KR20030056979A - Key input circuit in microwave oven - Google Patents

Abstract

PURPOSE: A key input circuit is provided to be capable of inputting a plurality of key signals using one input terminal. CONSTITUTION: A key panel(30) consists of a plurality of key switches. A microcomputer(40) outputs a key scan signal to the key panel and receives a key scan signal passing the key panel through one signal sense terminal. A plurality of zener diodes(ZD1-ZD4) are connected in parallel between the key panel and one signal sense terminal of the microcomputer and have different values. An input signal is judged by sensing a level of an output signal via a zener diode according to an input signal of the key input circuit.

Description

Key input circuit in microwave oven

The present invention relates to a microwave oven, and more particularly, to a key input circuit of a microwave oven for inputting a control signal to the microwave oven.

2. Description of the Related Art In general, a microwave oven is a cooking apparatus that drives a heater or a magnetron by using electricity and generates microwave waves or heat to cook. The microwave oven is a device that is used very simply because it uses electromagnetic as a driving source and does not require any additional driving means. In particular, the microwave oven is used in homes, businesses and convenience stores because it is easy to cook within a very short time.

In addition, in recent years, the population of microwave ovens is rapidly increasing so that many households have microwave ovens. In addition, as the range of cooking available in the microwave will expand, the utilization of the microwave will continue to increase.

As described above, the cost of the product is accompanied by the utilization and the population of the microwave oven. Many products are appearing and functions are diversified, but the most important part of consumers is manufacturing cost and supply cost.

If manufacturing costs are high due to expensive materials and other reasons, the demand population will be small. Conversely, if a product's supply is low compared to its function, the demand population is large. Therefore, a company that manufactures microwave ovens has more functions and wants to produce low-cost products. In this regard, the form or new proposal that can reduce the manufacturing cost of the microwave oven can be very important in many aspects of the product.

One reason to increase manufacturing costs in addition to internal components in a microwave oven is to hold a lot of keys. For example, most of the automatic cooking, manual cooking, other thawing, warming, etc. should be provided, and in the middle of the automatic cooking, popcorn cooking, steamed egg custard cooking, potato cooking, pizza cooking, etc., require a lot of keys.

Many of these keys are configured to generate a signal for each corresponding dish. That is, as shown in FIG. 1, in a conventional microwave oven, the key input circuit outputs a kisscan signal to the key panel 10 constituting a plurality of key switches and the key panel 10. And a microcomputer 20 for inputting a kisscan signal passing through the key panel 10. The key panel 10 is implemented in a matrix manner with respect to the kisscan output signal and the kisscan input signal.

The number of key switches configured in the key panel 10 is determined according to the function of the product. In addition, the microcomputer 20 determines the number of scans according to the kisscan signal output and the kisscan signal input according to the number of key switches provided in the key panel 10. The conventional key panel shown in Fig. 1 constitutes 20 key switches using four outputs and five inputs. In addition, resistors and capacitors C1 to C5 are connected between the key panel 10 and the microcomputer 20. In addition, resistors R1 to R5 are connected between the key panel 10 and the capacitor.

The conventional microwave oven key input circuit configured as described above operates as follows.

The microcomputer 20 outputs the kisscan signal to the key panel 10 at regular intervals. The kisscan signal output to the key panel 10 is input to the microcomputer 20 again through the key switch in the on-operation state.

That is, when an arbitrary key switch is selected by a user among a plurality of key switches provided in the key panel 10, the kisscan signal output from the microcomputer 20 is inputted by the microcomputer 20. It is inputted by returning to the terminal. However, the kisscan signal applied to the non-selected keyswitch is blocked by the keyswitch in the off state and cannot be transmitted to the microcomputer 20.

Therefore, the microcomputer 20 recognizes a key switch having an ON operation or an OFF operation state on the key panel 10 through the operation process. And it is to determine which operation each key switch is input. Thereafter, the cooking of the microwave is controlled by the determined value.

The key input circuit of the conventional microwave oven operating in this manner has the following problems.

The key switch to be provided according to the function of the microwave oven was determined, and accordingly the number of scans of the kisscan signal output and the kisscan signal input was determined. Therefore, the number of input terminals to be provided in the key input circuit must also increase according to the number of key switches to be provided. Therefore, the number of input terminals of the microcomputer, which is frequently used as the key input circuit, has to be increased according to the improvement of the function of the product, which leads to an increase in the manufacturing cost.

Accordingly, an object of the present invention is to provide a key input circuit of a microwave oven capable of inputting a plurality of key signals using one input terminal.

1 is a key input circuit of a microwave oven according to the prior art.

2 is a key input circuit of a microwave oven according to the present invention;

Explanation of symbols on the main parts of the drawings

10, 30: key panel 20, 40: key input circuit

R1 ~ R16: Resistor C1 ~ C11: Capacitor

The key input circuit of the microwave oven according to the present invention for achieving the above object is a key panel consisting of a plurality of key switches, and outputs a kiss can signal to the key panel, and the one key can be passed through the key panel And a plurality of zener diodes having different values between the key panel and one signal sensing terminal of the microcomputer and connected in parallel and inputting the input signal of the key input circuit. Accordingly, the input signal is judged by detecting the output level output through Zenerid.

Hereinafter, a key input circuit of a microwave oven according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a key input circuit of a microwave oven according to the present invention.

