JPH07193735A - View finder and video camera using the view finder - Google Patents

Abstract

PURPOSE:To reduce power consumption and unevenness in luminance by converting light radiated from a small light emitting body of a light emitting element at a wide solid angle into light almost parallel and having narrow directivity by a condenser lens. CONSTITUTION:Light radiated from the light emitting element 12 at a wide solid angle is converted into light almost parallel and having narrow directivity by the condenser lens 15 and made incident from the counter electrode side of a liquid crystal panel 16. An observer contacts his (or her) eye closely to an eyepiece cover 92 and observes a display picture on the panel 16. Namely the position of an observer's pupil is almost fixed. When it is supposed that all picture elements on the panel 16 allow light to go straight on, the lens 15 controls light radiated from the element 12 and made incident upon an effective area of the lens 15 so as to make all of it incident upon the observer's pupil after transmitting it through an enlarging lens 105. Thus the observer can observe the small display picture on the panel 16 as an enlarged image. Namely the observer can observe an enlarged virtual image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a viewfinder having an image display device and a video camera using the viewfinder.

[0002]

2. Description of the Related Art A display device using a liquid crystal panel is a CRT.
Since there is a high possibility that the display device will be lighter and thinner than a display device using, the research and development is active. In recent years, a twist nematic mode (TN mode) liquid crystal display device in which the optical rotatory power of a liquid crystal is applied to an image display has been put into practical use, and is used for a portable pocket television, a viewfinder of a video camera, and the like.

A conventional viewfinder will be described below. For example, as a conventional viewfinder, Japanese Patent Laid-Open No.
The one described in Japanese Patent Publication No. 2-111233 is shown. In this specification, a viewfinder includes at least a light source such as a light emitting element and an image display panel, which are integrally configured.

The external shape of the viewfinder is shown in FIG. A cross-sectional structure of a conventional viewfinder is shown in (Fig. 10). 91 is a body, 92 is an eyepiece cover, 10
6 is an eyepiece ring, and 104 is a TN liquid crystal panel. A TN liquid crystal panel, a backlight as a light source, and the like are stored in the body 91. A magnifying lens 105 is arranged inside the eyepiece ring 106, and the lens functions as a magnifying lens. By adjusting the insertion degree of the eyepiece ring 105, the focus can be adjusted according to the eyesight of the observer. TN
The liquid crystal panel 104 has a liquid crystal layer having a thickness of about 5 μm and includes a mosaic color filter. Also, TN
Polarizing plates 103a and 103b functioning as a polarizer and an analyzer are arranged on both sides of the liquid crystal panel. The viewfinder is attached to the video camera body by the mounting bracket 93. In addition, in order to make each drawing easy to understand,
Some parts are omitted, enlarged or reduced. For example (Fig. 1
In the sectional view of the viewfinder of 0), the eyepiece cover 92 and the like are omitted. The above also applies to the following drawings.

FIG. 11 shows a perspective view of the main elements shown in FIG. The light source is composed of a fluorescent tube box 101 in which fluorescent tubes are arranged, and a diffusion plate 102 arranged on the entire surface thereof. The diffusion plate 102 is used to diffuse the light emitted from the fluorescent plate box 101 to form a surface light source with uniform brightness.

The conventional viewfinder uses a rod-shaped fluorescent tube as a light generating means. The fluorescent tube has a diameter of 2 to 5 mm when the diagonal length of the display screen of the liquid crystal panel is as small as about 1 inch. When the display screen of the liquid crystal panel has a diagonal length of 1 inch or more, a plurality of fluorescent tubes are often used. Light is emitted forward and backward from the fluorescent tube. In order to utilize the light emitted to the rear of the fluorescent tube, a concave reflector is arranged behind the fluorescent tube. The light emitted rearward from the fluorescent tube is reflected forward by the reflector. A diffusion plate 1 is provided between the fluorescent tube and the TN liquid crystal panel 104.
Place 02. The diffusion plate 102 is used for diffusing light from the fluorescent tube and forming a surface light source. The diffusion plate 10
2 forms a surface light source, and the light from the surface light source enters the liquid crystal panel 104. The light diverging area of the surface light source is equal to or larger than the image display area of the liquid crystal panel 104.

A polarizing plate 103 is provided in front of and behind the TN liquid crystal panel.
a and 103b are arranged. The polarizer 103a arranged between the diffusion plate 102 and the TN liquid crystal panel 104 has a function of converting light from a surface light source into linearly polarized light. TN liquid crystal panel 1
04 and a polarizer 103 arranged between the viewer of the display screen
b has a function of blocking the light according to the degree of modulation of the light incident on the TN liquid crystal panel 104. Usually a polarizer 1
03a and the analyzer 103b are arranged so that the polarization directions thereof are orthogonal to each other.

