JPS61292126A - Liquid crystal shutter device - Google Patents

Abstract

PURPOSE:To substantially decrease the light leaking from a background part without using a metallic mask by utilizing the polarization characteristic of reflected light. CONSTITUTION:Light L0, when reflected by a reflection plate 102, is the elliptically polarized light L1 having the major axis in an arrow A direction. As angle theta between the arrow A direction and a polarizing plate 103a is thereupon selected, then the quantity of the incident light on a liquid crystal cell 104 is optionally set over a wide range. The light L2 polarized in an arrow B direction is made incident on the liquid crystal cell and rotates by 90 deg. along the twist of liquid crystal molecules and arrives as polarized light L3 at a polarizing plate 103b. Since the transmission axes intersect orthogonally with each other, the light L4 of a slight quantity arrives at a film 105. On the other hand, the liquid crystal loses the rotatory power and therefore the light L2 is made incident on the liquid crystal cell 104 when a prescribed voltage is impressed between the electrodes of the liquid crystal cell 104. Said light arrives as the polarized light L5 maintaining the polarized direction at the polarizing plate 103b. Since the transmission axes are parallel with each other, the light arrives as the light L6 having a large quantity at the film 105, thus exposing a pattern to the film 105.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates primarily to a liquid crystal shutter device used in an H imprinting device of a camera.

(B) Conventional technology In the liquid crystal shutter device used in the H imprinting device of a conventional camera, in order to photograph the date character pattern with sufficient density and contrast length, overexposure is applied through the pattern electrode of the liquid crystal cell. A large amount of light is supplied to the photosensitive film, and a metal mask is attached to the background area other than the pattern area to block light leaking from the frontal area to the film.

(c) Problems to be Solved by the Invention However, since it is required to process a window of around 100 squares in the metal mask and precisely align it with the pattern electrode, the conventional liquid crystal shutter device cannot However, there were problems in that the manufacturing process was complicated, the yield was low, and the cost was high.

This invention was made in view of these circumstances, and it reduces the light leaking from the background area other than the pattern area of the liquid crystal cell.
The object of the present invention is to provide a liquid crystal shutter device which is sufficiently reduced without using a metal mask, and which is practical and has good productivity.

(d) Means for solving the problem This type of liquid crystal shutter device, which is generally used in cameras, uses a reflector to make the storage space more compact, thereby reflecting a portion of the light from the light source. The liquid is supplied to the liquid crystal section and the film.

This invention focuses on the polarization characteristics of the reflected light from this reflector, and by utilizing the polarization characteristics, it can be used without changing the components of conventional liquid crystal shutter devices.
It is characterized by optimally adjusting the exposure amount of the film.

The configuration of this invention will be explained using FIG. 1 (ω).

(101) is a light source, (102) is a reflector that receives incident light (LO) from the light source (ioi> and emits elliptically polarized reflected light (11), and (103a) and (103b) are reflected light (L 1 ). Two polarizing plates with transmission axes (B) and (D) parallel to each other are provided in the optical path of , (104) is 90°
A nematic liquid crystal (104C) with positive dielectric anisotropy is sealed between a pair of transparent electrode substrates (104a) (104b) subjected to twisted nematic alignment treatment, and a polarizing plate (104C)
03a) This is a liquid crystal cell interposed between (103b).

These are such that the transmission axes of the polarizing plates (103a) and (103b) [direction of arrows (B) and angle(
θ), the substrate on the light incident side of the liquid crystal cell (104a)
The long axis direction [arrow (B)] of the liquid crystal molecules in contact with the inner surface of is parallel to the transmission axis [arrow (B) direction] of the polarizing plate (103a) (
or perpendicular) to constitute a liquid crystal shutter device.

Note that (1 ns) is a photographic film whose image is captured by this shutter device.

