JP2719412B2 - Infrared control device - Google Patents

Description

The present invention relates to an infrared control device that knows the temperature of a detected object based on infrared light from the detected object.

(B) Conventional technology Japanese Patent Publication No. Sho 56-42808 discloses a microwave oven equipped with an infrared control device that detects the temperature of a detected object based on infrared rays from the detected object. Infrared rays are led out from an infrared lead-out opening formed in the wall of the heating chamber, then intermittently driven by a motor-driven chopper, and under the configuration of detecting with an infrared detection object, a temperature signal output by the infrared detection unit is output. There is disclosed a technology for controlling the heating by knowing the food temperature based on the temperature. Further, there is disclosed a technique in which the chopper is moved so that the infrared detecting section cannot detect infrared light from food when it is not necessary to know the food temperature. In this case, the shortest path of water vapor, oil droplets, and the like generated from food to the infrared detection unit is blocked by the chopper located in front of the infrared detection unit, so that the infrared detection unit is less likely to become dirty.

Therefore, even in the event of a power failure, it is desired to move the chopper to a position where the infrared detecting unit cannot detect infrared light from food in order to enable the same contamination suppression. Can not do.

(C) Problems to be Solved by the Invention The present invention is to provide an infrared control device which can be made simple and inexpensive and can suppress the contamination of the infrared detection unit when a power failure occurs.

(D) Means for Solving the Problems An infrared control device according to the present invention includes a chopper for intermittently transmitting infrared rays from an object to be detected, and a chopper driving unit for applying periodic magnetic force to the chopper to intermittently drive the chopper. A power supply circuit that supplies electric power to the chopper drive unit, and an infrared detection unit that detects infrared light from the object detected by the chopper and outputs a temperature signal based on the temperature of the object. The power supply circuit has a power holding unit for holding power required to move the chopper to a position where the infrared detector detects infrared rays from the object to be detected when a power failure occurs. It is characterized by the following.

(E) Operation When a power outage occurs, the chopper drive unit is driven based on the power held by the power holding means in the power supply circuit,
The chopper moves to a position where the infrared detection unit blocks detection of infrared light from the detected object.Therefore, the shortest path for water vapor, oil droplets, and the like generated from the detected object to reach the infrared detection unit is as described above. Blocked by a chopper, the infrared detector is less likely to get dirty.

(F) Embodiment FIGS. 1 and 2 show the structure of a microwave oven equipped with an infrared controller according to an embodiment of the present invention.

Reference numeral 1 denotes a heating chamber in which a food 2 to be detected is placed, 3 denotes a magnetron that supplies a microwave for heating the food 2 in the heating chamber, and 4 denotes a food placed in an upper part of the heating chamber 1. The heater 5 for heating the heating chamber 2 is formed on the upper wall 6 of the heating chamber 1 and emits infrared rays from the food 2 to the heating chamber 1.
An infrared-ray opening 7 to be led out is an infrared-ray detecting device arranged above the opening.

To describe the details of the infrared detecting device 7, reference numeral 8 denotes an infrared detecting unit, 9 denotes a chopper formed of a rectangular plate for intermittently transmitting infrared light from the food 2 which is led out through the opening 5, and the chopper is Supported rotatably by the support shaft 10,
One end faces the infrared detector 8. 11 is a permanent magnet fixed to the other end of the chopper 9, 12 is an electromagnetic coil which is a chopper driving unit facing the permanent magnet, 13 is a temperature detecting diode for detecting the temperature of the chopper 9, and 14 and 15 are It is a stopper that regulates the rotation range of the chopper 9. The lower ends of these stoppers 14 and 15 are integrated flat plate 16
The flat plate 16 supports the lower end of the support shaft 10. Reference numeral 17 denotes the above-described infrared detector 8, support shaft 10, electromagnetic coil 12, temperature detecting diode 13, stoppers 14 and 15,
Is a case mounted on the substrate, 18 is a case which forms a closed space 19 together with the substrate 17, and the lower wall of the case receives infrared light from the food 2 led out through the opening 5. A small hole 20 for passing infrared light is formed to reach the chopper 9. In the closed space 19, the infrared detecting section 8, the chopper 9, the support shaft 10, the permanent magnet 11, the electromagnetic coil 12, the temperature detecting diode 13, the stoppers 14 and 15, and the flat plate 16 are compactly housed. I have.

 FIG. 3 shows the circuit of the microwave oven.

