JPS61248091A - Variable color display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a display device, and more particularly to a variable color display device that displays various information in variable colors.

[Prior art]

Conventionally, in this type of variable color display device, for example, as disclosed in Japanese Patent Application Laid-Open No. 17432/1980,
There is one in which filter polarizing plates of different colors are superposed on both the front and rear surfaces of a liquid crystal cell, so that a plurality of pieces of information can be selectively displayed in different colors.

[Problem that the invention seeks to solve]

However, in such a configuration, the display colors are inevitably limited to two types by each of the polarizing plate filters, so it is possible to selectively change colors of three or more pieces of information using three or more display colors. There is a problem in that it is not possible to respond to requests for displaying images in the same manner.

In order to cope with this problem, the present invention provides a variable color display device in which a light projecting means for emitting three colored lights is arranged behind a transmissive liquid crystal display means.

[Means for solving problems]

In order to solve this problem, the present invention has a configuration that includes a transmission type liquid crystal display means for displaying three types of information, and a transmission type liquid crystal display means disposed behind the liquid crystal display means to selectively transmit three different colored lights to the same liquid crystal display means. and a light projecting means for projecting light, and the liquid crystal display means displays any of the information in the color of the three colored lights according to one of the three colored lights from the light projecting means. It is in.

[Function and effect]

Therefore, by configuring the present invention in this way, three pieces of information can be selectively displayed in different colors with a simple configuration in which the light projecting means is disposed behind the liquid crystal display means. As a result, what is the problem with multi-color selection display of this kind of variable color display device? M recognition improves.

〔Example〕

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example in which the present invention is applied to a variable color speed display device for a vehicle. Main body 10 and speed sensor.

20, an oscillation circuit 30, a display control circuit 40 connected to the speed sensor 20, and a modulation circuit 50 connected to the speed sensor 20 and the oscillation circuit 30. The display device main body 10 is constructed by superposing a thin film electroluminescent element 10b on the back side of a transmissive liquid crystal cell 10a, and the liquid crystal cell 10a is a black guest-host type negative liquid crystal cell. The traveling speed of the vehicle is digitally displayed on the display screen using two-finger numbers in accordance with the value of the display control signal generated as follows. In such a case, the digital display portion of the display surface of the liquid crystal cell 10a becomes transparent and the remaining portion becomes black.

The thin film electroluminescent element 10b is formed by superposing the liquid crystal cell 10a as a variable color illumination source, and as shown in FIG. A transparent electrode 11, a charge injection layer 12, a fluorescent substance layer 13, a charge injection layer 14, and a back electrode 15 are sequentially polymerized to form the electrode. The transparent electrode 11 is formed by vacuum evaporating ITD with a thickness of 0.1 to 0.2 μm on the back surface of the liquid crystal cell 10a, and the charge injection layer 12 is made of yttrium oxide (Y2O2).
) with a thickness of 0.2 to 0.5 μm on the back surface of the transparent electrode 11, and the fluorescent material layer 13 is made of zinc sulfide (Zn
The charge injection layer 14 is formed on the back surface of the transparent electrode 11 with a thickness of 0.5 to 1 μm using yttrium oxide (S).
Y2O2) is formed on the back surface of the fluorescent material layer 13 to a thickness of 0.2 to 0.5 μm, and the back electrode 15 is formed by vacuum-depositing aluminum to a thickness of 1 μm on the back surface of the charge injection layer 14. It is formed.

The fluorescent material layer 13 contains samarium fluoride (SmF3) 13b and terbium fluoride (SmF3), which function as luminescent centers.
TbF3)13C is 1 to 3 wt% relative to the zinc sulfide
In addition, at the center of the fluorescent material layer 13 in the thickness direction, a plurality of aluminum layers 13a to 13a are arranged at intervals of 50 to 2, perpendicular to the same thickness direction.
It is formed to a thickness of 0.00 angstroms and functions as an emission layer and/or scattering layer for excitation electrons. However, 7.
Samarium fluoride 13b is applied to each aluminum layer 13a~
The terbium fluoride 13c is distributed and mixed into the zinc sulfide on one side of the aluminum layer 13a, while the terbium fluoride 13c is mixed into each aluminum layer 138.
~13a is distributed and mixed into the zinc sulfide on the other side.

