JPH0954317A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device of a segment display system capable of making display with a variety of changes by changing a background color to plural colors. SOLUTION: Phase difference plates 23, 24 are arranged between a liquid crystal cell 10 and a front side polarizing plate 21. The directions of the optical axes of the front and rear polarizing plates 2l, 22 and the phase difference plates 23, 24 and the liquid crystal molecule orientation direction of the liquid crystal cell 10 near the substrates are so set that the respective wavelength light rays are made into the light rays of the elliptically polarized light rays respectively varying in the polarization states by the double refractive effect of the phase difference plates and the liquid crystal layer while the incident linearly polarized light transmitted through the front side polarizing plate 21 transmits the phase difference plates 23, 24 and the liquid crystal layer 18 and that these light rays are transmitted through the rear side polarizing plate 22 and the ratios of the light intensitys of the respective wavelength light rays attain desired ratios. The liquid crystal cell 10 is provided with segment electrodes 13, a background part electrode 14 corresponding to nearly the entire part of the display region exclusive of the parts to be formed with these segment electrodes and a common electrode 15 facing the segment electrodes 13 and the background part electrode 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a segment display type reflective liquid crystal display device.

[0002]

2. Description of the Related Art As a segment display type liquid crystal display device, a reflection type liquid crystal display device is generally used which displays by utilizing external light such as natural light or indoor illumination light. In this liquid crystal display device, a liquid crystal layer in which liquid crystal molecules are twist-aligned is provided between a pair of substrates, a plurality of segment electrodes are provided on the inner surface of one substrate, and a common electrode facing the segment electrodes is provided on the inner surface of the other substrate. A liquid crystal cell provided with, and the front side and the back side polarizing plate arranged by sandwiching the liquid crystal cell,
And a reflector disposed behind the back side polarizing plate.

In this type of segment display type reflection type liquid crystal display device, the twist angle of the liquid crystal molecules of the liquid crystal cell is set to about 90 °, and the front and back polarizing plates are provided with their respective optical axes (transmission axis or absorption axis). A positive display type in which the two are arranged substantially orthogonal to each other is widely used.

[0004]

The conventional reflective liquid crystal display device of the segment display system can only perform a monotonous display in which display information is displayed in almost black on a substantially white background. It is an object of the present invention to provide a segment display type reflective liquid crystal display device capable of performing a variety of displays by changing the background color into a plurality of colors.

[0005]

The present invention, in a reflective liquid crystal display device of a segment display system, is provided with a light coloring means for selectively coloring the light incident on the background portion of the display area into a plurality of colors. It is characterized by that.

In the present invention, the photo-coloring means includes a pair of liquid crystal layers having a twist alignment of liquid crystal molecules provided between a pair of substrates having electrodes formed on the inner surfaces thereof, and a pair of liquid crystal layers sandwiching the liquid crystal layer. A polarizing plate and at least one retardation plate disposed between the one polarizing plate and the liquid crystal layer, and the directions of the optical axes of the pair of polarizing plates and the retardation plate. And the alignment direction of the liquid crystal molecules in the vicinity of the pair of substrates of the liquid crystal layer, linearly polarized light that is transmitted through one of the polarizing plates and is incident, while passing through the retardation plate and the liquid crystal layer, the phase difference. Due to the birefringence effect of the plate and the birefringence effect of the liquid crystal layer, each wavelength light becomes elliptically polarized light having a different polarization state, and the light is further transmitted through the other polarizing plate, The ratio of light intensity will be the desired ratio It is set to.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention include a liquid crystal cell having a liquid crystal layer in which liquid crystal molecules are twist-aligned between a pair of substrates, and front and back polarizations arranged with the liquid crystal cell in between. A plate and at least one retardation plate provided between one of the polarizing plates and the liquid crystal cell;
A reflection plate disposed behind the back side polarizing plate, and the orientation of the optical axis of each of the front side and back side polarizing plates and the retardation plate, and the alignment of liquid crystal molecules in the vicinity of both substrates of the liquid crystal cell. Direction, the linearly polarized light that has entered through the front-side polarizing plate, while passing through the liquid crystal layer of the retardation plate and the liquid crystal cell, the birefringence effect of the retardation plate and the birefringence effect of the liquid crystal layer. Each wavelength light becomes elliptically polarized light with different polarization state, and the elliptically polarized light further passes through the back side polarizing plate, and the light intensity ratio of each wavelength light becomes a desired ratio. With such a setting, on the inner surface of one substrate of the liquid crystal cell, a plurality of segment electrodes and a background electrode corresponding to almost the entire display area except the segment electrode forming portion are provided, and the other substrate is provided. On the inside, There is a configuration in which a segment electrode and the background electrode facing the common electrode.

According to the liquid crystal display device having such a structure,
Linearly polarized light that has passed through the front-side polarizing plate and is incident on it can be changed in polarization state by the birefringence action of the retardation plate and the liquid crystal layer in the process of passing through the retardation plate and the liquid crystal layer of the liquid crystal cell. Light that has become elliptically polarized light with a different polarization state is incident on the back-side polarizing plate, and the light that has passed through this back-side polarizing plate is a light of a color that corresponds to the ratio of the light intensities of the light components of that wavelength. Then, the light is reflected by the reflection plate and emitted to the front surface side of the liquid crystal display device.

