JP2000213989A - Temperature detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and accurately switch light-introduction and light-shielding, to enhance temperature detection accuracy and to reduce noise generated at the time of switching the light-introduction and the light shielding in a temperature detection device for detecting the temperature of an object to be detected by a non-contact, particularly in a shielding plate for controlling a light- introduction and a light-shielding of an infrared. SOLUTION: An infrared detector 3 detects infrared which an object to be measured radiates. A shielding plate 1 driven by a DC motor 10 is collided to a stopper 12 and is stopped in respective states of light-introduction and light-shielding of an infrared passage arriving at the infrared detector 3. A control means is driven so as to alternately reverse-rotating the DC motor and switches the light-introduction and the light-shielding. Therefore, light- introduction time and light-shielding time are stabilized and temperature detection with high accuracy can be carried out. Since an impact-absorbing mechanism is provided at a joint portion 1b collided with the stopper 12 of a light- shielding plate 1, an impact of the collision with the stopper 12 is made less and a collision sound can be reduced.

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.

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 number of revolutions fluctuates, the period of light input and light blocking changes, and the fluctuation of this period also fluctuates the output of the infrared detector, making accurate temperature detection impossible. 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. .

To solve these problems, a method as shown in FIG. 10 is conceivable. That is, the light-shielding plate 1 that shields infrared light incident on the infrared detector 3 is attached to the shaft 11 of the DC motor 10, and stoppers 12 a and 12 b are provided at stop positions of the light-shielding plate 1, and the rotation direction of the DC motor 10 is alternately reversed. Then, the light shielding plate 1 is
By driving between infrared rays a and 12b, the infrared ray incident on the infrared ray detector 3 is switched between entering and blocking. According to this method, the light shielding plate 1 driven by the DC motor 10 has the stoppers 12a, 12b provided at the stop positions.
By colliding with the object, the infrared detector 3
In this case, it is possible to stop in the respective states of light incidence and light shielding of the infrared light path leading to the light path, and to alternately reverse the rotation direction of the DC motor 10 to switch the state of light incidence and light shielding.
Since the light input time and the light shielding time by the driving of the light shielding plate 1 are stable, and the light shielding plate 1 does not swing at the stop position, even if the light shielding plate 1 is sufficiently small, it is possible to stably switch between the light incident state and the light shielding state. And highly accurate temperature detection can be performed.

[0010]

However, in the above-mentioned conventional method, a collision sound is generated when the light shielding plate collides with the stopper and stops. In particular, the body temperature is measured by detecting infrared rays emitted from the eardrum. In the radiation thermometer, the collision sound between the light-shielding plate and the stopper can be heard near the ear, so that there is a problem that the collision sound is harsh.

[0011]

According to the present invention, there is provided 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. It has a conversion means, the light-shielding plate is composed of a light-shielding part that shields the infrared rays and a joint part that collides with the stopper, an impact buffering mechanism is provided at least in the joint part, and the control means controls the rotation direction of the DC motor. The configuration is such that the light is alternately inverted so as to switch between incoming light and blocked light of an infrared light path reaching the infrared detector.

According to the invention, the shock absorbing mechanism is provided at least in the joint portion of the light shielding plate including the light shielding portion for shielding the infrared rays and the joint portion colliding with the stopper, and the light shielding plate is driven by the DC motor to collide with the stopper. To stop in the state of incoming and blocking of the infrared light path to the infrared detector,
The control means drives the DC motor to alternately reverse the light to switch between incoming and outgoing light, the infrared detector detects infrared radiation emitted by the device under test, and the temperature conversion device performs measurement based on the output of the infrared detector. Because the temperature of the object is converted, the impact buffering mechanism provided at the joint of the light-shielding plate can reduce the impact of collision with the stopper and reduce the collision sound. And the light-shielding state can be switched stably, so that small and highly accurate temperature detection can be performed quietly.

