JP3775024B2 - Temperature detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a temperature detection device that detects the temperature of an object in a non-contact manner, and more particularly to a light shielding plate that controls infrared light incident and light shielding.
[0002]
[Prior art]
Conventionally, in the case of using a pyroelectric infrared detector as a temperature detection device that detects the temperature of an object in a non-contact manner, a light shielding plate that switches between incident light and light shielding of infrared light incident on the infrared detector is provided. ing. 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 a rotating shaft of a DC motor or AC motor and rotated to drive infrared light incident on the infrared detector. There is a method of repeatedly interrupting. That is, as shown in FIG. 5, the semicircular arc-shaped light shielding plate 1 is attached to the rotating shaft of the direct current or alternating current motor 2 and is driven to rotate in the direction of the arrow to interrupt the infrared light incident on the infrared detector 3.
[0003]
There is also a method of intermittently irradiating infrared light by applying pulses at a predetermined cycle using a pulse motor as a rotation drive source and repeating forward rotation and reverse rotation at a predetermined angle, for example. 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. A chopper (light-shielding plate) 1 is driven to reciprocate by a quartz watch movement 4 which is a drive source based on the same principle as a pulse motor, and interrupts infrared light reaching the infrared detector 3. The quartz watch movement 4 includes a permanent magnet 5, a core 6 and a coil 7, and 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, the permanent magnet 5 rotates in response to the pulse input, and the chopper 1 reciprocates as indicated by arrows.
[0004]
[Problems to be solved by the invention]
However, in the case of the above conventional example in which the light shielding plate is rotated 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 incident time and the light shielding time. In general, the rotational speed of a DC motor fluctuates due to fluctuations in power supply voltage. If the rotation speed fluctuates, the period of incident light and light shielding 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 number of revolutions, a complicated control circuit is required which provides a means for detecting the number of revolutions such as a photo interrupter and a means for adjusting the power supply voltage and performs feedback control.
[0005]
When an AC motor is used as a drive source, the rotational speed is easier to stabilize than a DC motor under a relatively stable frequency like a commercial power source, but an AC power source such as a commercial power source is required. There is. This is difficult to achieve because it requires only a DC power source in the case of a battery power source such as a portable radiation thermometer or a radiation thermometer, and requires a complicated circuit for producing an AC power source with a stable frequency.
[0006]
When a quartz watch movement or pulse motor is used as the drive source, it is driven based on a digital signal from a microprocessor, etc., so the light incident and light shielding cycles can be interrupted with high accuracy, but the light shielding plate stops while swinging. Therefore, there is a problem that it is difficult to switch between incident light and light shielding with high accuracy. In other words, these driving sources are stopped by the balance between the attractive force and the repulsive force due to the magnetic force, and are driven by changing the polarity of the magnetic force. Therefore, at the moment of stopping, the shading plate swings to balance the attractive force and the repulsive force. It has the characteristic of letting it stop.
[0007]
FIG. 7 shows the characteristics of the behavior of the pulse motor. The abscissa is the elapsed time, and (a) is a drive pulse with CW (clockwise) and CCW (counterclockwise) pulses alternately output at a constant period t and a duty of 50%. When (b) reaches the stop position as shown in the figure at the rotation angle of the rotation shaft of the pulse motor, an overshoot occurs, and then an undershoot occurs, and the amplitude becomes stable while the amplitude decreases.
Since pulse motors and quartz watch movements generally have behavioral characteristics as shown in FIG. 7, if these are used as a light source for the light shielding plate and infrared light is interrupted, light is shielded from light incident or light incident from light shielding. At the moment of switching, there is a situation in which the incident light and the light shielding are switched at a very short interval. For this reason, there is a problem that the output of the infrared detector becomes unstable and the accuracy of temperature detection is lacking. In order to avoid this problem, there is a method of making the shape of the light shielding plate sufficiently large with respect to Δθ which is the maximum position of oscillation, but in this case, there is a problem that the temperature detection device itself is also increased in size. .