When the strength of the electric field applied to the liquid crystal layer of the liquid crystal cell is changed, the birefringence action of the liquid crystal layer is changed due to the change of the alignment state of the liquid crystal molecules due to the electric field, and the back side polarizing plate is accordingly accompanied. Since the polarization state of the light incident on is changed, the light intensity ratio of each wavelength light of the light transmitted through the back side polarizing plate is changed, and the color of the emitted light is changed.

In this liquid crystal display device, a segment electrode and a background electrode corresponding to almost the entire display area except for the portion where the segment electrode is formed are provided on the inner surface of one substrate of the liquid crystal cell, and the other electrode is provided on the inner surface of the other substrate. Since the common electrode facing the segment electrode and the background electrode is provided, the strength of the electric field applied to the liquid crystal layer is controlled by controlling the voltage applied between the background electrode and the unselected segment electrode and the common electrode. By changing the, the light incident on the background portion of the display area can be selectively colored into a plurality of colors to change the background color into a plurality of colors.

According to another embodiment of the present invention, a liquid crystal layer in which liquid crystal molecules are twist-aligned is provided between a pair of substrates, a plurality of segment electrodes are provided on the inner surface of one substrate, and the above-mentioned liquid crystal layer is provided on the inner surface of the other substrate. A display liquid crystal cell having a common electrode facing the segment electrodes and a liquid crystal layer in which liquid crystal molecules are twist-aligned are provided between a pair of substrates, and electrodes corresponding to almost the entire display area are provided on the inner surfaces of the pair of substrates. And a coloring liquid crystal cell arranged to face the back surface of the display liquid crystal cell, and at least one intermediate polarizing plate arranged between the display liquid crystal cell and the coloring liquid crystal cell, Any of a front-side polarizing plate disposed on the front surface side of the display liquid crystal cell, a back-side polarizing plate disposed on the back surface side of the coloring liquid crystal cell, the intermediate polarizing plate and the back-side polarizing plate. At least one retardation plate provided between the liquid crystal cell and one of the liquid crystal cells and a reflection plate disposed behind the back-side polarizing plate, and sandwiching the coloring liquid crystal cell. The direction of the optical axis of each of the intermediate polarizing plate, the back polarizing plate, and the retardation plate and the alignment direction of liquid crystal molecules in the vicinity of both substrates of the coloring liquid crystal cell are transmitted through the intermediate polarizing plate. While the incident linearly polarized light is transmitted through the retardation plate and the liquid crystal layer of the liquid crystal cell, each wavelength light has an ellipse having a different polarization state due to the birefringence effect of the retardation plate and the birefringence effect of the liquid crystal layer. There is a configuration in which the light becomes polarized light, and the elliptically polarized light is further transmitted through the back-side polarizing plate so that the ratio of the light intensity of each wavelength light becomes a desired ratio.

In the liquid crystal display device having this structure, the display information is displayed by the display liquid crystal cell and the front side polarizing plate and the intermediate polarizing plate which are arranged so as to sandwich the display liquid crystal cell, and the background portion of the display area is displayed. The light incident on is colored by the coloring liquid crystal cell, the intermediate polarizing plate and the rear polarizing plate which are arranged by sandwiching the coloring liquid crystal cell, and the retardation plate.

In this liquid crystal display device, the light incident on the background portion of the display area, that is, the linearly polarized light that is sequentially transmitted through the front-side polarizing plate and the liquid crystal cell for display and further transmitted through the intermediate polarizing plate, is In the process of passing through the retardation plate and the liquid crystal layer of the coloring liquid crystal cell, the polarization state is changed by the birefringence effect of the retardation plate and the liquid crystal layer, and each wavelength light becomes elliptically polarized light with a different polarization state. Then, the light that has entered the back-side polarizing plate and transmitted through this back-side polarizing plate becomes light of a color corresponding to the ratio of the light intensities of the light components of that wavelength, and the light is reflected by the reflector. And is emitted to the front surface side of the liquid crystal display device.

When the strength of the electric field applied to the liquid crystal layer of the coloring liquid crystal cell is changed, the birefringence action of the liquid crystal layer is changed due to the change in the alignment state of the liquid crystal molecules due to the electric field, and accordingly the birefringence effect is changed. Since the polarization state of the light incident on the back side polarizing plate changes, the light intensity ratio of each wavelength light of the light passing through this back side polarizing plate changes, and the color of the emitted light changes.

In this liquid crystal display device, since electrodes corresponding to almost the entire display area are provided on the inner surfaces of the pair of substrates of the coloring liquid crystal cell, the voltage applied between these electrodes is controlled. By changing the strength of the electric field applied to the liquid crystal layer of the coloring liquid crystal cell, the light incident on the background portion of the display area is selectively colored into a plurality of colors,
You can change the background color to multiple colors.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of the present invention will be described. FIGS. 1 to 5 show a first embodiment of the present invention.
2 is a sectional view of a part of the liquid crystal display device, and FIG. 2 is a plan view of a segment electrode and a background electrode formed on one substrate of the liquid crystal cell.

As shown in FIG. 1, the liquid crystal display device of this embodiment includes a liquid crystal cell 10, a front side polarizing plate 21 and a back side polarizing plate 21 which are arranged on the front side and the back side of the liquid crystal cell 10. The plate 22, the front polarizing plate 21, and the liquid crystal cell 1
Two retardation plates 2 which are stacked between each other and 0
3 and 24, and a reflection plate 25 arranged behind the back side polarizing plate 22. The reflector 25 is
It is an omnidirectional reflector in which a metal film such as silver or aluminum is deposited on the surface of a base sheet made of a resin film or the like.

