JPS5923744A - Drive control circuit in display device for motor vehicle - Google Patents

Abstract

PURPOSE:To obtain a control circuit which may be commonly used for both fluorescent display and liquid crystal display, by providing the control circuit with such a function that a clock signal having a suitable period and a control signal for expressing a period to be displayed are issued. CONSTITUTION:Connection is made such as shown by the solid line in the case of using a bluorescent display device 3a but is made such as shown by the chain line (a) in the case of using a liquid crystal display device 3b. In either one of cases, the same signal is issued from a control circuit 1 as a control signal Pc, but a signal converting circuit issues an output signal pd from an output terminal Tout when both terminals T1, T2 are at low level, but issues an output signal Pd' when the terminal T2 is at high level. Since an opposite phase signal with respect to a clock signal phic appears at the terminal T1, an alternate voltage Va is applied to the liquid display device 3b if the electrode of the liquid crystal device is connected between the terminals T1, Tout so that the liquid crystal is energized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive control circuit for an automobile display device.

In recent years, there has been a trend toward digitalization of automobile instruments, and digital display devices using fluorescent coatings are already available for speedometers, tachometers, dial meters, etc. .

However, in a display device using a fluorescent display tube, the power supply voltage (12
A high voltage such as 40-60V is required, which is much higher than V).

Therefore, a booster circuit is required to generate such a high voltage, which has the disadvantage that the driving circuit of the device becomes complicated and large, and power consumption also increases.

Therefore, digital display devices using liquid crystals instead of fluorescent display tubes have also been proposed. The liquid crystal display device is
Is the power consumption of the 11J pressurized machine a complicated pattern? It has the advantage of being easy to display. However, although there is still no liquid crystal that exhibits sufficient characteristics in relation to the environmental conditions of automobiles and temperature, it is rapidly being improved and is being used in some automobiles.

Moreover, in a liquid crystal display device, the method of driving the liquid crystal is different from that in a fluorescent display tube, and the driving method is designed to be controlled at a constant pressure. On the other hand, the above-mentioned costumes using fluorescent display tubes are driven by DC voltage. Therefore,
If the +1 value of the display device is different, the configuration of the driving circuit and the circular blood pressure must be changed.

Therefore, in the past, separate drive circuits had to be prepared for each display device, resulting in high costs. Also, b
Drive circuit so that it can also be used for misaligned display devices? To make it more general-purpose, it is necessary to integrate both drive circuits as previously proposed, but simply integrating both drive circuits would require a separate control circuit. Chimp size increases dramatically. Moreover, if each drive circuit of each display device is made into an integrated circuit, there is no versatility, and there is a problem that there are few merits to make it into an integrated circuit.
Ivy.

Therefore, the present invention can be used for both a display device driven by a direct M6 pressure and a display device driven by a current voltage.
The overall purpose of the present invention is to provide a complete drive control circuit for an automatic display device that is simple and suitable for engineering.

To this end, the present invention simply requires a control circuit that outputs a clock signal with an appropriate cycle and a control signal that indicates the entire period to be displayed, and an external control terminal that is fixed at an appropriate level. By providing a signal conversion circuit that outputs a desired drive signal sound according to the display device based on the above clock signal and control signal, a common control circuit can be used for display devices of any drive method. It has all the features that you can do or be able to do.

This invention will be fully explained below based on the drawings.

FIG. 1 shows an embodiment of a drive control circuit according to the present invention, where 2 is a control circuit, 21-1 is a signal conversion circuit, and 3 is a display device.

The signal conversion circuit 2 is operated by the clock signal φ0 and the control signal PQ supplied from the control circuit 1, and outputs the drive signal Pd? to the display device 3. Output. Also,
The signal conversion circuit 2 has an output terminal and a control terminal Tl for changing the state of the circuit by changing the external connection depending on the costume wt3 connected to this output terminal.
+T11 is provided.

First, let's assume that the control terminals 'r, ,'rz are respectively connected to ground, and that the control terminals 'r' and 'rz are fixed at a low level.