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides an infrared detector that detects infrared rays emitted from a measurement object, a light shielding plate that blocks infrared rays incident on the infrared detector, and a direct current motor that drives the light shielding plate. A stopper provided at a stop position of the light shielding plate, a control means for controlling the DC motor, and a temperature conversion means for converting the temperature of the object to be measured based on the output of the infrared detector, The control means includes a positive power supply means for rotating the DC motor in the light incident direction, and a negative power supply means for rotating in the light shielding direction, and the positive power supply means and the negative power supply. Each means includes initial power supply means for supplying power during a predetermined initial power supply period, and reduced power supply means for reducing and supplying power after the initial power supply period, and the initial power supply period Light shielding plate is set longer than the sum of the time period and the light shielding plate required for the stopper reaches to bounce natural stop from the stop, the light incident infrared light path to the said infrared detector by reversing the direction of rotation of the DC motor alternately And switching between light shielding.
[0009]
According to the above invention, the infrared detector detects the infrared ray radiated from the object to be measured, and the light shielding plate driven by the DC motor collides with the stopper constituted by the shock buffer and enters the infrared light path reaching the infrared detector. , Stop in each state of light shielding, the control means drives the DC motor to alternately reverse to switch between incident light and light shielding, and the temperature conversion means converts the temperature of the object to be measured based on the output of the infrared detector Therefore, the light incident time and the light shielding time due to the driving of the light shielding plate are stable, and the light shielding plate does not swing at the stop position. Therefore, even if the light shielding plate is sufficiently small, the light incident and light shielding conditions are stable. Small, highly accurate temperature detection can be performed , and the positive power supply means rotates the DC motor in the incident light direction, the negative power supply means rotates in the light shielding direction, and the initial power supply means The shading plate is Since long initial power supply period from the sum of the time to bounce naturally stopped from the time the stopper to reach, to supply the initial power to the DC motor, is then reduced power supply means for supplying reducing power to, the light shielding plate is reliably In addition, it can stop at the stopper position and switch between stable incident light and light shielding, improving the temperature detection accuracy and saving power consumption.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to an infrared detector that detects infrared rays emitted from an object to be measured, a light shielding plate that shields infrared rays incident on the infrared detector, a DC motor that drives the light shielding plate, and a stop position of the light shielding plate. A control unit that controls the DC motor, and a temperature conversion unit that converts the temperature of the object to be measured based on the output of the infrared detector, the stopper is made of an impact buffer material, The control means includes a positive power supply means for rotating the DC motor in the light incident direction and a negative power supply means for rotating in the light shielding direction, and each of the positive power supply means and the negative power supply means is a predetermined initial power. An initial power supply unit that supplies power during the supply period; and a reduced power supply unit that supplies power after decreasing the initial power supply period, and the light shielding plate is required for the stopper to reach the stopper during the initial power supply period. Between the light shielding plate is set longer than the sum of the time to bounce natural stop from the stopper, and configured to switch the light shielding and light incident infrared light path leading to the infrared detector the direction of rotation of the DC motor is reversed alternately Is.
[0011]
The infrared detector detects the infrared rays emitted from the object to be measured, and the light shielding plate driven by the direct current motor collides with a stopper made of an impact buffering agent to enter the infrared light path to the infrared detector and shield the light. The control means drives the DC motor to alternately invert and switches between incident light and light shielding, and the temperature conversion means converts the temperature of the object to be measured based on the output of the infrared detector. The light incident time and the light shielding time by driving are stable, and the light shielding plate does not swing at the stop position, so even if the light shielding plate is sufficiently small, the light incident and light shielding states can be switched stably. Small, highly accurate temperature detection is possible , and the positive power supply means rotates the DC motor in the incident light direction, the negative power supply means rotates in the light shielding direction, and the initial power supply means uses the light shielding plate as a stopper. Reach The initial power is supplied to the DC motor for an initial power supply period that is longer than the sum of the time required to bounce off the stopper and the natural stop, and then the reduced power supply means reduces the power and supplies it. The temperature detection accuracy can be improved and power consumption can be saved.
[0012]
The stopper is made of a soft rubber material.
[0013]
Since the light shielding plate collides with a stopper made of a soft rubber material and stops, the biting and rebounding of the light shielding plate due to the collision can be reduced, and the collision sound can be reduced.
[0014]
In addition, the stopper surface is coated with powder.