As described above, the surface light source is formed, and the light from the surface light source is converted into linearly polarized light by the polarizer 103a. In the TN liquid crystal panel 104, the linearly polarized light is modulated based on the applied video signal. Analyzer 1
Reference numeral 03b blocks or transmits light depending on the degree of modulation. The image is displayed as described above. The displayed image is
A magnifying lens 10 arranged between the analyzer 103b and the observer.
It can be enlarged and seen by 5.

[0009]

The video camera is required to be compact and lightweight in terms of portability and operability. Therefore, a liquid crystal panel is being introduced as a viewfinder display. However, at present, the power consumption of a viewfinder using a liquid crystal panel is considerably large. For example, the power consumption of the viewfinder using the TN liquid crystal panel is about 0.1 for the TN liquid crystal panel.
W, the light source consumes about 1.0 W, and there is an example of 1.1 W in total. Video cameras have a limited battery capacity to ensure compactness and light weight. When the power consumption of the viewfinder is large, the continuous use time becomes short, which is a big problem.

The following are possible causes of the large power consumption of the TN liquid crystal panel. As mentioned above, T
The N liquid crystal panel requires polarizing plates on the incident side and the emitting side, and the total transmittance of these two polarizing plates is about 30%.
This means that the light utilization efficiency is only 30% at the maximum. Further, the light box including the fluorescent tube and the reflecting plate needs to be a surface light source with less uneven brightness. Therefore, the diffusion plate 102 is arranged between the TN liquid crystal panel 104 and the fluorescent tube. If a diffusion plate 102 having a low light diffusion rate is used,
As shown in FIG. 12, a light emitting pattern 121 of the fluorescent tube appears, which can be seen through the display screen of the liquid crystal panel 104, which deteriorates the display quality. Therefore, the diffuser plate 102 having a high diffusivity is used, but generally, if the diffusivity is increased, the light transmittance of the diffuser plate decreases. In order to obtain the required brightness, there is no choice but to increase the amount of light output from the light source. This causes an increase in power consumption of the light source.

An object of the present invention is to solve the above problems and provide a viewfinder with low power consumption, small size and light weight, and a video camera using the viewfinder.

[0012]

The viewfinder of the present invention is as follows. The light emitted from the small area light emitting portion of the light emitting element in a wide solid angle is converted into light with a narrow directivity by a condenser lens and is incident on a liquid crystal panel which is a light modulating means. As the liquid crystal panel, a polymer dispersed liquid crystal panel that displays an image depending on the degree of light scattering is used. The liquid crystal panel displays the image by modulating the light emitted from the condenser lens according to the image signal. The displayed image can be magnified with a magnifying lens arranged between the observer's eyes and the liquid crystal panel. The condenser lens is attached to a ring-shaped member, and the condenser lens and the generating element can be brought close to each other by moving the position of the member.

In the viewfinder of the present invention, the size of the light source can be small, so that the power consumption of the light source is smaller than that of the conventional light box using the fluorescent tube. Also,
It is possible to reduce the size of the entire viewfinder.
Further, when a polymer dispersed liquid crystal panel is used, a polarizing plate is not necessary and the light utilization rate is high, so that the power consumption can be further reduced. Furthermore, since the position of the condenser lens can be moved, when the viewfinder is not used, the volume of the viewfinder can be reduced by moving the condenser lens so as to be in close contact with the light emitting element.

As the light emitting element of the viewfinder of the present invention, a fluorescent light emitting tube and an LED (Light Emitting Diode) are used.

[0015]

The viewfinder does not require a wide viewing angle because the position of the observer's pupil is almost fixed by the eyepiece cover. That is, when a liquid crystal panel is used for the viewfinder, the light source arranged behind it may have a narrow directivity. When a fluorescent backlight is used as a light source, only light that travels within a small solid angle in a certain direction from a region that is approximately the same size as the display region of the liquid crystal panel is used, and light that travels in another direction is not used.

In the present invention, a light source having a small luminous body is used,
The light emitted from the light-emitting body in a wide solid angle is converted into nearly parallel light by a condenser lens. In this case, the light emitted from the condenser lens has a narrow directivity, and the narrow directivity is sufficient for use in a viewfinder. If the size of the luminous body is small, naturally, the power consumption is also small.

The condenser lens has no aberration and the transmittance is 100%.
In the case, the luminance of the light emitting body viewed through the condenser lens is equal to the luminance of the light emitting body itself. The maximum transmittance of the liquid crystal panel including the color filter and the polarizing plate is 3%, the transmittance of the condenser lens is 90%, and the brightness required for the viewfinder is 15%.
With [ft-L], the brightness required for the light source is about 560.
It becomes [ft-L]. In the present invention, the fluorescent light emitting tube, L
Use ED.

In the viewfinder of the present invention, the light emitted from a light emitting element which has a small light emitting body or a small light emitting area as a light source efficiently collects light emitted in a wide solid angle by a condenser lens. The efficiency is high and the power consumption of the light source is low compared to the case of using.

Further, since the distance between the condenser lens and the light emitting element can be changed, when the viewfinder is not used,
The space between the light emitting element and the condenser lens can be shortened for storage. Therefore, the volume of the viewfinder can be reduced.