21 is a microcomputer that controls the microwave oven,
Reference numeral 22 denotes a keyboard for setting heating conditions such as a heating temperature in the computer; 23, a heating circuit including the magnetron 3 and the heater 4; 24, the output of the infrared detection unit 8 and the output of the temperature detection diode 13; A synthesis circuit that provides a synthesized output to the computer 21.

25 is a power supply circuit for supplying DC power to each part of the circuit,
In the power supply circuit, reference numeral 26 denotes a step-down transformer for stepping down a commercial AC power supply voltage, the transformer comprising a first and a second secondary winding 2.
It has 7, 28. 29 and 30 represent these first and second 2
First and second diode bridges 31 and 32, which are connected to the secondary windings 27 and 28 and rectify the stepped-down AC power supply voltage, are connected to the first and second diode bridges 29 and 30, respectively. , A second smoothing capacitor. The voltage smoothed and output by the first smoothing capacitor 31 is -5V
This voltage -5V is applied to the computer 21. The voltage output after being smoothed by the second smoothing capacitor 32 is -12V. In this case, the first smoothing capacitor 31 has a small capacity, and the second smoothing capacitor 32 has a large capacity. Since the second smoothing capacitor 32 has a large capacity, it serves as power holding means, and can hold a certain amount of power in preparation for a power failure.

A first transistor 33 has a collector and an emitter connected to both ends of the second smoothing capacitor 32 with a resistor 34.
And the base is connected to the computer 21. Such a base receives a -5V pulse P at a frequency of 3 Hz generated from the computer 21. In this case, the first transistor 33 is turned on when the pulse P is generated, and is turned off when the pulse P is not generated. When the first transistor 33 is turned on and off in this manner, the collector voltage a of the first transistor 33 is set to 0 V, -12
V (voltage smoothed by the second smoothing capacitor 32).

Reference numerals 35, 36, and 37 denote second, third, and fourth transistors, respectively. In this case, the bases of the second and third transistors 35 and 36 are both connected to the collector of the first transistor 33,
The emitters of the second and third transistors 35 and 36 are both directly connected to the second smoothing capacitor 32. The collector of the second transistor 35 is connected to one end K1 of the electromagnetic coil 12, and the collector of the third transistor 36 is grounded via a resistor 38. As for the fourth transistor 37, the base is connected to the collector of the third transistor 36, is grounded via the resistor 38, and the emitter is connected to the emitter of the third transistor 36. The collector is directly connected to the second smoothing capacitor 32, and the collector is connected to the other end K2 of the electromagnetic coil 12. Such an electromagnetic coil 12 has an intermediate portion grounded via a resistor 39,
It is divided into second coil sections 40 and 41.

When the first transistor 33 is turned on and the collector voltage a becomes 0 V, the second and third transistors 35 and 36 are turned on, and the respective collector voltages b and c become negative.
12V (voltage smoothed by the second smoothing capacitor 32). Further, when the collector voltage c becomes -12V, the fourth transistor 37 is turned off, and the collector voltage d of the transistor 37 becomes 0V. In this case, in the electromagnetic coil 12, only the first coil unit 40 is excited in a state where -12 V is applied to one end K1. Then, the first magnetic force acts on the chopper 9 via the permanent magnet 11, and the chopper 9 rotates in the direction of the arrow Y1. When the chopper 9 rotates to the position indicated by the one-dot chain line, the chopper 9 hits the stopper 15 and stops. At this time, the chopper 9 does not block the infrared rays from the food 2 passing through the openings 5 and the small holes 20 for passing infrared rays.

On the other hand, when the collector voltage a becomes -12 V due to the turning off of the first transistor 33, the second and third transistors 35 and 36 turn off, and the respective collector voltages b and c become low.
It becomes 0V. Further, when the collector voltage c becomes 0V, the fourth transistor 37 is turned on, and the collector voltage d of the transistor 37 becomes -12V. In this case, the electromagnetic coil 1
In (2), when −12 V is applied to the other end K2, the second
Only the coil part 41 is excited. Then, the permanent magnet 11
, A second magnetic force acts on the chopper 9 to rotate the chopper 9 in the direction of the arrow Y2. When the chopper 9 rotates to the position indicated by the solid line, the chopper 9 hits the stopper 14 and stops.
At this time, the chopper 9 is connected to the opening 5 and the small hole 20 for passing infrared rays.
Shields infrared light from food 2 passing through.

In this way, the electromagnetic coil 12 supplied with power from the power supply circuit 25 causes the first and second magnetic forces to act on the chopper 9 periodically based on the generation and non-generation of the pulse P having a frequency of 3 Hz. Accordingly, the chopper 9 periodically reaches a position at which the chopper 9 does not block the infrared rays from the food 2 and a position at which the chopper 9 blocks such infrared rays, and the infrared rays from the food 2 are interrupted.