[0015]
Since the powder is applied to the stopper, the adhesiveness can be reduced, and when the light-shielding plate collides and stops, it is possible to stably switch between light incident and light-shielding without adhering to the stopper.
[0016]
The stopper is configured by integrating the light incident stop position and the light shielding stop position of the light shielding plate.
[0017]
Since the stop at the light incident stop position and the stopper at the light shielding stop position are integrated, the distance between the stoppers can be configured with high accuracy, and the accuracy of the time difference from the generation of the drive signal to the light incident / light shielding state switching is improved. Therefore, temperature detection with high accuracy can be performed.
[0018]
【Example】
Example 1
An 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 detection device 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. FIG. 3 is a characteristic diagram of the generated sound. FIG. 4 is a timing chart for explaining the operation.
[0019]
In general, as a thermometer for measuring the surface temperature, it is possible to measure the body temperature almost by measuring the temperature of a part of the eardrum, oral cavity, anus and the like that is difficult to contact with outside air. In particular, the eardrum is close to the hypothalamus, which controls body temperature, and is known as an appropriate place for body temperature measurement. In FIG. 1, reference numeral 10 denotes an object to be measured for temperature, for example, an eardrum. Reference numeral 11 denotes a probe inserted into the ear canal, which has a diameter that decreases toward the tip and is easily inserted into the ear canal. A condensing means 12 condenses the infrared rays emitted from the eardrum 10 and is constituted by a concave mirror. The condensed infrared rays enter the infrared detector 3 through the light shielding plate 1.
[0020]
The light-shielding plate 1 is driven to reciprocate while colliding with the stopper 13 by the motor 2, and the infrared light reaching the infrared detector 3 is repeatedly switched between light incident and light-shielding states. The infrared detector 3 is a pyroelectric type, and its output changes in correlation with the differential value of the amount of infrared rays to be detected. Here, the light shielding plate 1 is made of metal, and when the light is shielded, the infrared light emitted from the infrared detector 3 itself is reflected by the metal surface and enters the infrared detector 3. That is, the output of the infrared detector 3 is correlated 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 14 for detecting the temperature of the infrared detector 3 is disposed in the vicinity of the infrared detector 3. The temperature sensor 14 is a generally known thermistor.
[0021]
The output of the infrared detector 3 is amplified by the amplifier 15, and the output voltage amplified by the amplifier 15 and the output voltage of the temperature sensor 14 are digitized by the AD converter 16. Reference numeral 17 denotes temperature conversion means for converting the temperature of the eardrum 10 based on the output of the AD converter 16. 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 temperature of the infrared detector 3 to the fourth power. Based on this relationship, the temperature conversion means 17 converts the temperature of the eardrum 10 and displays it on the display means 18.
[0022]
Reference numeral 19 denotes a control means for controlling the driving of the DC motor 2, and comprises a positive power supply means 20 for switching from the light shielding state to the light incident state, and a negative power supply means 21 for switching from the light incident state to the light shielding state. Further, the positive power supply means 20 includes an initial power supply means 20a for supplying power for driving the light shielding plate 1 and a reduced power supply means 20b for supplying power for holding the position of the stopper 13 by the light shielding plate 1. The means 21 also includes an initial power supply means 21 a for supplying power for driving the light shielding plate 1 and a reduced power supply means 21 b for supplying power for the light shielding plate 1 to hold the position of the stopper 13.
[0023]
In FIG. 2, reference numeral 1 denotes a light shielding plate that is stopped in a light incident state. Reference numeral 2 denotes a DC motor, and the light shielding plate 1 is fixed to the shaft 22 of the DC motor 2 via a light shielding plate fixing jig 23. The infrared detector 3 is enclosed in a housing 24 and receives infrared rays through a window 25 made of, for example, a silicon material that transmits infrared rays.
[0024]
The stopper 13 includes a light incident stop portion 13a that contacts when the light shielding plate 1 stops in the light incident state and a light shielding stop portion 13b that contacts when the light shielding plate 1 stops when the light shielding plate 1 stops in the light shielding state. In addition to facilitating assembly, the interval between the light incident stop portion 13a and the light shielding stop portion 13b can be managed with high accuracy until the light incident / light shielding state is switched after the light shielding plate 1 starts to be driven. The time accuracy can be maintained, and the measurement temperature accuracy can be improved.
