JPH0477926B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a bidirectional matrix input device that can double the number of inputs without increasing the number of selection signal lines. [Prior Art] Matrix circuits are used for input, in which only one intersection is selected by vertical and horizontal selection signals. In a normal matrix circuit, a microprocessor sequentially outputs a selection signal to a vertical selection signal line, and from the output of the vertical selection signal line at that time, a vertical selection signal line and a horizontal selection signal line are output. It determines the status of the switch connected between the [Problem to be solved by the invention] In the above-mentioned matrix circuit, (m+n) types of selection signal lines are required to configure (m×n) crossing parts, so the number of crossing parts is increased. In order to achieve this, it is necessary to increase the number of selection signal lines.
Generally, a microprocessor (MPU) is used to make such a matrix circuit for output (display) or key input, but since the number of input/output terminals of a microprocessor is limited, There is a drawback that it cannot be connected to a matrix circuit larger than a certain scale. Matrix circuits tend to become larger in size as several types of switches on front operation panels of in-vehicle equipment become multi-functional. However, there is also a conflicting demand for miniaturization in terms of space. The present invention aims to double the number of inputs that can be selected with the same number of selection signal lines by providing two input elements at one intersection and separating them using the polarity of a diode. It is. (Means for Solving the Problems) A bidirectional matrix input device of the present invention includes a plurality of vertical selection signal lines, a plurality of horizontal selection signal lines, and a pair of diodes connected with opposite polarities. a plurality of current direction limiting elements connected between the vertical selection signal line and the horizontal selection signal line; a plurality of switches connected in series to each of the diodes; and the vertical selection signal. Sequentially output selection signals to the horizontal selection signal lines and input the signals of the horizontal selection signal lines at that time, and output selection signals sequentially to the horizontal selection signal lines to input the signals of the vertical selection signal lines at that time. A signal is input, and the output state of the vertical selection signal line, the input state of the signal of the horizontal selection signal line at that time, the output state of the horizontal selection signal line, and the selection of the vertical selection at that time. The device is characterized by comprising a microprocessor that determines the state of the switch based on the input state of the signal on the signal line. [Operation] The pair of diodes in each cross section can polarize one cross section into two cross sections, thereby doubling the number of selection signals that can be input with the same number of lines. This will be explained in detail below with reference to illustrated embodiments. [Embodiment] FIG. 1 shows an embodiment of the present invention applied to an input matrix. Each intersection of the matrix circuit MTX includes a pair of diodes D ₁ , D ₂ , D ₃ , D ₄ ,...D ₁₇ , D ₁₈ connected in parallel with opposite polarities, and a switch S connected in series with each diode. ₁ , _S2 ,... _S18 are provided. MPU selects signals V0 to V2, H0
It is a microprocessor that generates ~H2 and scans the matrix circuit MTX, and uses an input/output port as shown in Figure 2. That is, MOS transistors Q ₁ to _{Q 3} constitute one input/output port, and MOS transistors Q ₄ to _{Q 6} constitute another input/output port. Transistors Q ₁ and Q ₄ are switched internally (controlled by the I/O terminal) and used as a high impedance state at input and as a pull-up resistor at output. Transistor Q ₂ ,
Q ₅ is for output driven by a signal from inside the MPU, and transistors Q ₃ and Q ₆ are for input driven by a signal from outside. Depending on whether these input/output ports are used as shown in the solid line or as shown in the broken line, one of the switches at the same intersection is selected (scanned). For example, taking the intersection of switches S ₁ and S ₂ as an example,
Turn off the output transistor Q ₂ , turn on the input/output switching transistor Q ₁ , set the selection signal H0 to 1, and monitor the current V0 as an input level with the input transistor Q ₆ (at this time, Q ₄ is turned off). ), if switch S ₁ is off, it is V0 and is grounded by pull-down resistor R ₂ , so it is 0; conversely, if switch S ₁ is on, it is H
1 of 0 is applied to resistor R ₂ through S ₁ and D ₁ .
V0=1, and accordingly transistor _Q6 is turned off (when V0=0) or on (when V0=1). On the contrary, the output transistor _Q5 is turned off, the input/output switching transistor _Q4 is turned on, the selection signal V0 is set to 1, the current H0 is set to the input level, and the transistor _Q3 (at this time, _Q1 is a high impedance If you monitor the state (state.), you will know whether switch _S2 is on or off based on the voltage generated across pull-down resistor _R1 . The table below is a logical table showing this.

[Table] This applies to all other intersections. In the case of an input matrix as in this example, the processor MPU monitors the ON/OFF status of all switches in the matrix circuit MTX while performing selective scanning at a constant timing. [Effects of the Invention] As described above, according to the present invention, two input elements are provided at each intersection of a matrix circuit having a plurality of intersections, and the polarities of the diodes are used to separate them. Therefore, the number of inputs that can be selected with the same number of selection signal lines can be doubled. Therefore, there is an advantage that the number of wires connecting the matrix circuit and the processor can be reduced, and that even if the processor has fewer input/output terminals, more inputs can be processed. Therefore, it is possible to effectively meet the contradictory demands for multi-functionality and miniaturization, such as in in-vehicle equipment.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention applied to an input matrix, and FIG. 2 is a main part circuit diagram for explaining its operation. In the figure, MTX is a matrix circuit, D ₁ , D ₂ , . . . are diodes, S ₁ , S ₂ , . . . are switches, and MPU is a microprocessor.

Claims (1)

[Scope of Claims] 1 A plurality of selection signal lines in the vertical direction, a plurality of selection signal lines in the horizontal direction, and a pair of diodes connected with opposite polarities. a plurality of current direction limiting elements connected between the signal line, a plurality of switches connected in series to each of the diodes, and a selection signal sequentially output to the vertical selection signal line to select the horizontal selection signal at that time; At the same time as inputting the signal of the selection signal line in the horizontal direction, selection signals are sequentially output to the selection signal line in the horizontal direction, and the signal of the selection signal line in the vertical direction at that time is inputted. The state of the switch is determined from the output state, the input state of the signal on the horizontal selection signal line at that time, the output state of the horizontal selection signal line, and the input state of the signal on the vertical selection signal line at that time. A bidirectional matrix input device characterized by comprising a microprocessor for determining.