The viewfinder of the present invention mainly uses polymer dispersed liquid crystal as an image panel. Since the polymer-dispersed liquid crystal panel does not require a polarizing plate, the brightness of the light source for obtaining the required screen brightness is lower than that of the TN liquid crystal panel. Therefore, the power consumption of the light source can be significantly reduced.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the viewfinder of the present invention. Inside the body 11,
An attachment holder 17 to which the condenser lens 15 and the liquid crystal panel 16 are attached is arranged. Further, an eyepiece ring 106 having a magnifying lens 105 is arranged inside the mounting holder 18. Reference numeral 12 denotes a fluorescent light emitting tube, and the light emitted by the fluorescent light emitting tube 12 is emitted from a hole 14 in the central portion of the light shielding plate 13. In order to absorb unnecessary light, the body and 11, the mounting holders 17, 18 and the like are coated with black or dark inner surfaces. Incidentally. The fluorescent light emitting tube 12 may be replaced with an LED.

By pulling the mounting holder 18 toward the observer, the mounting holder 17 is pulled,
(Fig. 2). (FIG. 1) shows a state in which the viewfinder is not used, that is, a stored state. In addition,
The mounting holders 17 and 18 may be integrated into a mounting holder 17a as shown in FIG. FIG. 2 shows a state in which an image on the liquid crystal panel is observed using the viewfinder. In the state of (FIG. 2), the focus of the condenser lens 15 is set to the light emitting surface of the light emitting element 12. By moving the mounting holder 17 and the like, the volume of the viewfinder can be reduced during storage and the total length can be shortened.

As an example, the diagonal length of the display area of the liquid crystal panel 16 is 28 mm, the effective diameter of the condenser lens 23 is 30 mm, and the focal length is 15 mm. Condenser lens 15
Is a plano-convex lens, the plane of which is directed toward the light emitting element 12 side. The condenser lens 15 and the magnifying lens 105 may be replaced with Fresnel lenses. If a Fresnel lens is used, the viewfinder volume can be reduced and the weight can be reduced.

Reference numeral 13 is a light-shielding plate having a circular hole in the center. It has a function of reducing the region where the light is emitted from the light emitting element 12 to a small region. The larger the area of the hole, the brighter the image displayed on the liquid crystal panel, but the lower the contrast. This is because the amount of light entering the condenser lens 15 increases, but the directivity of the incident light deteriorates.

The light emitted from the light emitting element 12 in a wide solid angle is converted into light with a narrow directivity by a condenser lens 15, and the light is converted into a light having a narrow directivity, which is an opposite electrode (not shown) of the liquid crystal panel 16.
Incident from the side. The liquid crystal panel 16 is preferably a polymer dispersion panel. The polymer-dispersed liquid crystal panel changes the amount of light transmitted through the liquid crystal or the degree of scattering of the liquid crystal in accordance with an applied video signal to form an image. The observer brings his or her eyes into close contact with the eyepiece cover 92 to see the display image on the liquid crystal panel 16. That is, the position of the observer's pupil is almost fixed. Assuming that all the pixels of the liquid crystal panel 16 let light travel straight, the condenser lens 15 is radiated from the light emitting element 12, and the light incident on the effective area of the condenser lens 15 is all observed after passing through the magnifying lens 105. Incident on the eyes of the person. In this way, the observer can magnify and see a small display image on the liquid crystal panel 16. In other words, you can see the enlarged virtual image.

Since the position of the observer's pupil of the viewfinder is substantially fixed by the eyepiece cover 92, the light source arranged behind it may have a narrow directivity. In a conventional viewfinder that uses a light box that uses a fluorescent tube as a light source, only light that travels within a small solid angle in one direction from a region that is almost the same size as the display region of the liquid crystal panel is used, and in the other direction. The traveling light is not used. That is, the light utilization efficiency is very poor.

In the present invention, a light source having a small luminous body is used,
The light emitted from the light-emitting body in a wide solid angle is converted into nearly parallel light by the condenser lens 15. In this way, the directivity of the light emitted from the condenser lens 15 becomes narrow. If the observer's viewpoint is fixed, the above-mentioned narrow directional light is sufficient for the viewfinder. If the size of the luminous body is small, naturally, the power consumption is also small. As described above, the viewfinder of the present invention utilizes that the observer views the displayed image with the viewpoint fixed. A normal direct-viewing liquid crystal panel requires a certain viewing angle, but a viewfinder is sufficient as an application if a displayed image can be satisfactorily observed from a predetermined direction.