[0013]

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. It has a conversion means, the light-shielding plate is composed of a light-shielding part that shields the infrared rays and a joint part that collides with the stopper, an impact buffering mechanism is provided at least in the joint part, and the control means controls the rotation direction of the DC motor. In this configuration, the light is alternately inverted to switch between light input and light blocking of an infrared light path reaching the infrared detector.

[0014] An impact buffering mechanism is provided at least at a joint portion of the light shielding plate comprising a light shielding portion for shielding infrared rays and a joint portion which collides with the stopper. The control means drives the DC motor to alternately reverse, switching between incoming and outgoing light, and the infrared detector detects infrared radiation emitted by the device under test. Since the temperature conversion means converts the temperature of the DUT based on the output of the infrared detector, the impact buffer mechanism provided at the joint of the light shielding plate reduces the impact of the collision with the stopper and reduces the impact noise. 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, so that small and highly accurate temperature detection can be performed quietly.

Further, the shock absorbing mechanism of the temperature detecting device according to claim 2 of the present invention has a structure in which a through hole is provided in a joint portion of the light shielding plate.

Since the through hole is provided in the joint portion of the light shielding plate, the mass of the light shielding plate is reduced, the impact at the time of collision with the stopper can be reduced, the collision sound can be reduced, and the light shielding can be achieved. Since the mass of the plate is reduced, the power of the DC motor for driving the light shielding plate can be small, and the power consumption can be reduced.

Further, the shock absorbing mechanism of the temperature detecting device according to the third aspect of the present invention has a structure in which a plurality of small through holes are provided in a joint portion of the light shielding plate.

Further, by providing a plurality of small through holes in the joint portion of the light-shielding plate, the strength of the light-shielding plate can be increased, and the noise of the collision with the stopper can be reduced by reducing the mass of the light-shielding plate. Power consumption can be reduced.

Further, in the temperature detecting device according to claim 4 of the present invention, the plurality of small through holes are circular.

Since the plurality of small through holes are formed in a circular shape, the light shielding plate can be easily processed, and the noise of the collision with the stopper can be reduced by reducing the mass of the light shielding plate.
Power consumption can be reduced.

According to a fifth aspect of the present invention, there is provided a temperature detecting device wherein a plurality of small through holes are formed in a honeycomb shape.

Since the plurality of small through holes are formed in a honeycomb shape, the ratio of the area of the small through holes to the joint can be increased, and the mass of the light shielding plate can be further reduced. Can be reduced, and power consumption can be reduced.

[0023]

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. 2 to 5 are enlarged views of a main part of a light shielding plate portion. FIG. 6 is a timing chart for explaining the operation.

Generally, as a thermometer for measuring the surface temperature, the body temperature can be almost measured by measuring the temperature of a portion which is hardly contacted with the outside air, such as the eardrum, the oral cavity, and the 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. 1, 13
Is an object to be measured whose temperature is, for example, an eardrum. 14
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 15 denotes a condensing means for condensing infrared rays emitted from the eardrum 13, and the condensed infrared rays enter 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 12 by the DC motor 10, and repeatedly switches between the state where the infrared light reaches 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 13 and the infrared detector 3 due to the intermittent operation of the light shielding plate 1. Further, a temperature sensor 16 for detecting the temperature of the infrared detector 3 is provided near the infrared detector 3. The temperature sensor 16 is based on a generally known thermistor.

The output of the infrared detector 3 is amplified by the amplifier 17, and the output voltage amplified by the amplifier 17 and the output voltage of the temperature sensor 16 are digitized by the AD converter 18. Reference numeral 19 denotes temperature conversion means for converting the temperature of the eardrum 13 based on the output of the AD converter 18. 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 13 and the fourth power of the temperature of the infrared detector 3. The temperature conversion means 19 converts the temperature of the eardrum 13 on the basis of this relationship and displays it on the display means 20.

