JP3018222U - Planarizing packing device for pyroelectric IR thermal sensing element - Google Patents

Abstract

(57) [Summary] [Object] To provide a flattening packing device for a pyroelectric IR thermal sensing element having a relatively large viewing angle without increasing cost or volume. [Structure] Two pyroelectric thermal sensing elements A1, A2 on top
And a circuit board 201 on which electrical elements related thereto are provided, and a cover having a window and an IR filter plate 308. A recess 305 is formed in a portion of the circuit board where the pyroelectric heat sensing element is mounted, and the pyroelectric heat sensing element is mounted so as to straddle the recess. The electrothermal sensing elements are formed so as to be positioned at an angle of 5 ° to 45 ° so as to be lifted and supported, and the inclination angles of the pyroelectric thermal sensing elements are adjusted as desired. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a flattened packing device for a pyroelectric IR thermal sensing element, and in particular to a device with a relatively large viewing angle for sensing.

[0002]

[Prior art]

 Recently, heat sensitive security monitor systems have become popular. The essence of such a system has been embodied as a result of the development of pyroelectric IR thermal sensing elements. The principle of operation of this pyroelectric IR thermal sensing element is that the element generates a corresponding electrical signal in response to an IR heat wave emitted from a nearby person or heat source. This electrical signal is amplified by an amplification circuit for preventive warning or activation function and security purpose. Such a pyroelectric IR heat sensing element has the following effects.

1. Since the pyroelectric function is itself an integral function of time, it can automatically suppress the background (static background heat source), resulting in a dynamic sensing effect and signal processing. Make it easy.

2. Since pyroelectricity is automatically generated without applying a bias voltage, noise from the bias voltage can be avoided.

3. The device can be formed by the simple techniques used to form typical ceramic capacitors. These devices are cheap to manufacture because they can only be formed by coating the electrodes on top and depositing a black body film on top.

With the above effects, an inexpensive and non-contact radiant heat sensing element that can operate at room temperature can be realized. Recently, such thermal sensing elements are widely used in security systems for the purpose of robbery and fire protection, as well as sensing devices used for light control to save power. As a result, further research is now being conducted on pyroelectric IR thermal sensing elements.

Generally, the heat sensing element needs to be formed as thin as possible so as to reduce the heat capacity, and at the same time, the structure lifted to reduce the heat loss, that is, increase the thermal impedance. Must be formed into. Therefore, some of the thermal energy is absorbed by the element, and the temperature of the element rises, that is, the thermal response increases. Therefore, the pyroelectric response is high. The requirement for thin lift support structures complicates the adhesive technique of assembling the sensing element and thus the manufacture of the pyroelectric IR thermal sensing element. That is, in general, complex structures and devices must be further improved in forming radiant heat sensing elements.

FIG. 1 shows an equivalent circuit of a known two-piece pyroelectric sensing element (indicated by the box within the dashed line). Here, the pyroelectric thermal sensing elements A1 and A2 are formed of a sheet of a pyroelectric material such as LiTaO ³ , PZT, PVF2 and TGS. Each of the pyroelectric sensing elements A1 and A2 is provided with electrodes on both sides, and a black main body film is coated on the upper surface to enhance the heat absorption effect. The two sheet sensing elements are excreted so that their polarities are opposite to each other, as shown by arrows, that is, one of them faces upward and the other faces downward. The static charge or voltage generated by the thermal induction of the elements A1 and A2 is transmitted to a high impedance field effect transistor (JFET) Q 1 which functions as an impedance buffer for an external circuit. This field effect transistor Q outputs a signal from the terminal L2. A high resistance load resistor RL is provided between the outputs of the sheet-like sensing elements A1 and A2 for enhancing the leakage balance of the pyroelectric inductive charge, transmitting low frequency noise, and selecting the bandwidth for the circuit. It is connected to the. The reason for providing the two pieces is to eliminate the common mode signal caused by the change in the background heat radiation and the faint noise caused by the vibration. The combination of the above elements must be installed in a sealed metal container to prevent the reduction of the signal to noise ratio due to the interference of electromagnetic noise. As shown in FIG. 6, when the element S is used in a thermal induction system, a complex IR focusing lens array L is placed in front of this element to divide the field of view of the system into a plurality of smaller fields of view. As a result, heat waves from the moving heat radiator, such as heat waves from a person, are alternately reflected and absorbed on the two pyroelectric sensing elements. Therefore, high and low temperatures are alternately generated in the two elements, and a differential signal having a frequency of about 1 to 10 Hz is generated and output.

