JP2003186006A - Display device, electronic viewfinder and image pickup device using these - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic viewfinder which is used for video display of an active matrix type liquid crystal display panel or the like provided with a thin film transistor for each pixel and whose light utilizing efficiency is enhanced. <P>SOLUTION: The electronic viewfinder having a light source (LED1), an active matrix type liquid crystal display panel (LCD3) provided with a thin film transistor (TFT11) in each pixel and a reflection part for reflecting light from the LED1 to the LCD3 is characterized in that the reflection part is provided with a polarized light separation film 2 for selectively reflecting a prescribed light component and selectively transmitting the other light component and a polarizing film 9 disposed on the side opposite to the LCD3 of the polarized light separation film 2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, an electronic viewfinder, and an image pickup device using the same, and more specifically, to an active matrix type liquid crystal display panel (Liquid Crystal Displp) having a thin film transistor in each pixel.
ay: hereinafter, it relates to a technique for improving light utilization efficiency in a reflection type electronic view finder (hereinafter, EVF) used for displaying images such as LCD.

[0002]

2. Description of the Related Art An electronic viewfinder is a device mounted on a video camera or the like for checking an image being picked up.
It has a built-in optical type and a liquid crystal display device such as an LCD that allows the light captured by the imaging lens to be spectrally viewed.
EVF that displays the image being captured as video data
There is. The EVF is mainly mounted on a digital video camera, a digital still camera, or the like.

The principle of a general reflection type electronic viewfinder is as shown in FIG.
The half mirror 20 that does not polarize the light from 01
Polarizing film 20 reflected by 2 and positioned below
The reflection type liquid crystal display panel (LCD) 204 is irradiated with the light through 3 and the light reflected by the reflection type LCD 204 is made visible again through the polarizing film 203, the half mirror 202, and the magnifying eyepiece convex lens 205. ing.

The polarizing film 203 allows only a desired light component of the light components from the light source to pass therethrough and prevents the other light components from passing therethrough. For example, as shown in FIG.
There is a transmission axis 203A and an absorption axis 203B which are orthogonal to each other. Here, the light component transmitted through the polarizing film 203 (light component necessary for LCD display) is a P wave, and the light component absorbed by the polarizing film 203 is S. Let it be a wave.

Therefore, in the above EVF configuration, the LED 20
The light from No. 1 is reflected by the half mirror 202, the light (P wave, S wave) is polarized by the polarizing film 203 into only P wave, and this P wave is irradiated to the LCD 204.

[0006]

However, the above-mentioned E
The VF configuration has a problem of low light utilization efficiency.
That is, in the EVF configuration, for example, assuming that the light from the LED 201 is 100%, the light is reflected by the half mirror 202, and the light component toward the LCD 204 side is about 50%.
Is further reduced to about 25% when passing through the polarizing film 203, and again the polarizing film 203
It is considered that the transmittance of light from the light source is reduced to about 12.5%, and finally the utilization efficiency of light from the light source is reduced to about 1/10.

Therefore, the present invention provides an electronic viewfinder which is used for image display of an active matrix type liquid crystal display panel or the like having a thin film transistor in each pixel and which improves the light utilization efficiency thereof. An object of the present invention is to provide a display device to be mounted, and an imaging device using the display device and the electronic viewfinder.

[0008]

In view of the above problems, a display device according to claim 1 of the present invention is directed to a light source, an active matrix type liquid crystal display panel having a thin film transistor in each pixel, and light from the light source. In the liquid crystal display panel having a reflection part, the reflection part selectively reflects a predetermined light component and selectively transmits another light component, and the polarization separation film. It is characterized by comprising a polarizing film disposed on the opposite side of the film from the liquid crystal display panel.

Further, in the display device according to claim 2 of the present invention, the polarizing film transmits the light component selectively transmitted by the polarization separating film and the light selectively reflected by the polarization separating film. It is characterized in that it is arranged so as to block the components.

Further, the display device according to claim 3 of the present invention is characterized in that the polarization separation film has a transmission axis and a reflection axis which are orthogonal to each other.

The display device according to claim 4 of the present invention is characterized in that the polarizing film has a transmission axis and an absorption axis which are orthogonal to each other.