The condenser lens 15 has no aberration and the transmittance is 10
In the case of 0%, the brightness of the light emitter viewed through the condenser lens 15 is equal to the brightness of the light emitter itself. If the maximum transmittance of the liquid crystal panel including the color filter, the polarizing plate, and the aperture ratio of the image is 3%, the transmittance of the condenser lens 15 is 90%, and the brightness required for the viewfinder is 15 [ft-L]. The luminance required for the light source is about 560 [ft-L]. Light emitting devices that satisfy these requirements include cathode ray tubes, fluorescent tubes, and other light emitting tubes that use the light emitting principle, fluorescent light emitting elements, xenon lamps,
Halogen lamp, tungsten lamp, metal halide lamp, LED, EL (Electro Lumine)
element that emits light by the action of electrons such as
PDP (Plasma Display Panel)
Illustrative examples include those that self-luminece such as those that emit light upon discharge. Although any of these light emitting elements may be used as the light generating means, the fluorescent light emitting tube or the LED is most preferable in view of low power consumption, small size, and white light emission.

Although a TN liquid crystal panel may be used as the liquid crystal panel 16, high brightness display can be performed by using a liquid crystal panel using polymer dispersed liquid crystal. The polymer dispersed liquid crystal panel does not use a polarizing plate. When the TN liquid crystal panel is used, the total light transmittance of the polarizer and the analyzer is about 30%, but the polymer-dispersed liquid crystal panel displays almost three times as high brightness as the TN liquid crystal panel. be able to. When the liquid crystal panel 16 is in the transmissive state, light having a narrow directivity is made to reach the observer's pupil by the condenser lens 16, and the liquid crystal panel 16 scatters the light in accordance with a video signal to cause the observer's pupil to be scattered. A system capable of performing black and white display without reaching the range is suitable as the optical system configuration of the viewfinder of the present invention. An example thereof is a liquid crystal panel using polymer dispersed liquid crystal, but the invention is not limited to this. For example, there are a liquid crystal panel using a dynamic scattering mode (DSM), a ferroelectric liquid crystal panel in a scattering mode, a display panel using PLZT, and the like, which can perform light modulation operations of scattering and transmission. It can be used as the light modulator of the present invention.

The polymer dispersed liquid crystal panel will be briefly described below. Polymer dispersed liquid crystals are roughly classified into two types depending on the dispersion state of liquid crystals and polymers. One is a type in which liquid crystals in the form of water droplets are dispersed in a polymer.
The liquid crystal exists in the polymer in a discontinuous state. Hereinafter, such a liquid crystal will be referred to as a PDLC, and a liquid crystal panel using the liquid crystal will be referred to as a PD liquid crystal panel.

The other type is a type in which liquid crystals are dispersed in a continuous state. Hereinafter, such a liquid crystal will be referred to as a PNLC, and a liquid crystal panel using the liquid crystal will be referred to as a PN liquid crystal panel. In order to display an image with the above-mentioned two kinds of liquid crystal panels, light scattering and transmission are controlled.

PDLC utilizes the property that the refractive index is different in the direction in which the liquid crystal is aligned. When no voltage is applied, each water droplet liquid crystal is oriented in an irregular direction. In this state, a difference in refractive index occurs between the polymer and the liquid crystal, and incident light is scattered. When a voltage is applied here, the alignment directions of the liquid crystal are aligned. If the refractive index when the liquid crystal is oriented in a certain direction is matched with the refractive index of the polymer in advance, incident light is transmitted without being scattered.

On the other hand, PNLC uses the irregularity of the alignment of liquid crystal molecules. The incident light is scattered in the irregular alignment state, that is, in the state where no voltage is applied.
On the other hand, when a voltage is applied and the arrangement state is made regular, light is transmitted. In the present invention, the PD liquid crystal panel is not limited to one of the PD liquid crystal panel and the PN liquid crystal panel, but the PD liquid crystal panel will be described as an example for ease of description. Also,
PDLC and PNLC are collectively referred to as polymer dispersed liquid crystal, and PD liquid crystal panel and PN liquid crystal panel are collectively referred to as polymer dispersed liquid crystal panel. Further, the liquid crystal dispersed in the polymer-dispersed liquid crystal layer in the form of water drops is called a water drop liquid crystal, and the resin component in the peripheral portion of the water drop liquid crystal is called a polymer.

Operation of polymer-dispersed liquid crystal (FIG. 5)
A brief description will be given using (a) and (b). (Fig. 5 (a)
(B) is an explanatory view of the operation of the polymer dispersed liquid crystal. In FIGS. 5A and 5B, 52 is an array substrate on which TFTs and the like are formed, 54 is a pixel electrode, 53 is a counter electrode, and 55.
Is a water droplet liquid crystal, 56 is a polymer, and 53 is a counter electrode substrate. A TFT (not shown) or the like is connected to the pixel electrode 54, and a voltage is applied to the pixel electrode by turning the TFT on and off to change the liquid crystal alignment direction on the pixel electrode to modulate light. As shown in (FIG. 5A), in the state in which no voltage is applied, the liquid crystal droplets 55 are oriented in irregular directions. In this state, a difference in refractive index occurs between the polymer 56 and the water droplet liquid crystal 55, and the incident light 57 is scattered. Here, as shown in FIG. 5B, when a voltage is applied to the pixel electrode 54, the directions of the liquid crystal are aligned. When the refractive index when the liquid crystal is aligned in a certain direction is matched with the refractive index of the polymer 56 in advance, incident light is emitted from the array substrate 52 without being scattered.

