JPH044609B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a key input device for household electrical appliances and the like having several types of keys. Conventional configurations and their problems Conventional control of household electrical appliances such as microwave ovens, televisions, and air conditioners has become complicated due to the use of microcomputers (hereinafter referred to as microcomputers), and the types of keys used to operate them have become complicated. is increasing. As a result, the number of input/output terminals for microcontroller key processing is increasing, and the more keys there are, the more terminals are required. FIG. 1 is an example of a conventional key input capture method. The way to import it is from the output terminal of microcontroller 1.
Outputs signals from O ₁ , O ₂ , and O ₃ to the operation key matrix 2 in a time-sharing manner, receives input from input terminals I ₁ , I ₂ , and I ₃ at each timing, and determines which key is pressed. It is something to investigate. The timing diagram is for when key _K1 is pressed. Microcomputer 1 is
It is determined that _{the K1} key has been input because the input of _I1 is input at the timing when O1 is output.
In such a configuration, as the number of keys increases, the number of input/output terminals O and I also increases, and the time-sharing process performed by the microcomputer 1 becomes longer and more complex. Further, FIG. 2 shows a conventional example 2 of the key input capture method. In the case of Fig. a, the detection voltage V _AD is determined by the division ratio R ₁ and R ₂ of the resistor R, and thus the key position can be determined. V _AD = V/R x R ₂ , R = R ₁ + R ₂ However, if two keys are pressed at the same time as shown in figure b, the detection voltage V _AD is V _AD = V/R ₁ + R ₂ x R ₃ , R=R ₁ +R ₂ +R ₃ =V/R-R ₃ ×R ₃ , and an intermediate voltage appears, making it impossible to determine the key position. OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and aims to process operation keys using a small number of input/output terminals. Configuration of the Invention In order to achieve the above object, the control unit of the present invention includes:
It is a configuration in which two rows of the same resistors are arranged in parallel, and the resistance value of each resistor changes depending on the position where the resistor and the conductive part come into contact, creating a voltage change that is detected by a microcomputer. The type of operation key can be detected by associating the position of the contact portion with the position of the operation key. With this configuration, detailed position detection is possible by accurately examining voltage changes, which means that many types of operation keys can be detected. In addition, the resistors are arranged in two rows, which prevents misjudgment due to noise.
It is also possible to process when more than one operation key is pressed at the same time. In recent years, a microcomputer with a built-in A-D converter having an 8-bit resolution (256 divisions) has been developed, and its use has the effect of easily and accurately processing a large number of operation keys. DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking a microwave oven as an example. FIG. 3 is a perspective view of a microwave oven main body according to an embodiment. A door body 4 which can be opened and closed is pivotally supported on the front surface of the main body 3, and is opened and closed by operating a handle 5.
The operation panel 6 is equipped with various operation keys, and a display tube 7 is arranged above it. FIG. 4 is a control block diagram of one embodiment. Operation keys SW ₁ , SW ₂ , SW ₃ , SW ₄ on the operation panel 6
By pressing , the voltage of V ₁ and V ₂ changes, and the voltage is applied to the A/D terminal of microcomputer 8 (A/D ₁ ,
A/D ₂ ) is input to the A/D converter (A/D ₁ converter, A/D ₂ converter) inside the microcomputer 8, and converted into digital data (hereinafter referred to as key level) and sent to the CPU.
determines the operation key by checking its key level.
Read which key of SW ₁ , SW ₂ , SW ₃ , or SW ₄ was pressed. Then, by outputting display data to the display tube 7 or outputting a signal to the relay control unit 17, the power supply to the heat generating source is controlled and the food to be cooked is heated. FIG. 5a is a block diagram of the key input section. The same resistors R ₁ and R ₂ are placed on the first insulator, and a second insulator with slits corresponding to the positions of the operation keys SW ₁ to _{SW 4} is placed on top of it. Further, a third insulator on which the types of operation keys SW ₁ to _{SW 4} are printed is arranged on the conductor 11,
The electrodes 13 and 14 are led from opposite directions of _R1 and _R2 , and the electrode 15 is also drawn out from the conductor 11, so that a total of three electrodes are drawn out. FIG. 5b is a diagram when the operation key is pressed.
When the operation keys SW ₁ to SW ₄ are pressed, the conductor 11 comes into contact with the resistors R ₁ and R ₂ through the slit of the second insulator due to pressure, and when the operation keys SW ₁ to _{SW 4} are released, the conductor 11 The structure is such that it returns to its original state and separates from the resistors R ₁ and R ₂ . Next, FIG. 6 is a diagram showing the principle of operation. By pressing the operation key at the position shown in the figure, the conductor 11 comes into contact with the resistors R ₁ and R ₂ at the arrowed portions. In this case, the effective range of resistor R ₁ is R ₁ D and also resistor R ₂
The effective range of is the R ₂ D part. Therefore, the voltage V ₁ of A/D ₁ is V ₁ = V _p × R ₁ D/R ₁ D + R _x (V _p is the power supply voltage R _x is a fixed resistance) and the voltage V ₂ of A/D ₂ is V ₂ = V _p × R ₂ D/R ₂ D + R _x . As a result, the microcomputer 8 in FIG.
By inputting V ₁ and V ₂ to A/D terminals A/D ₁ and A/D ₂ , the built-in A/D conversion section converts them to key levels, and the CPU 16 processes them. FIG. 7 is an example of key level correspondence when the operation keys SW ₁ to _{SW 4} are pressed. Figure a shows when SW ₁ is pressed and the key level is "1". b,
Figures c and d are when SW ₂ , SW ₃ , and SW ₄ are pressed, respectively, and the key levels at that time are "2", "3", and "4".
This is the case. FIG. 8 shows the correspondence with key levels. Figure a is
This is when SW ₁ is pressed. Since the resistor _R1 is in the same state as in FIG. 7a, the key level is "1". As for the resistor _R2 , since the electrodes come out from the opposite direction, it is considered that FIG. 7d is reversed, so the key level is "4". Figure 7b
Similarly, when SW ₃ is pressed, A/D ₁
The key level of A/D 2 is "3", and the key level of A/D ₂ is "2". In other words, when considering the correspondence between operation keys and key levels as in this example, the table below shows the correspondence.

