Radiation thermometer

In the head portion, the thermopile is arranged substantially in the center of the head portion. The preamplifier board is arranged near the thermopile. The heat diffusion member made of a high heat conductive material is arranged so as to surround the thermopile and the preamplifier board. The main board and the laser diode are arranged between the upper surface of the head casing and the upper surface of the heat diffusion member. The power supply board and the laser diode are arranged between the down surface of the head casing and the down surface of the heat diffusion member. The thermopile, the preamplifier board, the main board, the power supply board, and the laser diodes are arranged out of contact with the heat diffusion member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a radiation thermometer, which measures temperature of an object by detecting infrared energy radiated from the object.

2. Description of the Related Art

There has been, heretofore, a radiation thermometer (for example, refer to Japanese Patent Laid-Open No. 7-324981) which detects infrared energy radiated from an object to be measured and calibrates the infrared energy by emissivity of the object, hence to measure the actual temperature of the object to be measured.

Generally, a radiation thermometer detects infrared energy by heat sensitive element such as a thermopile. The thermopile includes an infrared radiation receiving portion (hot junction) having a plurality of thermocouples connected in a series. In this thermopile, when infrared radiation enters the infrared radiation receiving portion, there occurs a temperature difference between the hot junction and the cold junction depending on the amount of the incident infrared radiation, and thermo electromotive force is produced according to the difference. This thermo electromotive force corresponds to the temperature of the object to be measured.

The temperature of the cold junction of the thermopile changes according to the inner temperature of the thermopile. The temperature of the object measured by the thermopile is calibrated according to the inner temperature of the thermopile, while measuring the inner temperature of the thermopile with a thermistor. This can get an accurate temperature of the object to be measured.

In this radiation thermometer, since the infrared energy radiated from the object to be measured is invisible, a user cannot recognize which position of the object to be measured is being measured.

A radiation thermometer has been developed which can indicate a measuring position with light source such as laser diode (LD) or light emitting diode (LED) in order for a user to recognize the measuring position.

The radiation thermometer capable of indicating a measuring position, however, is apt to enlarge in size because it contains a light source such as a laser diode or a light emitting diode.

When the heat generated by the light source in order to indicate a measuring position is locally transmitted to the thermopile, the inner temperature of the thermopile becomes uneven. In this case, the thermistor cannot detect an accurate inner temperature of the thermopile.

Additionally, there is the case where the infrared radiation radiated from the peripheral members of the thermopile (for example, holding member of the thermopile and the like) enters the infrared radiation receiving portion. When the temperature of the peripheral members agrees with the inner temperature of the thermopile, the amount of the infrared radiation of the peripheral members entering the infrared radiation receiving portion can be calculated according to the inner temperature of the thermopile. By subtracting the infrared radiation amount of the peripheral members from all the infrared radiation amount entering the infrared radiation receiving portion, it is possible to accurately obtain the infrared radiation amount only for the object to be measured.

When the temperature of the peripheral members becomes uneven according to the heat of the light source, or when the temperature of the peripheral members is different from the inner temperature of the thermopile, the infrared radiation amount of the peripheral members entering the infrared radiation receiving portion cannot be calculated according to the inner temperature of the thermopile. It is impossible to accurately obtain the infrared radiation amount only for the object to be measured from all the infrared radiation entering the infrared radiation receiving portion.

In order to measure an accurate temperature of the object to be measured, it is necessary to set a distance between the thermopile and the light source as large as possible so as not to locally transmit heat to the thermopile and so as to make the atmospheric temperature near the thermopile equal to the inner temperature of the thermopile. As a result, downsizing of the radiation thermometer is increasingly difficult.

Since an output signal of the thermopile is very small, an output signal of the thermopile has to be amplified with a high amplification factor. When the output signal of the thermopile is affected by the noise, measurement accuracy is remarkably reduced.

SUMMARY OF THE INVENTION

The present invention is to provide a radiation thermomter which can indicate a measuring position and assure high measurement accuracy while downsizing.

The radiation thermometer according to the invention is a radiation thermometer for measuring temperature of an object to be measured, comprising: a casing having a first and a second surfaces mutually facing and a third and a fourth surfaces mutually facing and including an infrared radiation passing unit which passes the infrared radiation radiated from the object to be measured, on the first surface; a sensing element located within the casing, which detects the infrared energy of passing through the infrared radiation passing unit; a first board located within the casing between the second surface and the sensing element along the second surface, on which board a first circuit for amplifying an output signal of the sensing element is installed; a second board located within the casing between the third surface and the sensing element along the third surface, on which board a second circuit for calculating a temperature of the object to be measured according to a signal given from the first circuit of the first board is installed; a third board located within the casing between the fourth surface and the sensing element along the fourth surface, on which board a third circuit for supplying power to the first and the second circuits is installed; a first and a second light sources located within the casing, which emit light to the object to be measure and a heat diffusion member located within the casing, in which an infrared radiation passage for leading the infrared radiation from the infrared radiation passing unit to the sensing element is formed within the casing, the first and the second light sources are respectively located between the infrared radiation passage and the third surface and between the infrared radiation passage and the fourth surface, and the heat diffusion member is located between the infrared radiation passage and the first light source, between the infrared radiation passage and the second light source, between the second board and each of the sensing element and the first board, and between the third board and each of the sensing element and the first board.

According to the radiation thermometer of the invention, the first and the second light sources emit light to an object to be measured. The infrared radiation radiated from the object to be measured enters the sensing element through the infrared radiation passing unit on the first surface of the casing and the infrared radiation passage within the casing. The incident energy of the infrared radiation is detected by the sensing element. The output signal of the sensing element is amplified by the first circuit on the first board. The second circuit on the second board calculates the temperature of the object to be measured according to the signal given from the first circuit.

According to the radiation thermometer of the invention, a measurement position of the object to be measured is indicated by the light radiated from the first and second light sources to the object to be measured. In particular, two of the first and the second light sources are used, and by properly setting the indication form of a measurement position by the mutual light emitted from the both light sources, the measurement position can be indicated with high accuracy and the temperature can be measured with higher accuracy.

