JPS6069727A - Keyboard device - Google Patents

Abstract

PURPOSE:To decrease the number of connection lines by arraying impedance elements in the X and Y directions of a keyboard matrix in series and outputting the depression output of a key switch as variation in impedance. CONSTITUTION:A connection cable 3 consists of two signal lines 3A and 3B, which are connected to series connection resistances RH1...RH5, and RV1...RV4 in the X and Y directions of the key matrix. Respective rows and columns of the key matrix are connected to respective connection points of those series resistances, so a key which is depressed connects its row and column. For example, when a key switch K33 is pressed, resistances RV3, RV4, RH3, RH4, and RH5 are connected in series. Therefore, the impedance of the keyboard viewed from the main body side varies corresponding to a depressed key.

Description

[Detailed description of the invention] [Technical field] The present invention relates to a keyboard device.

[Prior Art] Conventionally, in a keyboard device such as an electronic desk calculator where the main body and the key fob device are separate units, a logic circuit that operates by receiving a drive power is built into the key fod device side, and the key Generally, when a key is pressed, the logic circuit operates and sends the code of the pressed key to the main body as an electrical signal.

However, such conventional keyboard devices require a large number of signal lines to connect to the main body, and additional power lines to drive the logic circuit, making the connection cables complicated and complicated. It had the disadvantage of being expensive. Furthermore, since the structure is complicated, there is a drawback that malfunctions are likely to occur due to noise or the like.

[Purpose] The present invention has been made in view of the conventional problems as described above, and its purpose is to have a simple configuration, effectively prevent malfunctions due to noise, etc., and to improve the connection between the main body and the keyboard device. The object of the present invention is to propose a keyboard device that can reduce the number of signal lines as much as possible.

Another object of the present invention is to propose a keyboard device that can operate without being supplied with power from the main body.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings showing a preferred example.

In FIG. 1, a main body 2 of a device such as an electronic desk calculator (comprised of a display device, a central processing unit, a power supply device, etc.) and a keyboard device l according to an embodiment of the present invention are in separate casings, and the main body 2 and the keyboard device @1 are connected by a connection cable 3.

FIG. 2 is a circuit diagram of the keyboard device l. The connection cable 3 consists of two signal lines 3A and 3B, and the signal line 3A is connected to resistors RH5 and RH4゜RH3+ RH2+ R.
A group of five X-direction signal lines of the keyboard matrix are formed via H1. Also, the signal line 3B is connected to the resistor R
v4, Rv3.

5 of the keyboard matrix via Rv2, Rv,
It forms a signal line 4I in the Y direction of the tree. Then, by each Shinkansen line group in the X and Y directions, 15. From 21 to 25. K31- to 35. K41- is configured with 45 degrees and K51- are configured with 55 key switches.

With the above circuit configuration, the signal line 3A is connected from the main body 2 side.
, 3B, it is infinite when no key switch is pressed.

Here, Rvl = Rv2 = Rv3 = Rv4 = IKΩR
Hl = RH2 = RH3 = RH4 = RHS If Ω is set to =5, if 33 is pressed on the key switch, the resistor R
HS −+ RH4→RH3−? RV 3-+ Ry
A closed loop is formed through 4, and the impedance between the two signal lines 3A and 3B from the main body 2 side is 5Ω + 5, Ω + 5, Ω + IKΩ + IKΩ; 17, Ω (
RH5) (RH4) (RH3) (RV3) (RV4).

Similarly, when the key switch Kll is pressed, Ω is set to 29.
, when 55 is pressed on the key switch, 5 becomes Ω.

Here, the signal line 3A when each key switch is pressed,
The impedance values between 3B are as shown in the table below.

Table (Unit: Ω) As shown in the table above, in the keypad matrix shown in Figure 2, the impedance value between signal lines 3A and 3B changes depending on the key switch pressed. It is. Therefore, by detecting and outputting the impedance between the signal lines 3A and 3B on the main body 2 side, it is possible to identify whether the key switch -1 has been pressed. Although not shown, it is clear that if an A-D converter (analog/digital) is used on the main body 2 side, the code can be easily converted into a digital code.

In the above explanation, a resistor was used as an impedance element, but it goes without saying that a coil (L) or a capacitor (C) can also be used.

[Effects] As described above, according to the present invention, malfunctions due to noise etc. are effectively prevented and reliability is improved. There are fewer signal lines for connection to the main body, and since no wires are required, the connection cable is simple and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is an external view of a device having a keypad device according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an example of the circuit of the keyboard device η. Here, 1...keyboard device, 2...main body, 3...
...connection cable.

Claims (1)

[Claims] Impedance elements are arranged in series in the X direction and the Y direction of a keyboard matrix constituting a key switch, and the output of the key chain matrix in response to pressing of the key switch is output as a change in impedance. keyfod device.