JP2000213988A - Temperature detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the impact force per unit area when a shielding plate collides with a stopper and reduce the rocking of the shielding plate when it is stopped by increasing the contact area between the joint section of the shielding plate and the stopper. SOLUTION: This device is provided with an infrared ray detector 3 detecting the infrared rays emitted from a measured object, a shielding plate 1 shielding the infrared rays fed to the infrared ray detector 3, a DC motor 13 driving the shielding plate 1, a stopper 14 provided at the stop position of the shielding plate 1, a control means 20 controlling the DC motor 13, and a temperature converting means 18 converting the temperature of the measured object based on the output of the infrared ray detector 3. The size of the shielding plate 1 is made larger at the end section than at the center section on the cross section in the rotating direction including a shield section shielding infrared rays and a contact portion with the stopper 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detecting device for detecting the temperature of an object in a non-contact manner, and more particularly, to a light shielding plate for controlling the incidence and shielding of infrared rays.

[0002]

2. Description of the Related Art Conventionally, in a device using a pyroelectric infrared detector as a temperature detecting device for detecting the temperature of an object in a non-contact manner, a light-shielding plate for switching between incident light of an infrared ray incident on the infrared detector and light shielding. Is provided. This light-shielding plate is made of a material that does not transmit infrared light, such as a metal plate, and its end is attached to the rotating shaft of a DC motor or AC motor and driven to rotate, and repeatedly enters and blocks infrared light reaching the infrared detector. There is a method of intermittent. That is, FIG.
As shown in (1), a semi-arc shaped light shielding plate 1 is attached to the rotating shaft of a DC or AC motor 2 and is driven to rotate in the direction of the arrow to interrupt the infrared rays incident on the infrared detector 3.

There is also a method in which a pulse is applied at a predetermined cycle using a pulse motor as a rotary drive source, and infrared light is intermittently transmitted by repeating, for example, normal rotation and inversion at a predetermined angle. For example, an example of a temperature measuring device disclosed in Japanese Patent Application Laid-Open No. 7-280652 will be described with reference to FIG. Chopper (light shield plate) 1
Is driven to reciprocate by a quartz timepiece movement 4, which is a driving source based on the same principle as a pulse motor,
The infrared rays reaching the infrared detector 3 are interrupted. The quartz watch movement 4 includes a permanent magnet 5, a core 6, and a coil 7,
The end of the chopper 1 is attached to the permanent magnet 5. The coil 7 receives a pulse input at the first and second input terminals 8 and 9, and in response to the pulse input, the permanent magnet 5 rotates and the chopper 1 reciprocates as indicated by the arrow.

[0004]

However, when the light shielding plate is rotated by using a DC motor as a drive source, there is a problem that the temperature measurement accuracy is low due to variations in the light input time and the light shielding time. The rotation speed of a DC motor generally fluctuates due to fluctuations in the power supply voltage or the like. If the rotation speed fluctuates,
The light-shielding period changes, and the fluctuation in the period also causes the output of the infrared detector to fluctuate, preventing accurate temperature detection. In order to stabilize the rotation speed, a complicated control circuit for performing feedback control by providing a means for detecting the rotation speed of a photo interrupter and the like and a means for adjusting the power supply voltage is required.

When an AC motor is used as a driving source,
Under a relatively stable frequency such as a commercial power supply, the number of rotations is easier to stabilize than a DC motor, but there is a problem that an AC power supply such as a commercial power supply is required. In the case of using a battery power supply such as a portable radiation thermometer or a radiation thermometer, this is only a DC power supply, and a complicated circuit for producing an AC power supply with a stable frequency is required, and it is difficult to realize this.

When a quartz clock movement or a pulse motor is used as a driving source, the driving is performed based on a digital signal from a microprocessor or the like. There is a problem that it is difficult to switch between light input and light shielding with high accuracy due to the stop while stopping. In other words, these driving sources are stopped by the balance of the attractive force and the repulsive force by the magnetic force, and are driven by changing the polarity of the magnetic force. At the moment of the stop, the light shielding plate swings and balances the attractive force and the repulsive force. There is a characteristic that it is stopped.

