JPH11133515A - Image exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and rapidly switch a color exposed by an exposure head in an image exposure device capable of obtaining the color image of one sheet by exposing the image color-separated by every exposure reference color such as R, G or B on photographic paper as a dot matrix by every color. SOLUTION: A shutter array 311 consisting of a PLZT element is arranged in a width direction (direction Y) orthogonal to the carrying direction (direction X) of the photographic paper 2, and a liquid crystal filter 315 transmitting only the exposure reference color such as R, G or B is arranged between a halogen lamp 312 and the shutter array 311. Then, the driving time (exposure time of the photographic paper 2) of a liquid crystal element corresponding to each color constituting a liquid crystal filter is controlled so as to expose the image on the photographic paper 2 on an optimum condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image exposure apparatus for exposing a digital image on a photosensitive material such as photographic paper.

[0002]

2. Description of the Related Art A general configuration of a conventional image exposure apparatus is shown in FIG. A conventional image exposure apparatus 1 includes a long photographic paper 2
An exposure head 100 for exposing a digital image on a line-by-line basis, and a photographic paper transport for transporting the exposed portion 2a of the photographic paper 2 by one line in the X direction to a position facing the shutter array 110 of the exposure head 100. A mechanism 200, an exposure head controller 150 for controlling the exposure head 100, for example, a photographic paper transport mechanism 200 and an exposure head controller based on image data of each exposure reference color such as R (red), G (green), and B (blue). Exposure control unit 210 for controlling synchronously with the unit 150, photographic paper transport control unit 201 for controlling the operation of the photographic paper transport mechanism 200, and exposure timing for synchronously controlling the image data output control unit 152 of the exposure head control unit 150 Control unit 2
11 and the like.

The exposure head 100 converts image data into an optical signal and outputs the optical signal on the photographic paper 2. The exposure head 100 is arranged along the width direction (Y direction) of the photographic paper 2 and outputs a light signal. Unit 110, a light source unit 120, a color separation filter 130 that transmits only specific light out of the light from the light source unit 120, an optical fiber array 140 that guides light transmitted through the color separation filter 130 to the shutter unit 110, and the like. It is configured.

[0004] As shown in FIG.
A shutter array 111 composed of a PLZT element or the like;
A diffusion filter 112 for diffusing the light guided by the optical fiber array 140 is provided.

[0005] The optical fiber array 140 includes a shutter unit 1.
On the side facing 10, the sheets are arranged linearly in the width direction (Y direction) of the printing paper 2 to face the shutter array 111 via the diffusion filter 112. On the other hand, on the light source unit 120 side, the light source unit 120 is bundled so as to have a substantially circular cross section so as to face the halogen lamp 121 via the color separation filter 130.

The light source unit 120 includes a halogen lamp 121 as a white light source, a dimming filter 122 for adjusting the amount of light, a lens barrel 123 whose inner surface is mirror-finished, and the like. As shown in FIG.
Are formed of two filters 122A and 122B that limit the color of transmitted light (hereinafter referred to as transmitted light color limiting filters) 122A and 122B, each having a cutout 122C formed on the emission opening 123A side of the lens barrel 123. Color limited filter 122A
, 122B, the exit aperture 1
By changing the opening area of 23A, the amount of light emitted from the light source unit 120 is adjusted. 8A shows a state in which the exit aperture 123A is almost fully opened, and FIG.
23A shows a state close to a half-open state, and FIG. 23C shows a state where the emission aperture 123A is almost closed.

As shown in FIG. 7, the color separation filter 130 comprises a substantially circular filter plate 131, a motor 132 for rotating the filter plate 131, and the like. Further, as shown in FIG.
A circular frame 131A having three fan-shaped openings formed for each degree, and filters 131R, 131G, 131B, etc., which are fitted in the respective openings of the frame 131A and transmit only the R, G, B reference colors, respectively. It is configured. The radius of the filter plate 131 is at least
The diameter is set to be larger than the diameter of the exit aperture 123A of the twenty lens barrel 123. In addition, halogen lamp 1
21 is always on, and the filter plate 131 is the motor 1
32 continuously rotates at a constant speed. Therefore, while the filters 131R, 131G, and 131B of the R, G, and B colors respectively pass through the regions facing the emission aperture 123A, the shutter array 1 of the exposure head 110
By controlling the opening and closing of the image 11, one line of R, G, B color images can be exposed on the photographic paper 2.
When the exposure of the R, G, and B images of one line is completed, the photographic paper transport unit 200 is driven to transport the photographic paper 2 by one line in the X direction, and the R, G, and B of the next line are processed. Each color image is exposed. By repeating this operation, a color image of a predetermined size is exposed on the photographic paper 2.
By developing the exposed photographic paper, one color photograph is obtained.

