JP2776016B2 - Keyboard device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a keyboard device for performing an input operation of a device controlled by a microcomputer such as a high-frequency heating device.

2. Description of the Related Art In recent years, keyboard devices have been used for input operations of devices controlled by a microcomputer such as a high-frequency heating device. These keyboard devices use an output line and a time line to detect which key is pressed. Keys are arranged at intersections where scanning output lines connected to the divided outputs are wired in a matrix. The number of multiplications of the number of output lines and the number of scanning output lines becomes the total number of keys. With the diversification of devices, the number of output lines and the number of scanning output lines increase as the number of keys increases.

Conventionally, a keyboard device of this type generally has a structure as shown in FIGS. Hereinafter, this configuration will be described.

As shown in the figure, six key contacts 1 to 6 are connected to two output lines 7, 8 and three scan output lines 9, 10, 11 connected to a time-division output (hereinafter referred to as key scan output). Connected to intersection. The same applies to three output lines and two scan output lines depending on the combination. When the key contact 1 is pressed while the key scan output as shown in FIGS. 9 (c), (d), and (e) is being output to the scanning output lines 9, 10, and 11, FIG. 9 (c)
Is transmitted to the output line 7 as shown in FIG. 9 (a), and it can be determined that the key contact 1 has been pressed.

This keyboard device is configured as shown in FIG.
The shielding plate 12 made of a thin film of aluminum that shields static electricity from the operation surface contacts a metal plate 13 which is a part of the chassis, and prevents intrusion of static electricity into the contact electrodes 14. The contact short-circuit electrode 15 is arranged at a slight spatial distance from the contact electrode. To maintain this spatial distance, a spacer 16 is provided. In addition, contact short-circuit electrode 15 and shield plate 12
An insulating sheet 17 is provided to insulate the sheet. Contact electrode
14 is printed on the second insulating sheet 18. A character film 19 on which characters and the like are printed is attached to the operation surface, and the contact electrodes are short-circuited by pressing the contact portion from the operation surface.

Problems to be Solved by the Invention In such a conventional keyboard device, the number of connection lines increases as the number of key contacts increases in the relationship of the number of keys = the number of output lines × the number of scanning output lines. Further, an insulating sheet 17 was required to insulate the contact short-circuit electrode 15 and the shield plate 12.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its first object to reduce the number of connection lines. A second object is to simplify the insulating configuration of the keyboard. It is a third object to provide a keyboard device having good environmental performance. A fourth object is to simplify the contact structure and reduce the number of connection lines. Also,
A fifth object is to provide a keyboard device that shares an output line with driving of a display element.

Means for Solving the Problems In order to achieve the first object, the present invention provides a method of combining an n-th output line, an r-th (1 <r ≦ n) output line and an output line less than r. A pair of key contacts disposed therebetween, and a third contact having a potential different from the potential of each of the output lines and disposed opposite to the pair of key contacts. The first problem-solving means is that the third contact and the pair of key contacts are in contact with each other, and the output lines respectively connected to the key contacts are connected to the third contact potential.

In order to achieve the second object, in addition to the first means for solving the above problems, the third contact is formed of a sheet made of a conductive material also serving as an electrostatic shielding plate, and the sheet is grounded to the device. This is the second means for solving the problem.

Further, in order to achieve the third object, in addition to the above-described first problem solving means, a third problem solving means is that each output line is fixed to a ground potential unexpectedly when a key is read. .

Further, in order to achieve the fourth object, n-1 output lines from 1 to n-1 and a key scan output are connected to each other.
To n scanning output lines, the n-th scanning output line and the r-th (1 ≦ r <n) output line, and the q-th (1 <q <n) A fourth problem-solving means is to provide a pair of key contacts between the output line and the output line.

In order to achieve the fifth object, in addition to the fourth means for solving the above problems, a display element such as a fluorescent display tube is connected to the scanning output line, and a diode is provided between the display element and the output line. The connection is defined as fifth problem solving means.

Operation The present invention achieves a maximum of n! / 2! (N−2)! Key contacts can be connected, and the number of connection lines can be reduced as compared with the conventional maximum number of key contacts = (na) × a (where a is a positive integer equal to or less than n).

Further, according to the third problem solving means, the configuration of the electrode can be simplified, and the insulating configuration can be simplified.

Further, according to the third problem solving means, a highly reliable keyboard can be provided without migration.

Further, by the fourth problem solving means, a maximum of n! / 2! / (N-2)! The number of keys can be connected, the number of connection lines can be reduced, and the contact can be configured to short-circuit between the contacts.

