JPS61283901A - Safety devices for equipment with operating parts - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to operation switches operated by the user of equipment, particularly membrane switches constituted by film-like opposed electrodes, or pushbutton switches, which are operated by the user. This invention relates to a safety device for determining a failure in the case of a failure of the operation switch or its attached circuit, in a device having an operation switch that is closed only while it is pressed (while it is shaking or buzzing). .

If a short-circuit failure occurs in an operation input means such as a conventional push button whose contacts are closed only while a person is pressing the button, the operation input means will output exactly the same signal as when the button is being pressed by a person. Therefore, when using this signal to start heating, for example, it is necessary to distinguish whether the signal from this operation input means is due to a malfunction or whether it was pressed by a person. Very difficult. In the conventional technology, the first method is to not process the signal when multiple key operations are performed at the same time, or the second method is to not process the signal once a key is pressed. If so, a method is adopted in which even if the next key input signal is received, it will not be processed until the signal from which this key is released is received.

Problems to be Solved by the Invention The problem with the prior art is that in either method, when a short-circuit failure occurs, it is impossible to determine whether or not it was due to normal operation. . Another disadvantage is that normal input operations by the operator cannot be accepted after a failure occurs.

The present invention overcomes the above-mentioned drawbacks of the prior art and makes the operating switch safer, less expensive, and easier to adapt to individual equipment.

Means for Solving the Problems The present invention provides an input processing means for inputting the output from the operation input means, an input storage means for storing the input state of the input processing means, a timer means for counting a predetermined time interval, an abnormality determining means that uses the input processing means, input storage means, and timer means as input to determine that the operation switch has been pressed for a predetermined period of time or more, and outputs the result; It is composed of load control means that cuts off power to the load depending on the output.

Function The safety device for equipment having a switch according to the present invention is for determining a failure of an operation switch.The state of the operation switch is inputted, a change in the state of the operation switch is detected by the input change detection means, and the input change detection means detects a change in the state of the operation switch. A short-circuit failure of the operating switch or the attached circuit is detected by the abnormality determining means which detects that the condition in which the abnormality is applied continues for a predetermined time period counted by the timer means and outputs an abnormality signal. The load is cut off according to the detection result.

Therefore, when the operating switch, especially the start switch that instructs the start of heating, is short-circuited, it is possible to prevent the heating from starting automatically and continuing for a long time.

5-BASE EMBODIMENT A safety device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the configuration of the present invention. FIG. 2 is a schematic circuit diagram showing a portion of the blocks of FIG. 1. Figure 3 shows the embodiments of Figures 1 and 2.
This is an example showing a main part wiring diagram when adopted in a household microwave oven.

FIG. 4 is an example of a time chart of waveforms of various parts in the above example.

With reference to Figures 1, 2, 3 and 4 below,
An embodiment of the present invention will be described.

Reference numeral 1 denotes an operation input means 9a shown in FIG.

It consists of a push button switch as shown by 9b and 9c, or a planar switch called a membrane switch, and its contacts are closed only while the operator presses the switch. Reference numeral 2 denotes a control logic, which is comprised of an input change detection means 3, a timer means 4, an abnormality determination means 5, and a load control means 6. Reference numeral 8 represents a load, that is, an electronic device 6. In a bazinger, it consists of a magnetron and a high-voltage device that oscillate radio waves to heat the food.

As a means of driving these loads 8, the relay 15
．． 16, relay drive transistors 13 and 14, relay power supply 17, and contacts 23 and 24 of these relays, each of which controls energization to the lamp 22 and load 8.
F. 2o turns on and off in conjunction with the opening and closing of the heating chamber door.
A door switch that turns OFF, a 19-Fi temperature fuse, 18 a power outlet, and 21 a control section including the entire control circuit. Additionally, a display tube 12 is provided to display the operating status as required.

Now, operation input means 1 # consists of three switches,
Each heating start switch 9a.

It consists of a heating time setting switch 9b and a stop switch 9c. These are configured to open and close the input sweep output 10 and output to input signals 11a, 11b, 11c depending on whether the switch is open or closed. These switches 9a, 9b, and 9c are all closed only while being pressed by the operator.

7 Now, these time charts are shown in Figure 4. In (A), the switch 9a is pressed between (F) and (G). In addition, the manual sweep output 10 is output as Hl, H2, and H3 at a constant period as shown in (B), and as a result, the input signal 11a has r/'i (Il, as shown by q),
The I2 pulse is input. These methods are commonly used in systems using microcomputers. In the present invention, the input sweep output 10 is not particularly required. The switches 9 & - 9c may also be connected to other constant potentials. Now, input signals 11a, 11b, 1l
The signal is input to the input change detection means 3 in the cVi control block 2. The input change detection means 3 takes in the input signal in synchronization with the output of each input sweep output, compares it with the previously input and stored input signal, and resets the timer means 4 when the state changes. At the same time, the abnormality determination means 5
Output to . That is, 11 degrees I2 and 13 in FIG. 4 are the points at which the inputs change.