Further, in the electronic viewfinder according to claim 5 of the present invention, a light source, an active matrix type liquid crystal display panel having a thin film transistor in each pixel, and a reflection for reflecting light from the light source to the liquid crystal display panel. In the one having a section, the reflection section selectively reflects a predetermined light component and selectively transmits another light component, and a side opposite to the liquid crystal display panel of the polarization separation film. And a polarizing film disposed on the.

Further, in the electronic viewfinder according to claim 6 of the present invention, the polarization film transmits the light component selectively transmitted by the polarization separation film, and the polarization separation film selectively reflects the light component. It is characterized in that it is arranged so as to block light components.

Furthermore, the electronic viewfinder according to claim 7 of the present invention is characterized in that the polarization separation film has a transmission axis and a reflection axis which are orthogonal to each other.

The electronic viewfinder according to claim 8 of the present invention is characterized in that the polarizing film has a transmission axis and an absorption axis which are orthogonal to each other.

An image pickup device according to claim 9 of the present invention is characterized by including the display device or the electronic viewfinder according to any one of claims 1 to 8.

With the above structure, in the present invention, by disposing the polarizing film behind the polarization separating film that reflects the light emitted from the light source side and irradiates the LCD, it is desired to transmit the light leaked from the polarization separating film. Light components that are not present can be absorbed, and the appearance of the image can be prevented from being impaired.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a display device, an electronic viewfinder, and an image pickup device using them according to the present invention will be described below with reference to the drawings. In the following description, a liquid crystal display panel (LCD) will be used as an example of the liquid crystal display panel.

(First Embodiment) The first embodiment will be described in detail below.

In FIG. 1, a reflection type electronic viewfinder (EVF) reflects light from a light source (for example, an LED) 1 by a polarization separation film 2 so that only a desired light component is reflected (polarized light) and is positioned below. The reflected LCD 3 is irradiated with the light, and the light reflected by the reflective LCD 3 is made visible through the polarization separation film 2 and the eyepiece convex lens 4 for enlargement.

The polarization separation film 2 reflects a desired light component of the light components from the light source and transmits other light components. For example, as shown in FIG. 2A, the polarization separation film 2 has a transmission axis 2A and a reflection axis 2B which are orthogonal to each other, and here, the light component reflected by the polarization separation film 2 (display of LCD). Is a P-wave, and the light component transmitted by the polarization separation film 2 is an S-wave.

In the above EVF configuration, the LED
When the LCD 3 is driven when the P wave formed by the light from the light 1 being reflected by the polarization separation film 2 is applied to the LCD 3, the P wave remains as it is.
Since the P wave is reflected to the side, and the P wave is reflected to the LED 1 side by the polarization separation film 2 (since it does not pass through the polarization separation film 2), it is visually recognized as black. Also LCD
3 is not driven, the P wave is converted into an S wave by the orientation of the LCD 3 and is reflected to the polarization separation film 2 side. Since the S wave passes through the polarization separation film 2, it becomes white. Will be seen.

A general use example of the above polarization separation film will be described. As shown in FIG.
3, the polarization separation film 2 is disposed between the backlight 10 and the backlight 10 which emits light from below, and the light from the backlight 10 is transmitted through the polarization separation film 2 to the LCD.
Irradiate 3 At this time, of the light components from the backlight 10, only the desired light component (for example, P wave) is transmitted by the polarization separation film 2, and the other light component (S wave) is transmitted.
Is to reflect to the backlight side. And
Of the S waves reflected by the polarization separation film 2, if there is one that has changed from the S wave to the P wave while the reflection between the polarization separation film 2 and the backlight 10 is repeated, the P wave is polarized. It is configured to pass through the separation film 2.

By using the polarization separation film 2 as described above, the conventional polarization film absorbs components other than the transmitted light component, and the light utilization efficiency drops to 50% at the time of transmission through the polarization film. However, in the polarization splitting film 2, after 50% of the light component is transmitted first, of the reflected light components, the light components that can be transmitted (from S wave to P
The changed amount (about 20 to 30%) is added to the light wave, and the light utilization efficiency is about 8 compared to the conventional polarizing film.
It can be improved to 0%. This embodiment focuses on the characteristics of the polarization separation film and uses the polarization separation film in a reflective EVF.