2 and 3 respectively illustrate different types of commonly used pyroelectric IR thermal sensing devices. As shown in FIG. 2, a pair of strip-shaped insulating pads 102 and 103 are pre-bonded to the metal base 101. Then, on this pad, a pair of pyroelectric sheet elements A1 and A2 (as shown in FIG. 1) are bridged at the focal point position of the optical system. Further, other elements such as the field effect transistor J FET and the load resistance RL as shown in FIG. 1 are provided on the pad 104 fixed to the metal base 101 so as not to be short-circuited to the base. . After such assembly, the necessary circuit connections are made by an ultrasonic wire welding process such as known semiconductor device packing techniques. The structure is then sealed by welding cover 106. A long wavelength infrared filter 105 made of multi-layer silicon is bonded to the cover in order to transmit heat waves having a wavelength of 6 to 14 microns but to block background light having other wavelengths.

In another type of pyroelectric IR heat sensing device, shown in FIG. 3, a plurality of curved weld wire rings 108 are provided on a ceramic insulating pad 107. And, a pyroelectric sheet element (illustrated schematically by reference numeral A) is attached to the upper end of the welding wire ring 108 to provide a lifted and supported thermal insulation structure.

[0011]

[Issues to be solved by the device]

 Both types of pyroelectric IR heat sensing devices use a technique of lifting, supporting, and stacking for the purpose of thermal insulation, which involves a relatively complex packing of the elements and the completed device. Therefore, it is not suitable for automatic manufacturing and the manufacturing cost increases. In addition, metal bases are expensive, occupy a relatively high percentage of material cost (about 25%), and insulating pads must be provided for the metal conduction of the base, which reduces manufacturing costs. Substantially higher.

In order to deal with the above drawbacks, a pyroelectric IR heat sensing device as shown in FIG. 4 has been proposed (ROC utility model registration No. 67164). In this device, a conductive copper foil 204 having a special circuit design is formed on the double-sided circuit board 201. The elements A1 and A2 as shown in FIG. 1 are arranged and connected on the copper foil by using the surface mount technology (SMT). A plurality of through holes 202 are formed in the circuit board 201, and the pins 203 are inserted into these through holes and attached by the automatic riveting technique. This serves a positioning function such that the pyroelectric element is precisely positioned in the desired position during the assembly process. This ROC utility model registration No. In the structure of 67164, the lower cut recess 205 is formed in the area of the circuit board on which the sheets of the pyroelectric elements A1 and A2 are arranged, and the sheet of the pyroelectric elements A1 and A2 is cut into the lower cut recess 205. It is characterized by being bridged over the area. This lower cut recess 205 is widened together with the copper foil 204. A side cross section of this structure is shown in FIG. When the pyroelectric elements A1, A2 are bridged over the area of the recess 205, a lifted and supported framework is formed and an excellent thermal insulation effect is obtained. On the other hand, in such a lifting and supporting structure, since the pyroelectric sheet elements A1 and A2 are all arranged on the same plane of the circuit board as other additional elements, automatic assembly is possible. Work can be done using surface mount technology and equipment. Furthermore, since the circuit board itself is electrically insulating, it is not necessary to add an insulating pad. Also, because the circuit board can be laid out to meet a variety of applications, the number of ultrasonic wire welds can be reduced. Further, the double side circuit board can effectively prevent the interference of electromagnetic noise.

After being assembled and tested, the device shown in FIGS. 4 (a) and 4 (b) can be loaded into a cover case. As shown in FIG. 5, an IR window 207 for accommodating the laminated thermal IR filter plate 208 is formed on the upper portion of the cover 206. This filter plate transmits radiant heat energy. Further, the cover 206 has a flange (not shown) on the inner edge of the cover 206, and when the circuit board 201 is placed in the cover 206, the circuit board 201 accurately abuts on the flange, and The relative distance between the electrical elements A1 and A2 and the IR window 207 is kept constant to improve the accuracy of optical sensitivity. Finally, an epoxy resin is injected on the side of the circuit board 201 opposite to the side located inside the cover 206, and thermally cured and sealed. The cover 206 can be formed of a metal molded by a press technique or a synthetic resin molded by an injection molding technique and lined with a metal so as to provide electric and noise insulation and water resistance.

Furthermore, many pins to be inserted into the through holes 202 of the circuit board 201 are not required. After being assembled and tested, a structure such as that shown in FIGS. 4 (a) and 4 (b) has the end of a known TO metal base pin (member 210 shown in FIGS. 7 (a) and 7 (b)). It can be welded to the part and lifted from the base surface. The metal cover with the filter window is then welded using standard TO metal packing equipment to obtain the final product.