[0025]
Further, since the stopper 13 is made of an impact buffer material that absorbs an impact caused by the collision of the light shielding plate 1, there is no deformation of the light shielding plate 1, and there is an effect of improving reliability and durability. In particular, when it is made of a soft rubber material, the sound generated when the light shielding plate 1 collides with the stopper 13 can be reduced, and the effect is great in a thermometer that detects temperature by putting it in the ear.
[0026]
FIG. 3 shows the characteristics of the hardness of the rubber material of the stopper 13 and the level of the generated sound. FIG. 3 is a result of an experiment in which the sound level was measured at a position 10 mm from the tip of the probe 11 with the above configuration, and the hardness of the rubber material was measured with a hardness meter of JISK6301. As shown in the figure, the softer the stopper material, the more effective the noise is. However, even if the collision noise is reduced to some extent, the sound generated by the rotation of the DC motor 2 itself is won and the sound level is not lowered. FIG. 3 means that it is desirable to use a soft rubber material of about HS40.
[0027]
In FIG. 2, reference numeral 26 denotes powder applied to the surface of the stopper 13, for example, natural pollen. By applying the powder 26 to the surface of the stopper 13, the adhesiveness of the rubber material can be removed, and the light shielding plate 1 can be driven more stably. 27 is a stopper fixing portion that is fixed by inserting the stopper 13, 28 is an infrared detector fixing portion that fixes the infrared detector 3 with the stopper fixing portion 27, and 29 is a motor fixing portion that holds the DC motor 2 as a stopper. It is fixed by being sandwiched between the fixing part 27. When the DC motor 2 repeats normal rotation and reverse rotation with the above configuration, the light shielding plate 1 collides with the light incident stop portion 13a and the light shielding stop portion 13b of the stopper 13 and stops, so that stable light incident and light shielding can be switched. .
[0028]
FIG. 4 shows a specific operation of the control means 19. The voltage applied to the DC motor 2 and the rotation angle of the DC motor 2 are shown. The period t1 in FIG. 4 is a positive power supply period in which the light-shielding plate 1 is driven into the light incident state and is stopped in the light incident state, and power is supplied by the positive power supply means 20. The period t2 is a negative power supply period in which the light shielding plate 1 is driven in the light shielding state and is kept stationary in the light shielding state, and power is supplied by the negative power supply means 21. In this embodiment, t1 and t2 are the same time, but may be set to different times.
[0029]
In the positive power supply period, t1a is an initial power supply period, and power is supplied by the initial power supply means 20a in order to drive the light-shielding plate 1 to the light incident state, and t1b is a reduced power supply period, and the light-shielding plate 1 is turned on. In order to keep the light incident stop portion 13a of the stopper 13 at the position, power is intermittently supplied by the reduced power supply means 20b. Similarly, in the negative power supply period, t2a is an initial power supply period, and power is supplied by the initial power supply means 21a to drive the light shielding plate 1 in a light shielding state, and t2b is a reduced power supply period, and the light shielding plate 1 Is held intermittently by the reduced power supply means 21b in order to hold the light at the position of the light shielding stop portion 13b.
[0030]
Here, the reduced power supply means 20b and 21b intermittently supply power, 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 power supply may be suspended if t1 and t2 are sufficiently short. This is because the vibration of the human hand is considered as a factor causing the light shielding plate 1 to deviate from the light incident stop portion 13a or the light shielding stop portion 13b of the stopper 13, but t1 and t2 are sufficiently short, for example, less than 0.1 second. If there is, the shading plate 1 is hardly displaced because the vibration period of the human hand is sufficiently long.
[0031]
In FIG. 4, Δθ is a swing that occurs because the light shielding plate 1 bites into the stopper 13 and rebounds, but is sufficiently smaller than Δθ of FIG. 7 shown in the conventional example. Here, t3 is the time required for the light shielding plate 1 to collide with the stopper 13 and start to bounce after starting to drive, and the initial power supply periods t1a and t2a have been rebounded from the stopper 13 by making this t3 longer. The light shielding plate 1 does not stop at the position, and light input and light shielding can be switched stably.