[0008]

Generally, the spectral distribution of light emitted from the halogen lamp 121 is not uniform. Further, filters 131R, 13 for each of R, G, B colors
The transmittances of 1G and 131B are not the same either. Furthermore, the sensitivity of the photographic paper 2 to be exposed to each of the R, G, and B colors is not constant. Therefore, when exposing images of R, G, and B colors on the photographic paper 2, optimal exposure conditions must be set in accordance with the characteristics of each image. Therefore, as described above, the light control filter 122 is controlled to adjust the intensity of light of each color of R, G, and B irradiated on the printing paper 2. as a result,
A photograph finally formed on the photographic paper 2 has an appropriate color and density.

However, as is apparent from FIG.
The exit aperture 123A of the lens barrel 123 of the light source unit 120 and the bundled end faces of the optical fiber array 140 each have a substantially circular cross section, whereas the two transmitted light color limiting filters 1
The opening formed by 22A and 122B has a substantially spindle shape, and the amount of light incident on the peripheral optical fiber among the bundled optical fibers is smaller than the amount of light incident on the central optical fiber. However, there is a problem that the light amount unevenness of the light incident on the shutter array 111 is large.

[0010] Further, R,
As a method for switching between G and B colors, the filter plate 131 is rotated by the motor 132, so that the filter plate 1
There was a problem that noise was generated due to the rotation of the motor 31. Furthermore, there is a limit in increasing the rotation speed of the filter plate 131 by the motor 132, and accordingly, there is also a certain limit in the filter switching speed. further,
The exposure time of each of the R, G, and B colors is also limited to the time during which the filters 131R, 131G, and 131B of each of the R, G, and B colors pass through a region facing the emission opening 123A. There was a problem that adjustment was difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is easy to switch the exposure of each exposure reference color such as R, G, B and the like and to control the exposure time, and it is also necessary to control the sound. An object of the present invention is to provide a quiet image exposure apparatus.

[0012]

In order to achieve the above object, an image exposure apparatus according to the present invention comprises a light source, a one-dimensionally arranged shutter array for controlling light transmission and light shielding, and a two-dimensional light source side end face. Optical fiber array for guiding light emitted from the light source to the shutter array, and selectively exposing only one of the exposure reference colors among the light emitted from the light source. And a liquid crystal filter for transmitting light.

The liquid crystal filters are R (red), G (green), B
Since only one of the exposure reference colors such as (blue), Y (yellow), M (magenta), and C (cyan) is transmitted, a color separation filter as in the conventional example is not required. Therefore, it is possible to reduce the size of the entire image exposure apparatus.
Further, since the switching of the exposure reference color and the control of the exposure time by the liquid crystal filter depend on the on / off of the liquid crystal element corresponding to each color, the sound is practically silent and the control is very easy.

In the above configuration, a liquid crystal filter may be provided between the light source and the optical fiber array. With this configuration, the light source and the liquid crystal filter can be solidified, and the vibration resistance is significantly improved.

Alternatively, a liquid crystal filter may be provided between the optical fiber array and the shutter array. With this configuration, the shutter array and the liquid crystal filter can be solidified, and the vibration resistance is significantly improved.

In each of the above-described configurations, the liquid crystal filter may include a plurality of liquid crystal elements that transmit only one of the exposure reference colors. For example, when R, G, and B are set as the exposure reference colors, liquid crystals that transmit only R, G, and B light when the liquid crystal elements are turned on are arranged, respectively, so that the light emitted from the light source is arranged. It is possible to easily realize a liquid crystal filter that selectively transmits only one of the exposure reference colors in the emitted light.