The above conventional technique has the following effects.

1. Since all components are mounted on one plane of the same circuit board, the commonly used surface bonding equipment simplifies the process for automated assembly operation, ensuring the lowest cost and quality. You can get a good product.

2. The pre-pressed lower cut recess 205 allows the pyroelectric element to be lifted and placed on the recess with a support structure without the use of a pad, reducing process steps and material. Can be saved and the cost of the device can be reduced.

3. Since a circuit board is used as a base, it is not necessary to use an expensive metal base. 4. Since no insulating pad is required for the sensing element, material costs and process steps can be reduced.

5. By making layout connections on the circuit board, the number of wire welds can be reduced.

However, the above ROC utility model registration No. All conventional devices, including the device disclosed in 67164, suffer from the drawback that the wide viewing angle of the thermal sensing element is limited to within 110 °. In addition to this viewing angle, material costs and device volume increase. The reason for this will be described below with reference to FIGS. 7 (a) and 7 (b).

FIG. 7A shows ROC utility model registration number. 67164 is a cross-sectional view of a packing structure of the device disclosed in 67164. FIG. From the rays rm1, rm2 it can be seen that the sensing device of such an arrangement has a maximum viewing angle θm of about 110 °. In use, such a viewing angle does not fully cover a half cycle, ie, 180 ° viewing angle, as it is blocked by the wall (as shown in FIG. 6). Two methods can be applied to increase this viewing angle.

The first way is to increase the dimension of the window 207 for the filter plate 208, ie W in the figure. However, in this method, since the filter plate 208 which passes the thermal IR of the wavelength of 8 to 14 microns is formed by the expensive silicon chip on which the 10 germanium film and the zinc sulfide film are coated, Increase both material costs and packing volume. Therefore, this filter is expensive and time consuming to manufacture. Furthermore, as the dimensions increase, so does the metal base used, increasing volume and material costs.

The second method is to shorten the distance H between the heat sensing elements A1 and A2 and the filter plate 208 as shown in FIG. 7 (a). This method does not have the drawbacks of the first method. However, the welding wire 209 must be connected to the upper surface of the heat sensing elements A1, A2 in order to connect with an external circuit, which requires a gap for the welding wire 209. This requires a larger volume and the viewing angle cannot be improved properly. That is, increasing the viewing angle is an unfavorable drawback to the cost and volume of the device.

In order to solve the problems related to the prior art, the first object of the present invention is to register the ROC utility model registration number. It is to provide a flattened packing device as well as a structure for a pyroelectric IR thermal sensing element improved from 67164.

Another object of the present invention is to provide a planarization packing device and structure for a pyroelectric IR thermal sensing element having a relatively large viewing angle without increasing cost or volume.

The other objects, effects and aspects of the present invention will be understood from the specification text.

[0027]

[Means for Solving the Problems]

 The flattening packing device for a pyroelectric IR thermal sensing element of the present invention comprises a circuit board having two pyroelectric thermal sensing elements and associated electrical elements thereon, a window and an IR. A cover having a filter plate, and a recess is formed in a portion of the circuit board where the pyroelectric heat sensing element is mounted, and the pyroelectric heat sensing element straddles the recess. In this way, the recess is formed so that the pyroelectric thermal sensing element is positioned so as to be inclined and lifted up and supported therein, and the inclination angle of these pyroelectric thermal sensing elements is desired. Adjusted accordingly.

[0028]

【Example】

 The present invention is based on R.P. O. C Utility model registration No. This is for further enlarging the viewing angle of the pyroelectric IR heat sensing device based on 67174. As shown in FIGS. 8 and 9, the flattened backing structure of the pyroelectric IR heat sensing device of the present invention includes a base 301, a cover 306 having an IR window 307 and an IR filter plate 308. It is equipped with. A recess 305 having a special shape is formed on the base 301. The recess 305 is formed on the upper surface of the base 301 by a pressing technique. The heat sensitive elements A1, A2 are located across the width of the recess 305 so as to form a lifted and supported structure.

Although the recess 305 has a rectangular shape, two pairs of recesses 305 ′ facing each other and extending in opposite directions are formed on both sides of the recess 305 that contact the heat sensing elements A 1 and A 2. As a result, the recess 305 is longer than the heat sensing elements A1 and A2 at the recess 305 '. The widths of the recesses 305 'are narrower than those of the heat sensing elements A1 and A2, respectively. Therefore, when the heat sensing elements A1 and A2 are welded to the base 301 (at the welding point 310), as shown in FIG. While facing each other, it stops in the recess 305 and partially falls in the recess 305 so as to be inclined with respect to the recess 305.