Further, the scanning output line can also be used for driving a display element such as a fluorescent display tube by the problem solving means of FIG. 5, and when a key is pressed, a signal flows backward from the keyboard device toward the display element. As a result, it is possible to prevent the display element from being erroneously turned on and the output line from being pulled to a negative potential due to the difference between the input and output voltages of the keyboard device and the display element.

Embodiment An embodiment of the present invention will be described below with reference to FIG. 1 and FIG.

As shown in the figure, four output lines 20 to 23 are provided.
Key contacts 24 to 26 are arranged between 23 and output lines 22, 21 and 20, and key contacts 27 and 28 are arranged between input line 22 and input lines 21 and 20. A key contact 29 is provided between the key contacts 20 and 20. The potential of each output line 20 to 23 is set to 5 V by the resistor 30, and a third contact 31 of 0 V which is a different potential from the output line is provided. The third contact 31 is provided to each of the key contacts 24 to 29, and the key is pressed. When
The third contact 31 and the key contacts 24 to 29 come into contact with each other, and each key contact 24
The third contact potential on the two output lines connected to
0V is transmitted. Therefore, the maximum of nC2 = n! / 2! / (N-
2)! Key contacts can be connected.

The shielding plate 32 made of an aluminum thin film that shields static electricity from the operation surface contacts a metal plate 33 that is a part of the chassis, and prevents intrusion of static electricity into the contact electrode 34. The third contact electrode 35 is arranged at a slight spatial distance from the contact electrode 34. A spacer 36 is provided to maintain this spatial distance. Since there is no insulating sheet between the third contact electrode 35 and the shielding plate 32 and the third contact electrode 35 is formed directly on the surface of the shielding plate 32 by printing, the metal plate 33 which is a part of the chassis is formed. The potential and the third contact electrode 35 are electrically connected and have the same potential. Therefore, an inexpensive keyboard device having a simple structure can be realized. The contact electrode 34 is printed on the insulating sheet 37. A character film 38 on which characters or the like are printed is attached to the operation surface, and the contact electrodes 34 are short-circuited via the third contact electrode 35 by pressing the contact portion from the operation surface.

The four transistors 39 to 42 are for pulling the four output lines 20 to 23 to 0 V at the same potential as the ground. 4
When inputting a signal from the output lines 20 to 23, the drive terminals 43 of the transistors 39 to 42 are set to 0 V to set the transistors 39 to
Turn off the collector and emitter of 42, and put the signal into input. In this way, the potential is applied to the electrode 34 of the key contact only when the signals of the key contacts 24 to 29 are read. Conventionally, when a potential is continuously applied to the contact electrode 34, there is a phenomenon called migration in which silver contained in the contact electrode 34 causes a short circuit between the electrodes by using moisture as a medium, which has been a problem. According to the present invention, since only a potential is applied to the contact electrodes 34 of the key contacts 24 to 29 for a short time for reading a key input signal, migration does not occur and a highly reliable keyboard device can be provided.

The operation of the above configuration will be described with reference to FIGS.
(E) shows four output lines 20 to 23 when the key contact 26 is pressed.
And the input / output waveform of the drive terminal 43 of the transistor. The drive terminal 43 of the transistor is normally at a high voltage.
Although it is 5V, it is 0V which is a low voltage having a width of about 2 milliseconds in a cycle of 20 milliseconds. At this time, four output lines 20 ~
Out of 23, the output lines 20 and 23 are at 0V, and it can be determined that the key contacts 26 are pressed at 5V in the other lines. The key contact
If the output timings 24 to 29 are performed immediately before the switching of the drive terminal 43 of the transistor as shown in FIG. 3A, instability such as dullness of the output waveform due to the capacitance component of the output terminal can be avoided.

Next, another embodiment of the present invention will be described with reference to FIG. As shown, three output lines 44-46
And three scan output lines 47 to 49 connected to the key scan output
With key contacts between scanning output line 47 and output lines 46, 45, 44
50 to 52, key contacts 53 and 54 are arranged between the output line 46 and the input lines 44 and 43, and a key contact 55 is similarly arranged between the output lines 45 and 44. Each output line when not pressed
The potentials of 44 to 46 are set to 0 V by resistors 56 to 58, and the scanning output lines 48 and 49 are connected to the output lines 46 and 45, respectively. A display element 59 such as a fluorescent display tube is connected to the scanning output lines 47 to 49 so that the scanning output lines 47 to 49 are shared. Diodes 60-62 between scan output lines 47-49 and key contacts 50-55
And key contacts 50-55 when the key is pressed
The display element 59 is erroneously turned on due to a signal flowing backward from the side to the scanning output lines 47 to 49, and the pull-down resistors 63 to 65 and the resistors 56 to
The potential difference at 58 prevents the output lines 44 to 46 from being pulled to a negative potential.