Reference numeral 21 denotes a control unit for controlling the driving of the DC motor 10. The control unit 21 includes a positive power supply unit 22 for switching from a light blocking state to a light receiving state, and a negative power supply unit 23 for switching from a light receiving state to a light blocking state. Furthermore, positive power supply means 2
Reference numeral 2 denotes an initial power supply means 22a for supplying electric power for driving the light-shielding plate 1, and a reduced power supply means 22b for supplying electric power for holding the position of the stopper 12 by the light-shielding plate 1. The light shielding plate 1 includes an initial power supply unit 23a for supplying electric power for driving the light source 1 and a reduced power supply unit 23b for supplying electric power for holding the position of the stopper 12 by the light shielding plate 1.

Next, the structure of the light shielding plate will be described in detail with reference to FIG. 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 is a circular light shielding portion 1a that shields infrared light incident on the infrared detector 3.
And a joint 1b fixed to the shaft 11 of the DC motor 10. The joint 1b has a through hole 24 as an impact buffering mechanism. The stopper 12 includes a light-shielding stop part 12a to which the joint part 1b contacts when the light-shielding part 1a stops in the light-shielding state that shields the infrared detector 3, and a light-receiving stop part 12b to contact when stopping in the light-receiving state. I have.

In the above configuration, when the DC motor 10 repeats normal rotation and reverse rotation, the joint portion 1b of the light shielding plate 1 collides with the light shielding stopping portion 12a and the light receiving stopping portion 12b of the stopper 12 and stops. Since there is no swinging at the time of stopping, 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, and it is possible to perform small and highly accurate temperature detection. And since the through-hole 24 was provided in the joint part 1b, the mass of the light-shielding plate 1 was reduced and the joint part 1 of the light-shielding plate 1 was reduced.
The impact when b collides with the stopper 12 can be reduced, and the collision noise can be reduced. This is particularly effective for a thermometer in which an ear is used to detect the temperature.
Further, since the mass of the light shielding plate 1 is reduced, the power of the DC motor 10 for driving the light shielding plate 1 can be small, and the power consumption can be reduced.

Although one through hole 24 is provided in the joint portion 1b, as shown in FIG.
A plurality of small through holes 25 may be provided in b. In this case, the strength of the light shielding plate 1 can be increased, and the noise of the collision with the stopper 12 and the power consumption of the DC motor 10 can be reduced by reducing the mass of the light shielding plate 1.

Further, by forming the small through-holes 25 in a circular shape as shown in FIG. 4, the processing of the light shielding plate becomes easy, the strength of the light shielding plate 1 is increased, and the mass is reduced. And the power consumption of the DC motor 10 can be reduced.

Further, by forming the small through holes 25 in a honeycomb shape as shown in FIG. 5, the ratio of the area of the small through holes 25 to the joint portion 1b can be made larger than that of a circular shape. 1 can be further reduced, so that the collision sound with the stopper 12 and the DC motor 1
0 power consumption can be reduced.

FIG. 6 shows a specific operation of the control means 21.
The voltage applied to the DC motor 10 and the rotation angle of the DC motor 10 are shown. 6 is a positive power supply period in which the light shielding plate 1 is driven in the light incident state and is stopped in the light incident state, and power is supplied by the positive power supply unit 22. 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 23. 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, and power is supplied by the initial power supply means 22a to drive the light shielding plate 1 to the light incident state, and t1b is a reduced power supply period, Power reducing means 2 for holding the plate 1 at the position of the light stop 12b of the stopper 12
Power is supplied intermittently by 2b. Similarly, in the negative power supply period, t2a is an initial power supply period, power is supplied by the initial power supply means 23a 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 means 23b in order to keep the light at the position of the light shielding stop portion 12a.

Here, the reduced power supply means 22b and 23b intermittently supply power, but this has the effect of simplifying the power supply circuit configuration, but does not limit 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 provided with the stopper 12, the light-shielding stop portion 12a or the light-entering stop portion 1.
The vibration of the human hand can be considered as a factor that deviates from 2b. However, if t1 and t2 are sufficiently short, for example, less than 0.1 second, the vibration period of the human hand is sufficiently longer. Is hardly shifted.