In the casing, since the first board is located between the second surface of the casing and the sensing element along the second surface, the distance between the sensing element and the first board can be shortened. In this case, since the wiring between the sensing element and the first board can be shortened, the output signal of the sensing element is hardly affected by noise. As a result, the radiation thermometer can calculate the temperature of the object to be measured with high accuracy.

Within the casing, since the heat diffusion member is located between the second board and each of the sensing element and the first board, even when there occurs heat in the second board, the heat is diffused by the heat diffusion member.

The third circuit installed on the third board is used for power supply and it easily generates heat. Since the heat diffusion member is located between the third board and each of the sensing element and the first board, even when heat is generated in the third board, the heat is diffused by the heat diffusion member.

The first and second light sources emit light, hence to generate heat. Since the heat diffusion member is located between each of the first and the second light sources and the infrared radiation passage, the heat of the first and the second light sources is diffused by the heat diffusion member.

Since the heat generated by the second and the third boards and the first and the second light sources is diffused by the heat diffusion member, the atmospheric temperature within the casing is kept substantially even. As a result, the local heat transmission to the sensing element is prevented and temperature can be measured with high accuracy.

In particular, since the first and the second light sources are located near the infrared radiation passage within the casing and not adjacent to the sensing element, the local heat transmission to the sensing element can be further prevented.

Thus, since the local heat transmission to the sensing element can be prevented owing to the arrangement of the heat diffusion member, it is possible to arrange the first and the second light sources, the first, the second, and the third boards, and the sensing element adjacently to each other within the casing. Then, the radiation thermometer can be downsized adequately.

Since the first and the second light sources are arranged in an empty space around the infrared radiation passage within the casing, it is possible to prevent from enlargement of the radiation thermometer resulting from providing the first and the second light sources.

The casing further has a fifth and a sixth surfaces. The heat diffusion member may be located between the fifth surface and each of the sensing element, the first board, and the infrared radiation passage. The heat diffusion member may be located between the sixth surface and each of the sensing element, the first board, and the infrared radiation passage.

In this case, since the heat diffusion member is located between the fifth surface and each of the sensing element, the first board and the infrared radiation passage and between the sixth surface and each of the sensing element, the first board, and the infrared radiation passage, the heat generated by the second and the third boards and the first and the second light sources is diffused over a wide range. Then, the temperature within the casing can be kept even. As a result, the local heat transmission to the sensing element can be further prevented and the highly accurate temperature measurement can be realized.

Space maybe provided between the heat diffusion member and each of the sensing element and the first board and between the heat diffusion member and each of the second board, the third board, the first light source, and the second light source.

In this case, air layer exists in the space between the heat diffusion member and each of the sensing element and the first board and in the space between the heat diffusion member and each of the second board, the third board, the first light source, and the second light source. This air layer works as a heat insulating layer and the heat generated in the second board, the third board, the first light source, and the second light source is hardly transmitted to the sensing element. In this state, the heat generated in the second board, the third board, the first light source, and the second light source is diffused by the heat diffusion member. Then, the temperature within the casing can be kept even and an increase in the temperature can be restrained within the casing.

The second circuit may include a first driving circuit for driving the first light source and a control circuit for calculating the temperature of the object to be measured according to the signal given from the first circuit and controlling the first driving circuit.

In this case, in the second board with the second circuit installed there, the first driving circuit for driving the first light source easily generates heat. Since the heat diffusion member is located between the second board and each of the sensing element and the first board, even when heat is generated in the second board, the heat is diffused by the heat diffusion member.

The second circuit may include the indication element and the control circuit may control the indication element according to the calculated temperature of the object to be measured.

In this case, in the second board with the second circuit installed there, the indication element easily generates heat. Since the heat diffusion member is located between the second board and each of the sensing element and the first board, even when heat is generated in the second board, the heat is diffused by the heat diffusion member.

The third circuit may include a second driving circuit for driving the second light source and the control circuit may control the second driving circuit. In this case, in the third board with the third circuit installed there, the second driving circuit for driving the second light source easily generates heat. Since the heat diffusion member is located between the third board and each of the sensing element and the first board, even when heat is generated in the third board, the heat is diffused by the heat diffusion member.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a radiation thermometer according to embodiments of the invention will be described according toFIG. 1toFIG. 24.

FIRST EMBODIMENT

(1) Functional Structure of the Radiation Thermometer

FIG. 1is a block diagram of a radiation thermometer according to the first embodiment. As illustrated inFIG. 1, a radiation thermometer100according to the first embodiment includes a head portion100A and a main body portion.

The head portion100A and the main body portion100B are connected to each other via a cable80. The main body portion100B is connected to an external device not illustrated via a cable81.

FIG. 2is a block diagram of the head portion100A ofFIG. 1andFIG. 3is a block diagram of the main body portion100B ofFIG. 1.

As illustrated inFIG. 2, the head portion100A includes a thermopile10, a preamplifier board20, a main board30, a power supply board40, a junction board50, and two laser diodes60and70.

The thermopile10includes an infrared radiation receiving portion11(infrared radiation detecting chip) and a thermistor12. The preamplifier board20includes a first signal amplifier21and a second signal amplifier22. The main board30includes a third signal amplifier31, analog-digital converters (hereinafter, abbreviated as AD converter)32and33, a CPU (Central Processing Unit)34, a storing unit35, an indication light36, and a laser driving circuit37.

The power supply board40includes a power supply circuit41, a communication circuit42, and a laser driving circuit43. The power supply board40is connected to a cable80including a power supply line and a signal line.

The junction board50is provided with a wired surface having a plurality of wirings, which electrically connects the main board30to the power supply board40. The junction board50is provided with a ground conductive surface described later, which is connected to the earth terminals of the respective components of the head portion10A.

In the thermopile10, the infrared radiation receiving portion11detects infrared energy radiated from an object to be measured. The thermistor12detects an inner temperature of the thermopile10.