In the thin film electroluminescent element 10b configured in this way, when a constant AC driving voltage is applied between the transparent electrode 11 and the back electrode 15 and the frequency f of this AC driving voltage is changed, the thin film electroluminescent element 10b The spectrum of the emission intensity is shown in FIG. According to this, when r=o and 8KHz, the wavelength λ
The red emission of samarium fluoride 13b near -550nm is dominant, and when f=3.2KHz, λ=640n
Green light emission near m is dominant, and f = 1.6KH
When z, intermediate light emission between red light emission and green light emission (yellow light emission)
is understood to be dominant. Further, when f is kept constant and the AC driving voltage is increased, the light emission sequentially changes to green light, yellow light, and red light accordingly.

A speed sensor 20 detects the speed at which the vehicle is traveling and generates a series of speed pulses at a frequency proportional to this. Oscillation circuit 30 generates a series of oscillation pulses at a predetermined frequency.

The display control circuit 40 calculates the traveling speed in response to each speed pulse from the speed sensor 20, and applies it to the liquid crystal cell 10a as a display output signal. The modulation circuit 50 is the oscillation circuit 3
0 and each speed pulse from the speed sensor 20, modulates the frequency of each oscillation pulse according to the frequency of each speed pulse and generates a modulated signal (
applied to the thin film electroluminescent device 10b). In such a case, the frequency of the modulation signal from the modulation circuit 50 is such that the frequency of each speed pulse is equal to the traveling speed 60 of the vehicle.
When it is below the value corresponding to Km/h, it becomes 3.2KHz,
The frequency of each speed pulse is the traveling speed of 1100K/
When it is equal to or greater than the value corresponding to h, it becomes 0.8 KHz. Also,
The frequency of the modulation signal is set at the traveling speed of 60 Km/h to
During the 1100K/h period, they ran the same way.

3.2KHz to 0 as line speed increases (or decreases)
．． The frequency changes continuously from 0.8 KHz to 3.2 KHz.

In this embodiment configured in this manner, when the vehicle is in a running state, the speed sensor 20 sequentially generates speed pulses, and the display control circuit 40 responds to each speed pulse from the speed sensor 20 to display the running speed. is calculated and generated as a display output signal, and the modulation circuit 50 generates a modulation signal according to the frequency of each oscillation pulse from the oscillation circuit 30 in accordance with the frequency of each speed pulse from the speed sensor 20.

As described above, when a display output signal is generated from the display control circuit 40, the liquid crystal cell 10a digitally displays the traveling speed of the vehicle based on the value of the display output signal. In such case,
If the traveling speed of the vehicle is 60 km/h or less, the thin film electroluminescent element 10b receives the modulation signal from the modulation circuit 50 between the transparent electrode 11 and the back electrode 15 and emits green light. Therefore, the green light from this thin film electroluminescent element 10b is transmitted to the liquid crystal cell 10.
The light passes through the digital display section a and is emitted to the front of the liquid crystal cell 10a. This means that the liquid crystal cell 10a digitally displays the traveling speed of the vehicle (60 km/h or less) in green in cooperation with the thin film electroluminescent element 10b. Well, if the running speed of the vehicle increases sequentially from 60 Km/h and changes to 1100 K/h or more, the color of light emitted from the thin film electroluminescent element 10b changes sequentially from green to yellow to red, and the digital display on the liquid crystal cell 10a changes. The color changes sequentially from green to yellow to red. In other words, the color of the displayed running speed on the digital display section of the liquid crystal cell 10a changes sequentially from green to yellow to red under the action of the thin film electroluminescence 10b as the running speed of the vehicle increases. The visibility of different color speed displays of the color speed display device is improved. Moreover, since the above-mentioned effects can be achieved simply by superposing the thin film electroluminescent element 10b on the liquid crystal cell 10a from the back side, this type of variable color speed display device can be easily manufactured.

