the cap 74 including the cut surface by the conductive bonding material S. It conducts and provides electrical shielding. In addition, as shown in FIG.
In order to improve airtightness in bonding to the cap, first, for example, preliminary bonding is performed with an epoxy resin-based insulating bonding material S1 and then electrical bonding is performed with a conductive bonding material S2. In the same manner, electrical shielding can be performed. The optical filter 75 has a configuration in which a frequency-selective insulating film 752 is provided on the front and back surfaces of a non-insulating substrate 751.

[0004]

The infrared detector as described above receives not only infrared rays but also other electromagnetic waves emitted from various electric devices through an optical filter. These other electromagnetic waves become harmful noises for the infrared detector and cause malfunction in infrared detection. By performing the above-described electrical shielding, other electromagnetic waves are grounded from a specific lead terminal via a metal cap and a metal base. As a result, the malfunction can be reduced to a certain level. However, recently, mobile communication and the like have rapidly increased, and high-frequency electric field noise generated from these has been sometimes insufficient with the above-mentioned shield, in combination with a large transmission output. In other words, the conductor or semiconductor portion exposed on the cut surface of the optical filter has a small surface area, and has a configuration in which surface tension is difficult to obtain, so that sufficient conduction cannot be obtained. This has caused a malfunction. Further, as shown in a partially enlarged cross-sectional view near the light incident window in FIG. 4, when the preliminary bonding is performed with an insulating bonding material, the bonding material for the preliminary bonding protrudes from the bonding surface between the cap and the optical filter. In some cases, many portions of the cut surface of the optical filter are covered. In such a case, the conductive bonding material applied later may not sufficiently adhere to the cut surface, and necessary conduction may not be obtained.

The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a pyroelectric infrared detector which has less malfunction even when high-frequency electric field noise having a large transmission output is incident on the infrared detector. It is the purpose.

[0006]

In order to solve the above problems, a pyroelectric infrared detector according to the present invention comprises a non-insulating substrate as a base inside a light incident window formed in a metal cap. At least an optical filter formed with a frequency-selective insulating film for transmitting infrared light on its surface is attached, and a pyroelectric infrared ray is formed by housing a pyroelectric element at a predetermined position inside a cap corresponding to the optical filter. A detector, wherein a portion of the non-insulating substrate is partially or entirely cut in the thickness direction on the non-insulating substrate in the vicinity of the outer periphery of the pyroelectric element, thereby exposing a portion of the non-insulating substrate. A thick portion and a thin portion are provided, and the optical filter abuts the opposite surface of the cut portion formation on the metal cap, and joins the thin portion and the metal cap with an insulating bonding material, The thick part An attribute cap conductive bonding material is characterized in that the electrical and mechanical joining.

[0007]

The surface on the pyroelectric element side near the outer periphery of the optical filter is partially cut to form a cut portion having a thin portion and a thick portion. In this cut portion, a non-insulating portion made of a conductor or a semiconductor of the optical filter is largely exposed. By applying a conductive bonding material to this portion and conductively bonding with the cap, the conduction state is improved and the electrical connection is improved. The shield is strengthened. Therefore, it is possible to sufficiently ground unnecessary electromagnetic waves that become noise. In addition, since a large surface tension can be obtained, the mechanical connection strength can be enhanced.

In the case of joining the cap and the optical filter in advance by preliminarily bonding with an insulating bonding material and then bonding the two with a conductive bonding material, as shown in FIG. The bonding material stops at a boundary portion (edge portion) of the thin portion due to surface tension. Therefore,
Since the cut portion of the thick portion can be kept exposed, sufficient electric shielding can be performed by applying the next conductive bonding material to the cut portion of the thick portion.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to the drawings, taking a pyroelectric infrared detector as an example. FIG. 1 is a sectional view of a pyroelectric infrared detector. The pyroelectric element 1 is made of a lead titanate-based pyroelectric ceramic, is polarized in the thickness direction, and is cut into a rectangular shape. Although not shown, two light receiving metal film electrodes (such as Cr or Ni—Cr) are provided on the front surface of the pyroelectric element 1 at predetermined intervals, and on the back surface, the light receiving metal film is provided. A metal film electrode (Ag or the like) corresponding to the electrode is provided. Note that the light receiving electrodes are commonly connected.