As the liquid crystal material used in the polymer dispersed liquid crystal panel of the viewfinder of the present invention, nematic liquid crystal, smectic liquid crystal and cholesteric liquid crystal are preferable, and single or two or more kinds of liquid crystal compounds or substances other than liquid crystal compounds are also preferable. It may be a mixture containing. Among them, among the liquid crystal materials described above, a cyanobiphenyl nematic liquid crystal having a relatively large difference between the extraordinary refractive index ne and the ordinary light refractive index no is preferable. In addition, a chloro nematic liquid crystal is preferable because it does not change with time and is stable. A transparent polymer is preferable as the polymer matrix material, and the polymer may be either a thermoplastic resin or a photocurable resin, but it is UV-curable from the viewpoint of ease of manufacturing process, separation from the liquid crystal layer, etc. It is preferred to use the type of resin. As a specific example, an ultraviolet curable acrylic resin is exemplified, and a resin containing an acrylic monomer or an acrylic oligomer which is polymerized and cured by ultraviolet irradiation is particularly preferable.

As such a polymer-forming monomer,
2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, neopentyl glycol acrylate, hexanediol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate,
Examples include trimethylolpropane triacrylate, pentaerythritol acrylate and the like.

Examples of the oligomer or prepolymer include polyester acrylate, epoxy acrylate and polyurethane acrylate.

A polymerization initiator may be used to accelerate the polymerization, and as an example, 2-hydroxy-2-methyl-1-phenylpropan-1-one-("Darocur 1173" manufactured by Merck & Co., Inc.) is used. , 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1-
ON (“Darocur 1116” manufactured by Merck & Co., Inc.), 1-vidroxycyclohexyl phenyl ketone (“Irgacure 651” manufactured by Ciba-Gaiki), and the like are applicable. In addition, a chain transfer agent, a photosensitizer, a dye, a cross-linking agent and the like may be appropriately used as an optional component.

Although the proportion of the liquid crystal material in the polymer dispersed liquid crystal is not specified here, it is generally 20% by weight to 95% by weight.
The degree is good, preferably about 50 to 85% by weight. If it is 20% by weight or less, the amount of water-drop liquid crystals is small, and the scattering effect is poor. Also, if it is more than 95% by weight, the polymer and the liquid crystal tend to be phase separated into upper and lower layers,
The proportion of the interface between the liquid crystal and the polymer becomes small, and the scattering characteristics deteriorate. The structure of the polymer-dispersed liquid crystal layer varies depending on the ratio of the liquid crystals. At about 50% by weight or less, the liquid crystals exist as independent droplets, and at 50% by weight or more, the polymer and the liquid crystals form a continuous layer.

The thickness of the liquid crystal layer is preferably in the range of 5 to 30 μm, more preferably 10 to 15 μm. If the film thickness is thin, the scattering characteristics deteriorate and the contrast cannot be obtained. On the other hand, if it is thick, high-voltage driving must be performed, making it difficult to design a drive IC that drives the liquid crystal. In addition, the power consumption of the drive IC also increases.

Further, the average value of the particle size of the water droplet liquid crystal is 0.
If it is not less than 5 μm and not more than 3.0 μm, the scattering characteristics are poor and sufficient contrast cannot be obtained. Moreover,
The particle diameter is preferably 1.5 μm or more and 2.5 μm or less. In the case of PNLC, the hole diameter of the polymer, that is, the hole diameter of the polymer network, corresponds to the above-mentioned particle diameter, which corresponds to the above-mentioned particle diameter.

In the polymer dispersed liquid crystal panel, the light scattering degree of each pixel changes when the voltage applied to each pixel is changed. The light scattering degree is the largest when no voltage is applied, and the light scattering degree decreases when the applied voltage is increased. When light with narrow directivity is incident on the liquid crystal panel 16 and the degree of light scattering is changed,
The amount of light that enters the viewer's pupil from that pixel changes. That is, the brightness of the pixel viewed from the observer changes, and this is utilized to display an image.

FIG. 7 is a signal circuit block diagram of the liquid crystal panel. In FIG. 7, reference numeral 71 is a video amplifier for amplifying a video signal to a predetermined value, 72 is a phase division circuit for producing a positive polarity and a negative polarity video signal, and 73 is an AC video signal whose polarity is inverted for each field. Output switching circuit, 16 is a liquid crystal panel, 74 is a source drive IC
75 is a driver control circuit for synchronizing and controlling the gate drive IC 76 and the gate drive IC 76.