(E) Function The function of this invention will be explained using FIGS. 1(a) to (C). The light (LO) emitted from the light source (101) vibrates in all directions without changing its electric vector. When this light (LO) is irradiated onto a reflective plate (102) such as a metal surface as shown in Figure 1, the reflective plate (
The vector component in the X-axis direction, which has a vibration direction within the surface of 102), is reflected most strongly, and the vector component in the V-axis direction is reflected most weakly. Produces elliptically polarized light with a large short axis length ratio.

Therefore, as shown in FIG. 1(a), when the light (LO) is reflected by the reflection plate (102), it becomes elliptically polarized light (Ll) with its long axis in the direction of the arrow (A). Therefore, if the transmission axis of the polarizing plate (103a) is aligned with the direction of the arrow (A), the largest amount of light corresponding to the long axis of the elliptically polarized light (Ll) will be incident on the liquid crystal cell (104), ) in the polarizing plate (1
When the transmission axes of 03a) are orthogonal to each other, the smallest light m corresponding to the short axis of the elliptically polarized light ([1)] is the liquid crystal cell (104).
is incident on the

That is, by selecting the angle (θ) between the arrow (A> direction and the polarizing plate (103a)), the change from the long axis (x axis) to the short axis (V axis) of the elliptically polarized light shown in FIG. Vector angle (
θ) is incident on the liquid crystal cell (104) via the polarizing plate (103a), and the amount of light incident on the liquid crystal cell (104) is arbitrarily set over a wide range.

In Figure 1(a), light (L2) polarized in the direction of arrow (B) enters the liquid crystal cell, rotates by 90° along the twist of the liquid crystal molecules, and becomes polarized light (L3). Polarizer(
103b). Polarized light (L3) and polarizing plate (103b
) are perpendicular to each other, most of the light is blocked there, and only a small amount of light (L4) reaches the film (107). On the other hand, when a predetermined voltage is applied between the electrodes of the liquid crystal cell (1oe), the liquid crystal between the electrode patterns loses its traveling property, so the light (L2) enters the liquid crystal cell (106) and passes through the electrode pattern part. Then, the polarized light (L5) remains in that polarization direction.
As a result, the light reaches the polarizing plate (103b). Since the transmission axes of the polarized light (L5) and the polarizing plate (103b) are parallel, most of the light passes through as is and reaches the film (107) as light with a large amount of light ([6), which creates a pattern on the film (107). expose to light.

Therefore, the amount of exposure due to light (1-4> (light from the background area other than the pattern area) is sufficiently unstable for the film, and the light from the pattern area ([6) is set to provide appropriate exposure for the film. Then, the amount of light (Ll) is selected by the angle (θ).

Therefore, with this configuration, there is no need to block the light in the background portion using a metal mask as in the conventional case.

(f) Embodiments From the following ten examples, the present invention will be described in detail based on the embodiments shown in the drawings. Note that this invention is not limited to this.

Figure 2 Ta) shows a liquid crystal shutter device used in a camera's date imprint device, where (1) is a light source, (2) is a reflector,
(3a) (3b) C polarizing plate, (4) liquid crystal cell,
(5) is the film, and (6) is the camera body.

The light source (1) is a tungsten lamp, the reflection plate (2) is an aluminum plate with a mirror-finished surface, and the polarizing plate (3a) (
3b) is LL02 82-188 type (manufactured by Royal Kasei ■)
are used respectively. In addition, glass substrates with a thickness of 0.55 mm are used for the two substrates of the liquid crystal cell (4),
On one side, a transparent pattern electrode for date and characters is formed by photo-etching using an ITO film, and on the other side, a transparent common electrode is formed in the same manner.

A rubbing process is applied to both of these substrate surfaces. As the liquid crystal, a nematic liquid crystal with a large refractive index anisotropy (80), for example, a trade name Nr, 2108 (manufactured by Roche) is used.