In the liquid crystal cell 10, a pair of transparent substrates (for example, glass substrates) 11 and 12 are bonded together via a frame-shaped sealing material (not shown), and the liquid crystal cell 10 is surrounded by the sealing material between the substrates 11 and 12. The display region is provided with a liquid crystal layer 18 in which liquid crystal molecules are twist-aligned, and one of the substrates,
For example, on the inner surface of the back substrate 11, a plurality of segment electrodes 13 having a shape corresponding to a display pattern, and a background electrode 14 corresponding to almost the entire display area except a portion where the segment electrodes 13 are formed are provided. A common electrode 15 facing the segment electrodes 13 and the background electrode 14 is provided on the inner surface of the front substrate 12, which is the other substrate.

The segment electrode 13, the background electrode 14 and the common electrode 15 are all transparent electrodes made of an ITO film or the like, and each segment electrode 13 is formed corresponding to each display portion of each display pattern. The partial electrode 14 is formed over almost the entire display region except the segment electrode forming portion, and the common electrode 15 is formed over almost the entire display region.

The liquid crystal display device of this embodiment is a display device used in a cassette tape recorder, and FIGS. 1 and 2 show a portion for displaying the tape feeding direction. There is provided a pair of segment electrodes 13 having a pattern representing forward feeding and backward feeding. Then, as shown in FIG. 2, the background portion electrode 14 is formed over almost the entire display region except each segment electrode 13 and its lead wire portion 13a.

An alignment film 16 is provided on the inner surface of the back substrate 11 so as to cover the segment electrodes 13 and the background electrode 14, and an alignment film 17 is provided on the inner surface of the front substrate 12 so as to cover the common electrode 15. It is provided.

Each of the alignment films 16 and 17 is a horizontal alignment film (for example, a polyimide film) subjected to an alignment treatment by rubbing, and the liquid crystal molecules of the liquid crystal layer 18 are aligned in the alignment directions in the vicinity of the substrates 11 and 12. The alignment film 16,
It is regulated by 17 and is tilted at a predetermined twist angle between both substrates 11 and 12 in a state of being inclined with a slight pretilt angle with respect to the surfaces of these alignment films 16 and 17.

In this liquid crystal display device, the optical axes of the front-side polarizing plate 21 and the back-side polarizing plate 22 and the two retardation plates 23 and 24 (transmission axis or absorption axis, retardation plate in the polarizing plate). Then, the linearly polarized light that has passed through the front-side polarizing plate 21 and is incident on the retardation plate 23 in the direction of the slow axis or the fast axis) and the orientation direction of the liquid crystal molecules in the vicinity of both substrates 11 and 12 of the liquid crystal cell 10. , 24 and liquid crystal cell 10
While passing through, the light of each wavelength becomes elliptically polarized light having a different polarization state due to the birefringence effect of the retardation films 23 and 24 and the birefringence effect of the liquid crystal layer 18 of the liquid crystal cell 10, and It is set so that the ratio of the light intensities of the respective wavelength lights transmitted through the back side polarizing plate 22 of them becomes a desired ratio.

FIG. 3 shows both substrates 11 of the liquid crystal cell 10,
12, the liquid crystal molecule alignment direction and each polarizing plate 21,
22 is a diagram of the optical axes of the phase difference plates 23 and 24 as viewed from the surface side of the liquid crystal display device. In this embodiment, the liquid crystal molecule twist angle of the liquid crystal cell 10 is 250 ° ± 20 °, and the front side and The rear side polarizing plates 21 and 22 have their transmission axes 21
a and 22a are arranged with the following orientation, and the phase difference plate 2
3, 24 are arranged with their slow axes 23a, 24a oriented as follows.

As shown in FIG. 3, the alignment direction of the liquid crystal molecules (alignment film 16) in the vicinity of the back substrate 11 of the liquid crystal cell 10.
Orientation direction 11a) is 35 ° ± 10 counterclockwise (counterclockwise in the figure) when viewed from the surface side with respect to the horizontal axis S of the liquid crystal cell 10.
The orientation direction of liquid crystal molecules in the vicinity of the front substrate 12 (orientation processing direction of the alignment film 16) 12a is clockwise with respect to the orientation direction 11a of liquid crystal molecules in the vicinity of the back substrate 11. The liquid crystal molecules are in the direction of 70 ° ± 10 °, and the liquid crystal molecules are directed from the back side substrate 11 to the front side substrate 12 as shown by the broken line arrow in the drawing.
When viewed from the surface side, the twist orientation is clockwise with a twist angle of 250 ° ± 20 °.

When the liquid crystal molecule alignment direction 11a in the vicinity of the back substrate 11 of the liquid crystal cell 10 is set to 0 °, the transmission axis 21a of the front polarizing plate 21 is the liquid crystal molecule of the liquid crystal cell 10 when viewed from the front side. The direction opposite to the twist direction (the twist direction viewed from the front side) is 50 ° ± 10 °, and the transmission axis 22a of the back side polarizing plate 22 is 45 ° in the same direction as the liquid crystal molecule twist direction when viewed from the front side. It is in the direction of ± 10 °.