First, referring to the connection relationship between the elements constituting the key input circuit, the microcomputer 40 is provided with one input sensing terminal P for sensing an input signal among many ports, and the signal sensing terminal P has a resistance ( Is connected to R) and the resistor R is grounded.

Meanwhile, the signal sensing terminal P of the microcomputer 40 is connected to the key panel 30. The key panel 30 includes four kisscan outputs and one kisscan input. The a ', b', c ', d', and e 'terminals connected to the key panel 30 are connected in parallel so that one kisscan input is performed. Zener diodes 1, 2, 3, and 4 (ZD 1, ZD 2, ZD 3, and ZD 4) are provided at terminals connected in parallel between the microcomputer 40 and the key panel 30.

That is, the a 'terminal of the key panel 30 is connected to the signal sensing terminal P of the microcomputer 40, and the b' terminal of the key panel 30 is connected to the zener diode 1 (ZD1). The c 'terminal is connected to zener diode 2 (ZD2), the d' terminal is connected to zener diode 3 (ZD3), and the e 'terminal is connected to zener diode 4 (ZD4). Zener diodes 1, 2, 3, and 4 (ZD1, ZD2, ZD3, and ZD4) are all grounded.

In the present invention, the key input circuit of the microwave oven, as shown, by using an analog input terminal for sensing an input to a microcomputer, that is, a signal detection terminal (P), the key signal selected by the user is input as an analog signal. do. Therefore, a signal input to one signal detecting terminal P may be recognized, and the selected key switch may be recognized according to a difference in input level.

That is, as shown, a plurality of zener diodes ZD1 to ZD4 are connected in parallel from one terminal of the microcomputer. The plurality of zener diodes all have different values. For example, in the present invention, the output values of the zener diodes are set in the order of ZD1> ZD2> ZD3> ZD4, but this is only an example and vice versa. A resistor is connected between the input terminal of the microcomputer 40 and the ground.

As shown in the drawing, the key panel 30 includes a plurality of zener diodes ZD1, ZD2, ZD3 and ZD4 and a plurality of switches between the kisscan signal output terminals. That is, the present invention compares the key panel 30 having up to 20 kisscan positions using 4 kisscan outputs and 5 kisscan inputs 5 according to the present invention. The key panel consists of four keyswitches.

Next, an operation process of the key input circuit of the microwave oven according to the present invention having the above configuration will be described.

The microcomputer 40 outputs the key scan channel at a predetermined cycle in order to detect the selection of the key switch. The output kisscan signal is applied to each switch provided in the key panel 30.

On the other hand, the key panel 30 is. While the microwave oven is in use, there are many states in which an on state switch or an off state switch is provided according to a user's selection operation. If there is a switch selected by the user, the kisscan signal output from the microcomputer 40 passes through the switch in the on state.

The kisscan signal thus passed passes through the zener diodes connected on the same line, and then continues to be transmitted to the signal detection terminal P of the microcomputer 40. If the key switch selected by the user is a switch on the a line of the key panel 30, the signal sensing terminal P of the microcomputer 40 passes from the a 'line through the line e' to which the Zener diode 4 (ZD4) is connected. Is entered. In addition, if the key switch selected by the user is a switch on the e line of the key panel 30, the signal sensing terminal P of the microcomputer 40 passes from the line a 'through the line e' to which the Zener diode 4 (ZD4) is connected. Is entered.

That is, the kisscan signal output from the microcomputer 40 passes through the key panel 30, and the output level is increased by a zener diode connected to the signal detection terminal P of the microcomputer 40. After differentiation, the signal is input to the signal detection terminal P of the microcomputer 40.

At this time, the output level is shown as shown in FIG.

The output level of the signal waveform output on the line a 'that does not pass through the zener diode and the output level of the signal waveform that is output from the line b' passing through the zener diode 1 (ZD1).

As described above, since the output level of the output waveform output after passing through each zener diode is different, the signal detection terminal of the key input circuit also senses different values according to the selected switch. On the other hand, as shown in the figure, each of the four ports of the kisscan output of the key panel 30 is output with the time waveform of the output waveform having the same voltage level.

As described above, according to the present invention, a zener diode for outputting different levels is installed in parallel on an output line of a key panel having a plurality of key switches, and then the keys having different output levels are passed through each zener diode. It is a basic technical idea to input a scan signal into a signal detection terminal provided in the microcomputer.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self-evident.

Therefore, the key input circuit of the microwave oven according to the present invention can expect the following effects.

First, it is possible to connect the zener diode to the output line of the key panel and input the kisscan signal of different input levels according to the position where the key switch is pressed.The kisscan signal can be input even if the microcomputer has only one signal input terminal. It is possible to detect.

Second, it is possible to include a large number of key switches even if the kisscan output terminal and the kisscan input terminal is smaller than in the related art, thereby reducing the number of parts as a whole to reduce the manufacturing cost.

Third, purchases of products can be expected to have a synergistic effect.

Claims (1)

A key panel comprising a plurality of key switches; A microcomputer for outputting a kisscan signal to the key panel, and inputting a kisscan signal passing through the key panel into one signal detection terminal; It comprises a plurality of zener diodes having different values between the key panel and one signal detection terminal of the microcomputer and connected in parallel, And a key input circuit of the microwave oven for determining an input signal by detecting an output level output through the Zener-Did according to the input signal of the key input circuit.