As shown in FIG. 9A, the tilted and supported structure of the present invention has the following effects.

(1) Due to the tilted and raised support, the outer edges of the heat sensing elements A1 and A2 separated from each other are shown in FIG. It is separated from the filter plate 308. As a result, the viewing angle of the device can be increased.

(2) In the structure in which the conventional heat sensing element is horizontally arranged as shown in FIG. 7, the “projection exposure” of the light incident on the heat sensing element is a projection of the incident light amount and the incident angle of the light. , That is, cos α, is calculated. Thus, the effective amount of received light changes depending on the incident angle. When the incident angle approaches 90 °, cos α approaches zero, and the sensitivity of the heat sensing device becomes low, making it difficult to increase the effective viewing angle. . In the structure of the present invention as shown in FIG. 9 (a), since the heat sensing element is inclined, the incident angle of light on the heat sensing element (α ′ in FIG. 9) is as shown in FIG. It is reduced to be smaller than α shown in 7. As a result, the effective amount of received light is much larger than that of the conventional structure. As shown in FIG. 10, the far field profile theory of signal strength at various tilt angles was calculated. From this figure, it can be seen that a large viewing angle can be obtained by tilting the thermal sensing element. Although a given signal is compensated to some extent for a relatively small viewing angle, this device allows a moving object to be sensed to one side at a large viewing angle (as indicated by moving direction P of the moving object in FIG. 7). The tilted structure is considered to be important for the detection result because the posture is set so that it traverses from.

FIG. 11 shows the measurement results from the samples examined by the inventors. The curve passing through the white dots shows the measurement results of commonly used (in Japan) known devices. The data indicated by the black dots are the measurement results of the device of the present invention having the thermal sensing element tilted at about 25 °. At half the maximum signal, the viewing angle is about 125 ° in the conventional device, about 150 ° in the present invention, and at 1/10 of the maximum signal, the viewing angle is about 140 ° in the conventional device. It is clear that the present invention approaches a half cycle (limit) and increases as about 170 °.

Next, an example of a method of constructing the pyroelectric IR heat sensing device according to the present invention will be described.

1. A base (having holes 302 and pins 303 as shown in FIG. 9C) is formed by circuit wiring and pressing as shown in FIG. Here, the points a, b 2, c and d all include interruption layers as well as the upper and lower copper foil layers (shaded areas).

2. Silver adhesive is applied at points b, c where the pyroelectric sensing elements A1, A2 are placed and at points e, f, g where the junction field effect transistor JFET and the load resistor RL are placed. Here, the adhesive at points b and c is applied on the PCB interruption layer.

3. The pyroelectric thermal sensing elements A1 and A2, like the junction field effect transistor JFET and the load resistor RL, are bonded in the positions shown and cured by heating in an oven.

4. Next, a silver adhesive is applied at points a and d and heated and cured in an oven, so that the copper foils P1 and P2 on the interruption layer are attached to the pyroelectric thermal sensing elements A1 and A2. It is electrically connected. This process avoids the difficulty of wire welding on inclined surfaces.

5. Wires are welded to make the necessary circuit connections.

6. After the above steps, the structure with the IR filter lens mounted was loaded into a metal case, adhesive was applied to the back side, and cured by heating in an oven to complete the pyroelectric IR heat sensing device. To be done.

Next, another example of the method for constructing the pyroelectric IR heat sensing device according to the present invention will be described.

1. A base (there is no pin 303 as shown in FIG. 8C) is formed by circuit wiring and a press as shown in FIG. Here, points a, b, c and d all include interruption layers as well as upper and lower copper foil layers (shaded areas).

2. Silver adhesive is applied at points b, c where the pyroelectric sensing elements A1, A2 are placed and at points e, f, g where the junction field effect transistor JFET and the load resistor RL are placed. Here, the adhesive at points b and c is applied on the PCB interruption layer.

3. The pyroelectric thermal sensing elements A1 and A2, like the junction field effect transistor JFET and the load resistor RL, are bonded in the positions shown and cured by heating in an oven.

4. Next, a silver adhesive is applied at points a and d and heated and cured in an oven, so that the copper foils P1 and P2 on the interruption layer are attached to the pyroelectric thermal sensing elements A1 and A2. It is electrically connected. This process avoids the difficulty of wire welding on inclined surfaces.

5. Wires are welded to make the necessary circuit connections.

6. The base 301 is supported higher than the pins of the TO metal base, aligned with the through holes 302, and welded.

7. The metal cover 306 and the metal base are sealed and welded to complete the device.

From the above description, the flattened packing structure by adhering the heat sensing element A1 to the recess 305 on the base 301 in a tilted and supported state can increase the material and volume. The viewing angle can be further increased without doing so.