Further, of the two retardation plates 23 and 24, the slow axis 23a of the first retardation plate 23 adjacent to the front side polarizing plate 21 is seen from the front side in the direction of 0 °. The second retardation plate 2 adjacent to the liquid crystal cell 10 in the direction of 25 ° ± 10 ° in the same direction as the liquid crystal molecule twist direction.
The slow axis 24a of No. 4 is 15 ° ± 15 ° in the direction opposite to the twist direction of the liquid crystal molecules when viewed from the surface side with respect to the direction of 0 °.
It is in the direction of 10 °.

Further, in this embodiment, the liquid crystal cell 10 is used.
As the first retardation plate 23, the value of the product Δnd of the refractive index anisotropy Δn of the liquid crystal 18 and the liquid crystal layer thickness d is 1350 nm ± 100 nm, and its retardation value is 1600 nm ± 30 nm. As the second retardation plate 24, a retardation value of 1 is used.
550 nm ± 30 nm is used.

The first and second used in this embodiment
The retardation films 23 and 24 of No. 2 each have a refractive index n _x in the stretching direction (slow axis direction) on the plane, and a refractive index n _{y in the} direction orthogonal to the stretching direction on the plane,
It is a biaxial retardation plate having a relationship of n _x > n _z > n _y with the refractive index n _{z in the} thickness direction.

This liquid crystal display device includes a liquid crystal layer 18 of the liquid crystal cell 10, a pair of front and back polarizing plates 21 and 22 arranged with the liquid crystal layer 18 in between, one polarizing plate 21 and the liquid crystal layer. Two phase difference plates 2 arranged between 18 and
Light incident on the background portion of the display area is selectively colored into a plurality of colors by the light coloring means composed of 3, 24. The color of the background portion is the background electrode 14 and the non-selected segment. It changes according to the voltage applied between the electrode 13 and the common electrode 15, and the display color in the background changes according to the applied voltage between the selected segment electrode 13 and the common electrode 15.

That is, in this liquid crystal display device,
Incident light from the surface side (outside light such as natural light or indoor illumination light) passes through the front-side polarization plate 21 to become linearly polarized light, and the light is the liquid crystal of the two retardation plates 23 and 24 and the liquid crystal cell 10. The light is transmitted through the layers 18 in order and is incident on the back side polarizing plate 22, and the light transmitted through the back side polarizing plate 22 is reflected by the reflecting plate 25.
And is transmitted through the back-side polarizing plate 22, the liquid crystal cell 10, the phase difference plates 24 and 23, and the front-side polarizing plate 21 in this order, and is emitted to the front surface side.

The liquid crystal molecules of the liquid crystal layer 18 of the liquid crystal cell 10 are vertically aligned while maintaining the twist alignment state according to the strength of the applied electric field. When the alignment state of the liquid crystal molecules is the twist alignment state, The linearly polarized light that has passed through the front-side polarizing plate 21 and is incident is the retardation plates 23 and 24 and the liquid crystal cell 1.
In the process of passing through the liquid crystal layer 18 of 0, the polarization state is changed by the birefringence effect of the phase difference plates 23 and 24 and the liquid crystal layer 18, and each wavelength light becomes elliptically polarized light having a different polarization state. The light that has entered the back-side polarizing plate 22 and has passed through the back-side polarizing plate 22 becomes light of a color corresponding to the ratio of the light intensities of the light components of the wavelengths, and the light is reflected by the reflection plate 25.
It is reflected by and is emitted to the surface side of the liquid crystal display device.

When the strength of the electric field applied to the liquid crystal layer 18 of the liquid crystal cell 10 is changed, the birefringence action of the liquid crystal layer 18 is changed by the change of the alignment state of the liquid crystal molecules due to the electric field. The birefringence of the liquid crystal layer 18 becomes smaller as the rising angle of liquid crystal molecules becomes larger.

When the birefringence of the liquid crystal layer 18 of the liquid crystal cell 10 changes in this way, the retardation plate 2 is accordingly changed.
Since the polarization state of light that passes through the liquid crystal layers 18 of the liquid crystal cells 10 and 3, 24 and enters the back side polarizing plate 22 changes,
The light intensity ratio of each wavelength light of the light transmitted through the back side polarizing plate 22 is changed, and the color of the light is changed.
The color of the light reflected by 5 and emitted to the surface side of the liquid crystal display device changes.

In this liquid crystal display device, the segment electrode 1 is formed on the inner surface of one substrate 11 of the liquid crystal cell 10.
3 and the background electrode 14 corresponding to almost the entire display area except the formation portion thereof, and the common electrode 15 facing the segment electrode 13 and the background electrode 14 on the inner surface of the other substrate 12. If the voltage applied between the background electrode 14 and the non-selected segment electrode 13 and the common electrode 15 is controlled to change the strength of the electric field applied to the liquid crystal layer 18, the background portion of the display area is changed. The background color can be changed to a plurality of colors by selectively coloring the incident light into a plurality of colors.

Further, the display in the background is displayed by controlling the voltage applied between the segment electrode 13 and the common electrode 15 selected according to the display information. , The display color in the background can also be changed to a plurality of colors.