In the preamplifier board20, the first signal amplifier21amplifies an output signal of the infrared radiation receiving portion11. The second signal amplifier22amplifies an output signal of the thermistor12.

In the main board30, the third signal amplifier31amplifies an output signal of the first signal amplifier21. The AD converter32converts an output signal of the first signal amplifier21into a digital signal, and gives the digital signal to the CPU34as a detected temperature of the object to be measured.

The AD converter33converts an output signal of the second signal amplifier22into a digital signal and gives the digital signal to the CPU34as an inner temperature of the thermopile10.

The storing unit35stores information about the thermopile10and arithmetic expression with which the CPU34calculates temperature of the object to be measured. The information about the thermopile10includes, for example, gain and offset of the infrared radiation receiving portion11, gain and offset of the thermistor12, and the range of measurement temperature and temperature scale of the thermopile.

The main body portion100B gives an emissivity and a check signal, described later, of the object to be measured to the CPU34through the cable80and the communication circuit42. The CPU34calculates an actual temperature of the object to be measured (hereinafter, referred to as a measured temperature) according to a detected temperature given from the AD converter32, an inner temperature given from the AD converter33, an emissivity given from the main body portion100B, and various information and the arithmetic expression stored into the storing unit35. The CPU34gives the measured temperature to the main body portion100B through the communication circuit42and the cable80.

The CPU34feedback controls the gain of the third signal amplifier31according to the level of the output signal of the AD converter32.

The CPU34controls the operations of the indication light36, the laser driving circuit37, and the laser driving circuit43of the power supply board40. The indication light36shows an ON/OFF state of the check signal while lighting on/off according to a control of the CPU34. The laser driving circuit37drives the laser diode60according to the control of the CPU34.

In the power supply board40, the power supply circuit41supplies the power from the main body portion100B to the respective components of the head portion100A through the cable80.

The communication circuit42and the laser driving circuit43are both connected to the CPU34of the main board30through the junction board50.

The communication circuit42communicates with the CPU34and the main body portion100B through the cable80, as mentioned above. The laser driving circuit43drives the laser diode70according to the control of the CPU34. The laser beams emitted from the laser diodes60and70are radiated at a measurement position of the object to be measured.

As illustrated inFIG. 3, the main body portion100B includes a power supply circuit91, a communication circuit92, CPU93, a display unit94, a storing unit95, an operation setting unit96, an external output circuit97, and an analog output circuit98.

The cable80is connected to the power supply circuit91and the communication circuit92. The power supply circuit91has a power source such as battery and supplies its power to the respective components of the main body portion100B and the head portion10A. The communication circuit92communicates with the CPU93and the head portion100A through the cable80.

The storing unit95stores the emissivity of the object to be measured, the arithmetic expression, and the threshold for judgment. A user can set the emissivity and threshold of the object to be measured while operating the operation setting unit96. The set emissivity and threshold are stored into the storing unit95.

The CPU93controls the operations of the respective components of the main body portion100B. The CPU93compares the measured temperature given by the head portion100A with the threshold stored into the storing unit95and supplies the result to the cable81through the external output circuit97as a check signal.

The check signal turns into an ON state, for example, when the measured temperature is higher than the threshold (for example, high level) and turns into an OFF state when the measure temperature is lower than the threshold (for example, low level).

The CPU93supplies the measured temperature given by the head portion100A to the cable81through the external output circuit97and supplies the analog signal corresponding to the measured temperature to the cable81through the analog output circuit98.

According to this, the radiation thermometer100according to the embodiment can display and output the measured temperature of the object to be measured as well as display and output the check result (ON state or OFF state) about whether the measured temperature is higher than the threshold or not.

(2) Schematic Structure of Head Portion of Radiation Thermometer

FIG. 4toFIG. 6are views for use in describing the basic structure of the head portion100A of the radiation thermometer100according to the first embodiment.FIG. 4shows an appearance perspective view of the head portion10A.FIG. 5shows a schematic cross-sectional view taken along the line A-A ofFIG. 4, andFIG. 6shows a schematic cross-sectional view taken along the line B-B ofFIG. 4.

The respective components of the head portion100A are built in a substantially rectangular head casing K. The head casing K has an upper surface KU, a down surface KD, a front surface KF, a back surface KB and side surfaces KS1and KS2.

In the following description, as indicated by the arrows X, Y, and Z inFIG. 4, a direction perpendicular to the side surfaces KS1and KS2is called an X-direction, a direction perpendicular to the front surface KF and the back surface KB is called a Y-direction, and a direction perpendicular to the upper surface KU and the down surface KD is called a Z-direction. The directions will be similarly defined in the figures followingFIG. 4.

InFIG. 4, the front surface KF of the head casing K is provided with an infrared radiation concentrating unit KH and laser radiating units K60and K70, its upper surface KU is provided with the indication light36formed by the light emitting diode, and its back surface KB is provided with a cable junction KJ. Since the indication light36is located on its upper surface KU, a user can recognize the lighting on/off state or blinking state of the indication light36easily.

The infrared radiation concentrating unit KH takes in the infrared radiation radiated from the object to be measured. Laser beams generated by the laser diodes60and70inFIG. 2are radiated at a measurement position respectively through the laser radiating units K60and K70. The detailed structure and operation will be described later.

The cable junction KJ has the cable80connected there. This cable80is connected to the main body portion100B as mentioned above.

The size of the head portion100A of the radiation thermometer100according to the embodiment is, by way of example, as follows. InFIG. 4, the height h of the head portion100A is about 34 mm, the width w is about 20 mm, and the depth1is about 48 mm.

As illustrated inFIG. 5andFIG. 6, the thermopile10of a substantially cylindrical shape in parallel to the Y-direction, inserted into the substantially cylindrical thermopile holder110in parallel to the Y-direction, is arranged almost in the middle of the head portion10A. At the back surface KB side of the thermopile10, the preamplifier board20is arranged near the thermopile10in parallel to the back surface KB.