Furthermore, in this embodiment, as an example of the polarization separation film 2, DBEF manufactured by Sumitomo 3M Limited is used.
(Dual Brightness Enhancement Film) has been described, but the present invention is not limited to this. For example, a brightness enhancement film (NIPOCS-PC manufactured by Nitto Denko Corporation)
F), a polarization beam splitter (PBS), a diffraction grating film or the like may be used.

Further, in the present embodiment, the light source unit adopts a structure in which the LED 1 is installed on the bottom of the frame 1a having a mortar shape as shown in FIG.
When the light from the ED 1 is diffused and is irradiated onto the LCD 3 via the polarization separation film 2, the irradiation efficiency is improved. Therefore, the surface of the groove portion of the frame 1a is mirror-finished or white. Then, this surface may be processed to have both reflection and diffusion effects.

As described above, the feature of the first embodiment is that the LCD 3 is provided by reflecting light from a light source in an image display such as an active matrix type liquid crystal display panel having a thin film transistor in each pixel. As the film to be irradiated on the top, the polarization separation film 2 that transmits only the desired light component of the light components from the LED 1 and reflects the other light components is used.

As a result, the light utilization efficiency can be improved. That is, in the conventional EVF configuration, for example, L
The light from the ED 201 is reflected by the half mirror 202,
This reflected light is transmitted through the polarizing film 203 and LC
The light utilization efficiency of the light irradiated on the D204 and reflected by the LCD 204 is reduced to about 1/10 of that of the light source before the light is transmitted through the polarizing film 203 again. Then, the light from the LED 1 is directly converted into the L
Since the surface of the CD3 is irradiated (polarized), the light use efficiency in this case is reduced to 50%, and the light use efficiency can be improved as compared with the conventional configuration. By arranging the polarized light separating film 2 so as to form a convex shape on the lower side, the light from the LED 1 can be applied to the surface of the LCD 3 while being diffused.

(Second Embodiment) The second embodiment will be described in detail below.

Here, the feature of the second embodiment is that, in addition to the configuration of the first embodiment, a polarization separation film is arranged in the immediate vicinity of the light source.

In FIG. 4, LED 1 is located in the immediate vicinity of LED 1.
1, a diffusion sheet 5 and a lens sheet 6 for making the point light source 1 into a surface light source, and the polarization separation film 2
The polarization separation film 7 is arranged with its arrangement direction reversed by 90 degrees.

Therefore, the polarization separation film 7 transmits the P wave, which is the opposite action of the polarization separation film 2, and reflects the S wave.

In FIG. 4, for the sake of convenience, the diffusion sheet 5 is used.
The lens sheet 6 and the lens sheet 6 are illustrated as if they are arranged one by one, but in this embodiment, two diffusion sheets 5 and two lens sheets 6 are arranged. However, the number of arranged sheets is not limited to two, and various combinations of various numbers are possible.

Thus, by disposing the polarization separation film 7 in the immediate vicinity of the LED 1, only the desired light component (P wave) is transmitted (polarization separation) through the polarization separation film 7 and other light components are transmitted. A light component (P wave) that can be transmitted while the (S wave) is reflected to the LED 1 side and this reflection is repeated.
The polarized light is transmitted through the polarization separation film 7.
As a result, the original P wave and the P wave changed from the S wave to the P wave are added, and the light (P wave) in a state where the light utilization efficiency is improved is irradiated to the polarization separation film 2 side. .

Hereinafter, as described in the first embodiment,
When the P wave reflected by the polarization separation film 2 is applied to the LCD 3 and the LCD 3 is driven as described above, the P wave is reflected as it is toward the polarization separation film 2 side. Wave is LE with polarization separation film 2
Since the light is reflected to the D1 side (does not pass through the polarization separation film 2), it is visually recognized as black. Further, when the LCD 3 is not driven, the P wave is converted into the S wave by the orientation of the LCD 3 and reflected on the polarization separation film 2 side, and the S wave passes through the polarization separation film 2. ,
It is seen as white.

As described above, the first feature of the present embodiment is to improve the light utilization efficiency on the light source side by disposing the polarization separation film 7 on the light source side.

