JPH0533232U - Keyboard matrix circuit - Google Patents

Abstract

(57) [Summary] The buffer element 11 has an input terminal connected to the column electrode R2, an output terminal connected to the row electrode L1, and a control terminal connected to the resistor r1 and one end of the switch S1. The other end of the switch S1 is grounded and the other end of the r1 is connected to 5V. The switch S1 uses a key switch having a single connection circuit (a switch that is closed when a key stop is pressed). The buffer elements 11 to 13 are
Since the logic on the input side appears at the output terminal when the control terminal is grounded, the row electrode L1 is held only while the switch is pressed.
When the column electrode R2 becomes conductive, the light emitting diodes D1, D2 and D3 are turned on. [Effect] The number of signal lines for lighting the light emitting diode corresponding to the key switch can be reduced.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a keyboard matrix circuit used for inputting data to a computer device or the like.

[0002]

[Prior Art]

 In the conventional keyboard matrix circuit, switches are connected to the intersections of the row and column electrode groups as shown in FIG. 4, and the key input is detected by opening and closing the switches. It was This matrix circuit is generally controlled by a keyboard interface LSI or the like, and a key switch that connects the electrodes when the key top of the switch is pressed is used for this switch. The scanning signal of the matrix circuit is designed to flow from the side of the column electrodes R1 to Rn to the side of the row electrodes L1 to Ln, and the scanning signal is made to sequentially scan the column electrodes R1 to Rn. ing. When one of the key switches is pressed in this state and the column electrode and the row electrode are connected, the scanning signal is taken into the row electrode side via the connected switch. The respective electrode wire numbers of the row electrode and the column electrode at this time are detected by a circuit (for example, a keyboard interface LSI) that controls this matrix circuit as information.

[0003]

[Problems to be solved by the device]

 In this conventional keyboard matrix circuit, in order to improve the operability and functionality of the keyboard, a light emitting diode is often provided corresponding to the key switch. However, in the conventional circuit form, in order to make each light emitting diode correspond to each key switch, a control port corresponding to the number of light emitting diodes is required, and there is a problem that the number of interface signal lines increases.

[0004]

[Means for Solving the Problems]

 The keyboard matrix circuit of the present invention detects the opening and closing of the intersection of the electrode line groups intersecting each other as key data, and the intersecting electrode lines are connected by the input / output terminals of a 3-state buffer element. A switch is connected to a control terminal that determines whether or not the operation of the state buffer element is possible.

[0005]

【Example】

 Next, the present invention will be described with reference to the drawings. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is a time chart for explaining the operation of this embodiment, and FIG. 3 is a block diagram of a peripheral circuit including this embodiment.

In this embodiment, L1 to Ln and R1 to Rn represent the row electrode group and the column electrode group of the matrix circuit, and the elements 11 to 13 represent the 3-state buffer elements with control terminals. Here, the element 11 has an input terminal connected to the column electrode R2 and an output terminal connected to the row electrode L1. Further, the control terminal of the element 11 is connected to the resistor r1 and one end of the switch S1, and the switch S1 uses a key switch having a single connection circuit (a switch that is closed when the key top is pressed). ing. In the elements 11 to 13, since the logic on the input side appears at the output terminal when the control terminal is grounded, the row electrode L1 and the column electrode R2 are in a conductive state only while the switch is pressed. Becomes equivalent.

Since the scanning signal of this matrix circuit flows from the column electrode to the row electrode side, when the switch S1 is pressed, the scanning signal is transmitted to the row electrode L1 via the element 11 and is shown in FIG. The keyboard interface LSI controlling the matrix circuit detects that the switch S1 has been pressed and notifies the CPU.

When the CPU receives a key input, a key input acceptance confirmation signal B is generated. This pulse width is created by the key input acceptance confirmation lighting signal generation circuit within a time width that allows the light emitting diode to be visually illuminated when the key switch is pressed. The key input acceptance confirmation lighting signal A is connected to one of the inputs of the logical sum elements of the elements 14 to 16, and the other input terminals of the elements are connected to the switches S1 to S3, respectively. Light emitting diodes D1 to D3 and resistors r4 to r6 are connected to the respective outputs of the OR elements 14 to 16, and S1 is pressed to generate a key input acceptance confirmation lighting signal A as shown in FIG. At this time, the output terminal of the element 14 becomes Low level, and the light emitting diode D1 lights up.

By doing so, the operation of the switches S1 to S3 in which the electrode lines of the electrode line groups that intersect each other are connected by the input / output terminals of the three-state buffer elements 11 to 13 and are connected to the control terminals of these elements Accordingly, the light emitting diode can be turned on by the logical sum of the key input acceptance confirmation lighting signal A and the key depression information a. Further, in the conventional example, when the light emitting diodes respectively corresponding to the plurality of key switches are turned on by receiving the key input, the control ports are required by the number corresponding to the number of the light emitting diodes. Since only one is required, the number of interface signal lines can be reduced. The reduction in the number of signal lines reduces the noise on the electric circuit and is less susceptible to the noise, so that the reliability of the circuit is improved.

[0010]

[Effect of the device]

 As described above, according to the present invention, the electrode lines of the intersecting electrode line groups are connected by the input / output terminals of the 3-state buffer element, and the switching terminals are connected to the control terminals that determine whether the 3-state buffer element can operate. By providing a device, it is possible to reduce the number of interface signal lines that turn on the light emitting diodes corresponding to the key switches in response to the key input.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the present embodiment.

FIG. 3 is a block diagram of a peripheral circuit including this embodiment.

FIG. 4 is a circuit diagram showing an example of a conventional keyboard matrix circuit.

[Explanation of symbols]

 L1 to Ln row electrode group R1 to Rn column electrode group 11 to 13 buffer element 14 to 16 logical sum element r1 to r3 pull-up resistor r4 to r6 current limiting resistor S1 to S3 key switch D1 to D3 light emitting diode A key input reception Confirmation lighting signal B key input acceptance confirmation signal

Claims (1)

[Scope of utility model registration request] 1. A keyboard matrix circuit for detecting opening / closing of an intersection of electrode line groups intersecting each other as key data, wherein the intersecting electrode lines are connected by an input / output terminal of a 3-state buffer element, and the 3-state buffer element is connected. A keyboard matrix circuit in which a switch is connected to a control terminal that determines whether or not the operation of the keyboard matrix.