[Table] From this table, when each operation key is pressed, the sum of the key levels of A/D ₁ and A/D ₂ is "5". Next, Figure 9 shows when two or more keys are pressed at the same time (hereinafter referred to as double key), at this time the key level of A/D ₁ is "1" and the key level of A/D ₂ is also "1". The sum of the key levels becomes "1" and the sum of the key levels becomes "2", which is different from "5" when a single operation key is pressed. The microcomputer 8 processes the double key based on this difference. In addition, if the highest priority key (operation key that can be accepted even in double key state) is placed in the SW ₁ position, even if other operation keys are pressed at the same time, the key level of A/D ₁ will be "1". Therefore, the microcomputer 8 can process the highest priority key. FIG. 10 is a flowchart of the internal processing of the microcomputer 8. First, it is determined whether the key level of A/D ₁ converted into a level by the A/D ₁ converter is "1" and if it is "1", it is the highest priority key and the process moves to SW ₁ priority processing. Also, if it is other than "1", calculate the sum with the key level of A/D ₂ , and if the sum is "5", it is regarded as a double key and enters invalidation processing, and if it is "5", the key level of A/D ₁ is calculated. The key level is determined and each operation key is processed. As described above, according to this embodiment, a large number of key input processes can be realized with a simple configuration and at low cost. Further, many input terminals of the microcomputer 8 are not required. Priorities can be assigned to keys, and double keys can also be reliably determined when multiple keys are input at the same time. Effects of the Invention According to the present invention, the following effects can be obtained. (1) By using A/D conversion, multiple key input processes can be performed with a simple configuration and realized at low cost. (2) Since the configuration of the key input section is simple, the number of terminals connected to the microcomputer can be reduced, making it possible to achieve low cost, and further reducing the probability of malfunction due to noise. (3) Software processing on a microcomputer can also achieve equivalent processing more easily than before. (4) Key priorities can be easily added. (5) Reliable judgment when many keys are pressed at the same time. (6) By connecting the conductor that constitutes the key input section to the main body, an effect can be obtained in which static electricity from the user who operates the keys is transferred to the main body.

[Brief explanation of drawings]

Figure 1a is a circuit diagram of a conventional key input device;
Figure 1b is a diagram of the same output waveform, Figures 2a and b are diagrams explaining the operating state of the conventional example, Figure 3 is a perspective view of a microwave oven that is an embodiment of the present invention, and Figure 4 is a diagram of the same output waveform. A control block diagram of the microwave oven, FIG. 5a is a configuration diagram of the key input section of the microwave oven, and FIG.
Figure c is a sectional view of the main part showing the state in which the operation key is pressed, Figure 6 is a diagram of the operating principle of the same control circuit, and Figure 7 a, b, c, and d are when each operation key is pressed. A diagram showing an example of key level correspondence, FIGS. 8a and 8b are diagrams showing an example of key level correspondence when the same operation key is pressed, and FIG. 9 is a diagram showing the key level when the same operation key is pressed,
FIG. 10 is an operation flowchart of the microcomputer. 6... Key input unit, 8... Microcomputer, 9... First insulator, 10... Second insulator, 12... Third insulator, 11... Conductive part,
R ₁ , R ₂ ...Resistor.

Claims (1)

[Claims] 1 Consists of a control means for controlling the output of a control device, an input means for inputting a control method, etc., and a microcomputer for controlling the control means by inputting a signal from the input means, and the input means is a first
two resistors disposed on the insulator, a second insulator on which a plurality of slits are provided along the resistor, and at least the second insulator on the second insulator. The portions facing the plurality of slit portions provided in the slits each have a conductive portion connected in series,
Furthermore, in a configuration having a third insulator thereon,
The conductive part short-circuits the corresponding parts of the two resistors via the slit part of the second insulator by the pressing input operation to the surface of the third insulator, and at this time, the conductive part short-circuits the corresponding parts of the two resistors through the slit part of the second insulator. Power is supplied so that an output signal having a magnitude corresponding to the resistance value between one end of the direction and the conductive part is output from each of the ends, and the output signal is input to the microcomputer through two A/D conversion circuits. A key input device configured to input data to a computer or an A/D input terminal of a microcomputer with a built-in A/D conversion circuit.