The second feature of this embodiment is that by arranging the polarizing film 8 behind the polarization separation film 7 on the light source side, a person who sees an image through the viewfinder can see L
It is possible to prevent the light from the LED 1 from being directly visually recognized instead of the light reflected from the CD 2.

That is, the polarization ratio of the polarization separation film 7 is about 90%, whereas the polarization ratio of the polarization film 8 is about 99.99%, and the light which the polarization separation film 7 alone does not want to transmit. The problem that the components are transmitted and the appearance is deteriorated can be suppressed by disposing the polarizing film 8 behind the polarization separating film 7 on the LED 1 side.

(Third Embodiment) Further, the light from the LED 1 in the configuration of the second embodiment is reflected to LC.
The third embodiment in which the polarizing film 9 is arranged behind the polarized light separating film 2 for irradiating D3 will be described in detail.

The feature of this embodiment is that, as shown in FIG. 5, due to the polarization film 9 disposed behind the polarization separation film 2, the light which the polarization separation film 2 does not want to transmit due to the above-mentioned polarization ratio. Ingredient (in this embodiment,
This is to prevent the P wave) from being transmitted to the wall surface side and impair the appearance of the image due to the light.

In the first, second and third embodiments, as a surface treatment of the eyepiece convex lens 4, an AR (Anti-Refrective) coating for preventing surface reflection is applied to prevent reflection by EVF external light. It can be suppressed and the visibility can be improved.

An active matrix LCD to which the present invention is applied will be described below with reference to the drawings.

Flat panel displays such as LCDs can be thinned, miniaturized and lightened and have low power consumption. LCDs have already been used as display units for various devices, including portable information devices and many other devices. Used in equipment. L
A CD or the like in which each pixel is provided with a thin film transistor or the like as a switch element is called an active matrix type, and since this panel is sure to maintain the display content for each pixel, high definition display and high display It is used as a liquid crystal display panel to achieve quality.

FIG. 6 shows an equivalent circuit for pixels of an active matrix LCD. Each pixel includes a thin film transistor 11 (TFT) connected to a gate line and a data line, and when the TFT is turned on by a selection signal output to the gate line, data corresponding to display contents is output from the data line through the TFT. Liquid crystal capacity 1
2 (Clc). Here, since it is necessary to surely hold the written display data from the time when the TFT is selected and the data is written to the time when the TFT is selected again, it is necessary to securely hold the written display data to the TFT.
An auxiliary capacitor 13 (Csc) is connected in parallel with c.

FIG. 7 shows a plane structure of a pixel portion on a TFT formation substrate (first substrate 100) of a conventional LCD, and FIG. 8 shows the LCD at a position along line XX of FIG.
The cross-sectional structure of is shown. The LCD has a structure in which liquid crystal is sealed between the first and second substrates. In the active matrix LCD, the T-shaped matrix is formed on the first substrate 100.
The FT 11, the pixel electrode 74, etc. are arranged, and the first substrate 100
The common voltage Vcom is applied to the second substrate 500, which is disposed opposite to
The common electrode 56 to which is applied, the color filter 54, and the like are formed. Then, each pixel electrode 74 and the liquid crystal 20
The liquid crystal capacitance Clc is driven for each pixel by a voltage applied between the common electrode 56 and the common electrode 56 that face each other with 0 interposed therebetween.

The TFT provided for each pixel on the side of the first substrate 100 is a so-called top gate type TF in which the gate electrode 60 is located above the active layer 64, as shown in FIG.
T. The active layer 64 of the TFT is shown on the substrate 100 in FIG.
A gate insulating film 66 is formed so as to cover the active layer 64, and a gate line which also serves as the gate electrode 60 is formed on the gate insulating film 66. The active layer 64 has a channel region at a position facing the gate electrode 60, and the drain region 64d and the source region 6 in which impurities are implanted on both sides of the channel region.
4s are formed.

The drain region 64d of the active layer 64 is connected to the drain electrode 70 which also serves as a data line, through a contact hole formed in the interlayer insulating film 68 which covers the gate electrode 60.

A flattening insulating film 72 is formed so as to cover the data lines and the drain electrode 70, and the source region 64s of the active layer 64 has ITO (Indium Tin Oxide) on the flattening insulating film 72. Pixel electrode 7 composed of etc.
4 is connected via a contact hole.

