JPH085516Y2 - Display circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention comprises a plurality of switches and a plurality of display elements connected to the switches, and when one of the switches is turned on, the corresponding display element lights up. Display circuit.

[Conventional technology]

As an application example of the display circuit including the switch and the display element described above, for example, there is a liquid surface position detection device shown in FIG. In the figure, a plurality of reed switches S are provided in the cylindrical body 1.
_{1 to} S ₃ are loaded and fixed in the liquid A. The liquid A has a ring-shaped magnet Mg embedded in a ring-shaped float 2, and the cylindrical body 1 is attached to the float 2
Install inside the. The terminals of the reed switches S _{1 to} S ₃ are connected to the display circuit unit 3, and the display circuit unit 3 is provided with LEDs D _{1 to} D ₄ for indicating the external liquid surface position in a straight line. ing.

In the above configuration, when the liquid surface position is displaced, the float 2 moves up and down and the magnet Mg also moves up and down accordingly.
Therefore, the position of this magnet Mg is reed switch S ₁ ~
When the switch is located on substantially the same plane as the corresponding switch of S ₃ , the switch is turned on. On the other hand, the display circuit section 3 monitors the on / off state of each of the reed switches S _{1 to} S ₃ , and when the reed switch is turned on, the corresponding LE
One of DD _{1 to} D ₄ lights up and the liquid level position is displayed.

The ON period characteristics with respect to the liquid surface position of the reed switches S _{1 to} S ₃ are the nth switch and the next (n + 1) th switch (n = 1 to 3) as shown in periods T ₁ and T ₂ in FIG. ) And ON period are set so as to partially overlap. This is because if the overlapping periods T ₁ and T ₂ are not provided, there may be a period in which all the switches S _{1 to} S ₃ are turned off depending on the liquid surface position, and all the LEDs D _{1 to} D ₄ may be turned off. Yes, and an overlapping period is provided to prevent this. However, each switch S ₁
The LED D ₁ to D ₄ corresponding to to S ₃ are merely when configured when turning on the switch that LED is lit, resulting in inconvenience that two LED lights simultaneously in the overlap period.

Therefore, in the display circuit section 3, when _one of the switches S _{1 to} S ₃ is turned on, the corresponding LED D _{1 to} D ₄ is turned on, and in the overlap period, an on state in which the lower liquid level position is sensed is sensed. The LED corresponding to the switch on is turned on, and the LED corresponding to the switch in the ON state that senses the higher one is turned off, regardless of the liquid level position, there is always one L
The ED is controlled so that it lights up. That is, the display circuit unit 3
It is controlled to provide a priority to the lighting of the LED D ₁ to D ₄ with respect to the on state of the switches S ₁ to S _3.

The display circuit section 3 is conventionally constructed as shown in FIG. In the figure, the LE at the other end that lights up at the lowest position
A power source V _B , a current limiting resistor R ₁₁ and a switch S ₁ are connected in series to DD ₁ . Also, the one end of the one that lights up at the highest position
LEDD ₄ has a power source V _B and a current limiting resistor R ₁₄ connected to its anode side, and an inverter 4 ₃ and an AND circuit 5 ₃ on its cathode side.
Is connected. Each switch S ₁ ~ is input to the AND circuit 5 _3.
S ₃ is connected. An LED that lights up in the middle position
The anode side of D ₂ and D ₃ has the same structure as D ₁ and D ₄ , and the cathode side is connected in series with inverters 4 ₁ and 4 ₂ and AND circuits 5 ₁ and 5 ₂ . Input of the AND circuit 5 ₁ is connected a switch S ₂ through the switches S ₁ and the inverter 4 _4, switch S ₂ via the switch S ₂ and the inverter 4 ₅ is connected to the input of the AND circuit 5 _2.

In the above configuration, when only the switch S ₁ is turned on, the LED D ₁ lights up and the other switches S ₂ and S ₃
Is off, the outputs of the inverters 4 ₄ and 4 ₅ are at "L" level. Therefore, the output of each AND circuit 5 _{1 to} 5 ₃ is “L”.
Level, and the output of inverter ₄₁ to ₃ is the LED D ₂ to D ₄ for the "H" level to turn off. Similarly, when only the switches S ₂ and S ₃ are turned on, only the output of the corresponding inverter 4 ₄ or 4 ₅ becomes “H” level.
The outputs of the AND circuits 5 ₁ and 5 ₂ become the “H” level. Therefore,
Only the inverter 4 ₁ or 4 ₂ connected to it has its output at the “L” level and lights the LED D ₂ or D ₃ . Further all the switches S ₁ to S ₃ is turned off, only the output of the AND circuit ₃ becomes "H" level, the LED D ₄ is turned inverter 4 ₃ becomes "L" level.