FIG. 9 shows the behavior characteristics of the pulse motor, that is, the driving pulse and the rotation angle of the rotation shaft of the pulse motor.
The horizontal axis is the elapsed time. The driving pulse alternately outputs CW (clockwise) and CCW (counterclockwise) pulses at a constant period t and a duty of 50%. Then, the rotation angle of the rotary shaft of the pulse motor causes an overshoot at the time of reaching the stop position as shown in the figure, then causes an undershoot, and the amplitude is reduced and stabilized at the stop position.

Since pulse motors and quartz timepiece movements generally have the behavior characteristics shown in FIG. 9, when these are used as a driving source of a light shielding plate to intermittently emit infrared light, light is blocked from entering light, or light is blocked from entering light. At the moment of switching to light, a situation occurs in which light input and light shielding are switched at very short intervals, which makes the output of the infrared detector unstable,
There is a problem that accuracy of temperature detection is lacking. In order to avoid this problem, there is a method in which the shape of the light-shielding plate is sufficiently large with respect to Δθ which is the maximum position of the swing, but in this case, there is a problem that the temperature detecting device itself also becomes large. .

[0009]

According to the present invention, there is provided an infrared detector for detecting infrared rays emitted by an object to be measured, a light shielding plate for shielding infrared rays incident on the infrared detector, A DC motor for driving the light shielding plate, a stopper provided at a stop position of the light shielding plate, control means for controlling the DC motor, and a temperature for converting the temperature of the device under test based on the output of the infrared detector. The light-shielding plate includes a light-shielding portion that shields the infrared light and a joint that contacts the stopper, and the joint has a dimension of an end portion in a cross section in a rotation direction including a portion that contacts the stopper. Is larger than the size of the central portion, and the control means alternately reverses the rotation direction of the DC motor to switch between incoming light and blocked light of an infrared light path to the infrared detector.

[0010] According to the above invention, the light shielding plate having a configuration in which the size of the end portion is larger than the size of the central portion in the cross section in the rotation direction including the portion in contact with the stopper of the joint portion is driven by the DC motor, and The control means drives the DC motor so that it alternately reverses the light input and the light shielding, and switches between the light input and the light shielding. Since the temperature conversion means converts the temperature of the device under test based on the output of the infrared detector, the contact area between the joint of the light-shielding plate and the stopper can be increased, and the light-shielding plate can be detected. The impact force per unit area when colliding with the stopper is reduced, so the swing when stopping the light shield plate can be reduced. Tegiri Since it is possible to replace, it can perform accurate temperature detection small.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A temperature detecting device according to a first aspect of the present invention includes an infrared detector for detecting infrared rays emitted from an object to be measured, a light shielding plate for shielding infrared rays incident on the infrared detector, A DC motor for driving the light shielding plate, a stopper provided at a stop position of the light shielding plate, control means for controlling the DC motor, and a temperature for converting the temperature of the device under test based on the output of the infrared detector. The light-shielding plate includes a light-shielding portion that shields the infrared light and a joint that contacts the stopper, and the joint has a dimension of an end portion in a cross section in a rotation direction including a portion that contacts the stopper. Is larger than the size of the central part, and the control means alternately reverses the rotation direction of the DC motor to switch between incoming and outgoing light of an infrared light path to the infrared detector.

Then, a light-shielding plate having a configuration in which an end portion is larger in size in a rotational direction including a portion in contact with a stopper of the joint portion than a center portion is driven by a DC motor to collide with the stopper, thereby causing infrared rays to collide with the stopper. The control means drives the DC motor to alternately invert and switch between light input and light blocking, and the infrared detector emits infrared light from the device under test. And the temperature conversion means converts the temperature of the device under test based on the output of the infrared detector, so that the contact area between the joint of the light shielding plate and the stopper can be increased, and the light shielding plate collides with the stopper. Since the impact force per unit area at the time of light reduction is small, swing when the light shielding plate stops can be reduced, and even if the light shielding plate is sufficiently small, it is possible to stably switch between the light incident state and the light shielding state. Since it is, it is possible to perform highly accurate temperature detection is compact.