The colors that can be displayed in the above liquid crystal display device are the twist angle of the liquid crystal molecules of the liquid crystal cell 10, the value of Δnd of this liquid crystal cell 10 and the retardation values of the phase difference plates 23 and 24, the front side polarizing plate 21 and the back side polarized light. It is determined by the directions of the optical axes of the plate 22 and the phase difference plates 23 and 24. As in this embodiment, the twist angle of the liquid crystal molecules of the liquid crystal cell 10 is 250 ° ± 20 °, and Δ of the liquid crystal cell 10 is Δ.
The value of nd is 1350 nm ± 100 nm, the value of retardation of the first retardation plate 23 is 1600 nm ± 30 nm,
The retardation value of the second retardation plate 24 is set to 1550n.
The display color when the directions of the transmission axes 21a and 22a of the front and back polarizing plates 21 and 22 and the directions of the slow axes 23a and 24a of the phase difference plates 23 and 24 are set to the direction of FIG. When the incident light is white light, it is white which is an achromatic color and red, green and blue which are the three primary colors of light.

FIG. 4 is a CIE chromaticity diagram showing a change in display color of the above liquid crystal display device. The display color of this color liquid crystal display device has an electric field that causes liquid crystal molecules to rise and align in the liquid crystal layer 18 of the liquid crystal cell 10. In a non-selected state where no voltage is applied, that is, in a state where the liquid crystal molecules are twist-aligned at the initial pretilt angle at which they are most laid down with respect to the surfaces of the substrates 11 and 12, it is white, and when an electric field is applied to the liquid crystal layer 18, the As the electric field is strengthened, the display color changes from white, which is the initial display color, in the order of red, blue, and green.

The electric field applied to the liquid crystal layer 18 (effective value)
The relationship between the display color and the display color is, for example, 2.04 V or less ... White 2.15 V to 2.17 V ... Red 2.18 V to 2.22 V ... Green 2.26 V or more ... Blue.

As described above, the liquid crystal display device is capable of changing the background color to a plurality of colors. Therefore, it is possible to perform a variety of displays and
The background color can also represent some information.

FIG. 5 shows an example of the display, in which the tape feed direction is displayed in the tape feed direction display portion. In this display example, the display A of the tape feeding direction and the like is displayed in white, and the remaining battery level of the cassette tape recorder is displayed in different colors of the background B.
When the battery level is sufficient, the color of the background B is set to blue as shown in FIG.

When the battery level is reduced to about half, the background color B is changed to green as shown in FIG. 5B, and the battery level is reduced to the extent that battery replacement is required. At this time, the color of the background B is set to red as shown in FIG. 5C to notify the user of the cassette tape recorder that it is time to replace the battery.

In order to display the remaining battery level with the color of the background B, the cassette tape recorder is provided with means for measuring the remaining battery level, and the background electrode 14 and the non-selected segment electrode 13 are based on the measured value. It can be realized by controlling the voltage to be supplied.

The display example of FIG. 5 is an example in which the display A of the tape feeding direction and the like is always displayed in white, but the liquid crystal display device can change the display color in the background to a plurality of colors. Therefore, both the background color and the display color can be changed to provide a more varied display, and the combination of the background color and the display color enables recording,
It is possible to represent a lot of information such as confirmation information of switching operation to each mode such as reproduction, fast forward, pause, rewind and the like.

The combination of the background color and the display color in that case is as follows. There are numerous combinations of.

In addition, the above liquid crystal display device includes the liquid crystal cell 10
Since the retardation plates 23 and 24 are disposed between the front side polarizing plate 21 and the front side polarizing plate 21 disposed on the surface side, when light is transmitted vertically through the liquid crystal layer 18 of the liquid crystal cell 10 and when transmitted obliquely. Since the phase difference between and is compensated by the phase difference plates 23 and 24, the viewing angle dependence that the display color changes depending on the viewing direction can be reduced, and the viewing angle can be widened.

Further, in the retardation films 23 and 24, the change in the birefringence due to the change in temperature is much smaller than the change in the birefringence of the liquid crystal layer 18 of the liquid crystal cell 10, so that the liquid crystal of the liquid crystal cell 10 is changed. The temperature dependence of the total birefringence of the layer 18 and the retardation plate 22 is reduced, and therefore, according to the liquid crystal display device described above, the change in display color due to temperature can be reduced.

The above liquid crystal display device has a liquid crystal cell 10.
Can be applied to display devices of various electronic devices by changing the size and the shape and number of the segment electrodes 13 provided on one of the substrates 11.

FIG. 6 shows a display example when the above liquid crystal display device is applied to a display device of an electronic blood pressure monitor. In addition, in FIG. 6, the characters "highest blood pressure" and "lowest blood pressure" are printed characters on the display surface.

In this display example, the display A'of the measured maximum blood pressure value and the measured minimum blood pressure value is displayed in white, and the diagnostic result based on the blood pressure value is displayed in a different color of the background B '. For example, when the systolic blood pressure value is 120 and the diastolic blood pressure value is 80 and the diagnosis result is normal as shown in FIG. 6A, the background B ′ is colored in green.

When the systolic blood pressure value is 150 and the diastolic blood pressure value is 100, and the diagnosis result is hypertension, as shown in FIG. 6B, the background B is colored red, and FIG. When the maximum blood pressure value is 80, the minimum blood pressure value is 50, and the diagnosis result is low blood pressure as in c), the background B is colored blue.