In the above arrangement, the driving time of each liquid crystal element corresponding to each exposure reference color may be arbitrarily set. With this configuration, for example, the exposure time can be adjusted according to the sensitivity of the photosensitive material such as photographic paper to each exposure reference color, and the conventionally required light control filter can be omitted. As a result, exposure unevenness can be reduced.

Alternatively, in each of the above structures, the maximum transmittance of each liquid crystal element corresponding to each exposure reference color may be set according to the sensitivity of the medium to be exposed. With this configuration,
The dimming filter conventionally required can be omitted, and the exposure time can be made constant regardless of the sensitivity of the photosensitive material such as photographic paper to each exposure reference color. As a result, exposure unevenness can be reduced.

A guest-host type liquid crystal element may be used as the liquid crystal element. For example, as an exposure reference color,
If the above R, G, B are set,
Three guest-host type liquid crystal elements in which dyes corresponding to G and B are dissolved as guest in host liquid crystal are arranged on an optical path,
By controlling the switching of each liquid crystal element, it is possible to easily realize a liquid crystal filter that selectively transmits only one of the exposure reference colors out of the light emitted from the light source.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIG. 1 shows the configuration of a photographic processing apparatus using the image exposure apparatus of the present invention. The photographic processing apparatus fetches image data from an external device such as an image scanner or a personal computer and stores the image data from a first exposure processing unit 10 that projects an image of the negative film 11 or the like onto the photographic paper 2 and exposes the photographic paper 2. Image information capturing unit 20
And a second exposure processing unit 30 for converting the image data of the image information capturing unit 20 into an optical signal, outputting the optical signal on photographic paper, and exposing the photographic paper, and a developing processing unit 40 for developing the exposed photographic paper.
And a cutting unit 50 for cutting the developed photographic paper frame by frame, a system controller 60 for controlling the operation of the entire system, and the like. The image exposure apparatus of the present invention is used as the second exposure processing section 30.

The first exposure processing section 10 transports each frame of the developed negative film 11 to an exposure position,
The long photographic paper 2 wound in a roll is transported to the exposure position 2b, and the image of each frame of the negative film 11 is exposed on the photographic paper 2 respectively. The image information acquisition unit 20 includes a frame image data storage unit 21 for storing image data acquired from an external device, and a reference image for measuring each pixel density of an image on photographic paper exposed by the second exposure processing unit 30. A reference image data storage unit 22 that stores data in advance,
A line buffer 2 for reading out and temporarily storing image data for one line of the image exposed by the exposure processing unit 30 from the frame image data storage unit 21 or the reference image data storage unit 22
3 and so on.

The second exposure processing section 30 includes the image information capturing section 2
0, the exposure area 2a of the photographic paper 2 is exposed with an image of an exposure reference color such as R, G, B or the like one line at a time based on the image data taken in by 0. Convey by the line. By repeating this operation, an image is exposed on the photographic paper 2.

The development processing section 40 has a liquid tank 41 filled with a developing solution, and the photographic paper 2 exposed by the first exposure processing section 10 and / or the second exposure processing section 30 is stored in the liquid tank 41. The image (latent image) exposed on the photographic paper 2 is made obvious by immersing the photographic paper 2 in the developer. The cutting unit 50 cuts the photographic paper 2 developed in the development processing unit 40 and then dried in the width direction, and divides the photographic paper 2 into one frame unit. 1
The cut photographic paper divided into frame units is discharged to a discharge tray or the like (not shown).

Next, an embodiment of the image exposure apparatus of the present invention used as the second exposure processing section 30 will be described with reference to FIGS. FIG. 2 is a perspective view showing the configuration of the present embodiment.
Is an exposure head 310 for exposing a digital image line by line on the elongate photographic paper 2, and the exposed portion 2 a of the photographic paper 2 is positioned in the X direction at a position facing the shutter array 311 of the exposure head 310. A photographic paper transport mechanism 200 that transports one line at a time, an exposure head controller 320 that controls the exposure head 310, and a photographic paper transport mechanism 200 and an exposure head controller based on image data of each exposure reference color such as R, G, and B. Exposure control section 210 for controlling synchronously with section 320, photographic paper transport control section 201 for controlling the operation of photographic paper transport mechanism 200, and exposure for synchronously controlling image data output control section 322 of exposure head control section 320. It comprises a timing control section 211 and the like.