In this case, one input terminal of the exclusive OR circuit G1 is always kept at a low level, so that it operates as an OR gate. Therefore, exclusive CAR circuit G.

The control signal Po supplied to the other input terminal of the gate GI becomes the output signal of the gate GI.

On the other hand, when the control terminal Tz is fixed at a low level, one input terminal of the AND circuit Gi is always kept in a no-repel state by the inverter 4ci valve, and the AND circuit G2
The gate is left open.

Since one input terminal of the blue, AN, and D circuit G3 is brought to a low level by the inverter 4dK, the gate of the AND circuit 03 is kept closed.

As a result, the output of exclusive OR circuit GL is inverted via inverter 4b'fr, and output to AIJD circuit GL.

It passes through only the open gate G2 of G3.

Then, by the low level output of the AND circuit G3,
Since one input terminal of the NOR circuit G4 is set to a low level, the NOR circuit G4 operates as an inverter, and outputs the output signal H of the AND circuit G2 after completely inverting it. This signal is further inverted by an inverter 4θ and outputted from an output terminal to the display device 3.

Therefore, in this case, the output signal Pd of the signal conversion circuit 2 is
The control signal P is shown in FIG. 2 (CD). This results in a signal with the opposite phase. The control signal PC is the control circuit 1
Accordingly, the signal corresponding to the corresponding segment of the display device 1τ3 is outputted as a signal for the lighting period kid. As a result, if the output signal P a k of the signal conversion circuit 2 is applied to a display device driven by DC voltage, such as a fluorescent display tube, through a dry valve such as an inverter, a control signal P is obtained. (corresponding segment)
k can be turned on.

Next, level gold 1. of the control terminal T. +! d
Consider a state in which the control terminal Tzki is connected to the source voltage and fixed at a high level.

In this case, one input terminal of the exclusive OR circuit GI is connected to the inverter 4a (5 bits and the clock 'ff4 signal φ
. The inverted signal φ. will be supplied.

Therefore, the control signal P supplied to the other input terminal of the exclusive OR circuit G. When is low level, OR
It is operated as a gate, and the output a of the inverter 4a is
. passes through that 11/7-g+'tr. Therefore, the control signal P. When is changed to a high level,
Exclusive OR circuit G is operated as an inverter. 7, so that the same signal as the clock signal φ is output from the circuit G, which is delayed by half a cycle from the output φC of the inverter 4a. become.

On the other hand, when control '4a T2 is fixed at a high level, the gate of AND circuit G2 is closed, and the gate of AND circuit 03 is opened. Therefore, the output of the AND circuit G2 is fixed at a low level, and based on this, the NOR circuit G4 is operated as an inverter. As a result, the output (clock φ) of the exclusive OR circuit G1 is obtained.

(in phase) is inverted twice by the NOR circuit G4 and inverter 4θ, and is in phase with the original signal, that is, the clock signal P. A signal Pd' having the same phase as 11. is output from the output terminal. It turns out to be true.

Therefore, in this case, the liquid crystal water discharging device is all connected between the control terminal T1 and the output terminal, and the output signal φ of the inverter 4a is sent to the common electrode through the control terminals T and tk. If the output signal Pa' is supplied to the segment electrodes alternately, the voltage between the electrodes of the liquid crystal will be as shown in Fig. 3 (
f'), the control signal P. The current voltage is applied only during the period when tL is at a high level. By working on this, the seventh liquid crystal segment is the control signal P. is kept in the display state only during the period Jυ] when is at a high level. When the control PC No. 18 is at low level, the common electrode and segment electrode of the liquid crystal are connected to each other.
The J phase signal will be supplied! Then, the liquid crystal segment is put into a non-display state.

Note that the above clock signal φ. is generated by frequency-dividing the clock signal from the t oscillation circuit provided in the control circuit 1.

FIG. 3 shows a good state in which a display device 3a made of a fluorescent display tube or a liquid crystal display device 3b is connected to the drive control circuit.