Next, the positional relationship and effect with respect to the optical path in FIG. 2(a) will be explained using the second example. Light emitted from light source (1) (
When the light (MO) is reflected by the reflector (2), the reflected light (M
1) becomes elliptically polarized light, with its long axis in the direction of arrow (A1) and its short axis in the direction of arrow (A2). The polarizing plates (3a) (3b) are arranged so that their transmission axes [in the directions of arrows (B1) and (Dl)] are perpendicular to the long axis [in the direction of arrow (A1)] of the elliptically polarized light of the reflected light (Ml). , that is, the short axis of the elliptically polarized light of the reflected light (Ml) [arrow (
A2) direction]. Liquid crystal cell (
4), the rubbed substrate (4a) is attached to the polarizing plate (3).
a), and the long axis direction (fubing direction) of the liquid crystal molecules in contact with the inner surface of the substrate (4a) is the transmission axis (3a) of the polarizing plate (3a).
arrow (B1) direction].

Therefore, in the reflected light (Ml), only the component in the short axis direction of the elliptically polarized light passes through the polarizing plate (3a), becomes light (M2), and enters the cell (4). The light (M2) has its polarization axis aligned with the cell (4
) is twisted by 90° and becomes light (M3), which reaches the polarizing plate (3b). The transmission axis of the polarizing plate (3b) is the light (M
3), most of the light (M3) is absorbed by the polarizing plate (3b) and reaches the film (5) as a very small amount of light (M4) (background light).

On the other hand, when a predetermined voltage is applied between the electrodes of the substrates (4a) and (4b) of the cell (4), the liquid crystal between the electrodes aligns in the direction of the electric field and loses its 90° optical rotation. )
The light is not rotated by the cell (4), but passes through the patterned part of the electrode, becomes light (M5), and reaches the polarizing plate (3b). Since the transmission axis of the polarizing plate (3b) is parallel to the polarization axis of the light (M5), most of the light (M5) passes through the polarizing plate (3b).
) and reaches the film (5) as light (MO) (light from the patterned portion). Light (M
The contrast ratio, which is the ratio of the amounts of light between O) and M4, is determined by the characteristics of the liquid crystal cell (4), but in this example it is a common value of 60:1.

Figure 3 shows the 4-carriage film (5) used in this example.
3 is a graph showing an example of the characteristic of density (E) with respect to exposure amount (D). Film (5) is light (MO) and (M4)
When exposed to light, their corresponding films (
The exposure amount to 5) is (E6) (E4), and the corresponding density of film (5) is (B6) (B4), respectively.
becomes. At this time, (F6):(F4) is 60:1.

By the way, in the conventional liquid crystal shutter device, the polarization axes of the polarizing plates (3a) (3b) are arranged parallel to the long axis of the elliptically polarized light (Ml). Therefore, light (MO) and (M4)
Even though the contrast ratio with the film (5) is 60:1, the amount of light is large, so the exposure amount (E) for the film (5) is (F6') (E4') as shown in Figure 3, respectively.
The density change in the background area becomes large. In other words, the corresponding film densities (D) are (D6') (
D4'), and not only the pattern part but also the background part is imprinted on the film with high density. Therefore,
In the conventional liquid crystal shutter device, a metal mask must be used for the cell (4) in order to suppress this exposure amount (E4').

On the other hand, according to this embodiment, the character pattern area is covered with a film (with sufficient density) without using a metal mask.
5) However, there is provided a liquid crystal shutter device in which the background portion has a very low density and is hardly imprinted.

As another embodiment of the present invention, a case where the liquid crystal is a nematic liquid crystal containing a dichroic dye will be described.