The joint of the light shielding plate of the temperature detecting device according to the second aspect of the present invention is formed by bending a metal plate.

Since the joint portion of the light-shielding plate is formed by bending a sheet metal, the contact area between the joint portion of the light-shielding plate and the stopper can be increased with a simple structure. Since the impact force per unit area is reduced, the swing of the light shielding plate at the time of collision can be reduced, and even if the light shielding plate is sufficiently small, it is possible to stably switch between the light incident state and the light shielding state, Small and highly accurate temperature detection can be performed. Small and highly accurate temperature detection can be performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a configuration block diagram of an application example in which a temperature detector is mounted on a thermometer as an embodiment of the present invention. FIG. 2 is an enlarged view of a main part of the light shielding plate, and FIGS. 3 to 5 are sectional views of the light shielding plate. FIG. 6 is a timing chart for explaining the operation.

In general, as a thermometer for measuring the surface temperature, the body temperature can be almost measured by measuring the temperature of a portion hardly contacting the outside air, such as the eardrum, oral cavity, and anus. In particular, the eardrum is known as a suitable place for measuring body temperature because the hypothalamus for controlling body temperature may be close. In FIG.
Is an object to be measured whose temperature is, for example, an eardrum. 11
Is a probe to be inserted into the ear canal, the diameter of which is reduced toward the tip so that it can be easily inserted into the ear canal. Reference numeral 12 denotes a condensing means for condensing infrared light emitted from the eardrum 10, and the condensed infrared light enters the infrared detector 3 via the light shielding plate 1.

The light-shielding plate 1 is reciprocally driven to rotate while colliding with the stopper 14 by the DC motor 13, and repeatedly switches between the state of input of infrared light reaching the infrared detector 3 and the state of shading. The infrared detector 3 is of a pyroelectric type, and its output changes in correlation with the differential value of the amount of infrared light to be detected. Here the light shielding plate 1
Is made of metal, and when light is shielded, infrared rays emitted by the infrared detector 3 itself are reflected on the metal surface and enter the infrared detector 3. That is, the output of the infrared detector 3 has a correlation with the temperature difference between the eardrum 10 and the infrared detector 3 due to the intermittent operation of the light shielding plate 1. A temperature sensor 15 for detecting the temperature of the infrared detector 3 is provided near the infrared detector 3. The temperature sensor 15 is based on a generally known thermistor.

The output of the infrared detector 3 is amplified by the amplifier 16, and the output voltage amplified by the amplifier 16 and the output voltage of the temperature sensor 15 are digitized by the AD converter 17. Reference numeral 18 denotes a temperature conversion means for converting the temperature of the eardrum 10 based on the output of the AD converter 17. The output of the infrared detector 3 becomes an AC waveform due to the intermittent operation of the light shielding plate 1, and its amplitude is proportional to the difference between the temperature of the eardrum 10 and the fourth power of the temperature of the infrared detector 3. The temperature conversion means 18 converts the temperature of the eardrum 10 based on this relationship and displays it on the display means 19.

Reference numeral 20 denotes a control unit for controlling the driving of the DC motor 13, and comprises a positive power supply unit 21 for switching from a light blocking state to a light receiving state and a negative power supply unit 22 for switching from a light receiving state to a light blocking state. Furthermore, positive power supply means 2
Reference numeral 1 denotes an initial power supply unit 21a for supplying electric power for driving the light shielding plate 1, and a reduced power supply unit 21b for supplying electric power for holding the position of the stopper 14 to the light shielding plate 1. The light-shielding plate 1 includes an initial power supply unit 22a for supplying power for driving the first light-emitting device 1 and a reduced power supply unit 22b for supplying power for holding the position of the stopper 14 in the light shielding plate 1.