In order to display the blood pressure diagnosis result in such a color of the background B ', the electronic blood pressure monitor is provided with a calculation unit for judging whether the blood pressure is high or low based on the measured systolic blood pressure value and diastolic blood pressure value.
This can be realized by controlling the voltage supplied to the background electrode 14 and the non-selected segment electrode 13 based on the measured value.

Further, in the above embodiment, the phase difference plates 23, 2
Although a biaxial one was used as 4, the phase difference plate 23,
24 is the refractive index n _x in the stretching direction on the plane,
It may be a uniaxial retardation plate in which the refractive index n _{y in the} direction orthogonal to the stretching direction on the plane has a relationship of n _x > n _y .

Further, in the above embodiment, the phase difference plates 23,
Although 24 is provided between the front polarizing plate 21 and the liquid crystal cell 10, the retardation plates 23 and 24 may be arranged between the back polarizing plate 22 and the liquid crystal cell 10.

The number of retardation plates is not limited to two, and at least one retardation plate may be provided. For example, even when only one retardation plate is used, if a retardation plate having a relatively large retardation value is used, A plurality of colors can be displayed with sufficiently high color purity.

FIG. 7 is a sectional view of a part of a liquid crystal display device showing a second embodiment of the present invention. The liquid crystal display device faces a display liquid crystal cell 31 and a rear surface of the display liquid crystal cell 31. The arranged coloring liquid crystal cell 41, the intermediate polarizing plate 52 arranged between the display liquid crystal cell 31 and the coloring liquid crystal cell 41, and the surface side of the display liquid crystal cell 30 are arranged. The front side polarizing plate 51, the back side polarizing plate 53 arranged on the back side of the coloring liquid crystal cell 41, and one retardation plate 54 provided between the intermediate polarizing plate 52 and the coloring liquid crystal cell 41. And a reflection plate 55 arranged behind the back side polarizing plate 53. The reflector 55 is the reflector 25 used in the first embodiment described above.
It has the same structure as.

In the display liquid crystal cell 31, a pair of transparent substrates (for example, glass substrates) 32 and 33 are joined via a frame-shaped sealing material (not shown), and surrounded by the sealing material between the substrates 32 and 33. A liquid crystal layer 38 in which liquid crystal molecules are twist-aligned is provided in the display area, and a plurality of segment electrodes (transparent) having a shape corresponding to the display pattern are formed on the inner surface of one of the substrates, for example, the back substrate 32. Electrode) 3
4 is provided, and a common electrode (transparent electrode) 35 facing the segment electrode 34 is provided on the inner surface of the front substrate 33 which is the other substrate.

Alignment films 36 and 37 are provided on the inner surfaces of the substrates 32 and 33 so as to cover the electrodes 34 and 35 and are subjected to an alignment treatment in directions substantially orthogonal to each other. The liquid crystal molecules of the layer 38 are
The alignment direction in the vicinity of 33 is regulated by the alignment films 36 and 37, and is tilted at a slight pretilt angle with respect to the surfaces of these alignment films 36 and 37, and a twist angle of approximately 90 ° is provided between the substrates 32 and 33. It has a twist orientation.

The optical axes (transmission axis or absorption axis) of the front polarizing plate 51 and the intermediate polarizing plate 52, which are arranged with the liquid crystal cell 31 for display interposed therebetween, are substantially perpendicular to each other, and the optical axes are the same. Both substrates 3 of the display liquid crystal cell 31
TN (Twisted Nematic) for performing positive display is provided by the polarizing plates 51, 52 and the display liquid crystal cell 31 so as to be substantially parallel to or orthogonal to the alignment direction of liquid crystal molecules in the vicinity of 1, 32. The information display means 30 having the same configuration as the) type liquid crystal display device is configured.

In the coloring liquid crystal cell 41, a pair of transparent substrates (for example, glass substrates) 42 and 43 are joined together via a frame-shaped sealing material (not shown), and these substrates 42 and 4 are joined together.
A liquid crystal layer 48 in which liquid crystal molecules are twist-aligned is provided in a display region surrounded by the sealing material between the three, and the display regions are provided on the inner surfaces of both substrates 42 and 43 of the coloring liquid crystal cell 41, respectively. The single-film transparent electrodes 44 and 45 corresponding to almost the whole are provided.

On the inner surfaces of the substrates 42 and 43, there are provided alignment films 46 and 47 which cover the electrodes 44 and 45, respectively, and which have been subjected to an alignment treatment in a predetermined direction.
The molecules of the liquid crystal of the liquid crystal layer 48 are regulated in the alignment direction in the vicinity of the substrates 42 and 43 by the alignment films 46 and 47, and are tilted with a slight pretilt angle with respect to the surfaces of the alignment films 46 and 47. The substrates 42 and 43 are twist-aligned at a predetermined twist angle, for example, a twist angle of 250 ° ± 20 °.

Further, the intermediate polarizing plate 52 and the back side polarizing plate 53 which are arranged so as to sandwich the coloring liquid crystal cell 41, and the retardation plate which is arranged between the intermediate polarizing plate 52 and the coloring liquid crystal cell 41. 54 and respective optical axes (transmission axis or absorption axis in polarizing plate, slow axis or fast axis in retardation plate)
And the alignment direction of the liquid crystal molecules in the vicinity of the substrates 42 and 43 of the coloring liquid crystal cell 41, linearly polarized light that has passed through the intermediate polarizing plate 52 and is incident on the retardation plate 54 and the coloring liquid crystal cell 41. While transmitting the light, each wavelength light becomes elliptically polarized light having a different polarization state due to the birefringence effect of the retardation plate 54 and the birefringence effect of the liquid crystal layer 48 of the coloring liquid crystal cell 41. The light intensity ratio of each wavelength light transmitted through the back side polarizing plate 53 is set to a desired ratio, and the coloring liquid crystal cell 41 and the intermediate polarizing plate 52, the back side polarizing plate 53, and the retardation plate. 54 and 54 constitute a light coloring means 40 for coloring the light incident on the background portion of the display area.