The exposure head 310 is connected to the line buffer 23
The image data for each of the R, G, and B exposure reference colors sent from the printer is converted into a light signal of a predetermined light intensity in pixel units and output on the photographic paper 2, as shown in FIG. 2 or FIG. As shown in the figure, the shutter unit 310A including the PLZT shutter array 311 and the diffusion filter 313 and the halogen lamp 31
2 and a light source section 310B including a liquid crystal filter 315 are separated, and a shutter section 310A and a light source section 310B are connected by an optical fiber array 314. Shutter unit 3
10A is provided along the width direction (Y direction) of the photographic paper 2.

The optical fiber array 314 includes the shutter unit 3
On the side facing 10A, the sheet is arranged linearly in the width direction (Y direction) of the printing paper 2 to face the shutter array 311 via the diffusion filter 312. On the other hand, on the light source section 310B side, the sections are bundled so as to have a substantially circular cross section.

The light source 310B selectively emits, for example, any one of R, G, and B exposure reference colors among the light emitted from the halogen lamp 312 and the light emitted from the halogen lamp 312. Liquid crystal filter 315 for transmission
And a lens barrel 316 whose inner surface is mirror-finished.

As shown in FIG.
Is composed of guest-host type liquid crystal elements 350R, 350G, 350B corresponding to each of the R, G, and B exposure reference colors and a linear polarizer 351 disposed on an optical path connecting the light source 312 and the optical fiber array 314. ing. The guest-host type liquid crystal element is obtained by dissolving a dichroic dye (guest) having anisotropy in absorption of visible light in the major axis and minor axis directions of molecules in a liquid crystal (host) having a fixed molecular arrangement. When a voltage is applied to the guest-host type liquid crystal element, the molecular arrangement of the host liquid crystal changes, and accordingly, the molecular arrangement of the guest dye also changes. As a result, the amount of visible light absorbed by the dichroic dye can be electrically controlled. By appropriately selecting a dichroic dye, a liquid crystal element that transmits only one of the exposure reference colors such as R, G, B, Y, M, and C can be obtained.

Further, the guest-host type liquid crystal element 350R,
When manufacturing 350G and 350B, depending on the sensitivity of the non-exposure medium such as photographic paper 2 to each of the R, G, and B exposure reference colors,
By adjusting the amount of the guest dye, the maximum transmittance of each of the guest-host type liquid crystal elements 350R, 350G, and 350B can be arbitrarily set. For example, photographic paper 2
Depending on the type, the sensitivity to a specific exposure reference color is high, and even if the drive speed of the PLZT shutter array 311 is set to the highest speed, the exposure may still be over. In this case, the photographic paper 2 can be properly exposed by lowering the maximum transmittance of the corresponding guest-host type liquid crystal element.

Returning to FIG. 2, the exposure head controller 320
The liquid crystal filter control unit 321, P adjusts the exposure time by driving each guest-host type liquid crystal element 350R, 350G, 350B constituting the liquid crystal filter 315.
The LZT shutter array 311 includes an image data output control unit 322 that controls opening and closing of each shutter unit.

The PLZT shutter array 311 is made of a transparent ferroelectric ceramic material obtained by adding lanthanum to lead zirconate titanate, and utilizes the electro-optic effect of the material. As shown in FIGS. 5A and 5B, the PLZT shutter array 311 includes a plurality of long PLZT elements 350 that are shifted from each other by half a pitch on both sides of a concave groove 351 formed at the center in the longitudinal direction. The protrusions 352 and 353 are formed, and the concave groove 351 and the concave groove 351 of the protrusions 352 and 353 are formed.
The common electrode 354 is formed on the surface of the
52 and 353 on the opposite side to the concave groove 351 and PLZT
Driving electrodes 355 and 356 are formed on the plane portion of the element 350. Also, the protrusion 352 of the PLZT element 350
The deflection films 357 and 358 having deflection surfaces orthogonal to each other are arranged on the 353 side and the bottom side.