The device of the present invention has been described with a preferred embodiment of a pyroelectric IR heat sensing device. It will be appreciated that various modifications and changes can be made to the embodiments by those skilled in the art without departing from the scope of the utility model registration claim. For example, the pyroelectric IR heat sensitive elements A1, A2 can be replaced by a similar size heat sensitive resistive sheet element (bolometer), or other element having a similar heat inducing function.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of a conventional two-piece pyroelectric sensing element.

FIG. 2 is an exploded perspective view of a known pyroelectric sensing device.

FIG. 3 illustrates another known type of pyroelectric sensing device,
(A) is a whole exploded perspective view, and (b) is a partial exploded perspective view.

FIG. 4 shows another type of pyroelectric sensing device in which a thermal sensing element is supported on a PCB, (a) is a perspective view, and (b) is a partial cross-sectional view.

5 is an exploded perspective view of the entire apparatus shown in FIG.

FIG. 6 is a diagram showing a field of view divided by an array of IR lenses.

FIG. 7 shows the packing structure shown in FIG. 5, (a) being a cross-sectional view and (b) being a bottom view.

FIG. 8 is an exploded perspective view showing a packing structure of a pyroelectric heat sensing element according to an embodiment of the present invention.

9 shows a packing structure of the pyroelectric sensing element shown in FIG. 8, (a) is a cross-sectional view, (b) is a bottom view, and (c) is a cross-section taken along line CC of FIG. It is a figure.

FIG. 10 is a diagram showing signal response distribution curves of the pyroelectric sensing element of the present invention at various tilt angles.

FIG. 11 is a diagram showing a distant field profile of measured signal strength for a 25 ° tilted thin pyroelectric plate.

FIG. 12 is a top view showing a pyroelectric heat sensing device of the present invention.

[Explanation of symbols]

301 ... Base, 305 ... Recess, 306 ... Cover, 307
... IR window, 308 ... IR filter plate, A1, A2 ... Thermal sensing element.

Front Page Continuation (72) Inventor Guo-Down Chang Taiwan, Taipei Sien, She-Cha Chen, She-Ching Road, Lane 14, No.7, 3F (72) Inventor Jin- Shoun Si Taiwan, Xinchu, Chen-Kun Road First, Lane 70, Number 7, 1F (72) Inventor Chain-Sun Wan Taiwan, Xinchu, Park Road, Lane 216, Number 12 (72) Creator Pin-Kuo Wuen Taiwan, Taoyuan Shen, Per-Thai Siang, Chang-Shen Rhod, No. 16-6, 5 EF (72) Creator Min Del Lin Taiwan, Xinchu, Chu-Tsuen・ Road second, number 12-3

Claims (7)

[Scope of utility model registration request] 1. A circuit board provided with two pyroelectric thermal sensing elements and associated electrical elements thereon,
A cover having a window and an IR filter plate is provided, and a recess is formed in a portion of the circuit board where the pyroelectric heat sensing element is mounted. It is mounted so as to straddle the place, and the recess is formed so that the pyroelectric thermal sensing element is positioned so as to be inclined and lifted up and supported therein. A planarization packing device for a pyroelectric IR thermal sensing element, adjusted as desired. 2. The inclination angle is in the range of 5 ° to 45 °,
A flattening packing device for a pyroelectric IR thermal sensing element according to claim 1 and preferably in the range 10 ° to 30 °. 3. The pyroelectric IR heat sensing element according to claim 1, wherein a plurality of through holes are formed in the circuit board, and pins for external connection are inserted and riveted into the through holes. For flattening packing equipment. 4. The flattening packing device for the pyroelectric IR heat sensing element of claim 1, wherein the circuit board is formed of a ceramic plate in which the recess is formed in a predetermined shape. 5. The pyroelectric IR of claim 1 wherein the cover is stamped from a metal container or injection cold made of a metal backed synthetic resin to insulate electrical noise. Planarizing packing device for thermal sensing element. 6. The circuit board has an external lead and a pin protruding from a metal base aligned and welded, and a metal cover and a metal base sealed and welded to form a final product. A planarization packing device for a pyroelectric IR thermal sensing element according to claim 1 supported on a TO metal base. 7. The planarization packing apparatus for the pyroelectric IR heat sensing element of claim 1, wherein the pyroelectric IR heat sensing element is replaced with an IR heat sensing sheet member formed of a heat sensing resistor material.