The pyroelectric element 1 is mounted on a printed wiring board 2 via supports 61 and 62. Further, circuit components 21 and 22 such as FETs and resistors constituting an external circuit are attached to the back surface of the printed wiring board 2 to make necessary electrical connections with the pyroelectric element. Base 3
The lead terminals 31 and 32 are planted in a metal shell 3a via insulating glass, and the lead terminal 33 is planted in a state of being electrically connected to the shell 3a. The printed wiring board is mounted on these lead terminals, and necessary electrical connections are made.

The cap 4 for sealing these components is made of metal, and a light incident window 41 is provided on the upper surface. FIG. 2 is an enlarged cross-sectional view of the optical filter portion of FIG. 1. As shown in FIG. 2, the optical filter 5 attached inside the light-incident window 41 includes a non-insulating substrate 51 such as silicon. Frequency-selective insulating film 52 for transmitting only infrared rays on the front and back surfaces of (conductor or semiconductor)
And the pyroelectric element side near the outer periphery of the optical filter is cut, the non-insulating substrate 51 below the insulating film 52 is exposed, and the cut portion 5a having a thin portion and a thick portion is formed. Has formed. First, an epoxy resin-based insulating bonding material S1 is applied to the opposing surfaces of the cap 4 and the optical filter 5, and these are brought into contact with each other to mechanically perform preliminary bonding. Even if the applied amount of the insulating bonding material S1 used here is large, the insulating bonding material S1 stops at the edge of the thin portion of the cutting portion 5a due to its surface tension. Then, by applying the conductive bonding material S2 to the cut portion 5a of the thick portion, the cap 4 and the optical filter 5 are electrically connected and the mechanical connection is strengthened. After mounting the necessary components on the base, the cap is hermetically sealed to complete the pyroelectric infrared detector.

If necessary, an epoxy-based bonding material or the like may be applied on the conductive bonding material to enhance mechanical bonding or airtightness. When a conductive bonding material having excellent airtightness is used, the pre-adhesion is not required as described above, and electrical and mechanical bonding may be performed using only the conductive bonding material. Further, the circuit components need not necessarily be arranged inside the cap, and may be configured to be externally attached to an external printed circuit board or the like.

[0013]

According to the present invention, the surface on the pyroelectric element side near the outer periphery of the optical filter is partially cut to form a cut portion having a thin portion and a thick portion. Since a non-insulating portion made of a conductor or a semiconductor is largely exposed, a conductive bonding material is applied to this portion and conductively bonded to the cap, thereby improving the conduction state and strengthening the electric shield. In particular, in joining the cap and the optical filter, when preliminarily bonding with an insulating bonding material, and then bonding the two with a conductive bonding material, the insulating bonding material that is bonded first has a thin portion. It can be stopped at the boundary part (edge part) by surface tension. Therefore, a state where the cut portion of the thick portion is exposed can be ensured, and sufficient electrical shielding can be performed by applying the next conductive bonding material to the cut portion of the thick portion. As described above, it is possible to sufficiently shield unnecessary electromagnetic waves that become noise and to ground them.
Even if high-frequency electric field noise having a large transmission output from a mobile communication device, which has been rapidly increasing recently, enters this infrared detector, a pyroelectric infrared detector with less malfunction can be obtained. Further, since a large surface tension can be obtained, the mechanical connection strength can be enhanced, and the airtightness of the cap can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a pyroelectric infrared detector according to the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a sectional view showing a conventional example.

FIG. 4 is a partially enlarged sectional view showing another conventional example.

[Explanation of symbols]

1, 71 Pyroelectric element 2, 72 Printed wiring board 3, 73 Base 31, 32, 33, 731, 732, 733 Lead terminal 4, 74 Cap 5, 75 Optical filter 5a Cutting part

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01J 1/02-1/06 G01J 5/02 G01V 9/04 G08B 13/19-13/191 G08B 17 / 00

Claims (1)

(57) [Scope of request for utility model registration] Inside of 1. A light entrance window which is formed on the metal cap, attach the optical filter and the non-insulating substrate to form a frequency-selective insulating film for transmitting infrared rays to at least the surface of the substrate A pyroelectric infrared detector including a pyroelectric element housed in a predetermined position inside a cap corresponding to the optical filter, wherein the non-insulating substrate has a portion near an outer periphery on a pyroelectric element side. Or by forming a cut part that is cut in the thickness direction
Thick and thin portions where a part of the non-insulating substrate is exposed.
Is provided, and the optical filter is opposite to the cut portion formation.
The thin portion and the metal
With the conductive cap with an insulating bonding material,
The thick portion and the metallic cap are electrically connected with a conductive bonding material.
A pyroelectric infrared detector characterized by being mechanically joined .