The thermopile holder110used as the peripheral member of the thermopile10is used in order to make the inner temperature of the thermopile10almost equal to its peripheral temperature. Thus, the thermopile holder110has to be made of a material of high heat conductivity. The details will be described later.

Further, a heat diffusion member90is arranged so as to surround the thermopile10, the thermopile holder110, and the preamplifier board20. The heat diffusion member90has a substantially C-shaped cross section along the YZ plane of the head portion100A as illustrated inFIG. 5and it also has a substantially C-shaped cross section along the XZ plane as illustrated inFIG. 6.

Specifically, the heat diffusion member90has an upper surface90u,a down surface90d,a back surface90b,and a side surface90s,and the heat diffusion member90is open on the side of the front surface KF of the head portion100A and on the side of one side surface KS1.

This induces the infrared radiation radiated from the object to be measured to the infrared radiation receiving portion11of the thermopile10(refer toFIG. 2) through the infrared radiation concentrating unit KH.

The heat diffusion member90is made of a material of high heat conductivity. Preferably, the heat diffusion member90is formed, in particular, by metal such as copper, silver, aluminum, iron, or gold. In the embodiment, the heat diffusion member90is formed by coating copper with nickel. In this case, the copper can achieve a higher heat conductivity and the coated nickel can prevent from oxidization of copper as well as improve corrosion resistance.

As illustrated inFIG. 6, the junction board50is placed at the opening position on the side of the one side surface KS1of the heat diffusion member90in parallel to the side surface KS1. As mentioned above, the junction board50includes the wired surface50C and the ground conductive surface50G. The wired surface50C is arranged on the side of the thermopile10and the ground conductive surface50G is arranged on the side of the side surface KS1.

Similarly to the heat diffusion member90, the ground conductive surface50G is made of a material of high heat conductivity, preferably, a metal such as copper, silver, aluminum, iron, or gold. In the embodiment, the material of the ground conductive surface50G is the same as that of the heat diffusion member90.

According to this, the thermopile10, the thermopile holder110, and the preamplifier board20are surrounded by the diffusion member90and the ground conductive surface50G of high heat conductive material in all the directions other than the front surface KF. The thermopile holder110has a rectangular shape in the Y-direction but does not protrude from the opening of the heat diffusion member90on the front surface KF.

As illustrated inFIG. 5, the main board30and the laser diode60are arranged between the upper surface KU of the head casing K and the upper surface90uof the heat diffusion member90. The laser diode60is adjacent to the laser radiating unit K60and positioned at a predetermined distance from the thermopile10. Thus, the laser beam generated by the laser diode60is efficiently radiated at the object to be measured through the laser radiating unit K60. The main board30is positioned near the side of the back surface KB of the head casing K in parallel to the upper surface KU.

The power supply board40and the laser diode70are positioned between the down surface KD of the head casing K and the down surface90dof the heat diffusion member90. The laser diode70is adjacent to the laser radiating unit K70and positioned at a predetermined distance from the thermopile10. Thus, the laser beam generated by the laser diode70is efficiently radiated at the object to be measured through the laser radiating unit K70. The power supply board40is arranged near the side of the back surface KB of the head casing K in parallel to the down surface KD.

The thermopile10and the thermopile holder110are arranged out of contact with the heat diffusion member90. The main board30, the power supply board40, and the laser diodes60and70are also arranged out of contact with the heat diffusion member90. Thus, each air layer exists between the heat diffusion member90and the thermopile holder110with the thermopile10inserted there and between the heat diffusion member90and each of the main board30, the power supply board40, and the laser diodes60and70. These air layers work as heat insulating layers. The cable80is electrically connected to the power supply board40.

As mentioned above, in the radiation thermometer100according to the embodiment, the laser beams generated by the two laser diodes60and70are radiated at the object to be measured through the laser radiating units K60and K70of the head casing K. Thus, a measurement position is indicated by the laser beams. In particular, when the two laser diodes60and70are used, a more accurate temperature can be measured by properly setting the indication format of a measurement position by the both laser beams. The indication format of a measurement position will be described later.

In the embodiment, the thermopile10is arranged near the preamplifier board20. This can shorten a wiring between the thermopile10and the preamplifier board20. Thus, a feeble output signal of the thermopile10is hardly affected by noise. As a result, the CPU34can calculate the temperature of the object to be measured with high accuracy.

In the embodiment, the heat diffusion member90and the ground conductive surface50G are arranged so as to surround the thermopile10and the preamplifier board20within the head casing K of the head portion10A. The main board30, the power supply board40, and the laser diodes60and70are arranged between the heat diffusion member90and the head casing K.

In this case, since there exists the air layer working as the heat insulating layer between the thermopile10and each of the main board30, the power supply board40, and the laser diodes60and70, the heat generated by the main board30, the power supply board40, and the laser diodes60and70is hardly transmitted to the thermopile10.

The heat transmitted from the main board30, the power supply board40, and the laser diodes60and70to the heat diffusion member90is spread over the heat diffusion member90diffusively. In this way, the heat is hardly transmitted to the thermopile10, and the atmospheric temperature within the head casing K is kept substantially even.

That can prevent from local heat transmission to the thermopile10and make the inner temperature of the thermopile10substantially equal to the temperature of the peripheral member (for example, the thermopile holder110) of the thermopile10. As a result, the CPU34can calculate the temperature of the object to be measured with high accuracy.

As mentioned above, in the head portion100A in the radiation thermometer100according to the embodiment, since the above arrangement of the heat diffusion member90and the ground conductive surface50G can prevent from local heat transmission to the thermopile10, the respective components can be arranged adjacently to each other within the head casing K.

Since the laser diodes60and70are arranged in an open space around the passage of infrared radiation within the head casing K and not adjacent to the thermopile10, local heat transmission to the thermopile10can be prevented. Further, it can prevent from upsizing of the head portion100A caused by the provision of the laser diodes60and70.