In the PLZT shutter array 311 thus configured, the common electrode 354 and the driving electrode 355
When a predetermined level of drive voltage is applied between the deflecting film 358 and the projection 352, respectively.
And 353, the light is transmitted to the deflection film 357 side, and when the application of the voltage is stopped, the light is blocked. That is, portions of the protrusions 352 and 353 on the deflection film 357 side (FIG. 5).
The portion indicated by the dot (a)) is a shutter unit (light output unit) that controls the transmission of light on and off, and each shutter unit corresponds to each pixel of the image data. Thus, when a drive voltage is applied to the shutter portion at a position corresponding to each pixel of the image data, the shutter portion is opened and output from the halogen lamp 312, and the liquid crystal filter 315
And the exposure reference colors of the respective colors diffused by the diffusion filter 313 so as to have a substantially uniform light amount are irradiated onto the photographic paper 2. As a result, the printing paper 2 is exposed.

The PLZT shutter array 311
Is configured so as to match the number of pixels for one line of image data (in this embodiment, 2048), and the exposure control unit 210 outputs 1 from the line buffer 23. The image data for each color of R, G, B for the line is sent to the exposure head control unit 320.

The image data output control section 322 of the exposure head control section 320 outputs a signal to a corresponding shutter section based on the image data sent from the line buffer 23, and outputs a signal to each shutter section of the PLZT shutter array 311. , G, and B, applying a different drive voltage to each exposure reference color, opening a shutter unit corresponding to each pixel of the image data,
Each color light from the light source unit 310B is output onto the photographic paper 2 via the diffusion filter 313, and an area on the same line on the photographic paper 2 is exposed three times with light of each color of R, G, and B.

The liquid crystal filter control unit 321 of the exposure head control unit 320 includes guest-host type liquid crystal elements 350R and 35 corresponding to each of the R, G, and B exposure reference colors arranged on the optical path.
Which of the liquid crystal elements to drive is selected from 0G and 350B. Further, each guest-host type liquid crystal element 350 is selected according to the sensitivity of the photographic paper 2 to each of the R, G, and B exposure reference colors.
The drive time of R, 350G, and 350B (exposure time of photographic paper 2) is controlled. As a result, R, G, B
An image based on each exposure reference color is exposed under optimum conditions.

When the exposure based on the image data for one line is completed, the photographic paper transport mechanism 200 is driven, and the photographic paper 2
3 is transported downstream by a length for performing exposure for the next one line. Subsequently, the above procedure is repeated, and exposure based on the next one line of image data is performed. The exposure timing controller 211 controls
By synchronizing the exposure time for the line and the transport of the photographic paper 2 by the photographic paper transport mechanism 200, the entire exposed area 2a of the photographic paper 2 is finally exposed, and one image (latent image) is formed. It is formed.

In the above embodiment, the liquid crystal filter 3
A guest-host type liquid crystal element was used as a liquid crystal element corresponding to each of the R, G, and B exposure reference colors constituting the pixel 12. However, the present invention is not limited to this. Other types of liquid crystal elements may be used as long as they allow transmission.

Further, R (red), G
The case where (green) and B (blue) are used has been described, but the present invention is not limited to this, and Y (yellow), M (magenta), C (cyan), and any other exposure reference colors are used. It goes without saying that the same effect is obtained even in this case.

[0039]

As described above, according to the image exposure apparatus of the present invention, the light source, the shutter array which is arranged one-dimensionally, and controls the light transmission and light shielding, and the light source side end face are arranged two-dimensionally. An optical fiber array in which an end surface on a shutter array side is one-dimensionally arranged to guide light emitted from a light source to a shutter array; and a liquid crystal filter for selectively transmitting only one of exposure reference colors among light emitted from the light source. Therefore, the color separation filter as in the conventional example becomes unnecessary. as a result,
It is possible to reduce the size of the entire image exposure apparatus. Further, since the switching of the exposure reference color and the control of the exposure time by the liquid crystal filter depend on the on / off of the liquid crystal element corresponding to each color, the sound is practically silent and the control is very easy. As a result, it is possible to provide an image exposure apparatus in which the switching of the exposure of each exposure reference color such as R, G, and B and the control of the exposure time are easy and the sound is quiet.

Further, by providing the liquid crystal filter between the light source and the optical fiber array, the light source and the liquid crystal filter can be made solid, and the vibration resistance can be significantly improved. Alternatively, by providing a liquid crystal filter between the optical fiber array and the shutter array,
The shutter array and the liquid crystal filter can be made solid, and the vibration resistance can be significantly improved.