Next, a modification of the first embodiment will be described. In this modification, in place of the oscillation circuit 30 and modulation circuit 50 described in the first embodiment, as shown in FIG.
Speed determination circuit 60, relay drive circuit 70, oscillation circuit 80
The structure is characterized by the adoption of the light emitting drive circuit 90.

The speed determination circuit 60 includes a frequency-voltage converter 61 (hereinafter referred to as
The F-V converter 61 converts the frequency of each speed pulse from the speed sensor 20 into an analog voltage having a proportional level. The speed determination circuit 60 also includes a pair of voltage dividers 62.6.
3 and a pair of comparators 64 and 65, the voltage divider 62 divides the DC voltage +Vcc from the DC power supply by a variable resistor 62a and a resistor 62b connected in series, and divides the DC voltage +Vcc from the common terminal of the variable resistor 62a and resistor 62b. Generated as a reference voltage. In such a case, the reference voltage from the voltage divider 62 corresponds to a predetermined running speed of the vehicle of 60 km/h.

The voltage divider 63 includes a variable resistor 63a and a resistor 63 connected in series.
b divides the DC voltage of 10 Vcc from the DC power source and generates it as a reference voltage from the common terminal of the variable resistor 63a and the resistor 63b. In such a case, the reference voltage from the voltage divider 623 corresponds to another predetermined running speed of the vehicle of 1100 K/h. The comparator 64 generates a high level signal (or a low level signal) when the analog voltage from the F-V converter 61 is higher (or lower) than the reference voltage from the voltage divider 62. Comparator 65 detects that the analog voltage from F-V converter 61 is higher than the reference voltage from voltage divider 63 (
or low) when high level signal (or low level signal)
occurs.

The relay drive circuit 70 includes a pair of transistors 71 and 72.
The transistor 71 has a comparator 64 at its base via a resistor 71a and an inverter 71b.
is connected to the output terminal of

Thus, the transistor 71 becomes conductive (or non-conductive) under the control of the resistor 71a under the inverting action of the inverter 71b in response to the low level signal (or high level signal) from the comparator 64. The base of transistor 72 is connected to the output terminal of comparator 75 via resistor 72a and inverter 72b. Thus, the transistor 72 becomes conductive (or non-conductive) under the control of the resistor 72a under the inverting action of the inverter 72b in response to the low level signal (or high level signal) from the comparator 65.

The oscillation circuit 80 includes inverters 81a connected in series with each other.
, 81b, 81c, 81d, and each resistor 82a, 82b,
82c, 82d, capacitor 83, and each relay 84.
85, and a series circuit consisting of a resistor 82a, a normally open switch 84b of the relay 84, and a resistor 82b is connected between the input terminals of the inverter 81a. Also,
In the series circuit consisting of the resistor 2b and the switch 84b,
A series circuit consisting of a resistor 82c and a normally open switch 85b of a relay 85 and a resistor 82d are connected in parallel. The capacitor 83 is connected to the inverter 81 at one end.
The other end of this capacitor 83 is connected to the input terminal of an inverter 81b via a resistor 82d.

The relay 84 has an electromagnetic coil 84a, and one end of the electromagnetic coil 84a is connected to the DC power supply to receive DC voltage +Vcc from the DC power supply, and the other end is connected to the collector of the transistor 71. ing.

Thus, the electromagnetic coil 84a of the relay 84 is energized (or demagnetized) in response to the conduction (or non-conduction) of the transistor 71, thereby closing (or opening) the switch 84b. Also,
The relay 85 has an electronic coil 85a, and the electromagnetic coil 85a is connected at one end to the DC power supply to receive DC voltage +Vcc from the DC power supply, and connected to the collector of the transistor 72 at the other end. has been done. Thus, the electromagnetic coil 85a of the relay 85 is energized (or demagnetized) in response to the conduction (or non-conduction) of the transistor 72, thereby closing (or opening) the switch 85b.

