JP2847224B2 - microwave - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven whose operation is controlled by a microcomputer based on a key input from a key input section for setting operating conditions.

[0002]

2. Description of the Related Art In a microwave oven of this type, reading of a key by a microcomputer is conventionally performed as follows.

That is, first, a plurality of types of key strobe signals are simultaneously turned on, and the states of a plurality of key input ports of the microcomputer at that time are read. At this time, if all the key input ports are off (inactive), it is determined that no key input has been made, and one reading operation is completed. If any key input port is on (active state), it is determined that a key input has occurred,
The strobe signals are sequentially turned on one by one, and the state of the key input port at that time is read. When the key input port is turned on, one reading operation is completed, and the type of the key being pressed is determined based on the combination of the strobe signal and the key input port that are turned on at that time.

[0004]

However, in the conventional microwave oven, since the key is read as described above, even though the key is not actually pressed, noise or short-circuit of the circuit may occur. There is a risk of erroneous reading in which a key is erroneously determined to be pressed.

In order to prevent such erroneous reading, there is a device that performs reading a plurality of times. In this case, erroneous reading due to noise can be prevented, but the key input port is turned on due to a short circuit or the like. In such a case, erroneous reading cannot be prevented.

Next, the reason will be described in detail with reference to the timing chart of FIG.

FIG. 4 shows eight types of strobe signals S1 to S8.
And strobe signals S1 to S8 when signals are read using the four key input ports a to d and the signals (input port signals) Ka to Kd of the key input ports a to d. partial normal conditions, part of B indicates an abnormal condition where misreading <br/> seen write only occurs. In the following description, for the strobe signals S1 to S8, the ON state is "H" (High) and the OFF state is "L" (Lo).
w), the input port signals Ka to Kd may be represented by "1" for the on state and "0" for the off state.

In FIG. 4, when the key is not pressed in the normal state, all the strobe signals S1 to S8 at time T1.
Is set to "H", the signals (input port signals) Ka to Kd of the four key input ports a to d are all "0".
Therefore, it is determined that there is no key input, and the reading is terminated.

When the key corresponding to the eighth strobe signal S8 and the fourth input port d is pressed, all the strobe signals S1 to S8 are set to "H" at time T2, and the fourth input port signal Kd becomes "1". "become. Therefore, it is determined that a key input has been made, and then the strobe signals S1 to S8 are set to "H" sequentially from the first strobe signal S1, and the input port signals Ka to Kd at that time are read. The first strobe signal S1 (time T3), the second strobe signal S2 (time T4), the third strobe signal S3 to the sixth strobe signal S6 (not shown) and the seventh strobe signal S7 (time T5) are sequentially set to "H". In any case, since the input port signals Ka to Kd are all "0", the eighth strobe signal S8 is set to "H" at time T6. In this case, the fourth input port signal Kd is set to "1". The 8th
It is determined that the key corresponding to the strobe signal S8 and the fourth input port d has been pressed, and the reading is terminated.

If the second input port signal Kb is set to "1" due to a short circuit or the like without the key being pressed, all the strobe signals S1 at time T7.
To S8 at "H", the second input port signal Kb
Is "1", it is erroneously determined that a key input has been made. Then, the strobe signals S1 to S8 are sequentially set to "H" from the first strobe signal S1, and the input port signals Ka to Read Kd. When the first strobe signal S1 is set to "H" at time T8, the second input port signal Kb is "1", so that the key corresponding to the first strobe signal S1 and the second input port b is set. It is determined that is pressed by mistake and the reading is terminated.

In this case, even if reading is performed a plurality of times to prevent erroneous reading, the second input port signal K
Since b remains "1", it is erroneously determined that the key corresponding to the first strobe signal S1 and the second input port b has been pressed.

[0012] For this reason, if the key that has been determined by mistake, such as a direct start key, cooking by mistake to not press the key will be the start, also, continue to this key and press <br/> In the case of a key that increases the cooking time by, for example, one minute, there is a serious problem that cooking does not end forever.

An object of the present invention is to solve the above problems,
Incorrectly reading the key due to a short circuit can be reliably prevented ,
In addition, costs are increased to prevent erroneous reading of keys.
It is to provide a microwave oven that does not Ka.

