JPH0478915A - Key input device - Google Patents

Abstract

PURPOSE:To decrease the number of output terminals, and the number of pieces of wirings by providing external output terminals for which connecting terminals of each switch and each connecting terminal of a display device are both connected in common. CONSTITUTION:External output terminals 3 controlled by the output control part 2 of the inside of a controller 1 are connected to both of a switching part 4 formed by a key switch, and a display part 5 formed by a display element. The switching part 4 sends the data of an internal state of the switching part 4 to a key input control part 7 through an external input terminal 6. The display part 5 is connected to the external output terminal 3 and the display control terminal 8, and the display control terminal 8 is controlled by a control part 9. That is, the driving output terminal of the display part 5 and the driving output terminal of a key switch are connected in common, and the respective driving signals are subjected to time division. In such a manner, the number of terminals, and the number of wirings can be decreased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a key input device composed of a key switch and a display device such as an LED, and the key switch and the display device share a drive output terminal. This makes it possible to downsize the system.

[Prior art 1] In a system that displays an indication on a display device such as an LED in response to the pressed state of a key switch, conventionally, an external output terminal for driving the key switch and an external output terminal for driving the key switch are connected to each other. An external input terminal is required to input the current state, but in order to drive the display device, a drive current output terminal and a drive current input terminal are also required for each element.Number of terminals required There is also the problem that the number of wiring increases as the number of key switches and display elements increases.

[Problems to be Solved by the Invention] However, the conventional technology has a problem in that as the number of key switches and display elements increases, the number of required external output terminals, external input terminals, and respective wiring increases.

Therefore, in order to solve these conventional problems, the present invention aims to provide a key input device that suppresses the increase in the number of terminals by using a common external output terminal for driving the key switch and display element. There is.

Means for Solving Problem Cf1] A key input device of the present invention includes: a plurality of external output terminals, a plurality of external input terminals, a plurality of switches whose respective terminals are connected to the external output terminal and the input terminal, and the switch. A key input device comprising a display device for displaying the state of the key input device, characterized in that the connection terminals of each of the switches and the connection terminals of the display device both have an external output terminal commonly connected. do.

[Function 1] By making the display device's drive output terminal and the key switch's drive output terminal common, and by time-sharing the respective drive signals, the number of terminals and wiring can be reduced.

[Examples] The present invention will be described in detail below based on Examples.

FIG. 1 is a block diagram of one embodiment of the present invention. An external output terminal 3 controlled by an output control section 2 inside the control device l is connected to a switch section 4 made up of a key switch and a display section 5 made up of a display element. .

The switch section 4 sends data on the internal state of the switch section 4 to the key input control section 7 via the external input terminal 6. The display section 5 is connected to the external output terminal 3 and the display control terminal 8 , and the display control terminal 8 is controlled by the display control section 9 .

FIG. 2 shows an embodiment of the switch section.

The output terminal 11 is fixed at the VDD level by the resistor 12, and if the switch drive terminal 0 is at the Vss level, the switch connected to the terminal 1o is turned ON.
When the switch is in the state, the output terminal 11 corresponding to the switch becomes the ■311 level.

Figure 3 is an example of one display section, with LED as the display element.
This is what was used. When the display control terminal 13 is at the Vas level, the external output terminal 14 becomes the Vss level, and a current flows through the transistor 15 to the corresponding LED 16, thereby performing a display operation.

FIG. 4 shows examples of the timing signal of the external output terminal 3, the timing of taking in the external input signal of the key input control section 7, and the control signal of the display control terminal. Since the external output terminal drives the switch section and the display section using a common output terminal, driving of the key switch and output of a drive signal for the display section are performed in a time-sharing manner.

A timing section 17 is a driving period of the key switch, and the key input control unit 7 is activated at the external input acquisition timing 17.
The ON10FF information of the key switch is taken in. A timing section 19 is a period for outputting display information of the display unit, and display is performed when the display control signal 20 output from the display control terminal 8 is at the VHz level.

In the example of the display section, the external output terminal common to the switch section is connected to the base of the transistor 15 via a resistor, but it is also possible to connect it to the LED side and connect the display control terminal to the resistor at the base of the transistor 15. You can also do it. It is possible to operate even if the signals and timing at this time are the same as those shown in FIG.

[Effects of the Invention] As described above, the key input device of the present invention shares the external output terminal for driving the keyswitch and the external output terminal for driving the display element, and time-divides each drive signal. By outputting, it is possible to reduce the number of output terminals and the number of wires, and it is possible to create a system that is efficient in terms of area.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an example of a key input device of the present invention. FIG. 2 is a diagram showing an example of a switch section. FIG. 3 is a diagram showing an example of a display section. FIG. 4 is a diagram showing an example of signals at each terminal. 1...control device Output control section External output terminal Switch part Display section External input terminal Key input control section Display control terminal Display control section switch element PNP transistor Light emitting diode (LED) Key switch drive period Display drive period Display control signal Key switch and display drive signal that's all

Claims (1)

[Claims] A key input device comprising a plurality of external output terminals, a plurality of external input terminals, a plurality of switches each having a terminal connected to the external output terminal and the external input terminal, and a display device for displaying the states of the switches. In,
A key input device characterized in that the connection terminals of each of the switches and the connection terminals of the display device both have an external output terminal connected in common.