In FIG. 6, .DELTA..theta.
2, which is a swing which occurs due to bouncing by the reaction, but is sufficiently small as compared with Δθ of FIG. 9 shown in the conventional example. Here, t3 is the time required for the light-shielding plate 1 to collide with the stopper 12 from the start of driving and to dig back. 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 intended to limit 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.

[0038]

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

(1) An impact buffering mechanism is provided at least at a joint of a light-shielding plate comprising a light-shielding portion that shields infrared rays and a joint that collides with the stopper, and the light-shielding plate is driven by a DC motor to collide with the stopper to detect infrared rays. The control means drives the DC motor to alternately invert and switch between incoming light and blocked light, and the infrared detector emits infrared light radiated from the device under test. The temperature conversion means converts the temperature of the DUT based on the output of the infrared detector, so that the impact of the collision with the stopper is reduced by the shock absorbing mechanism provided at the joint of the light shielding plate to reduce the impact sound. 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, so that small and highly accurate temperature detection can be performed quietly.

(2) By providing a through hole at the joint of the light-shielding plate, the mass of the light-shielding plate is reduced, the impact at the time of collision with the stopper can be reduced, and the collision sound can be reduced. Since the mass of the light-shielding plate is reduced, the power of the DC motor that drives the light-shielding plate can be reduced, and the power consumption can be reduced.

(3) By providing a plurality of small through holes in the joint portion of the light shielding plate, the strength of the light shielding plate can be increased.
By reducing the mass of the light-shielding plate, the impact at the time of collision with the stopper can be reduced, the collision noise can be reduced, and the mass of the light-shielding plate becomes lighter, so that the power of the DC motor driving the light-shielding plate is reduced. It can be small and power consumption can be reduced.

(4) Since the plurality of small through holes are formed in a circular shape, it is easy to process the light shielding plate, and since the mass of the light shielding plate is reduced, the impact at the time of collision with the stopper can be reduced, and the collision noise can be reduced. Can be reduced and the mass of the light shielding plate is reduced, so that the power of the DC motor for driving the light shielding plate can be reduced, and the power consumption can be reduced.

(5) Since the plurality of through holes are formed in a honeycomb shape, the ratio of the area of the through holes to the joint portion can be increased, and the mass of the light shielding plate can be further reduced. The impact at the time of collision can be reduced, the collision sound can be reduced, and the mass of the light shielding plate is reduced, so that the power of the DC motor that drives the light shielding plate can be reduced and the power consumption can be reduced. Can be.

[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 an enlarged view of a main part of a light shielding plate of the temperature detecting device.

FIG. 4 is an enlarged view of a main part of a light shielding plate of the temperature detecting device.

FIG. 5 is an enlarged view of a main part 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.

FIG. 10 is a configuration diagram of a conventional temperature detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shield plate 1a Shield part 1b Joint part 3 Infrared detector 10 DC motor 12 Stopper 13 Object under test 19 Temperature conversion means 21 Control means 24 Through hole 25 Through small hole

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuyuki Kanazawa 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Term (reference) 2G066 AA20 AC13 BA01 BA35 CA20

Claims (5)

[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 The joint comprises a light-shielding portion and a joint which collides with the stopper. At least the shock-absorbing mechanism is provided at the joint, and the control means alternately reverses the rotation direction of the DC motor to enter an infrared light path leading to the infrared detector. A temperature detector that switches between light and light. 2. The temperature detecting device according to claim 1, wherein the shock absorbing mechanism has a through hole formed in a joint portion of the light shielding plate. 3. The temperature detecting device according to claim 1, wherein the shock absorbing mechanism has a plurality of small through holes in a joint portion of the light shielding plate. 4. A plurality of through holes are circular in shape.
The temperature detection device as described in the above. 5. The temperature detecting device according to claim 3, wherein the plurality of small through holes are formed in a honeycomb shape.