A dichroic dye such as an anthraquinone dye CLD was used as the liquid crystal of the liquid crystal cell (4) of the example shown in FIG.
When a nematic liquid crystal containing 506% by double and having positive dielectric anisotropy and a large refractive index anisotropy is used, the dye follows the orientation of the liquid crystal molecules. Therefore, the light (M2) incident on the liquid crystal cell (4) is rotated by 90° while being absorbed by the dichroic dye, and reaches the polarizing plate (3h) as light (M3). This dichroic pigment absorbs light with a wavelength of 600 to 700 nlB, so if the wavelength of light (M3) is 600 nlB,
The component of ~1000m is attenuated inside the liquid crystal cell (4), and further blocked by the polarizing plate (3b) to transmit the transmitted light (M4).
Almost no light (light from the background) reaches the film (5). On the other hand, when a voltage is applied to the electrodes, the absorption axis of the dye between the electrodes also follows the liquid crystal molecules and becomes perpendicular to the substrates (4a) (4fi), so the incident light (M2) is hardly absorbed; The polarization axis passes through the electrode pattern without being rotated and becomes light (M5) on the polarizing plate (
3b) is reached. The transmission axis of the polarizing plate (3b) is light (M5)
Since the light (M5) is parallel to the polarization axis of the light (M5), most of the light (M5) directly becomes light (M6) (light of the pattern portion) and reaches the film (5).

By the way, the photosensitivity characteristics of general photographic films with respect to the wavelength of light are shown as shown in Figure 4.
Its sensitivity to light with a wavelength of 00 nm is ﾾ. As mentioned above, in this example, the light (M4) reaching the film (5) as background light is absorbed inside the cell (4) in this wavelength range, so the light (M4) as seen from the film (5) The substantial contrast ratio between lights (M6) and (M4) is even larger, approximately 10 in this example.
0: becomes 1.

Therefore, exposure # of film (5)! As shown in FIG. 3, (E) is (E6) for light (M6), which is almost the same as the above example, but for light (M4), it is (E4''), The corresponding density (D) is extremely low and almost equal to zero.In this way, by mixing one liquid crystal with a dichroic dye that absorbs light at a wavelength that is well sensitive to the film, the pattern area Light from other background areas is further attenuated and is no longer exposed to the film, allowing only the pattern area to be photographed successfully.

(G) Effects of the Invention According to this invention, by adjusting the film exposure amount of the pattern portion to be imprinted on the photographic film and its background portion by using the polarization characteristics of the reflector that reflects the light from the light source, While maintaining the appropriate film density in the pattern area,
Since it is possible to sufficiently reduce the appearance of Film II in the background portion, there is no need to provide a metal mask in the background portion, and a practical liquid crystal shutter device with good productivity is provided.

[Brief explanation of the drawing]

FIG. 1(a) is an explanatory diagram showing the configuration of the present invention, FIG.
tn (C) is an explanatory diagram showing the polarization of the reflector, Fig. 2 (a
) is an explanatory diagram showing one embodiment of the present invention, FIG. 2+to is an explanatory diagram showing the structure of FIG. )...Light source, (2)...Reflector, (3a) (3b)...Polarizing plate, (4
)...Liquid crystal cell, (5)...Photographic film. Figure 1 (b) Figure 1 (C)

Claims (1)

[Scope of Claims] 1. A light source, a reflecting plate that reflects the light from the light source and makes it elliptically polarized, and two polarizing plates provided in the optical path of the reflecting plate and having mutually parallel transmission axes; ° a liquid crystal cell formed by sealing a nematic liquid crystal with positive induction anisotropy between a pair of transparent electrode substrates subjected to twisted nematic alignment treatment and interposed between the polarizing plates; The transmission axis of the plate makes a predetermined angle with the long axis of the elliptically polarized light reflected by the reflecting plate, and the long axis direction of the liquid crystal molecules in contact with the inner surface of the substrate on the light incident side of the liquid crystal cell is transmitted through the polarizing plate. A liquid crystal shutter device configured to be parallel or perpendicular to the axis. 2. The liquid crystal shutter device according to claim 1, wherein the transmission axes of the two polarizing plates are orthogonal to the long axis of the elliptically polarized light reflected by the reflecting plate. 3. The liquid crystal shutter device according to claim 1, wherein the nematic liquid crystal contains a dichroic dye that absorbs wavelengths of 600 to 700 nm.