As a result, it is possible to calculate the temperature of the object to be measured with high accuracy and downsize the whole radiation thermometer100.

(3) Detailed Structure of Head Portion of Radiation Thermometer

A concrete structure and operation of the radiation thermometer100according to the embodiment will be described hereinafter.

Each ofFIG. 7toFIG. 9shows the detailed structure of the head portion100A of the radiation thermometer100according to the first embodiment, andFIG. 10toFIG. 16are perspective views each showing the assembly procedure of the head portion100A ofFIG. 7.

FIG. 7Ashows a front view (front surface) of the head portion10A, andFIG. 7Bshows a lateral side view of the head portion10A.FIG. 8is a detailed cross-sectional view taken along the line A-A inFIG. 7A, andFIG. 9is a detailed cross-sectional view taken along the line B-B inFIG. 7B. In each figure followingFIG. 7, the cable80connected to the head portion100A is omitted.

In the head portion100A of this example, through holes KT are respectively located in the upper and the lower portions of the respective side surfaces KS1and KS2of the head casing K, as illustrated in the lateral side view ofFIG. 7B. These through holes KT are used to fix the head portion100A at a desired position.

As illustrated inFIG. 8, openings36C for passing the beams of the indication light36are formed on the upper surface KU. The infrared radiation concentrating unit KH on the front surface KF is formed by the infrared radiation concentrating lens200L, and the laser radiating units K60and K70are respectively formed by the laser lens covers LC.

As illustrated inFIG. 8andFIG. 9, the thermopile10is supported by the thermopile holder110, within the head casing K. The thermopile10will be mounted into the thermopile holder110in the following way.

FIG. 10shows a state of mounting the thermopile10into the thermopile holder110.

As illustrated inFIG. 10, the thermopile holder110has a cylindrical portion111and a fixing block portion112. The fixing block portion112has a substantially rectangular shape and the cylindrical portion111is integrated with the fixing block portion112in a way of extending in the Y-direction from its one surface parallel to the XZ plane.

A thermopile housing hole112H is bored in the fixing block portion112. The thermopile housing hole112H communicates with the inner space of the cylindrical portion

A first circular slit member111S is formed in the inner surface of the cylindrical portion111. A second circular slit member112S is attached to the front side of the first slit member111S of the cylindrical portion111.

As illustrated inFIG. 8, the diameter of the circular slit (bore) formed in the first slit member111S is smaller than the diameter of the circular slit (bore) formed in the second slit member112S. The first slit member111S and the second slit member112S restrict the passage of the infrared radiation so that the infrared radiation concentrated by the infrared radiation concentrating lens200L can enter the thermopile10.

According to this, the infrared radiation externally entering the head portion100A through the infrared radiation concentrating lens200L can enter the infrared radiation receiving portion11of the thermopile10without being reflected by various members within the head portion100A (the inner surface of the thermopile holder110and a lens holder described later). As a result, only the infrared radiation directly radiated from the object to be measured enters the infrared radiation receiving portion11.

As illustrated inFIG. 10, a fixing ring120, the thermopile10, and a fixing rear cap130are sequentially inserted into the thermopile housing hole112H of the fixing block portion112. Thus, the thermopile10is fixed within the thermopile holder110, as illustrated inFIG. 8.

The thermopile holder110, the second slit member112S, and the fixing rear cap130are made of a material of high heat conductivity and high electric conductivity such as copper, silver, aluminum, iron, or gold. This makes it possible to keep the temperature around the thermopile10even and to make the inner temperature of the thermopile10substantially equal to the temperature of the thermopile holder110, the second slit member112S, and the fixing rear cap130.

Even when the infrared radiation radiated from the peripheral members (the thermopile holder110, the second slit member112S, and the like) of the thermopile10enters the infrared radiation receiving portion11, the CPU34can calculate the infrared radiation amount of the peripheral members of the thermopile10according to the inner temperature of the thermopile10. Further, it can subtract the infrared radiation amount of the peripheral members of the thermopile10from all the infrared radiation amount entering the infrared radiation receiving portion11. As a result, it is possible to measure the infrared radiation amount only for the object to be measured accurately, of all the infrared radiation amount entering the infrared radiation receiving portion11, hence to get an accurate measured temperature.

Since the thermopile holder110, the second slit member112S, and the fixing rear cap130are formed by the material of high electric conductivity, the thermopile10which generates a feeble output signal can be electrically shielded from the external electromagnetic environment, by grounding the respective members.

As mentioned above, the fixing ring120is inserted into the thermopile housing hole112H. By adjusting the form and the material of the fixing ring120, it is possible to adjust the heat transmission condition from the thermopile holder110to the thermopile10and a distance between the thermopile10and the infrared radiation concentrating lens200L.

As illustrated inFIG. 8, a lens holder200and an amplifier attachment spacer140are attached to the thermopile holder110with the thermopile10inserted there.

The lens holder200and the amplifier attachment spacer140are attached to the thermopile holder110in the following way.

FIG. 11shows the state of attaching the lens holder200and the amplifier attachment spacer140to the thermopile holder110.FIG. 12shows an appearance of the infrared radiation concentrating unit completed after mounting the lens holder200and the amplifier attachment spacer140into the thermopile holder110.FIG. 13is a cross-sectional view of the infrared radiation concentrating unit ofFIG. 12taken along the line C-C.FIG. 13shows one portion of the lens holder200in a dotted line, for the sake of easy understanding.

As illustrated inFIG. 11, the infrared radiation concentrating lens200L is attached to the front end of the lens holder200by the lens fixing ring210. A laser supporting pole260(refer toFIG. 8) and a laser supporting pole270are formed on the outer surface of the lens holder200in the Z-direction in a protruding way. The laser supporting pole260supports the laser diode60and the laser supporting pole270supports the laser diode70.

Holder fixing pieces201and202are formed at the rear end of the lens holder200. The lens holder200is attached to the cylindrical portion111of the thermopile holder110. Thus, the thermopile holder110and the lens holder200are fixed.