[0014]

A microwave oven according to the present invention includes a control microcomputer and a key input section for setting operating conditions, and the microcomputer turns on a key strobe signal to set a state of a key input port. In a microwave oven that reads a key by reading a key, before turning on the strobe signal, the state of the key input port is read with the strobe signal turned off, and all key input ports are turned off. In the case of (1), the key is read by turning on the strobe signal, and the key is not read when any key input port is on.

[0015]

For example, in the case of an abnormality such as a certain key input port being turned on due to a short circuit, when the state of the key input port is read with the strobe signal turned off prior to reading the key. , because either Re not have a key input port is turned on, it is judged to be abnormal, the reading is not performed. Therefore, no erroneous reading occurs.

If there is no abnormality as described above, all key input ports are turned off when the state of the key input ports is read with the strobe signal turned off prior to key reading, so that normal operation is performed. Is read. The strobe signal and key input port
The strobe signal
To read the state of the key input port with it turned off
Software programs attached to a microcomputer
By simply adding, it is possible to prevent erroneous reading.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall block diagram of a microwave oven (one-key range).

This microwave oven uses a key input unit (1) for giving operating conditions, a display unit (2) for displaying operating conditions, temperature, time, etc., and a buzzer to notify the end of cooking. And a relay output unit (4) for controlling a magnetron, etc., a microcomputer (5) for controlling the whole of them, and a power supply unit (6).

The microcomputer (5) and the key input section (1) are connected by a strobe signal output line (7) and a key input line (8), and a key is connected from the microcomputer (5) through the strobe signal output line (7). Eight types of strobe signals S1 to S8 are input to the input section (1).
The key input data is sent from the key input unit (1) to the four key input ports a to d of the microcomputer (5) through the key input line (8). When a key in the key input section (1) is pressed, the corresponding input ports a to d are turned on when the strobe signals S1 to S8 corresponding to the key are turned on, and the keys are turned on. The combination of the strobe signals S1 to S8 and the input ports a to d determines the type of the pressed key. Therefore, under normal conditions, the input port will not be turned on unless the corresponding strobe signal is turned on.

Next, referring to the flowchart of FIG.
An example of a key reading operation by the microcomputer will be described.

First, prior to reading, all strobe signals S1 to S8 are set to "L" (step 1), and the four input port signals Ka to Kd at that time are read to determine whether all of them are "0". (Step 2).

In step 2, if any one of the four input port signals Ka to Kd is "1", it is determined that there is an abnormality, and the flow advances to step 11 to perform processing without key input. To terminate the reading process.

In step 2, the input port signal Ka
If ~ Kd are all "0", it is determined that it is normal and
Start the actual key reading. That is, first, all the strobe signals S1 to S8 are set to H (step 3),
The four input port signals Ka to Kd at that time are read to check whether any one of them is "1" (step 4).

In step 4, the input port signal Ka
If .about.Kd are all "0", the process proceeds to step 10, after all the strobe signals S1 to S8 are set to "L", a process without key input is performed (step 11), and the reading process is terminated. . This is a case where no key input is made in a normal state.

In step 4, if any one of the four input port signals Ka to Kd is "1", it is determined that a normal key input has been made, and the routine proceeds to step 5, where all strobe signals are output. S1 to S8 are set to "L", and strobe signals S1 to S8 are numbered (1 to 8).
Is set to an initial value 1 for a variable x representing.

Next, the strobe signal Sx is set to "H" (step 6), and the four input port signals Ka at that time are set.
.About.Kd and checks whether any one of them is "1" (step 7).

In step 7, if any one of the four input port signals Ka to Kd is "1", the strobe signal Sx which is "H" at that time.
It is determined that the keys corresponding to the input port signals Ka to Kd which are "1" are normally pressed, and
After all the strobe signals S1 to S8 are set to "L", the processing with the key input and the key discrimination based on the strobe signal Sx and the input port signals Ka to Kd at that time are performed (step 13) and read. The process ends.

In step 7, the input port signal Ka
If Kd are all "0", the process proceeds to step 8, and S
After setting x to "L" and increasing x by "1", it is checked whether or not x has become "9" (step 9).

In step 9, if x is not "9", the process returns to step 6, and the above operation is repeated until any of the input port signals Ka to Kd becomes "1" in step 7.

In step 9, when x becomes "9", the process proceeds to step 10.

In the above flowchart, step 3
13 are the same as those of the conventional key reading operation described above. If steps 1 and 2 are not included in the above-described flowchart, erroneous reading due to a short circuit cannot be prevented as described above with reference to FIG.