Further, by configuring the liquid crystal filter to include a plurality of liquid crystal elements each transmitting only one of the exposure reference colors, the liquid crystal elements corresponding to the number of exposure reference colors are arranged on the optical path. By controlling the switching of the liquid crystal element, it is possible to easily realize a liquid crystal filter that selectively transmits only one of the exposure reference colors out of the light emitted from the light source.

Also, by setting the drive time of each liquid crystal element corresponding to each exposure reference color arbitrarily, the exposure time can be adjusted according to the sensitivity of the photosensitive material such as photographic paper to each exposure reference color. It is possible to omit the dimming filter which is conventionally required. As a result, exposure unevenness can be reduced. Alternatively, by setting the maximum transmittance of each liquid crystal element corresponding to each exposure reference color in accordance with the sensitivity of the medium to be exposed, it is possible to omit the dimming filter which has been conventionally required, and to use, for example, photographic paper. The exposure time can be made constant regardless of the sensitivity of the photosensitive material to each exposure reference color. As a result, exposure unevenness can be reduced.

Further, by using a guest-host type liquid crystal element as the liquid crystal element, when the above R, G, and B are set as the exposure reference colors, R, G, and B are respectively set.
3 dissolved in host liquid crystal as a guest corresponding to
By arranging two guest-host type liquid crystal elements on the optical path and controlling the switching of each liquid crystal element, a liquid crystal filter that selectively transmits only one of the exposure reference colors out of the light emitted from the light source can be easily formed. It can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a photographic processing apparatus using an image exposure apparatus of the present invention.

FIG. 2 is a diagram illustrating a configuration of an embodiment of an image exposure apparatus of the present invention.

FIG. 3 is a diagram showing details of an exposure head in the embodiment.

FIG. 4 is a diagram showing a configuration of a liquid crystal filter in the embodiment.

5A and 5B are diagrams showing a configuration of a PLZT shutter array, wherein FIG. 5A is a plan view and FIG. 5B is a side view.

FIG. 6 is a diagram illustrating a configuration of a conventional image exposure apparatus.

FIG. 7 is a view showing details of an exposure head in a conventional image exposure apparatus.

FIGS. 8A to 8C are diagrams illustrating the operation of a light control filter in a conventional image exposure apparatus.

FIG. 9 is a diagram illustrating a configuration of a color separation filter in a conventional image exposure apparatus.

[Explanation of symbols]

 300: Image exposure apparatus 310: Exposure head 310A: Shutter section 310B: Light source section 311: PLZT shutter array 312: Halogen lamp 313: Diffusion filter 314: Optical fiber array 315: Liquid crystal filter 316: Lens barrel 350R: R (red) compatible Guest-host type liquid crystal element 350G: Guest-host type liquid crystal element corresponding to G (green) 350B: Guest-host type liquid crystal element corresponding to B (blue)

Claims (7)

[Claims] A light source, a shutter array arranged one-dimensionally to control light transmission and light shielding, the light source side end surface is arranged two-dimensionally, and the shutter array side end surface is arranged one-dimensionally; An image exposure apparatus comprising: an optical fiber array that guides light emitted from the light source to the shutter array; and a liquid crystal filter that selectively transmits only one of the exposure reference colors out of the light emitted from the light source. 2. The liquid crystal filter according to claim 1, wherein the liquid crystal filter is provided between the light source and the optical fiber array.
The image exposure apparatus according to claim 1. 3. An image exposure apparatus according to claim 1, wherein said liquid crystal filter is provided between said optical fiber array and said shutter array. 4. The image exposure apparatus according to claim 1, wherein the liquid crystal filter includes a plurality of liquid crystal elements each transmitting only one of the exposure reference colors. 5. The image exposure apparatus according to claim 4, wherein the drive time of each liquid crystal element corresponding to each of said exposure reference colors can be set arbitrarily. 6. The image exposure apparatus according to claim 4, wherein the maximum transmittance of each liquid crystal element corresponding to each of said exposure reference colors is set according to the sensitivity of a medium to be exposed. 7. The image exposure apparatus according to claim 4, wherein the liquid crystal element is a guest-host type liquid crystal element.