The amplifier attachment spacer140is attached to the rear end of the thermopile holder110. The amplifier attachment spacer140has two board holders141and142. These board holders141and142support the preamplifier board20(refer toFIG. 8andFIG. 12). Thus, the infrared radiation concentrating unit900is completed.

The lens holder200and the amplifier attachment spacer140are formed by a material of, for example, resin. When using, in particular, a resin of low heat conductivity, the heat generated by the laser diodes60and70is difficult to transmit to the lens holder200. This can reduce the transmission of the heat generated by the laser diodes60and70to the thermopile10.

In the infrared radiation concentrating unit900, a distance J between a plurality of terminals10T of the thermopile10and the preamplifier board20is shortened, as illustrated inFIG. 13. According to this, the wiring length between the terminals10T of the thermopile10and the preamplifier board20can be shortened.

As illustrated inFIG. 8andFIG. 9, the infrared radiation concentrating unit900is fixed within the head casing K by a main frame300. The main frame300supports the main board30and the power supply board40.

FIG. 14shows the state of installing the infrared radiation concentrating unit900into the main frame300and attaching the main board30and the power supply board40to the main frame300.

As illustrated inFIG. 14, the main frame300is integrally formed by four supporters301,302,303, and304and four holders305,306,307, and308. The four supporters301to304are mutually connected into a substantial square and the holders305to308are respectively jointed to the junctions of the supporters perpendicularly.

The main board30is attached to the supporter302and the holders305and306, the power supply board40is attached to the supporter304and the holders307and308, and the thermopile holder110of the infrared radiation concentrating unit900is inserted into a space formed by the supporter303and the holders306and307.

The thermopile holder110of the infrared radiation concentrating unit900is accommodated into a space surrounded by the supporters301to304and the holders305to308. The board holders141and142(refer toFIG. 11) of the infrared radiation concentrating unit900are attached to the holders305and308.

The junction board50is fixed by the main frame300. The junction board50is electrically connected to the main board30and the power supply board40fixed to the main frame300, within the head casing K.

With the main board30, the power supply board40, and the infrared radiation concentrating unit900fixed to the main frame300, the main board30is electrically connected to the preamplifier board20through a flexible wiring circuit board not illustrated.

The assembled body including the main board30, the power supply board40, the junction board50, the main frame300, and the infrared radiation concentrating unit900is accommodated into the head casing K. At this time, the heat diffusion member90and the laser diodes60and70also are further attached to the assembled body.

FIG. 15shows the state of accommodating the assembled body ofFIG. 14into the head casing K.FIG. 16shows the state of mounting the laser diodes60and70in the assembled body800.

As illustrated inFIG. 15andFIG. 16, the laser diodes60and70are mounted in the assembled body800. This will be performed as follows.

A protruding portion271is formed extending from the end surface of the laser supporting pole270of the lens holder200. As illustrated inFIG. 16A, a laser holding member72is joined to the protruding portion271through a joint member71.

The joint member71has a bore71X in the X-direction and a bore71Z in the Z-direction. According to this, as illustrated inFIG. 16B, the joint member71is attached to the protruding portion271of the lens holder200rotatably in a direction of the arrow R1.

The laser holding member72holds the laser diode70and the laser lens70L. As illustrated inFIG. 16A, the protruding portion72T extending in the X-direction is formed on the laser holding member72.

According to this, the laser holding member72is inserted into the bore71X of the joint member71in a rotatable way in a direction of the arrow R2, as illustrated inFIG. 16B. As a result, the radiation direction of the laser beam generated by the laser diode70is easily adjusted.

Though the joint member61and the laser holding member62attached to the laser supporting pole260(refer toFIG. 8) of the lens holder200are not illustrated inFIG. 16, the structure of the joint member61and the laser holding member62is the same as that of the joint member71and the laser holding member72. The joint member61and the laser holding member62are similarly inserted into the laser supporting pole260.

The above heat diffusion member90is mounted in the assembled body800having the laser diodes60and70.

There are a space SD between the supporter304of the main frame300and the power supply board40and a space SU between the supporter302of the main frame300and the main board30, in the assembled body800inFIG. 15. One of the upper surface90uand one of the down surface90dof the heat diffusion member90are respectively inserted into the space SU and the space SD.

The heat diffusion member90is provided with cut-off portions in accordance with the laser supporting poles260and270. At a time of attaching the heat diffusion member90to the assembled body800, the upper surface90uand the down surface90dof the heat diffusion member90are arranged between the lens holder200and the laser diodes60and70.

Thus, the upper surface, the down surface, the back surface and the one lateral side surface of the assembled body800are covered with the heat diffusion member90and the heat diffusion member90is arranged between the thermopile holder110and each of the main board30, the power supply board40, and the laser diodes60and70.

At last, the assembled body800with the heat diffusion member90attached is accommodated into the head casing K including two members. In the above structure within the head casing K, the main board30and the power supply board40are electrically connected to the laser diode60and the laser diode70respectively, by the flexible wiring circuit board not illustrated.

FIG. 17is a view showing the state of indicating a measurement position by the laser diodes60and70ofFIG. 8. In the following description, the laser beams L1and L2are respectively radiated from the laser diodes60and70of the head portion10A.

For example, as illustrated inFIG. 17A, the laser beam L1indicates the upper end of the measurement position SP and the laser beam L2indicates the lower end of the measurement position SP. In this case, a user can easily understand the range of the measurement position SP.

As illustrated inFIG. 17B, each angle of the laser diode60and the laser diode70is set so as to cross the laser beam L1and the laser beam L2at the center of the measurement position SP. In this case, a user can easily know whether the distance Q between the head portion100A and the measurement position SP is proper or not.

As illustrated inFIG. 17C, each angle of the laser diode60and the laser diode70is set so as to cross the laser beam L1and the laser beam L2at the center of the measurement position SP and at the same time, the laser beams L1and L2are spread to have a predetermined width. In this case, a user can easily know whether the distance Q between the head portion100A and the measurement position SP is proper or not as well as the range of the measurement position SP.