In the oscillation circuit 80 configured in this way, each inverter 81a to 81d is connected to a capacitor 83 and resistors 82b, 8
2C and/or 82d to generate a series of oscillating pulses. In such a case, when a parallel circuit of each resistor 82b, 82c, and 82d is established, the frequency of each oscillation pulse from the oscillation circuit 80 becomes 3.2 KHz, and both resistors 82
When the parallel circuit of 2c and 82d is established, the frequency of each oscillation pulse from the oscillation circuit 80 is 1.6KHz, and when the resistor 82d does not form a parallel circuit with both resistors 82b and 82c, the frequency of each oscillation pulse from the oscillation circuit 80 is 1.6KHz. frequency is 0
．． 8KHz, each resistor 82b, 82c, 82
The resistance value of d and the capacitance of the capacitor 83 are determined.

The light emitting drive circuit 90 has a pair of transistors 91 and 92, and the transistor 91 has a resistor 93 at its base.
It is connected to the output terminal of the inverter 81d through a resistor 94 at its collector, and receives DC voltage +vh from the DC power supply through a resistor 94.
It is connected to the same DC power supply to receive the power. On the other hand, the transistor 92 has its base connected to the output terminal of the inverter 81C via a resistor 95, and its collector connected to the DC power supply through a resistor 96 to receive DC voltage +vh from the DC power supply. This means that both transistors 91 and 92 are alternately and intermittently rendered conductive under the opposing inversion effects of both inverters 81C and 81d based on the frequency of each oscillation pulse from oscillation circuit 80. However, each collector of both transistors 91 and 92 is connected to the transparent electrode 11 of the thin film electroluminescent element 10b.
and the back electrode 15, respectively.

In this modified example configured in this way, when the vehicle is in a running state, the speed sensor 20 sequentially generates speed pulses, the display control circuit 40 generates a display output signal in the same manner as described above, and performs F-V conversion. A device 61 generates an analog voltage in response to each speed pulse from the speed sensor 20 and outputs an analog voltage to the liquid crystal cell 10.
a digitally displays the traveling speed of the vehicle based on the value of the display output signal from the display control circuit 40. In such case,
If the traveling speed of the vehicle is 60km/h or less, F-
The analog voltage from the V converter 61 is applied to both voltage dividers 62 and 63.
Both comparators 64.
65 both generate a low level signal, and transistors 7.
1 becomes conductive in response to the inverting action of inverter 71b responsive to the low level signal from comparator 64, and transistor 72 becomes conductive in response to the inverting action of inverter 72b responsive to the low level signal from comparator 65.

Then, the relay 84 closes the switch 84b by energizing the electromagnetic coil 84a in response to the conduction of the transistor 71, and the relay 85 closes the switch 85 by energizing the electromagnetic coil 85a in response to the conduction of the transistor 72. This means that a parallel circuit of the resistors 82b, 82C, and 82d is established.

When the parallel circuit of the resistors 82b, 82c and 82d is established in this way, the oscillation circuit 80 generates a series of oscillation pulses at a frequency of 3.2 KHz from each inverter 81c and 81d in opposite phases, and both transistors 91. 92
are alternately and intermittently conductive, and in response to these, the thin film electroluminescent element 10b emits green light. Therefore, this thin film electroluminescent element 10b
The green light from the liquid crystal cell 10a passes through the digital display section of the liquid crystal cell 10a and is emitted to the front of the liquid crystal cell 10a.

This means that the liquid crystal cell 10a digitally displays the traveling speed of the vehicle (60 km/h or less) in green, as described above.