On the other hand, during a period in which the switches S ₁ and S ₂ are both turned on (period T _{1 in} FIG. 6), the LED D ₁ is turned on, but the two inputs of the AND circuit 5 ₁ are at “H” and “L” levels, respectively, and the output thereof. Is "L"
Since it becomes the level, the output of the inverter 4 ₁ becomes the “H” level and the LED D ₂ is turned off. Further, during the period in which the switches S ₂ and S ₃ are both turned on (period T _{2 in} FIG. 6), the two inputs of the AND circuit 5 ₁ are both at the “H” level and the LED D ₂ lights up, but A
2 input of the ND circuit 5 ₂ becomes "H" and "L" level, L
EDD ₃ goes off.

From the above operation, during the period in which both the switches S _n and S _{n + 1} are turned on, only the LEDD _n is turned on, and other LEDD _{n + 1} is included.
LED goes out. Therefore, there is always one L depending on the liquid level change.
Only the ED lights up and the liquid level position is displayed.

[Problems to be solved by the device]

In the above-described conventional configuration, many logic circuits such as an AND circuit and an inverter are required, and since the logic circuit is composed of many transistor elements and the like, the circuit configuration is complicated and the cost is high.

Therefore, it is an object of the present invention to provide a display circuit with a simple structure and cost reduction.

[Means for solving the problem]

In order to solve the above problems, a display circuit according to the present invention comprises a plurality of linearly arranged display elements and the display arranged at one end where one end is grounded and the other end is connected to a power source. A plurality of display elements other than the display element, which are connected in series between the display element and the ground, are sequentially turned on according to a predetermined amount of information, and have two periods corresponding to adjacent display elements that are simultaneously turned on. Switch,
A plurality of driving transistors respectively connected between the power source in series with the remaining display elements other than the display element arranged at the other end, and a control terminal of each of the plurality of driving transistors and ground. A control terminal is connected to one end of the display element on the other end side adjacent to the display element connected in series with the driving transistor and connected in series with the display element on the other end side adjacent to the display element. A control transistor that is turned off when the connected switch is turned on or when the drive transistor connected in series with the display element on the other end side adjacent to the switch is turned off, and turns off the drive transistor. It is characterized by that.

[Operation] In the above configuration, when all the switches are off, the display elements connected in series with the switches are turned off, but the control terminals are connected to one end of these display elements. Since the driving transistor is turned on, the driving transistor whose control transistor is connected to the control terminal is turned on. Therefore, only the display element at one end where the switches are not connected in series is turned on.

When a switch connected in series with the display element at the other end is turned on, a current flows to the ground through the power supply, the display element and the switch, and the switch connected in series with the switch that is turned on is turned on, and the switch is connected in series with this switch. The control transistor connected to the control terminal is turned off at one end of the connected display element, and when the control transistor is turned off, the drive transistor connected to the control terminal is turned off. .
When the driving transistor is turned off, the display element at one end, as well as the display element connected in series with the switch that is not turned on, excluding the display element at the other end, is turned off.

Furthermore, when only one arbitrary switch other than the switch connected in series with the display element at the other end is turned on, the control terminal is connected to one end of the display element connected in series with this switch by turning on this switch. The control transistor connected to is turned off. When this control transistor is turned off, all the drive transistors on one end side connected to the control terminal are turned off. Therefore, let alone the display element connected in series with the switch that is not turned on. , The display element at one end, to which the switch is not connected in series, remains off.

When two switches connected in series with two adjacent display elements are turned on at the same time,
Since the control transistor whose control terminal is connected to one end of the display element connected in series with these switches is turned off, the display on the one end side where these control transistors are connected to the control terminal The driving transistor connected in series with the element is also turned off. The display element on the one end side adjacent to the drive transistor, which is turned off in series, cannot be turned on even when the switch is turned on, but the display element on the other end side adjacent to the display element cannot be turned on. Since the driving transistor connected in series with this is in the ON state, it is turned on.

As described above, by using only the driving transistor and the control transistor, even if the two switches corresponding to the adjacent display elements have a period in which they are simultaneously turned on, the two adjacent display elements are simultaneously turned on. Is eliminated, and only one display element on the other end side is turned on.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as those in FIG. 4 are designated by the same reference numerals. The LED D ₁ at the other end, which indicates the lowest position, has a switch S ₁ , a resistor R ₁₁ , and a power supply V _B connected in series, as in FIG. Further, between the anodes of the other LEDs D _{2 to} D ₄ and the power source V _B , the emitters of the PNP type driving transistors Q _{11 to} Q ₁₃ are connected.
The collector paths are connected in series, and the bases of NPN type control transistors Q _{21 to} Q ₂₃ are connected to the anodes of D _{1 to} D ₃ except LEDs D ₄ which indicate the highest position via resistors R _{41 to} R ₄₃ . Connected. Each drive transistor Q _{11 to} Q ₁₃
Resistors R _{21 to} R ₂₃ are connected between the emitter and base of
And its base is connected to the collector of the control transistor Q ₂₁ to Q ₂₃ through a resistor R ₃₁ to R _33. Resistors R _{51 to} R are provided between the emitters and bases of the transistors Q _{21 to} Q ₂₃ , respectively.
₅₃ are connected, the emitter thereof is grounded similarly to the other end of the switch S ₁ to S _3. The cathode of LED D ₄ at one end is similarly grounded.