[0032]
The embodiment has been described as an application example in which the temperature detection device of the present invention is mounted on a portable thermometer that measures the temperature of the eardrum in a non-contact manner, but this does not limit the present invention. It can be applied to a microwave oven or an air conditioner that detects and controls the temperature in a non-contact manner by incorporating it in a device, and the same effect can be obtained.
[0033]
【The invention's effect】
As described above, the temperature detector of the present invention has the following effects.
(1) An infrared detector detects infrared rays emitted from the object to be measured, and a light shielding plate driven by a DC motor collides with a stopper constituted by an impact buffering agent, and enters and blocks the infrared light path reaching the infrared detector. The control means is driven to alternately reverse the DC motor to switch between incident light and light shielding, and the temperature converting means converts the temperature of the object to be measured based on the output of the infrared detector. The light incident time and the light shielding time due to the driving of the plate are stable, and the light shielding plate does not swing at the stop position. Therefore, even if the light shielding plate is sufficiently small, the light incident and light shielding states can be switched stably. It is possible to detect the temperature with a small size and high accuracy . Further, the positive power supply means rotates the DC motor in the light incident direction, the negative power supply means rotates in the light shielding direction, and the initial power supply means has a light shielding plate. Reach the stopper The initial power is supplied to the DC motor for an initial power supply period that is longer than the sum of the time required to bounce off the stopper and the natural stop, and then the reduced power supply means reduces the power and supplies it. The temperature detection accuracy can be improved and power consumption can be saved.
[0034]
(2) Since the light shielding plate collides with a stopper made of a soft rubber material and stops, there is little biting and rebounding of the light shielding plate due to the collision, and the light incident and light shielding states can be switched stably. Accurate temperature detection can be performed, and collision noise can be reduced.
[0035]
(3) Since the powder is applied to the stopper, the adhesiveness can be reduced, and when the light-shielding plate collides and stops, it is possible to switch between incident light and light-blocking stably without adhering to the stopper. High temperature detection can be performed.
[0036]
(4) Since the stopper at the light incident stop position and the stopper at the light shielding stop position are integrated, the distance between the stoppers can be configured with high accuracy, and the time difference from the generation of the drive signal to the light incident / light shielding state switching is accurate. And temperature detection with high accuracy 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 portion of the temperature detection device. FIG. 3 is a characteristic diagram of sound generated by the temperature detection device. FIG. 4 is a timing chart for explaining the operation of the temperature detection device. FIG. 5 is a configuration diagram of a conventional temperature detection device. FIG. 6 is a configuration diagram of a conventional temperature detection device. Timing chart to explain
DESCRIPTION OF SYMBOLS 1 Light-shielding plate 2 DC motor 3 Infrared detector 10 Measured object 13 Stopper 17 Temperature conversion means 19 Control means 20 Positive power supply means 21 Negative power supply means 20a, 21a Initial power supply means 20b, 21b Decrease power supply means 26 Powder

Claims (4)

Infrared detector for detecting infrared rays emitted from the 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, and a stopper provided at a stop position of the light shielding plate And a control means for controlling the DC motor, and a temperature conversion means for converting the temperature of the object to be measured based on the output of the infrared detector, the stopper is made of an impact buffer material, and the control means A positive power supply means for rotating the direct current motor in the light incident direction; and a negative power supply means for rotating in the light shielding direction. The positive power supply means and the negative power supply means are each in a predetermined initial power supply period. Initial power supply means for supplying power, and reduced power supply means for supplying power after decreasing the initial power supply period, and the initial power supply period is a time required for the light shielding plate to reach the stopper Light shielding plate is set longer than the sum of the time to bounce natural stop from the stopper, temperature sensing device for switching the light-shielding and light incident infrared light path to the said infrared detector by reversing the direction of rotation of the DC motor alternately. The temperature detection device according to claim 1, wherein the stopper is made of a soft rubber material. The temperature detection device according to claim 1, wherein powder is applied to the stopper surface. The temperature detection device according to claim 1, wherein the stopper is formed by integrating a light incident stop position and a light shielding stop position of the light shielding plate.

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