Next, the structure of the light shielding plate will be described in detail with reference to FIGS. In FIG. 2, a state where the light shielding plate 1 is stopped in the light shielding state is indicated by a solid line, and a state where the light shielding plate 1 is stopped in the light incident state is indicated by a broken line. The light-shielding plate 1 includes a circular light-shielding portion 1a that shields infrared light incident on the infrared detector 3, and a joint portion 1b fixed to the shaft 23 of the DC motor 13. The stopper 14 includes a light-shielding stop part 14a to which the joint part 1b contacts when the light-shielding part 1a stops in a light-shielding state that shields the infrared detector 3, and a light-receiving stop part 14b to contact when stopping in the light-receiving state. I have.

FIG. 3 shows that the joint portion 1b of the light shielding plate 1 has the stopper 1
FIG. 3 is a cross-sectional view along the rotation direction of the light-shielding plate 1 including a portion that contacts a light-shielding stop portion 14a, that is, a straight line AB in FIG. The joint portion 1b is formed by bending a sheet metal, and the size d1 of the end portion 24 is larger than the size d2 of the center portion 25.

In the above configuration, when the DC motor 13 repeats normal rotation and reverse rotation, the joint portion 1b of the light shielding plate 1 collides with the light shielding stop portion 14a and the light stop portion 14b of the stopper 14 and stops. Here, by setting the dimension d1 of the end portion 24 of the joint portion 1b to be larger than the dimension d2 of the center portion 25, the contact area between the joint portion 1b of the light shielding plate 1 and the stopper 14 can be increased, and Since the impact force per unit area when the plate 1 collides with the stopper 14 becomes small,
The swing of the light shielding plate 1 at the time of stop can be made extremely small, and even if the light shielding plate 1 is sufficiently small, it is possible to stably switch between the state of entering light and the state of light shielding. It can be performed.

By forming the joint 1b of the light shielding plate 1 by bending sheet metal, the strength of the light shielding plate 1 can be increased with a simple structure, and the contact area between the joint 1b and the stopper 14 can be increased. However, the same effect can be obtained by forming the joint portion 1b as shown in FIGS.

FIG. 6 shows the specific operation of the control means 20, that is, the voltage applied to the DC motor 13 and the rotation angle of the DC motor 13. The period t1 in FIG. 6 is a positive power supply period in which the light shielding plate 1 is driven in the light incident state and stopped in the light incident state, and power is supplied by the positive power supply unit 21. The period of t2 is a negative power supply period in which the light shielding plate 1 is driven in the light shielding state and stopped in the light shielding state, and power is supplied by the negative power supply means 22. In this embodiment, t1 and t2 are set to the same time, but may be set to different times.

In the positive power supply period, t1a is an initial power supply period, power is supplied by the initial power supply means 21a to drive the light shielding plate 1 into a light-entering state, and t1b is a reduced power supply period, The reduced power supply means 2 for holding the plate 1 at the position of the light stop portion 14b of the stopper 14
1b intermittently supplies power. Similarly, in the negative power supply period, t2a is an initial power supply period, power is supplied by the initial power supply means 22a to drive the light shielding plate 1 to the light shielding state, and t2b is a reduced power supply period, Is intermittently supplied by the reduced power supply unit 22b in order to keep the light at the position of the light-blocking stop 14a.

Here, the reduced power supply means 21b and 22b supply power intermittently, but this has the effect of simplifying the power supply circuit configuration, but does not restrict the present invention. For example, power may be supplied at a constant power and less than the initial power supply period, or the power supply may be suspended if t1 and t2 are sufficiently short. That is, the light-shielding plate 1 is a light-shielding stop portion 14a or a light-incident stop portion 1 of the stopper 14.
Although the vibration of the human hand can be considered as a factor deviating from 4b, if t1 and t2 are sufficiently short, for example, less than 0.1 second, the vibration period of the human hand is sufficiently long. Is hardly shifted.