The signal processing circuit of the liquid crystal panel will be described below. First, the video signal is subjected to gain adjustment by the video amplifier 71 so that the video output amplitude corresponds to the electro-optical characteristics of the liquid crystal. Next, the gain-adjusted video signal enters the phase division circuit 72, and two video signals of positive polarity and negative polarity are produced. These two video signals enter the output switching circuit 73, and the video signals whose polarities are inverted for each field are output. The reason for inverting the polarity of the signal for each field is to prevent the liquid crystal from being deteriorated by applying the AC voltage. Next, the video signal from the output switching circuit 73 is input to the source drive IC 75, and the source drive IC 75 performs signal processing such as level shift and sample hold of the video signal according to the control signal from the drive control circuit 74 to perform gate drive. A predetermined voltage is output to the source signal line of the liquid crystal panel 215 in synchronization with the IC 76.

When an ON voltage is applied to the gate signal line,
The TFT connected to the gate signal line is turned on, and the video signal output to the source signal line is applied to the pixel electrode. Further, the TFT is turned off by applying the off voltage to the gate signal line, and the signal applied to the pixel voltage is held for one field. In the case of the polymer-dispersed liquid crystal, a driving voltage higher than that of the TN liquid crystal is required, and a maximum voltage of about ± 6.5 V must be applied to the liquid crystal.

A mosaic color filter (not shown) is attached to the liquid crystal panel 16. The pixel arrangement is a so-called delta arrangement. Color filters are red, green,
Transmits one of the colors blue. The film thickness of each color may be controlled by the composition of the color filter. The film thickness of the color filter is adjusted and formed when the color filter is manufactured. That is, the thickness of the color filter is changed between red, green and blue. The thickness of the liquid crystal on each pixel can be adjusted according to the color of each color filter by the thickness of the color filter. The condenser lens 15 has a flat surface, that is, a surface having a large radius of curvature facing the light emitting element 12 side. This is because it is easy to satisfy the sine condition and the brightness uniformity of the display image on the liquid crystal panel 16 is improved. However, it goes without saying that the condenser lens 15 is not limited to the above-described plano-convex lens and may be a normal positive lens. Further, it may be replaced with a Fresnel lens or the like.

By adjusting the degree of insertion of the eyepiece ring 106 into the body 11, the focus can be adjusted according to the visual acuity of the observer. Since the position of the observer's eyes is fixed by the eyepiece cover 92, the viewpoint position rarely shifts during use of the viewfinder.
If the viewpoint is fixed, the observer can see a good image even if the directivity of light to the liquid crystal panel 16 is narrow.
In order to make it look better, the emission direction of the light from the light emitting element 12 may be moved to an optimum direction.

As shown in FIG. 3, a diaphragm 31 may be used to vary the light emitting area of the light emitting element. The diaphragm 31 may be a variable diaphragm used in a camera, and the hole diameter 14 of the diaphragm 31 may be changed by rotating a lever (not shown) taken out of the body 11. However, it is necessary to arrange so that the center of the diaphragm 31 passes through the central axis of the condenser lens 15. Aperture 3
When the size of 1 is changed, the size of the light emitting portion of the light emitting element 12 is changed and the directivity of the light emitted from the condenser lens 15 is changed. Therefore, the contrast of the display image on the liquid crystal panel 16 is changed. You can The viewing angle can also be adjusted.
While observing the displayed image, the observer can adjust the position to obtain the best display by using the lever.

FIG. 6 is a sectional view of a fluorescent light emitting tube used in the viewfinder of the present invention. As shown in (FIG. 6), the fluorescent light emitting tube has a miniature bulb shape in appearance.
61 is a case made of glass and has a diameter of 5 mm to 2
It is 0 mm. 63 is a filament, DC 4V ~
By applying a voltage of about 8 V, the filament 63
To heat. 64 is an anode and the applied voltage is DC 15
It is about 25V. The anode voltage accelerates the electrons emitted by heating the filament 63. Mercury molecules (not shown) are enclosed in the case 61,
The accelerated electrons emit ultraviolet rays by colliding with mercury molecules. This ultraviolet ray excites the phosphor 62 to generate visible light.

The amount of emitted light can be adjusted by performing pulse driving. The pulse period is 30 hertz or more, preferably 60 hertz or more. By making the voltage applied to the anode a pulse signal, the amount of emitted light can be varied in proportion to the pulse width.

As shown in FIG. 6B, if a light shielding film 65 is formed on the case 61 to reduce the emission area of the light emitted from the light emitting element, the light shielding as shown in FIG. Boards are no longer needed.

A white light emitting LED may be used as the light emitting element. The light-emitting body of the LED is composed of light-emitting chips of three colors of red, green and blue, and each terminal of the light-emitting chips of each color is provided with a common terminal and a total of four terminals. The three light emitting chips are molded with transparent resin. The optimum number of light emitting chips of each color are densely molded so as to achieve color balance so as to obtain white light.

The LED can adjust the emission color by controlling the voltage or current applied to each of the red, green and blue light emitting chips, and can also adjust the chromaticity of the image displayed on the liquid crystal panel 16. it can. This chromaticity adjustment is extremely easy as compared with the case where the backlight 101 is used.