In addition, the traveling speed of the vehicle is 60km/h and 1100km/h.
/h, the analog voltage from the F-V converter 61 is between the reference voltage from the voltage divider 62 and the reference voltage from the voltage divider 63, so the comparator 64 outputs a high level signal. On the other hand, the comparator 65 generates a low level signal. Then, transistor 72 becomes conductive under the inverting action of inverter 72b responsive to the low level signal from comparator 65 while transistor 71 is non-conductive, and relay 85 closes switch 85b by energizing electromagnetic coil 85a.

This means that a parallel circuit of both resistors 82C and 82d is established.

When the parallel circuit of both resistors 82C and 82d is established in this way, the oscillation circuit 80 generates a series of oscillation pulses at a frequency of 1.6 KHz, and both transistors 91 and 92 are alternately and intermittently turned on, causing thin film electroluminescence. element ta
b emits yellow light and transmits this yellow light through the digital display section of the liquid crystal cell 10a. This means that the liquid crystal cell 10
a is the traveling speed of the vehicle (60Km/h to 100Km/
h) means to digitally display in yellow.

Furthermore, when the running speed of the vehicle is higher than 1100 K/h, both comparators 64 and 65 are A high level signal is generated, and both relays 8
4. Keep each of the 85 switches 84b and 85b open. Then, both oscillation circuits 80 generate a series of oscillation pulses at a frequency of 0.8 KHz, and both transistors 91°92
are alternately and intermittently conductive, the thin film electroluminescent element 10b emits red light, and this red light is transmitted to the liquid crystal cell 1.
Transmits the digital display section 0a. This means that the liquid crystal cell 10a digitally displays the traveling speed (100 km/h or more) of the vehicle in red. As a result, in this embodiment, the same effects as in the previous embodiment can be achieved.

Next, a second embodiment of the present invention will be explained with reference to the drawings. In this embodiment, in place of the thin film electroluminescent device 10b described in the first embodiment, the thin film electroluminescent device 10b shown in FIGS. As shown in FIG.
The structure is characterized by employing a modulation circuit 110 and a drive circuit 120 instead of the oscillation circuit 30 and modulation circuit 50 described in the embodiment.

The electric field controlled birefringence mode liquid crystal element 100 is a liquid crystal cell 10a.
The white light source 100a is plate-shaped and is arranged in parallel behind the electric field controlled birefringence mode liquid crystal element 100. The white light source 100a projects white light to the electric field controlled birefringence mode liquid crystal element 100. The electric field controlled birefringence mode liquid crystal element '100 includes a polarizing plate 101, a transparent glass substrate 102, a transparent electrode 103,
Alignment film 104, liquid crystal 105, alignment I! J! 106, a transparent electrode 107, a transparent glass substrate 10, and a polarizing plate 109 are sequentially polymerized to have a HAN type electric field controlled birefringence mode.

In this case, the polarization axes of both polarizing plates 101 and 109 are orthogonal to each other. The reorientation films 04 and 106 are both for electric field controlled birefringence mode elements, and the reorientation film 104 is subjected to parallel alignment treatment by rubbing after coating with polyimide, while the reorientation film 111106 is a film of monobasic carboxylic acid chromium complex. Vertical alignment treatment is applied by coating. Orientation 111
The parallel alignment processing direction of 1104 is the orthogonal polarizing plate 101.1.
This direction is at an angle of 45° with the polarization axis of 09. The liquid crystal 105 is for an electric field controlled birefringence mode element and is made of P-type nematic liquid crystal.

The modulation circuit 110 includes the speed determination circuit 60 described in the modification of the first embodiment and a pair of transistors 111, 11.
2, and the transistor 111 has its base connected to the output terminal of the comparator 64 via a resistor 113. Further, the emitter of the transistor 111 is grounded, and the collector of the transistor 111 is connected to the DC power supply through resistors 114 and 115 to receive the DC voltage +Vcc from the DC power supply.

Thus, the transistor 111 becomes non-conductive (or conductive) in response to the low level signal (or high level signal) from the comparator 64.