In the radiation thermometer100according to the embodiment, each radiation direction of the laser beams L1and L2generated by the laser diodes60and70can be easily adjusted thanks to the structure of the head portion100A shown inFIGS. 16A and 16B. The method of indicating the measurement position SP is not restricted to the examples ofFIGS. 17A,17B, and17C.

SECOND EMBODIMENT

A radiation thermometer according to the second embodiment is different from the radiation thermometer100of the first embodiment in the following points. In the radiation thermometer according to the embodiment, the appearance shape of the head portion is the same as the head portion100A of the radiation thermometer100according to the first embodiment.

FIG. 18is a detailed cross-sectional view of the head portion of the radiation thermometer taken along the YZ plane according to the second embodiment and it corresponds to the detailed cross-sectional view ofFIG. 7Ataken along the line A-A.FIG. 19is a detailed cross-sectional view of the head portion of the radiation thermometer taken along the XZ plane according to the second embodiment and it corresponds to the detailed cross-sectional view ofFIG. 7Btaken along the line B-B.

As illustrated inFIG. 18andFIG. 19, in the head portion100A of the radiation thermometer of this embodiment, the structure of the infrared radiation concentrating unit900included in the head casing K is different from the structure of the infrared radiation concentrating unit900used for the first embodiment. The detailed structure of the infrared radiation concentrating unit900used for the embodiment will be described.

FIG. 20is a view showing the state of assembling the infrared radiation concentrating unit900used for the head portion100A of the radiation thermometer according to the second embodiment. In the following drawings (FIG. 20toFIG. 24), the amplifier attachment spacer140(FIG. 18) and the preamplifier board20(FIG. 18) of the infrared radiation concentrating unit900are not illustrated.

As illustrated inFIG. 20, the thermopile holder410has a front cylindrical portion411a,a rear cylindrical portion411b,and a fixing block portion412. The fixing block portion412is formed in a cylindrical shape along the Y-direction. The rear cylindrical portion411band the front cylindrical portion411aare integrally formed in a way of extending from one surface parallel to the XZ plane of the fixing block portion412in the Y-direction.

The fixing block portion412is formed in that its thickness in the Z-direction is thicker than that in the X-direction in a cross-section taken along the XZ plane (refer toFIG. 19). The thickness in the Z-direction of the fixing block portion412is much thicker than that of the fixing block portion112according to the first embodiment.

The rear cylindrical portion411bis formed in a substantially cylindrical shape along the Y-direction with the outer diameter smaller than fixing block portion412. Similarly to the fixing block portion412, the rear cylindrical portion411bis also formed in that the thickness in the Z-direction is thicker than that in the X-direction. The thickness of the rear cylindrical portion411bin the Z-direction is much thicker than the thickness of the cylindrical portion111according to the first embodiment.

While the front cylindrical portion411ais formed in a cylindrical shape along the Y-direction with the outer diameter further smaller than the rear cylindrical portion411b.The front cylindrical portion411ais formed to be of even thickness.

Also in the embodiment, the thermopile holder410is made of a material of high heat conductivity and high electric conductivity such as copper, silver, aluminum, iron, or gold.

As mentioned above, since its thickness is fairly thick, the thermopile holder410has a higher thermal capacity than the thermopile holder110of the first embodiment.

According to this, when the thermopile10is inserted into the thermopile holder410, it is possible to keep even the temperature near the thermopile10and make the inner temperature of the thermopile10equal to the temperature of the peripheral members of the thermopile10described later. As a result, a more accurate measured temperature can be obtained by using the thermopile holder410.

The thermopile housing hole412H is provided in the fixing block portion412. The fixing block portion412communicates with the inner space of the front cylindrical portion411aand the rear cylindrical portion411b.

As illustrated by the arrow F1inFIG. 20, the fixing ring420, the thermopile10, and the fixing rear cap430are sequentially inserted into the thermopile housing hole412H of the fixing block portion412.

As illustrated by the arrow F2inFIG. 20, a first circular slit member411S and a second circular slit member412S are inserted into the front cylindrical portion411aand the rear cylindrical portion411b.A third circular slit member413S is attached to the end portion of the cylindrical portion411ain the Y-direction.

In this state, a lens holder500is attached to the front cylindrical portion411aof the thermopile holder410. The infrared radiation concentrating lens200L is attached to the end portion of the lens holder500. The length of this lens holder500is shorter than that of the lens holder200of the first embodiment in the Y-direction.

Similarly to the first embodiment, the amplifier attachment spacer140is attached to this assembled body including the thermopile10and its peripheral members, and by the amplifier attachment spacer140holding the preamplifier board20, the infrared radiation concentrating unit900is completed (refer toFIG. 18). The inner structure of the infrared radiation concentrating unit900will be described in detail.

FIG. 21is a side lateral view (YZ plane view viewed from the X-direction) and a-front view of the infrared radiation concentrating unit900of the radiation thermometer according to the second embodiment, andFIG. 22is an appearance perspective view of the infrared radiation concentrating unit900of the radiation thermometer according to the second embodiment.

FIG. 23is a cross-sectional view along the line D-D of the infrared radiation concentrating unit900ofFIG. 22, andFIG. 24is an enlarged cross-sectional view of the portion indicated by the dotted line N ofFIG. 23.

As illustrated inFIG. 21andFIG. 22, holder fixing pieces501and502are formed at the rear end of the lens holder500, and the lens holder500is fixed to the end of the thermopile holder410by the holder pieces501and502.

Similarly to the lens holder200of the first embodiment, the lens holder500has the laser supporting pole560and the laser supporting pole570protruding in the Z-direction.

As illustrated inFIG. 23, from the side of the fixing block portion412, a slit projection411T, a first knot411f,and a second knot412fare sequentially formed in the inner surfaces of the front cylindrical portion411aand the rear cylindrical portion411b.