The number of signal conversion circuits 2i't corresponds to the number of segments forming the display pattern. When using the display device 3a consisting of a fluorescent display tube, each output terminal T of the signal conversion circuit 2.2, .
A driver circuit 5 consisting of an inverter is connected to each OutVcX, and the driver circuit 5 generates a fluorescent display g3.
Let each segment of a be lit.

In this case, the driver circuit 5 is supplied with the battery voltage (12V) -i40 to 60V'E from the booster circuit 6, and is supplied with a phosphorescent voltage of 40 to 60V'E.
It is driven by high voltage such as V.

Further, the control terminals T1 and T: are connected to ground, respectively. Good, control terminals 'ri and T! is each signal conversion circuit 2.2,...
... [arranged so that it can be shared by the river? fMI-r.

The ERI circuit is connected to tl.

Next, when driving the liquid crystal display device 3b using the drive control circuit sound, connect the circuit shown by the chain line A in FIG. 19. Output terminal Tout of each signal conversion circuit 2
K is connected to the segment electrode of the liquid crystal display device 3b, and the control terminal T is connected to a common electrode. Also,
Control terminal T! , connect all power supply voltages and fix them at high level.

A control signal P is output from the control circuit 1 even when any of the display devices 3a and 3b is connected. teeth,
If the display data is the same, the same signal may be used, and the control circuit 1 deduces the display data based on the input signals from each raccoon sensor such as the vehicle speed sensor 7a and the rotation speed detector 7b.
A control signal P is sent to the signal conversion circuit 2 which determines the segment to be displayed and corresponds to the segment to be displayed. Output.

Even if the signal conversion circuit 2 receives the same control No. 4m Pc signal, the level of the control terminals TI+T1 (
The output changes depending on the connection status). In other words, terminals TI, T
2 are both low level, the output terminal Tout to the second
An output signal Pd as shown in Figure (D) is output. Further, when the terminal T2 is at a high level, an output signal p aL as shown in FIG. 2(L) is output from the output terminal Tout. l
In addition, a clock signal φ is connected to the terminal T. Since a negative phase signal is received, if the electrodes of the liquid crystal display device are connected between the terminals TI and Tout, a transformer voltage as shown in Fig. 3(F) is applied, and the liquid crystal is driven. There is nothing special about it.

In addition, a warning light 8' using a light emitting diode tube is installed on the instrument panel to indicate whether the vehicle speed is at a certain set speed (for example, 1
100 k/hour), control signal P is sent from control circuit 1. 'The sound output type may be configured to turn on the switch element SW using a transistor so as to dazzle the 82 warning lights.

Equably, the drive control circuit can drive a display device M':'c that simultaneously displays a speedometer, odometer, tachometer, fuel meter, timer, etc. Furthermore, it is of course possible to drive not only the fluorescent display tube and liquid crystal display device used in the above embodiments, but also other display devices such as those using light emitting diodes.

As explained above, the present invention is capable of fixing an externally provided control terminal to an appropriate level in both circuits. By just doing this, a signal conversion circuit is connected that outputs the desired drive signal according to the display device based on the above clock signal and control signal, so the display is driven by direct current 1. Device manufacturer η [A common circuit can be used for any display device driven by voltage, and the same control signal can be used for either drive method? Since it can be used, fl+! I control circuit? Can be shared. Therefore, the circuit construction is extremely simple, and θ can be set easily. ! −
Because of this, it becomes easier to convert the process into C, reducing costs. You can see the effect of being able to achieve this goal.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of a drive control circuit for a display device for an automobile according to the present invention, Fig. 2 is a timing chart of 7, and Fig. 3 is a method of connecting a display device to this drive control circuit. FIG. 1... Control unit (control circuit), 2... Signal conversion circuit,
φ. ...Kron Kui'E, PC...control signal, TI, T2...control terminal.

Claims (1)

[Claims] (1) Calculate the Horitsu data based on various input data,
A control unit that uses control signals and clock signals, and a control terminal that can set the level from the outside according to the display device connected to the control signal and clock signal input signals, and the control fA terminal. A drive control circuit for a display device for an automobile, characterized in that, depending on an applied potential, a signal conversion circuit outputs a drive signal sound consisting of a DC voltage "f" or an AC voltage.