JPH0255807B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a bidirectional matrix display device that can double the number of outputs without increasing the number of selection signal lines. [Prior Art] A matrix circuit in which only one intersection is selected by vertical and horizontal selection signals is used for output (display). Figure 3 shows an example of a conventional display matrix circuit, in which one of 3×3=9 light emitting diodes LED ₁ , LED ₂ , .
+3 = 6 types of selection signals V0 to V2, H0 to H2
It is designed to be selected by . _T1 to _T3 are H (high) and L (low) of vertical selection signals V0 to V2
Transistors turned on and off by T ₄ to _{T 6}
are transistors that are turned on and off depending on H and L of the horizontal selection signals H0 to H2. To select one light emitting diode in this matrix circuit, only one vertical selection signal is set to H, and only one horizontal selection signal is set to L.
For example, to select light emitting diode LED ₁ , V0
= (V1 = V2 = L) to turn on the transistor _T1 , and set H0 = L (H1 = H2 = H) to turn off the transistor _T4 , so that the current from the power supply V _DD passes only through LED _{1 and} turns on the transistor T1. Make it flow to T ₁ . At this time, LED ₂ and LED ₃ are also transistors.
is connected to T ₁ , but since transistors T ₅ and T ₆ are on, their anodes are grounded,
It does not emit light. [Problems 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) intersections, so in order to increase the number of intersections, For this purpose, the number of selection signal lines must be increased. Generally, a microprocessor (MPU) is used to make such a matrix circuit for output (display), but since the number of output terminals of a microprocessor is limited, matrix circuits over a certain scale are There is a problem with not being able to connect to. Matrix circuits tend to become larger in size as several types of displays on front operation panels of in-vehicle equipment become multi-functional. However, there are conflicting demands such as the need to downsize in terms of space. The present invention aims to double the number of outputs that can be selected with the same number of selection signal lines by providing two output elements at one intersection and separating them using the polarity of diodes. It is. [Means for Solving the Problems] The present invention comprises a plurality of vertical selection signal lines, a plurality of horizontal selection signal lines, and a pair of light emitting diodes connected with opposite polarities. a plurality of display elements connected between the selection signal line and the horizontal selection signal line; and an all selection signal line of only one of the vertical selection signal line and the horizontal selection signal line. a switching circuit for supplying a voltage to a first switching circuit for selectively grounding the vertical selection signal line;
The present invention is characterized by comprising a control circuit and a second control circuit that selectively grounds the horizontal selection signal line. [Function] 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 output with the same number of lines. This will be explained in detail below with reference to illustrated embodiments. [Embodiment] FIG. 1 is a circuit diagram showing an embodiment of the present invention.
MTX is a display matrix circuit having (4×4) intersections. A pair of light emitting diodes (LED ₁ , LED ₂ ), (LED ₃ ,
LED ₄ ), ... (LED ₃₁ , LED ₃₂ ) are connected in parallel with opposite polarity. T ₁₀ to _{T 13} are vertical selection signals V
Transistor that turns on and off at 0~V3, _T20 ~
_T23 is a transistor that is turned on and off by the horizontal selection signals H0 to H3. T ₃₀ to _{T 32} are transistors forming a switching circuit PS of the power supply V _DD . This power supply switching circuit PS selects a vertical selection circuit SEL ₁ consisting of transistors T ₁₀ to T ₁₃ by an odd-even selection signal EN.
Alternatively, supply the power supply V _DD to either one of the lateral selection circuits SEL ₂ . In other words, when the signal EN is 1 (H), the transistors T ₃₁ and T ₃₀ are turned on, and the odd numbered light emitting diodes LED ₁ , LED ₃ , ... LED ₃₁
becomes selectable. Conversely, signal EN is 0 (L)
At this time, the transistor _T32 is turned on and the even numbered light emitting diodes _LED2 , _LED4 , . . . _LED32 become selectable. In a selection circuit that is supplied with power from the circuit PS, an off transistor has meaning, and in a selection circuit that is not supplied with power, an on transistor has meaning. As a driving method for the display matrix circuit MTX, there is a dynamic driving method in which, for example, H0 to H3 are sequentially switched as timing signals, and V0 to V3 are provided with data according to the display contents. In this example, an odd-even switching signal EN is added to this to double the number of display elements. The operation will be explained below with reference to FIG. This figure is a main part circuit diagram centered on the light emitting diodes LED ₁ and LED ₂ of FIG. 1. Odd-even selection signal EN is 1
(odd number), transistors T ₃₀ and T ₃₁ are turned on and V _DD is applied to the collector of transistor T ₂₀ . At this time, if the signal H0 is 0 (L) and the transistor T ₂₀ is off, and the signal V0 is 1 (H) and the transistor T ₁₀ is on, the current flows along the path indicated by the solid arrow in the figure, and the odd-numbered light is emitted. diode
LED ₁ lights up. Conversely, when the odd-even selection signal EN is 0 (even number), the transistor _T32 is turned on and _VDD is applied to the collector of the transistor _T10 .
Therefore, if the signal H0 is 1 and the transistor T ₂₀ is on, and the signal V0 is 0 and the transistor T ₁₀ is off, a current flows along the path indicated by the broken arrow in the figure, and the even numbered light emitting diode LED ₂ lights up. . The above logic is shown in Table 1.

[Table] Also, the overall logic is shown in Table 2 (when EN=1) and Table 3
(When EN=0)

【table】

【table】

〔Effect of the invention〕

As described above, according to the present invention, two output elements are provided at each intersection of a matrix circuit having a plurality of intersections, and they are separated using the polarity of the diode. The number of outputs that can be selected by the number of selection signal lines can be doubled. Therefore, there is an advantage that the number of wires connected between the matrix circuit and the processor can be reduced, and more outputs can be processed even if the number of output terminals of the processor is small. Therefore, it is possible to effectively meet the contradictory demands of multi-functionality and miniaturization, such as in in-vehicle equipment.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
The figure is a circuit diagram of a main part for explaining its operation, and FIG. 3 is a circuit diagram showing an example of a conventional unidirectional matrix. In the figure, MTX is a matrix circuit, LED ₁ ,
LED ₂ , ... are light emitting diodes, MPU is a microprocessor, and PS is a power supply switching circuit.

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 light emitting diodes connected with opposite polarities. a plurality of display elements connected between the selection signal line and the selection signal line; and a switching circuit that supplies voltage to all selection signal lines of only one of the selection signal line in the vertical direction and the selection signal line in the horizontal direction. A bidirectional matrix display comprising: a first control circuit that selectively grounds the vertical selection signal line; and a second control circuit that selectively grounds the horizontal selection signal line. Device.