The abnormality determination means 5 determines that the heating start switch has been pressed based on the signal from the input change detection means 3, outputs a signal to the load control means 6, and energizes the load 8 as shown in FIG. 4(E). It is started as follows. Further, the timer means 4 is reset at the time Jl, and from then on, the timer means 4 starts counting a predetermined judgment time interval. (
C! Since the switch 9a was released at the time point I2, the input change detection means 3 detects that the switch 9a is released and receives a signal from the abnormality determination means 5, indicating that the input is released. The load continues to be energized from then on (as this is normal operation). The above is the case when the switch 9a is operated normally, and is the operation shown in the left half of FIG. 4. To make the operation of the present invention easier to understand, the microcomputer shown in FIGS. To repeat the explanation, including an example of the flowchart when the present invention is implemented using -, the steps from "beginning" to "a" in Fig. 5 are the initial steps normally performed when using a microcomputer. , and is not particularly related to the present invention. (a) to (b)
Now, input the input signal 11&, and the part from (b) to (/9) corresponds to the input change detection means 3, and when the input signal's 9b' state, that is, the state of the switch 9a changes, If there is no change, proceed to (c). (C) and subsequent sections correspond to the abnormality determination means 5, (E) and subsequent sections correspond to the timer means 4, and (6) and subsequent sections correspond to the load control means 6. Now, if the switch is pressed, go to ) and go to (
In the part shown in (g), the necessary processing corresponding to the switch is performed (for example, processing to start energizing the load).

The current input state is stored in the memory and the timer means 4 is reset.

The timer means 4 is always counted up.

Now, let us consider a case where a short circuit failure occurs in the switch 9a.

If the switch 9a is short-circuited at the time point shown by (K) in FIG. The output is generated at , the timer means 4 is reset, and energization to the load is started. In the flowchart of FIG. 5, as in the previous explanation, (B) → (E) →
It is in an advanced state.

The following input timings I5, 16. I7゜I8
In this case, there is no change in the switch 9a, and it is in the pressed state of 10 pages. On the other hand, the timer means 4 continues to count time toward a predetermined determination time T. The above judgment time T is longer than the time an ordinary operator would press a switch, for example 2 seconds, and it would be inconvenient if the equipment continues to operate abnormally (for example, if it continues to operate automatically due to a short-circuit failure of the switch). It is predetermined in advance to be a shorter period of time than the actual occurrence, for example 10 seconds.

In the flowchart, the process goes from (b) to (c), and since the operation switch remains pressed, (proceeding to the example), it is determined whether or not the timer means 4 has exceeded the predetermined determination time T. Since it has not been exceeded yet, proceed to (su) and set the timer means 4.
Continue counting to 0.

Now, when I9 is input, it is detected in the example part of the flowchart that the time of the timer means 4 has exceeded the judgment time T. That is, it is detected that the switch 9a is normally kept pressed. Since the button has been pressed for a long time (judgment time T), it can be determined that an abnormality has occurred, and the flowchart moves to (to) (Figure 6). The power to the load is cut off to maintain safety.This is the JxO point in Figure 4.

As described above, the abnormality determination means 5 in the present invention outputs an output when the operation switch is kept pressed for longer than the predetermined determination time T.

In the flowchart of FIG. 5, (C) and (Force part) correspond.

As explained above, the configuration of the present invention determines whether the operation input means is malfunctioning by determining whether or not the input state continues to be input for a predetermined determination time or longer. Therefore, the necessary configuration requirements are the operation input means 1
, input change detection means 3, timer means 4 for measuring determination time, and abnormality determination means 5 for making the above-mentioned abnormality determination.

Further, in the embodiment, an example using a microcomputer is shown, but it is obvious that the structure can be constructed using an ordinary logic IC. Furthermore, although an example of application to a household microwave oven has been shown as an example, it is obvious that the invention can also be applied to dishwashers, air conditioners, and the like.

Effects of the Invention As described above, the safety device of the present invention can reliably detect a short-circuit failure in the operation switch, thereby dramatically improving safety.

Furthermore, it is easy to handle because it does not change at all during normal use. Furthermore, by setting the determination time depending on the equipment used, it is possible to create a safety device suitable for each equipment. Further, although a push button switch has been described as an example of the operation input means, the present invention can also be applied to a contact or proximity switch, or a semiconductor type switch, and has a wide range of versatility. Furthermore, if a second-class microcomputer is used, this can be achieved without increasing the memory, so this safety device does not cause any unnecessary connections, which is extremely advantageous in practice. .

[Brief explanation of drawings]

Page 13 Figure 1 is a block diagram of an embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the specific configuration of the block diagram in Figure 1, and Figure 3 is a diagram of the microwave oven of the above embodiment. FIG. 4 is a timing chart showing the operation of an embodiment of the present invention, and FIGS. 5 and 6 are electrical circuit diagrams of one embodiment of the present invention. This is an example of a 70-chart for a microcomputer. 1... Operation input means, 3... Input change detection means, 4... Timer means, 5...
- Abnormality determination means, 6...Load control means, 9a,
9b, 9c...operation switch. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
At the beginning of Figure 5, the memory is cleared for the first time, and Mu=* is compared to low. Haou M; Chi NJ- 2,000 NO SINNAKU\(T)
, Ref- Tojiou-no? 6th
figure

Claims (2)

[Claims] (1) An operation input means that is operated by a user and outputs a signal while the user operates, an input change detection means that outputs an output when the output of the operation input means changes, and the input change detection means a timer means that is reset by the output of the means and counts a predetermined determination time; the output of the input change detection means, the operation input means, and the timer means are input; A safety device for equipment having an operating section comprising an abnormality determining means that outputs a signal when a signal indicating that a user is operating the same operating section from the operating input means continues. (2) The safety device for equipment having an operating section according to claim 1, wherein the operation input means is comprised of a switch whose contacts are closed only while being pressed by the operator.