In FIG. 6, Δθ indicates that the light shielding plate 1 is the stopper 1
4, the light-shielding plate 1 in which the size of the end portion 24 of the joint portion 1b is larger than the size of the central portion 25 is driven by the DC motor 13, and the stopper 14 is provided. The control means 20 drives the DC motor 13 to alternately reverse the light input and the light shielding, thereby stopping the light input and the light shielding of the infrared light path leading to the infrared detector 3 by colliding with the light source. As compared with Δθ in FIG. 9 shown in the example, it is sufficiently small. Here, t3 is a time required for the light shielding plate 1 to collide with the stopper 14 and start to bounce after the start of driving. The initial power supply periods t1a and t2a are longer than the time t3, so that the initial power supply period is deviated from the stopper 14. The light-shielding plate 1 does not stop at the position, so that it is possible to stably switch between light input and light shielding.

The embodiment has been described above as an application example in which the temperature detecting device of the present invention is mounted on a portable thermometer for non-contact measurement of the temperature of the eardrum, but this is a limitation of the present invention. For example, the present invention may be applied to a microwave oven, an air conditioner, or the like which is incorporated in a device and detects and controls the temperature in a non-contact manner.

[0029]

As described above, the temperature detector of the present invention has the following effects.

(1) A light-shielding plate having a configuration in which an end portion is larger in size in a rotational direction including a portion in contact with a stopper of a joint portion than a center portion is driven by a DC motor to collide with the stopper. The infrared light path leading to the infrared detector is stopped in the state of incoming and outgoing light, respectively, and the control means switches the DC motor to alternately invert the incoming and outgoing light, and the infrared detector emits light from the device under test. Since the infrared ray is detected and the temperature conversion means converts the temperature of the device under test based on the output of the infrared detector, the contact area between the joint of the light shielding plate and the stopper can be increased, and the light shielding plate can Since the impact force per unit area at the time of collision is reduced, the swing when stopping the light shielding plate can be reduced, and even if the light shielding plate is sufficiently small, it is possible to stably switch between the light entering state and the light shielding state Because it can be performed with high accuracy temperature detection small.

(2) Since the joint portion of the light-shielding plate is formed by bending sheet metal, the contact area between the joint portion of the light-shielding plate and the stopper can be increased with a simple structure, and when the light-shielding plate collides with the stopper. Since the impact force per unit area of the light-shielding plate becomes small, the shaking of the light-shielding plate at the time of collision can be reduced. In addition, small and highly accurate temperature detection can be performed. Small and highly accurate temperature detection can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a temperature detection device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of a light shielding plate of the temperature detecting device.

FIG. 3 is a cross-sectional view of a light shielding plate portion of the temperature detection device.

FIG. 4 is a cross-sectional view of a light shielding plate of the temperature detecting device.

FIG. 5 is a cross-sectional view of a light shielding plate of the temperature detecting device.

FIG. 6 is a timing chart illustrating the operation of the temperature detection device.

FIG. 7 is a configuration diagram of a conventional temperature detection device.

FIG. 8 is a configuration diagram of a conventional temperature detection device.

FIG. 9 is a timing chart illustrating the operation of the temperature detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shield plate 1a Shield part 1b Joint part 3 Infrared detector 10 Device under test 13 DC motor 14 Stopper 18 Temperature conversion means 20 Control means 24 End part 25 Central part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuyuki Kanazawa 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Term (reference) 2G066 BA01 BA35 BB13 BC07 BC15 CA08

Claims (2)

[Claims] 1. An infrared detector for detecting infrared radiation emitted by an object to be measured, a light shield plate for shielding infrared light incident on the infrared detector, a DC motor for driving the light shield plate, and a stop of the light shield plate. A stopper provided at a position, control means for controlling the DC motor, and temperature conversion means for converting the temperature of the device under test based on the output of the infrared detector, wherein the light shielding plate shields the infrared light A light-shielding portion and a joint portion that contacts the stopper, wherein the joint portion has a configuration in which a size of an end portion is larger than a size of a center portion in a cross section in a rotation direction including a portion that contacts the stopper, and the control means includes: A temperature detecting device for alternately reversing the direction of rotation of a DC motor to switch between entering and blocking an infrared light path to the infrared detector. 2. The temperature detecting device according to claim 1, wherein the joint is formed by bending a sheet metal.