The coloring liquid crystal cell 41 has substantially the same size as the displaying liquid crystal cell 31, and the coloring liquid crystal cell 41, the intermediate polarizing plate 52 and the back polarizing plate 53.
The light coloring means 40 composed of the above and the retardation plate 54 faces the entire display area of the information display means 30.

In the liquid crystal display device of this embodiment, the display information is displayed by the display liquid crystal cell 31 and the front side polarizing plate 51 and the intermediate polarizing plate 52 which are arranged with the display liquid crystal cell 31 interposed therebetween. The light incident on the background portion of the display area is supplied to the coloring liquid crystal cell 41 and the coloring liquid crystal cell 41.
The intermediate polarizing plate 52, the back polarizing plate 53, and the retardation plate 54 which are sandwiched in between are colored.

In this liquid crystal display device, the light incident on the background portion of the display area, that is, the front side polarizing plate 51 and the display liquid crystal cell 31 are sequentially transmitted, and further the intermediate polarizing plate 52.
The linearly polarized light that has been transmitted through and is incident on the retardation plate 5 in the process of passing through the retardation plate 54 and the liquid crystal layer 48 of the coloring liquid crystal cell 41.
The polarization state is changed by the birefringence action of the liquid crystal layer 4 and the liquid crystal layer 48, and each wavelength light becomes elliptically polarized light having a different polarization state, enters the back side polarizing plate 53, and is transmitted through the back side polarizing plate 53. The converted light becomes light of a color corresponding to the ratio of the light intensities of the light components of the respective wavelengths, and the light is reflected by the reflector plate 5.
The light is reflected at 5 and is emitted to the front surface side of the liquid crystal display device.

Further, the liquid crystal layer 4 of the coloring liquid crystal cell 41.
When the strength of the electric field applied to 8 is changed, the birefringence action of the liquid crystal layer 48 is changed by the change of the alignment state of the liquid crystal molecules due to the electric field, and the polarization state of the light incident on the back side polarizing plate 53 is accordingly changed. Since it changes, this back side polarizing plate 5
The light intensity ratio of each wavelength light of the light passing through 3 changes, and the color of the emitted light changes.

In this liquid crystal display device, electrodes 44 and 45 corresponding to almost the entire display area are provided on the inner surfaces of the pair of substrates 42 and 43 of the coloring liquid crystal cell 41. , 45 is controlled to change the strength of the electric field applied to the liquid crystal layer 48 of the coloring liquid crystal cell 41, the light incident on the background portion of the display area is selectively converted into a plurality of colors. It can be colored to change the background color to multiple colors.

Since the information display means 30 composed of the display liquid crystal cell 31, the front side polarizing plate 51 and the intermediate polarizing plate 52 performs positive display, the display color in the background is almost black. Is.

The background color that can be displayed in the liquid crystal display device of this embodiment is the intermediate value between the twist angle of the liquid crystal molecules of the coloring liquid crystal cell 41, the Δnd of the liquid crystal cell 41 and the retardation value of the retardation plate 54. It is determined by the polarization plate 52, the back polarization plate 53, and the direction of the optical axis of the retardation plate 54. By selecting them, the background color is a desired color (for example, white which is an achromatic color and three primary colors of light). Red, green, blue).

In the above embodiment, the retardation plate 54, which is a component of the light coloring means 40, is provided between the coloring liquid crystal cell 41 and the intermediate polarizing plate 52.
4 may be arranged between the coloring liquid crystal cell 41 and the back side polarizing plate 53. Further, the retardation plate 54 may be a biaxial retardation plate or a biaxial retardation plate, and the number thereof is not limited to one, and a plurality of them may be arranged on top of each other.

Further, in the above-mentioned embodiment, one intermediate polarizing plate 52 is disposed between the display liquid crystal cell 31 and the coloring liquid crystal cell 41, and this intermediate polarizing plate 52 is combined with the information display means 30 and light coloring. Although it is also used as the means 40, two intermediate polarizing plates are disposed between the display liquid crystal cell 31 and the coloring liquid crystal cell 41, and the intermediate polarizing plate on the display liquid crystal cell 31 side is used as the information display means. The intermediate polarizing plate on the side of the coloring liquid crystal cell 41 may be used for the light coloring means 40. Furthermore, by making the reflection plate a semi-transmissive type and providing a backlight behind it, a reflection type liquid crystal display device which doubles as a transmission type can be obtained.

[0072]

According to the present invention, in the reflective liquid crystal display device of the segment display system, a light coloring means for selectively coloring the light incident on the background portion of the display area into a plurality of colors is provided. Therefore, it is possible to change the background color into a plurality of colors for display with various changes.

[Brief description of drawings]

FIG. 1 is a sectional view of a part of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a plan view of a segment electrode and a background electrode formed on one substrate of a liquid crystal cell.