The transistor 112 has its base connected to the output terminal of the comparator 65 through a resistor 116, its emitter is grounded, and its collector is connected to the common terminal of both resistors 114 and 115 through a resistor 117. It is connected. However, transistor 11
2 becomes conductive (or non-conductive) in response to a high level signal (or low level signal) from the comparator 65. The base of the transistor 118 is grounded via a resistor 119, and a resistor 115 is connected between the base and collector of the transistor 118. Therefore, this transistor 118 receives the DC voltage +
It becomes conductive under the biasing action of resistor 119 via resistor 115 responsive to Vcc.

In the modulation circuit 110 configured in this manner, when both transistors 111 and 112 are non-conducting, both resistors 115 and 119 are connected in series with each other, so that transistor 118 is connected to the DC voltage voltage Vc from the DC power source.
It is generated by setting c as the first variable voltage. Further, when the transistor 111 is conductive and the transistor 112 is non-conductive, the parallel circuit consisting of both resistors 114 and 119 and the resistor 115 are connected in series with each other, so that the transistor 118 generates a second modulated voltage based on the DC voltage +Vcc. do. In addition, when both transistors 111 and 112 are conductive, a parallel circuit consisting of each resistor 114 and 117 and 119 and a resistor 11
5 are in series with each other, the transistor 118
generates a third modulation voltage based on the DC voltage element Vcc. In such a case, the above 1. Each resistor 114 is configured such that the second and third modulating voltages specify green, yellow, and red light, respectively, from the field-controlled birefringence mode liquid crystal device 100.
, 115, 117, and 119 resistance values are determined.

The drive circuit 120 selects white light, green light, yellow light, or red light from the white light source 100a for the electric field controlled birefringence mode liquid crystal element 100 in response to the first, second, or third modulation voltage from the modulation circuit 110. The first thing necessary for control. Electric field controlled birefringence mode liquid crystal element 1 that generates a second or third control voltage
Assigned to 00. The rest of the structure is the same as that of the first embodiment.

In this embodiment configured as described above, when the vehicle is in a running state, the speed sensor 20 sequentially generates speed pulses, the display control circuit 40 generates a display output signal in the same manner as described above, and performs F-V conversion. A device 61 generates an analog voltage in response to each speed pulse from the speed sensor 20 and outputs an analog voltage to the liquid crystal cell 10.
a digitally displays the traveling speed of the vehicle based on the value of the display output signal from the display control circuit 40.

In such a case, if the traveling speed of the vehicle is 60 km/h or less, the analog voltage from the F-V converter 61 is lower than each reference voltage from both voltage dividers 62 and 63 (ffl), so both comparators 64 and 65 both generate low level signals, transistor 111 becomes non-conductive in response to the low level signal from comparator 64, and transistor 112
becomes non-conductive in response to a low level signal from comparator 65. Then, the transistor 118 generates the DC voltage +Vcc from the DC power supply as a first modulated voltage based on the series resistance value of the series resistors 115 and 119, and in response, the drive circuit 120 generates the first control voltage.

Next, the electric field controlled birefringence mode liquid crystal device 100 responds to the first control voltage from the drive circuit 120 to turn on the white light source 100.
The liquid crystal cell 10 is selectively controlled to select green light from the white light emitted from a.
The light is transmitted forward through the digital display section a. This means that the liquid crystal cell 10a digitally displays the traveling speed (60 km/h) of the vehicle in green under the variable color filter effect of the electric field controlled birefringence mode liquid crystal element 100.

In addition, the traveling speed of the vehicle is 60km/h and 1100km/h.
/h, the analog from the F-V converter 61 is between the reference voltage from the voltage divider 62 and the reference voltage from the voltage divider 63, so the comparator 64 outputs a high level signal. occurs and makes transistor 111 conductive.

At this time, transistor 112 remains non-conductive.

This means that a parallel circuit of both resistors 11.4 and 119 and a series circuit of resistor 115 are established. Then, when such a series circuit is established, the transistor 118 generates a second modulation voltage, and in response, the drive circuit 120 generates a second control voltage.