The slit projection411T protrudes from the inner surface of the rear cylindrical portion411btoward its center and it has a circular slit (hole).

The first slit member411S is attached to the first knot411f.The second slit member412S is attached to the second knot412f.

Each circular slit (hole) of the third slit member413S, the second slit member412S, the first slit member411S, and the slit projection411T becomes smaller in this order.

A rear slit421S is formed at the front end412aof the thermopile housing hole412H of the fixing block portion412. The circular slit (hole) in the rear slit421S is further smaller than the slit of the slit projection411T.

These first slit member411S, second slit member412S, third slit member413S, slit projection411T, and rear slit421S restrict the passage of the infrared radiation so that the infrared radiation concentrated by the infrared radiation concentrating lens200L can enter the thermopile10.

In this embodiment, since the five slits restrict the passage of the infrared radiation, the infrared radiation externally entering the head portion100A through the infrared radiation concentrating lens200L can entering the infrared radiation receiving portion11of the thermopile10without being reflected by the various materials within the head portion10A. As a result, only the infrared radiation directly radiated from the measurement object can assuredly enter the infrared radiation receiving portion11.

As illustrated by the enlarged cross-sectional view ofFIG. 24, a fixing ring420attached to the rear portion of the rear slit421S is formed in a substantially cylindrical shape, in the thermopile housing hole412H. The rear end of the fixing ring420is a little protrudent inwardly. This protrudent portion is hereinafter referred to as a rear protrudent portion420t.

The thermopile10has such a structure that a metal cap16with a circular window is attached to one side of a circular base15with the infrared radiation receiving portion11fixed there. From the other side of the circular base15, a plurality of terminals10T are extended in the Y-direction.

The thermopile10having the above structure has a brim10R all around the circular base15at a connected portion of the circular base15and the metal cap16(refer to the dotted line ofFIG. 24andFIG. 20).

The fixing rear cap430has a stepped portion432for firmly fixing the thermopile10therein.

As mentioned above, when the fixing ring420, the thermopile10, and the fixing rear cap430are sequentially inserted into the thermopile housing hole412H, the brim10R is pinched between the rear end protrudent portion420tof the fixing ring420and the stepped portion432of the fixing rear cap430and fixed there.

The metal cap16of the thermopile10is arranged so as to cover the infrared radiation receiving portion11.

When there occurs a change in the temperature around the metal cap16positioned at the detecting surface of the infrared radiation receiving portion11, error may occur in the detected temperature.

The local temperature change in the metal cap16easily occurs in a contact portion of the fixing ring420for fixing the thermopile10and the metal cap16.

In the infrared radiation concentrating unit900of the embodiment, the contract portion of the fixing ring420and the thermopile10is restricted to the brim10R that is the contact portion of the circular base15and the metal cap16. This can restrain the local temperature change in the metal cap16positioned at the detecting surface of the infrared radiation receiving portion11and the error generation in the detected temperature fully.

The circular slit of the rear slit421S integrated with the thermopile holder410is formed smaller than the circular window of the metal cap16.

As mentioned above, the thermopile10is assuredly located within the thermopile holder410according to the fixing ring420and the fixing rear cap430. Thus, the visual angle on the side of the front surface KF (refer toFIG. 7) of the infrared radiation concentrating unit11within the metal cap16is accurately set by the rear slit421S regardless of the shape of the window of the metal cap16.

Similarly to the first embodiment, the above assembled infrared radiation concentrating unit900is built in the head casing K as the assembled body together with the main board30, the power supply board40, the junction board50and the main frame300. In these ways, the head portion100A of the radiation thermometer100according to the second embodiment is completed (refer toFIG. 18andFIG. 19).

Also in this embodiment, the thermopile holder410is arranged out of contact with the heat diffusion member90. As a result, there exists an air layer between the thermopile holder410with the thermopile10inserted and the heat diffusion member90. This air layer works as a heat insulating layer. As a result, the heat generated by the main board30, the power supply board40, and the laser diodes60and70are difficult to transmit to the thermopile holder410and the thermopile10through the heat diffusion member90.

In this embodiment, the first slit member411S, the second slit member412S, the third slit member413S, and the fixing rear cap430are also made of a material of high heat conductivity and high electric conductivity such as copper, silver, aluminum, iron, or gold. Also in the embodiment, it is possible to keep the temperature around the thermopile10even, similarly to the first embodiment.

The above lens holder500is made of a material of low heat conductivity such as resin, similarly to the lens holder200of the first embodiment. This makes it difficult to transmit the heat generated by the laser diodes60and70to the lens holder500. Thus, the heat generated by the laser diodes60and70is difficult to transmit to the thermopile10.

In the radiation thermometers100according to the first embodiment and the second embodiment, the head casing K corresponds to a casing, the front surface KF corresponds to a first surface, the back surface KB corresponds to a second surface, the upper surface KU corresponds to a third surface, the down surface KD corresponds to a fourth surface, the side surface KS1corresponds to a fifth surface, the side surface KS2corresponds to a sixth surface, and the infrared radiation concentrating unit KH corresponds to an infrared radiation passing unit.

The thermopile10corresponds to a sensing element, the first signal amplifier21and the second signal amplifier22correspond to a first circuit, the preamplifier board20corresponds to a first board, the circuit including the CPU34corresponds to a second circuit, the main board30corresponds to a second board, the circuit including the power supply circuit41corresponds to a third circuit, and the power supply board40corresponds to a third board.

The heat diffusion member90and the ground conductive surface50G of the junction board50correspond to a heat diffusion member, the laser diode60corresponds to a first light source, the laser diode70corresponds to a second light source, the laser driving circuit37corresponds to a first driving circuit, and the laser driving circuit43corresponds to a second driving circuit.

The CPU34corresponds to a control circuit, the indication light36corresponds to an indication element, and the air layers between the thermopile10and the heat diffusion member90and between each of the main board30, the power supply board40, and the laser diodes60and70and the heat diffusion member90correspond to a space.

The invention is applicable to detect the infrared energy radiated from an object.