On the other hand, in the case of this embodiment, since steps 1 and 2 are added to the same read operation as in the prior art, erroneous read due to a short circuit can be reliably prevented.

Next, the reason will be described in detail with reference to the flowchart of FIG. 2 and the timing chart of FIG. FIG. 3 corresponds to FIG. 4 described above.

If the key is not pressed in the normal state, first, steps 1 and 2 are executed at time T10, and the four input port signals Ka to are set in a state where all the strobe signals S1 to S8 are set to "L". Kd is read. At this time, since the input port signals Ka to Kd are all "0", steps 3 and 4 are executed at time T11, and the four input signals are set with all the strobe signals S1 to S8 at "H". The port signals Ka to Kd are read. At this time, the input port signals Ka to Kd are all "0". Therefore, the process proceeds from step 4 to step 11, where the process without key input is performed, and the reading process is completed.

The operation at time T11 at this time is the same as the operation at time T1 in FIG.

When the key corresponding to the eighth strobe signal S8 and the fourth input port d is pressed, first, steps 1 and 2 are executed at time T12, and all the strobe signals S1
To S8 are set to "L" and the four input port signals Ka
~ Kd are read. At this time, the input port signal Ka
.About.Kd are all "0", steps 3 and 4 are executed at time T13, and all strobe signals S1.
With S8 set to "H", the four input port signals Ka.about.
Kd is read. At this time, the fourth input port signal K
Since d is “1”, at time T14, step 5,
6 and 7 are executed, and the strobe signal Sx (= S1)
Are set to “H”, the four input port signals Ka to Kd
Is read. At this time, four input port signals Ka
To Kd are all "0", so that steps 7 to 8 and 9 are executed, and the strobe signal Sx (= S
After 1) is set to “L”, x is increased by “1” to “2”
And return to step 6. When the second strobe signal S2 to the seventh strobe signal S7 are sequentially set to "H",
In any case, since the input port signals Ka to Kd are "0", the strobe signal Sx (= S2) is set to "H" at time T15, and then x is increased by "1" at time T15.
Steps 6 to 9 are repeated until the strobe signal Sx (= S7) is set to "H" at 16. After this,
At time T17, steps 6 and 7 are executed, and the strobe signal Sx (= S8) is turned on and the input port signal K is turned on.
When a.about.Kd is read, the fourth input port signal Kd is "1" at this time.
Step 13 is executed, the key input process and the key determination are performed, and the reading process ends.

The operation at time T13 to T17 at this time is the same as the operation at time T2 to T6 in FIG.

If the second input port signal Kb becomes "1" due to a short circuit or the like without the key being pressed, steps 1 and 2 are executed at time T18, and all strobes are executed. When four input port signals Ka to Kd are read in a state where the signals S1 to S8 are set to "L", the second input port signal K2 is "1". Then, the processing without key input is performed, and the reading processing ends. Therefore, erroneous reading of the key does not occur.

[0040]

According to the microwave oven of the present invention, as described above, even when a certain key input port is turned on due to a short circuit or the like, erroneous reading of a key is reliably prevented. Therefore, it is possible to prevent malfunction due to erroneous reading of the key. I
The strobe signal originally required for reading the key
To the microcomputer using the key and key input port.
Key misreading just by adding a software program
Can be prevented by hardware
Need not be added. Therefore, if there are many keys
Also increase costs to prevent erroneous reading
There is no.

[Brief description of the drawings]

FIG. 1 is an overall block diagram of a microwave oven showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a key reading operation by a microcomputer of the microwave oven of FIG. 1;

3 is a timing chart showing a strobe signal and an input port signal when a key is read by the microcomputer of the microwave oven shown in FIG. 1;

FIG. 4 is a timing chart showing a strobe signal and an input port signal when a key is read by a microcomputer of a conventional microwave oven.

[Explanation of symbols]

 (1) Key input section (5) Microcomputer (7) Strobe signal input line (8) Key input line

Claims (1)

(57) [Claims] A microcomputer for control and a key input unit for setting operating conditions are provided, and the microcomputer reads a key by turning on a key strobe signal and reading a state of a key input port. Before turning on the strobe signal in a microwave oven, the state of the key input port is read with the strobe signal turned off.If all the key input ports are off, the strobe signal is turned on and the key input port is turned on. A microwave oven which reads a key and does not read a key when any key input port is on.