In such a configuration, when the switch S ₁ to S ₃ is turned on, the corresponding control transistor Q ₂₁ to Q ₂₃ is turned off from on, if the transistor Q ₂₁ to Q ₂₃ is turned off, the driving transistor Q ₁₁ ~ Since the base power supply does not flow to Q _13, it is off, and if it is on, the base current flows, so it is in the on state.

When only the switch S ₁ is turned on, the current of the power source V _B flows to the LED D ₁ and lights up. When only the switch S ₂ is turned on, the control transistor Q ₂₁ is turned on, so the driving transistor Q ₁₁ is turned on and the power source V _B → Q ₁₁ → LEDD ₂ → switch S ₂
An electric current flows through the path of, and D ₂ lights up. Similarly, when only the switch S ₃ is turned on, only the LED D ₃ is turned on. If all the switches are turned off, the control transistor Q ₂₃ is turned on, so that the driving transistor Q ₁₃ is turned on and the LED D ₄ is turned on. To do.

On the other hand, if both switches S ₁ and S ₂ are turned on, LE
DD ₁ lights up as above, but control transistor Q
_Since the switch ₂₁ is off because the switch S ₁ is on, the driving transistor Q ₁₁ is off and the LED D ₂ is off. When both the switches S ₂ and S ₃ are turned on, the control transistor Q ₂₁ is turned on, the drive transistor Q ₁₁ is turned on, and the control transistor Q ₂₂ is turned off. Transistor Q ₁₂ turns off. Therefore, only LEDD ₂ is turned on and LEDD ₃ is turned off. That is, when both the switches S _n and S _{n + 1} are turned on, the drive transistor Q _1n is turned on and Q _{1 (n + 1)} is turned off, so that only the LED D _n is turned on.

FIG. 2 shows another embodiment of the present invention, and in FIG.
The LED D ₁ to D ₄ and the direction of power in the reverse, the driver transistor Q ₁₁ to Q ₁₃ and an NPN type, the control transistor Q ₂₁ to Q
₂₃ is a PNP type, and its operation is the same as in FIG.

The Figure 3 shows another embodiment of the present invention, which uses the incandescent lamp L ₁ ~L ₄ as a display device, based of the control transistor Q ₂₁ to Q ₂₃ are each lamp L ₁ ~L ₃ Connected between the switch and switches S _{1 to} S ₃ , and current limiting resistors R _{11 to} R 3.
₁₄ is omitted. Even in the configuration shown in FIG.
The operation is the same as in FIG.

〔effect〕

As described above, according to the present invention, even if two switches corresponding to adjacent display elements among a plurality of display elements arranged in a straight line are turned on at the same time, the two switches are turned on. The display element priority function with respect to the overlapping ON period is realized only by using the driving and control transistors without using a logic circuit, and it is possible to prevent two adjacent display elements from lighting at the same time. Since only the display element will be turned on,
The circuit can be simplified and the cost can be reduced.

[Brief description of drawings]

1 to 3 are circuit diagrams showing an embodiment according to the present invention, FIG. 4 is a circuit diagram showing a conventional display circuit, and FIG. 5 is a liquid surface position to which the present invention and the conventional display circuit are applied. FIG. 6 is a diagram showing a display device, and FIG. 6 is a diagram showing switch characteristics with respect to the liquid surface position in FIG. _{S 1, S 2, S 3} ...... _{switches, D 1, D 2, D} 3 ...... LED, L 1, L 2, L 3
…… Lamp, Q ₁₁ , Q ₁₂ , Q ₁₃ …… Driving transistor, Q
₂₁ , Q ₂₂ , Q ₂₃ ...... Control transistor, R ₁₁ ,, R ₁₂ ,, R ₁₃ ......
Current limiting resistor.

Claims (1)

[Scope of utility model registration request] 1. A plurality of display elements arranged linearly, and grounding in series with the remaining display elements except the display element arranged at one end, one end of which is grounded and the other end of which is connected to a power source. A plurality of switches, each of which is connected in series between the two, sequentially turned on according to a predetermined amount of information, and having a period in which two corresponding display elements are simultaneously turned on, and the display arranged at the other end. A plurality of driving transistors connected to a power source in series with the remaining display elements except the elements, and connected between each control terminal of each of the plurality of driving transistors and ground; The control terminal is connected to one end of the display element on the other end side adjacent to the display element connected in series with the use transistor, and the switch connected in series with the display element on the other end side adjacent to the display element. Display transistor on the other side of the other adjacent end of the drive transistor is turned off when the drive transistor is turned off, the control transistor for turning off the drive transistor. circuit.