JPH05333983A - Keyboard device - Google Patents

Abstract

PURPOSE:To enable maintenance before the unit fails completely by recognizing the abnormality when the number of generating chatterings reaches a certain value during one key depression time. CONSTITUTION:A scan signal output means applies scan signal to one contact of a key switch 3a corresponding to all keys 3 in 20ms cycle. When the specific key 3 is depressed in this state, a return signal is outputted from the other contact of the key switch 3a corresponding to the key 3. The number of pulses of a scan signal during one key depression time is compared with the number of pulses of a return signal by a comparing means. When the return signal is one pulse, the state is recognized as 'abnormal' (chattering generation) state, '1' is added to a counter. When the count value exceeds the limit value, the abnormality is recognized. Since the recognition of abnormality is displayed by means of a display lamp or the like, the maintenance is enabled before the unit fails completely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a keyboard device.

[0002]

2. Description of the Related Art When inputting data from a keyboard, there are individual differences, but it can be said that the normal time for pressing each key is within a certain range. On the other hand, when used for a long period of time, a chattering phenomenon may occur at the contact of the key switch corresponding to each key.

[0003]

If chattering occurs frequently, it eventually leads to a failure and it becomes impossible to input from the keys. However, the operator cannot accurately grasp the change leading to the failure. For this reason, suddenly input from a specific key becomes impossible, and if the cash register keyboard breaks down in a store with many customers, the inside of the store becomes very confused. In particular, in a store that is open late at night, the keyboard cannot be replaced, which poses a serious problem in business.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a keyboard having a large number of keys corresponding to a large number of key switches, and a scan signal is output at a constant cycle shorter than a normal single key pressing time. Scan signal output means, reading means for reading the number of pulses of the return signal output from each of the key switches during a period in which a plurality of pulses are continuously output from the scan signal output means, and one key press Comparison means for comparing the number of pulses of the scan signal and the number of pulses of the return signal during time, and the number of occurrences of a state in which the number of pulses of the return signal is smaller than the number of pulses of the scan signal as the comparison result of the comparison means. And coefficient recognition means for recognizing an abnormality when the count value of the coefficient means reaches a constant value. It was.

[0005]

[Function] Chattering occurs when the number of pulses of the return signal of the key switch is less than the specified number of times during one key pressing time. Therefore, it is possible to have a margin for performing maintenance before a complete failure occurs.

[0006]

An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 2, a keyboard 4 having a large number of keys 3 is provided on an upper portion of a main body 2 of the electronic cash register 1.
A receipt printer 5 and a display 6 are provided. Further, the main body 2 is provided with a power key 7 and a hard disk 8 for accessing program data. The main body 2 is placed on a drawer (not shown). Further, as shown in FIG. 4, the key switches 3a corresponding to the respective keys 4 are arranged on the same plane.

Next, FIG. 3 shows an electronic circuit. CPU9
The ROM 10 in which the program is written and the RAM 11 in which the variable data is written are connected on the bus line. Further, the CPU 9 has a keyboard control circuit 12 for controlling the keyboard 4, a printer control circuit 13 for controlling the receipt printer 5, a display control circuit 14 for controlling the display 6, and a control for controlling the hard disk 8. The circuit 15 is connected.

Further, although not shown in the drawings, all keys 3 have a constant cycle shorter than a normal key pressing time.
Scan signal output means for outputting a scan signal to one contact of the key switch 3a, and from the other contact of each of the key switches 3a during a period in which a plurality of pulses are continuously output from the scan signal output means. Reading means for reading the number of pulses of the output return signal, comparing means for comparing the number of pulses of the scan signal and the number of pulses of the return signal during one key pressing time, and the comparison result of the comparing means Coefficient means for coefficienting the number of occurrences of the state where the number of pulses of the return signal is smaller than the number of pulses of the scan signal, and abnormality recognition means for recognizing abnormality when the count value of the coefficient means reaches a constant value are provided. ing.

In such a configuration, the process from operation of the key 3 to recognition of an abnormality will be described with reference to the flowchart shown in FIG. First, as shown in FIG. 4, the scan signal output means applies a scan signal to one contact of the key switch 3a corresponding to all the keys 3 at a cycle of 20 ms. When a specific key 3 is pressed in this state, a return signal is output from the other contact of the key switch 3a corresponding to that key 3.

Here, as shown in FIG. 5, assuming that the normal pressing time for pressing the key 3 once is t, in the present embodiment, the cycle of the scan signal is approximately one half of the key pressing time t.
It is set to 20 ms which is the following. Therefore, if normal, two consecutive return signals are read by the reading means. Next, the number of pulses of the scan signal and the number of pulses of the return signal during one key pressing time are compared by the comparison means. In the present embodiment, a one-pulse return signal is stored in a memory (not shown),
When the return signal is read for two consecutive pulses, it is recognized as a normal state, and is input to the main CPU as data from the corresponding key 3. If the return signal is one pulse, it is recognized as an abnormal state (occurrence of chattering), and 1 is added to the counter as the coefficient means each time. Then, the count value is a limit value (for example, 10
When the value exceeds 0), the abnormality recognition means recognizes the abnormality. The abnormality is recognized by, for example, displaying it with a display lamp (not shown) or the like, or transmitting it to a host computer as a host device that manages the electronic cash register 1. Therefore, by allowing a margin for the limit value to be compared with the count value of the counter, it is possible to have a margin for performing maintenance before the key switch 3a completely fails.

[0011]

According to the present invention, a keyboard having a large number of keys corresponding to a large number of key switches, and a scan signal output means for outputting a scan signal at a constant period shorter than a normal key pressing time. Reading means for reading the number of pulses of the return signal output from each of the key switches during a period in which a plurality of pulses are continuously output from the scan signal output means, and the reading means during one key pressing time. Comparing means for comparing the number of pulses of the scan signal and the number of pulses of the return signal, and a coefficient for counting the number of occurrences of the state where the number of pulses of the return signal is smaller than the number of pulses of the scan signal as a comparison result of the comparing means. Since the means and the abnormality recognizing means for recognizing an abnormality when the count value of the coefficient means reach a constant value, Chattering occurs when the number of pulses of the return signal of the key switch is less than the specified number of times during the key pressing time, but when this number of chattering reaches a certain value, it may be recognized as an abnormality. As a result, there is an effect that it is possible to have a margin for performing maintenance before a complete failure occurs.

[Brief description of drawings]

FIG. 1 is a flowchart for executing a chattering detection process.

FIG. 2 is a perspective view of an electronic cash register.

FIG. 3 is a block diagram showing an electronic circuit.

FIG. 4 is an explanatory diagram showing an arrangement of key switches.

FIG. 5 is a timing chart.

[Explanation of symbols]

 3 keys 3a key switch 4 keyboard

Claims (1)

[Claims] 1. A keyboard having a large number of keys corresponding to a large number of key switches, a scan signal output means for outputting a scan signal at a constant period shorter than a normal key press time, and a scan for this scan. Reading means for reading the number of pulses of the return signal output from each of the key switches during the period in which the plurality of pulses are continuously output from the signal output means, and the pulse of the scan signal during one key pressing time The number of pulses of the return signal, a comparison means for comparing the number of pulses of the return signal, and a coefficient means for counting the number of occurrences of a state in which the number of pulses of the return signal is smaller than the number of pulses of the scan signal as a comparison result of the comparison means; A keyboard comprising an abnormality recognizing means for recognizing an abnormality when the count value of the coefficient means reaches a constant value. apparatus.