Next, the electric field controlled birefringence mode liquid crystal device 100 responds to the second control voltage from the drive circuit 120 to turn on the white light source 100.
The liquid crystal cell 10 is selectively controlled to select yellow light from the white light emitted from a.
The light is transmitted forward through the digital display section a. This means that the liquid crystal cell 10a digitally displays the traveling speed of the vehicle (60 km/h to lOOKm/h) in yellow under the variable color filter effect of the electric field controlled birefringence mode liquid crystal element 100. do.

Furthermore, when the traveling speed of the vehicle is higher than 1100 K/h, both comparators 64 and 65 are A high level signal is generated to make both transistors 111 and 112 conductive. This means that the parallel circuit of each resistor 114, 117, 119 and the resistor 1
This means that a series circuit with 15 is established. Then, when such a series circuit is established, the transistor 118 generates a third modulation voltage, and in response, the drive circuit 120 generates a third control voltage.

Next, the electric field-controlled birefringence mode liquid crystal device 100 responds to the third control voltage from the drive circuit 120 to turn on the white light source 100.
The liquid crystal cell 1' is selectively controlled to select red light from the white light emitted from a.
The light is transmitted forward through the digital display section of Oa. This means that the liquid crystal cell 10a digitally displays the traveling speed of the vehicle (100 km/h or more) in red under the variable color filter effect of the electric field controlled birefringence mode liquid crystal element 100. Thus, in this second embodiment, the same effects as in the first embodiment can be achieved by simply superposing the field-controlled birefringence mode liquid crystal element 100 on the liquid crystal cell 10a from the back side.

In the first embodiment, an example was described in which each oscillation pulse from the oscillation circuit 30 is frequency-modulated by the modulation circuit 50, but the invention is not limited to this. The same effects as in the first embodiment can also be achieved by employing a voltage generator that generates , and modulating the alternating current voltage from the voltage generator in accordance with the output from the speed sensor 20.

Further, in the second embodiment, a HAN type electric field controlled birefringence mode liquid crystal element is used as the electric field controlled birefringence mode liquid crystal cell 100, but the invention is not limited to this, and an electric field controlled birefringence mode liquid crystal element such as a DAP type may be used. It may also be carried out.

Furthermore, in implementing the present invention, a guest-host type positive-type liquid crystal cell or a TN type liquid crystal cell may be employed as the liquid crystal cell 10a in each of the above embodiments.

Further, in each of the above embodiments and modifications, an example in which the present invention is applied to a variable color speed display device for a vehicle has been described, but the present invention is not limited to this, for example, a variable color temperature display device for a vehicle,
The present invention may be applied not only to other vehicles but also to variable color display devices that display three or more pieces of information in different display colors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention, FIG. 2 is an enlarged sectional view of main parts of the display device main body in FIG. 1, and FIG.
The figure is a graph showing the emission intensity in relation to the light wavelength λ of the thin film electroluminescent device in Fig. 2, Fig. 4 is a block diagram showing a partial modification of the first embodiment, and Fig. 5 is a graph showing the emission intensity of the thin film electroluminescent device in relation to the light wavelength λ. Block diagram showing the second embodiment, No. 6
The figure is an enlarged cross-sectional view of the main part of the display device main body in FIG. 5, and FIG. 7 is a detailed circuit diagram of the modulation path in FIG. 5. Explanation of symbols 10...Display device main body, tOa...Liquid crystal cell, 10
b... thin film electroluminescent element, 100.
...Electric field controlled birefringence mode liquid crystal element, 100a...White light source. Figure 2 Figure 3 λ (nrr8→

Claims (1)

[Claims] The above-mentioned apparatus comprises a transmissive liquid crystal display means for displaying three types of information, and a light projecting means disposed behind the liquid crystal display means for selectively projecting three mutually different colored lights onto the liquid crystal display means. A variable color display device, wherein the liquid crystal display means displays any of the information in the color of the three colored lights according to one of the three colored lights from the light projecting means.