As shown in FIG. 1, by making the mounting holder 17 movable, the volume and overall length when using the viewfinder can be reduced. further,
To shorten the total length, the structure as shown in FIG. 4 may be used. The light emitted from the light emitting element 12 is reflected by the mirror 42.
The light is deflected in the direction of incidence and enters the condenser lens 15. A portion of the body 11 into which the light emitting element 12 is inserted is inserted into the video camera body. That is, the positive lens 105 is rotatable about the portion where the light emitting element 12 is inserted so that the positive lens 105 can be oriented horizontally or vertically. The display image on the liquid crystal panel 16 can be viewed by freely changing the direction in the upward direction or the horizontal direction. The light from the light emitting element 12 is reflected by the mirror 42.
The light is deflected in the direction of 0 ° and enters the condenser lens 15. Since the other parts and matters are the same as the configurations and contents already described, the description thereof will be omitted.

As described above, in the viewfinder of the present invention, the light emitted from the small light-emitting body of the light-emitting element 12 in a wide solid angle is efficiently condensed by the condenser lens 15, so that the surface using the fluorescent tube is used. The power consumption of the light source can be significantly reduced as compared with the case of using the backlight of the light source.

By using a polymer dispersed liquid crystal panel as the liquid crystal panel 16, it is possible to increase the brightness of the displayed image or to significantly reduce the power consumption, but it is naturally possible to use the TN liquid crystal panel. Although the TN liquid crystal panel displays pixels by transmitting and blocking light, it is clear that in the viewfinder structure of the present invention, the light from the light emitting element 12 is modulated and a virtual image can be seen through the magnifying lens 105. It is necessary to dispose polarizing plates before and after the TN liquid crystal panel. However, due to the transmittance loss of the two polarizing plates, in order to ensure the required brightness, the light source of The output increases, and the power consumption increases in proportion to the output. However, since the size of the light emitting body of the light source may be small, the power consumption is smaller than that in the case of using a backlight as in the conventional viewfinder. Moreover, since the diffusion plate 102 is used, no brightness distribution occurs on the screen. Further, since the light incident on the liquid crystal panel has a narrow directivity, the display contrast is improved. In addition, the TN liquid crystal panel includes a liquid crystal panel using a super twist nematic (STN) mode in which a twist angle of liquid crystal molecules is 90 degrees or more. Of course, it is not limited to the active matrix type liquid crystal panel,
A simple matrix type liquid crystal panel may be used. Further, a liquid crystal panel using ferroelectric liquid crystal may be used. As described above, the liquid crystal panel used in the viewfinder of the present invention is not limited to the polymer dispersed liquid crystal panel, and other liquid crystal panels may be used. Further, any display device capable of modulating light may be used. For example, a display panel using PLZT may be used.

FIG. 8 is an explanatory view showing a state in which the viewfinder of the present invention is attached to a video camera. The body 11 of the viewfinder is attached to the video main body by the same fittings as the conventional example shown in FIG. Reference numeral 16 is a polymer dispersed liquid crystal display panel, and the diagonal length of the display screen is 0.7 inch. Reference numeral 84 is a drive circuit for the liquid crystal panel mainly shown in (FIG. 7). Light emitting element 12
Fluorescent light produced by Mini Pyro Electric Co. (Lunalight-0
7 series). The arc tube has a diameter of 7 mm and emits white light. A voltage is supplied from the arc tube power supply circuit 83 to the fluorescent arc tube. The arc tube power supply circuit 83 is
A heater voltage of 5.0 V and an anode voltage of 23 V are supplied to the fluorescent light emitting tube 12. Both voltages are DC voltages. The arc tube power supply circuit 83 has a circuit for pulse-modulating the anode voltage. The pulse period is 60 hertz. By making the voltage applied to the anode a pulse signal, the amount of emitted light can be varied in proportion to the pulse width. The ratio of pulse width can be continuously changed from 0 to 1/1 by rotating a volume attached to the video body. As an example, when the pulse width is 1/2, the brightness of the arc tube 12 is about 800 (ft-L). In the case of 1/1, that is, the state where the anode voltage is continuously applied, it doubles to 1600 (ft-L). Brightness of arc tube is 8
When it is 00 (ft-L), the power consumption of the light source is about 0.4W.
Met. On the other hand, a video signal is output from the CCD sensor 81 and applied to the video amplifier 71 of the liquid crystal drive circuit 84 to display an image on the liquid crystal panel 16. The video signal recorded on the video tape is reproduced by the reproducing circuit 85 and applied to the video amplifier 71. Reference numeral 82 denotes a battery attached to the main body of the video camera, which includes an arc tube power supply circuit 83, a liquid crystal drive circuit 84, and a reproduction circuit 85.
Supply power to.