FIG. 3 is a view of the alignment direction of liquid crystal molecules in the vicinity of both substrates of a liquid crystal cell and the orientations of optical axes of each polarizing plate and a retardation plate as viewed from the surface side of a liquid crystal display device.

FIG. 4 is a CIE chromaticity diagram showing a change in display color of a liquid crystal display device.

FIG. 5 is a diagram showing a display example of a liquid crystal display device.

FIG. 6 is a diagram showing another display example of the liquid crystal display device.

FIG. 7 is a cross-sectional view of a part of a liquid crystal display device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Liquid crystal cell 13 ... Segment electrode 14 ... Background electrode 15 ... Common electrode 21 ... Front-side polarizing plate 22 ... Back-side polarizing plate 23, 24 ... Phase difference plate 25 ... Reflector plate 30 ... Information display means 31 ... Display liquid crystal cell 34 ... segment electrode 35 ... common electrode 40 ... light coloring means 41 ... coloring liquid crystal cells 44, 45 ... electrode 51 ... front side polarizing plate 52 ... intermediate polarizing plate 53 ... back side polarizing plate 54 ... retardation plate 55 ... reflecting plate

Claims (4)

[Claims] 1. A reflective liquid crystal display device of a segment display type, comprising a light coloring means for selectively coloring light incident on a background portion of the display area into a plurality of colors. Type liquid crystal display device. 2. The light coloring means comprises a liquid crystal layer in which liquid crystal molecules are twist-aligned, provided between a pair of substrates having electrodes formed on the inner surfaces thereof, and a pair of polarizing plates arranged with the liquid crystal layer interposed therebetween. , One of the polarizing plates and at least one retardation plate disposed between the liquid crystal layer, the optical axes of the pair of polarizing plates and the retardation plate, and the liquid crystal. The alignment direction of the liquid crystal molecules in the vicinity of the pair of substrates of the layer, while the linearly polarized light incident through one of the polarizing plates is transmitted through the retardation plate and the liquid crystal layer, Due to the refraction effect and the birefringence effect of the liquid crystal layer, each wavelength light becomes elliptically polarized light having a different polarization state, and the light further passes through the other polarizing plate,
The reflective liquid crystal display device according to claim 1, wherein the ratio of the light intensity of each wavelength light is set to a desired ratio. 3. A segment display type reflective liquid crystal display device, comprising a liquid crystal cell having a liquid crystal layer in which liquid crystal molecules are twist-aligned between a pair of substrates, and a front side having the liquid crystal cell sandwiched therebetween. And a back-side polarizing plate, at least one retardation plate provided between the one polarizing plate and the liquid crystal cell, and a reflecting plate disposed behind the back-side polarizing plate, and The direction of the optical axis of each of the front-side and back-side polarizing plates and the retardation plate and the alignment direction of the liquid crystal molecules in the vicinity of both substrates of the liquid crystal cell are linearly polarized light that has been transmitted through the front-side polarizing plate and incident. While passing through the retardation plate and the liquid crystal layer of the liquid crystal cell, each wavelength light becomes elliptically polarized light having a different polarization state due to the birefringence effect of the retardation plate and the birefringence effect of the liquid crystal layer. The light is behind While passing through the light plate, the ratio of the light intensity of each wavelength light is set to a desired ratio, and on the inner surface of one substrate of the liquid crystal cell, a plurality of segment electrodes and a portion where the segment electrodes are formed. The reflective liquid crystal display device is characterized in that a background electrode corresponding to almost the entire display area is provided, and a common electrode facing the segment electrodes and the background electrode is provided on the inner surface of the other substrate. 4. A reflective liquid crystal display device of a segment display system, wherein a liquid crystal layer in which liquid crystal molecules are twist-aligned is provided between a pair of substrates, and a plurality of segment electrodes are provided on the inner surface of one substrate and the other is provided. A display liquid crystal cell in which a common electrode facing the segment electrodes is provided on the inner surface of the substrate, and a liquid crystal layer in which liquid crystal molecules are twist-aligned is provided between the pair of substrates, and the inner surfaces of the pair of substrates cover substantially the entire display area. A coloring liquid crystal cell which is provided with corresponding electrodes and is arranged to face the back surface of the display liquid crystal cell; and at least one sheet which is arranged between the display liquid crystal cell and the coloring liquid crystal cell. An intermediate polarizing plate, a front polarizing plate arranged on the front surface side of the display liquid crystal cell, a back polarizing plate arranged on the back surface side of the coloring liquid crystal cell, the intermediate polarizing plate and the At least one retardation plate provided between any one of the side polarizing plates and the coloring liquid crystal cell, and a reflecting plate arranged behind the back side polarizing plate, and the coloring The directions of the optical axes of the intermediate polarizing plate, the back polarizing plate, and the retardation plate that are arranged with the liquid crystal cell in between, and the alignment direction of liquid crystal molecules in the vicinity of both substrates of the coloring liquid crystal cell. While the linearly polarized light that has entered through the intermediate polarizing plate is transmitted through the retardation plate and the liquid crystal layer of the liquid crystal cell, the birefringence effect of the retardation plate and the birefringence effect of the liquid crystal layer cause The wavelength light becomes elliptically polarized light with different polarization states, and the light is further transmitted through the back side polarizing plate, and the ratio of the light intensity of each wavelength light is set to a desired ratio. Reflective liquid crystal display device.