The intermittent infrared light is transmitted to the infrared detecting unit 8.
, And a temperature signal based on the temperature of the food 2 is output from the infrared detection unit 8 based on this. Specifically, a temperature signal indicating the difference between the temperature of the food 2 and the temperature of the chopper 9 is output from the infrared detection unit 8. Such a temperature signal is then synthesized by the synthesizing circuit 24 with the chopper temperature signal output by the temperature detecting diode 13, and as a result, the synthesizing circuit 24 outputs a temperature signal corresponding to the temperature of the food itself. The computer 21 inputs the temperature signal to know the food temperature, and controls the driving of the heating circuit 23 based on whether or not the food temperature has reached the heating temperature set by the keyboard 22.

By the way, when cooking by such drive control is completed,
The generation of the pulse P having the frequency of 3 Hz stops, the pulse P stops generating thereafter, and as can be understood from the above description, the chopper 9 stops at the position where the infrared rays from the food 2 are blocked. In this case, the shortest path of water vapor, oil droplets, and the like generated from the food 2 at the time of heating to the infrared detection unit 8 is blocked by the chopper 9, and water vapor, oil droplets, and the like hardly reach the infrared detection unit 8, Dirt on the infrared detecting unit 8 is suppressed. Moreover, when the chopper 9 stops at a position where the infrared rays from the food 2 are blocked, the small holes 20 for passing the infrared rays
Is closed (not closed),
It is difficult for water vapor, oil droplets, and the like to reach the infrared detection unit 8,
Dirt on the infrared detecting unit 8 is suppressed.

Thus, when a power failure occurs, the first smoothing capacitor 31
Is small, the voltage smoothed by the first smoothing capacitor 31 and output is immediately reduced from -5V to 0V,
Since the second smoothing capacitor 32 is a large-capacity power holding means, the voltage smoothed and output by the second smoothing capacitor 32 is held at -12 V for a while (about one second). During the holding, the second and third transistors 35, 35
While the transistor 36 is turned off, the fourth transistor 37 is kept on, whereby only the second coil portion 41 of the electromagnetic coil 12 is excited, and the chopper 9 blocks infrared rays from the food 2 as described above. Stop at the position. Therefore, even at the time of a power failure, contamination of the infrared detection unit 8 is suppressed.

In the above embodiment, if the shutter 42 for opening and closing the opening 5 is provided as shown by the broken line in FIG. 1 and the opening 5 is closed by the shutter 42 at the end of cooking, etc., Is further suppressed.

(G) Effects of the Invention According to the infrared control device of the present invention, a chopper for intermittently transmitting infrared light from an object to be detected, a chopper driving unit for applying periodic magnetic force to the chopper to intermittently drive the chopper, A power supply circuit that supplies electric power to the chopper drive unit, and an infrared detection unit that detects infrared light from the detected object intermittently output by the chopper and outputs a temperature signal based on the temperature of the detected object. The power circuit is
When a power failure occurs, a power holding means for holding power required to move the chopper is provided at a position where the infrared detection unit prevents detection of infrared light from the detection object. It is possible to prevent the infrared detection unit from being stained at the time of occurrence.

Furthermore, such contamination suppression at the time of occurrence of a power failure can be achieved simply and inexpensively by simply providing a power holding unit in a power supply circuit that supplies power to a chopper driving unit that intermittently drives the chopper.

[Brief description of the drawings]

The drawings relate to a microwave oven equipped with an infrared control device according to an embodiment of the present invention. FIG. 1 is a front sectional view, and FIG. 2 is II-II in FIG.
FIG. 3 is a circuit diagram. 8 ... Infrared detector, 9 ... Chopper, 12 ... Electromagnetic coil (chopper drive unit), 25 ... Power circuit, 32 ... Second smoothing capacitor (power holding means).

Claims (1)

(57) [Claims] A chopper for intermittently transmitting infrared light from an object to be detected, a chopper drive unit for intermittently driving the chopper by applying a periodic magnetic force to the chopper, and a power supply circuit for supplying power to the chopper drive unit. An infrared detector that detects infrared light from the object detected by the chopper and outputs a temperature signal based on the temperature of the object. The power supply circuit detects the infrared light when a power failure occurs. An infrared control device, comprising: a power holding unit that holds power required to move the chopper at a position where the unit blocks detection of infrared rays from the detection object.