[0059]

As is apparent from the above description, the viewfinder of the present invention allows light emitted from a small light emitting element of a light emitting element in a wide solid angle to be parallel to a condensing lens and has a narrow directivity. Since the image is converted into the image and modulated by the liquid crystal panel to display the image, the power consumption is small and the uneven brightness is small. In addition, the drive circuit of the light emitting element has a simpler structure than that of a conventional viewfinder that uses a backlight, so that a compact and lightweight viewfinder can be provided. If a polymer-dispersed liquid crystal panel is used as the liquid crystal panel, the power consumption can be further reduced as compared with the TN liquid crystal panel.

Further, since the distance between the condenser lens and the light emitting element is variable, the volume and the total length of the viewfinder can be shortened when the viewfinder is used. A video camera is desired to be compact, and by using the viewfinder of the present invention, both low power consumption and compactness can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a viewfinder according to an embodiment of the present invention when it is stored.

FIG. 2 is a sectional view of the viewfinder in use according to an embodiment of the present invention.

FIG. 3 is a sectional view of a viewfinder according to another embodiment of the present invention.

FIG. 4 is a sectional view of a viewfinder according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram of the operation of the polymer-dispersed liquid crystal.

FIG. 6 is a sectional view of a light emitting element of a viewfinder.

FIG. 7 is a block diagram of a signal processing circuit of a liquid crystal panel.

FIG. 8 is a block diagram when the viewfinder of the present invention is attached to a video camera.

FIG. 9 is an external perspective view of a conventional viewfinder.

FIG. 10 is a sectional view of a conventional viewfinder.

FIG. 11 is a perspective view of main components of a conventional viewfinder.

FIG. 12 is a plan view of the light box.

FIG. 13 is a sectional view of a viewfinder according to another embodiment of the present invention.

[Explanation of symbols]

 11, 91 Body 12 Fluorescent arc tube 13 Light-shielding plate 14, 41 Hole 15 Condensing lens 16 Polymer dispersed liquid crystal panel 17, 18, 17a Mounting holder 31 Aperture 42 Mirror 51 Counter electrode substrate 52 Array substrate 53 Counter substrate 54 Pixel electrode 55 Water-drop liquid crystal 56 Polymer 57 Incident light 61 Case 62 Phosphor 63 Filament 64 Anode 65 Light-shielding film 71 Amplifier 72 Phase division circuit 73 Output switching circuit 74 Drive control circuit 75 Source drive IC 76 Gate drive IC 81 CCD sensor 82 Battery 83 Arc tube Power supply circuit 84 Liquid crystal panel drive circuit 85 Playback circuit 92 Eyepiece cover 93 Mounting bracket 101 Fluorescent tube box 102 Diffusing plates 103a and 103b Polarizing plate 104 TN liquid crystal panel 105 Magnifying lens 106 Eyepiece 121 Luminous pattern of fluorescent tube

Claims (12)

[Claims] 1. A light generating means, a light collecting means for converting light emitted from the light generating means into substantially parallel light, and a light modulation for modulating light emitted from the light collecting means to form an optical image. And a means for changing the distance between the light condensing means and the light generating means. 2. A light generating means for emitting white light, a condensing means for converting the light emitted from the light generating means into substantially parallel light, and a light emitted from the condensing means is modulated to form an optical image. And a magnifying display means for magnifying the optical image and displaying the magnified optical image so that it can be seen by an observer, and a first member to which the condensing means and the light modulating means are attached. A second member to which the magnifying display means is attached, and the distance between the light generating means and the condensing means is variable by moving the position of the first member. A viewfinder characterized in that the distance between the light modulating means and the magnifying display means can be varied by moving the position of the member. 3. The viewfinder according to claim 1, wherein the light modulating means is a display panel which forms an optical image as a change of a light scattering state according to a video signal. 4. The light collecting means is characterized in that the light emitted from the light generating means and entering the effective area of the light collecting means and traveling straight through the light modulating means reaches the observer's pupil. The viewfinder according to claim 1 or 2. 5. The viewfinder according to claim 1, wherein the light emitting area of the light generating means is smaller than the image display area of the light modulating means. 6. The viewfinder according to claim 1, wherein the light modulating means is a polymer dispersed liquid crystal panel which forms an optical image as a change of a light scattering state according to a video signal. 7. The viewfinder according to claim 2, wherein an eyepiece cover capable of substantially fixing the viewpoint position of the observer is arranged between the magnifying display means and the observer. 8. The viewfinder according to claim 1, wherein the light converging means is a plano-convex lens, and the plane portion of the lens is arranged so as to face the light generating means. 9. The viewfinder according to claim 1 or 2, wherein the light generating means has one of an LED and a fluorescent light emitting tube as a light emitting source. 10. A diaphragm for changing the region for emitting light is provided on the light emitting surface of the light generating means.
Alternatively, the viewfinder according to claim 2. 11. The viewfinder according to claim 1, wherein a mirror that bends the traveling direction of light is arranged between the light generating means and the light collecting means. 12. A video camera comprising the viewfinder according to claim 1 or 2, and a power supply for supplying electric power to the light generating means and the light modulating means of the viewfinder.