The operation of the above configuration will be described with reference to FIG.
FIG. 6C shows output waveforms of the scanning output lines 47 to 49, and FIG.
(C) shows the input waveforms of the output lines 44 to 46 when the key is not pressed. If the key contact 51 is pressed, the signal of the scanning output line 47 is output to the output line 45 connected to the key contact 51.
And the output waveforms of the output lines 44 to 46 are shown in FIG.
The result is as shown in FIG. Therefore, it can be determined from the state of the output line 45 that the key contact 51 has been pressed. The same applies to other keys. If two or more keys are pressed, it is possible to determine that two or more keys are pressed because the signals of the corresponding scanning output lines are mixed with the output lines. The structure of the keyboard device is the same as that of the conventional example shown in FIG.

Effects of the Invention As is apparent from the above embodiments, according to the present invention, n
A pair of key contacts disposed between the two output lines, the r-th output line, and an output line less than r; and a potential different from the potential of each of the input lines, and the pair of key contacts. A pair of third contacts, wherein when the key is pressed, the third contact and a pair of key contacts come into contact with each other, and input lines respectively connected to the key contacts are connected to the third contact potential , The maximum of n! / 2! / (N-2)! Key contacts can be connected, connectors and lead wires for connecting the keyboard device and the main unit can be saved, so that inexpensive devices can be supplied, and measures against noise entering from the keyboard device and lead wires are facilitated. An inexpensive system as a whole can be provided.

Further, the third contact is formed of a sheet made of a conductive material that also serves as an electrostatic shielding plate, and the sheet is grounded to the device, so that the insulating configuration can be simplified, and it can be made inexpensively and easily.

In addition, since each output line is fixed to the ground potential except when the key is read, migration does not occur and reliability can be improved.

Also, n-1 output lines from 1 to n-1, n-1 scan output lines from 2 to n connected to the key scan output, r-th scan output line and r-th (where 1 ≦ r <
n) and the q-th output line (where 1 <q <
Since a pair of key contacts is provided between the output line of n) and the output line of the number less than q, the maximum number of n!
! / (N-2)! Since a number of key contacts can be connected and a key having the same structure as the conventional one can be used, reliability can be ensured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a keyboard device according to one embodiment of the present invention;
2 is a sectional view of the keyboard device, FIG. 3 is an input / output waveform diagram of the keyboard device, FIG. 4 is a circuit diagram of a keyboard device according to another embodiment of the present invention, and FIG. FIG. 6 is an input / output waveform diagram when the key contacts of the keyboard device are not pressed, FIG. 7 is an input / output waveform diagram when the key contacts of the keyboard device are pressed, and FIG. FIG. 9 is a circuit diagram of a conventional keyboard device, FIG. 9 is an input / output waveform diagram of the keyboard device, and FIG. 10 is a sectional view of the keyboard device. 20 to 23 output lines, 24 to 29 key contacts, 31 third contacts.

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Jun Nomura 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. In-company (56) References JP-A-59-105131 (JP, A) JP-A-63-298931 (JP, A) JP-A-1-295319 (JP, A) JP-A-2-1466653 (JP, A) ) Hikaru 1-135536 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G06F 3/02 G06F 3/023

Claims (5)

(57) [Claims] 1. An n-th output line and an r-th output line (where 1 <r
≦ n) and a pair of key contacts disposed between the output line less than r and an output line having a potential different from the potential of each of the output lines. With three contacts,
A keyboard device wherein, when a key is pressed, the third contact and a pair of key contacts come into contact, and output lines respectively connected to the key contacts are connected to the third contact potential. 2. The keyboard device according to claim 1, wherein the third contact is formed of a sheet made of a conductive material also serving as an electrostatic shield, and the sheet is grounded to the device. 3. The keyboard device according to claim 1, wherein each output line is fixed to a ground potential when the key is read. 4. An n-1 output line from 1 to n-1;
N-1 scanning output lines from 2 to n connected to the time-division output, the n-th scanning output line, and the r-th (1 ≦ r
<N) and the q-th (where 1 <q <
A keyboard device comprising a pair of key contacts between an output line of n) and an output line of a number less than q. 5. The keyboard device according to claim 1, wherein a display element such as a fluorescent display tube is connected to the scanning output line, and a diode is connected between the display element and the output line.