The source region 64s of the active layer 64 further includes
It also serves as the first electrode 80 of the auxiliary capacitance Csc provided in each pixel, and further extends from the contact region with the pixel electrode 74, as shown in FIG. Second auxiliary capacitance Csc
The electrode 84 is simultaneously formed in the same layer as the gate electrode 60 as shown in FIG. 8, and is formed in another region with a predetermined gap from the gate electrode 60. The gate insulating film 66 also serves as a dielectric between the first electrode 80 and the second electrode 84. In addition, the second electrode 84 of the auxiliary capacitance Csc is
As shown in FIG. 7, each pixel is not independent, extends in the row direction in the pixel region like the gate line 60, and a predetermined auxiliary capacitance voltage Vsc is applied.

By providing the auxiliary capacitance Csc in each pixel in this manner, during the non-selection period of the TFT, the charge corresponding to the display content to be applied to the liquid crystal capacitance Clc is held in the auxiliary capacitance Csc. Therefore, it is possible to suppress the potential variation of the pixel electrode 74 and retain the display content.

A digital video camera (image pickup device) equipped with the LCD and EVF will be described below with reference to FIG.

The digital video camera 101 includes a main body 102, an image pickup section 103, an EVF 104, and an LCD panel 1.
05 is arranged. The image of the subject captured by the imaging unit 103 is converted into digital data, recorded on a recording medium (not shown), and displayed on the viewfinder 106 and the LCD panel 105 of the EVF 104.
The EVF can simplify the optical system because it is not necessary to disperse the image being picked up. Further, since the imaging light is not reduced by the spectroscopic analysis, higher contrast imaging is possible.

In the image pickup device of the present invention, the LC
By mounting the D and EVF, the visibility is improved as compared with the conventional device.

In the above description, an LCD is taken as an example of the active matrix type liquid crystal display panel, but the present invention is not limited to the active matrix type display device requiring an auxiliary capacitance for each pixel, for example, an active matrix type electro-luminescent device. It can also be applied to a luminescence display device or the like, and the same effect can be obtained.

[0055]

According to the present invention, by disposing the polarizing film behind the polarization separating film that reflects the light emitted from the light source side and irradiates it to the LCD, it is desired to transmit the light leaked from the polarization separating film. Light components that are not present can be absorbed, the appearance of the image can be prevented from being impaired, and the visibility is improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an electronic viewfinder according to a first embodiment of the present invention.

FIG. 2 is a principle view of a polarized light separation film.

FIG. 3 is a perspective sectional view showing a light source section of the electronic viewfinder of the present invention.

FIG. 4 is a sectional view showing a configuration of an electronic viewfinder according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a configuration of an electronic viewfinder according to a third embodiment of the present invention.

FIG. 6 is a diagram showing an equivalent circuit per pixel of an active matrix type liquid crystal display panel to which the present invention is applied.

FIG. 7 is a diagram showing a schematic planar structure of a pixel region in an active matrix type liquid crystal display panel to which the present invention is applied.

8 is a diagram showing a schematic sectional structure of an active matrix type liquid crystal display panel at a position along line XX in FIG.

FIG. 9 is a perspective view showing an external structure of an image pickup apparatus to which the present invention is applied.

FIG. 10 is a cross-sectional view showing a configuration of a conventional electronic viewfinder.

FIG. 11 is a principle view of a polarizing film.

[Explanation of symbols]

1 Light source (LED), 2 Polarization separation film, 3 Liquid crystal display panel (LCD), 4 Eyepiece convex lens, 5 Diffusion sheet, 6 Lens sheet, 7 Polarization separation film, 8
Polarizing film, 9 polarizing film, 11 thin film transistor (TFT), 12 liquid crystal capacitance (Clc), 13 auxiliary capacitance (Csc), 54 color filter, 56 common electrode, 60 gate line (also used as gate), 64 active layer (drain region, Channel region, source region), 66
Gate insulating film, 70 data line (also used as drain), 72 flattening insulating film, 74 pixel electrode, 80 first electrode of auxiliary capacitance, 84 second electrode of auxiliary capacitance, 100
First substrate 101 Imaging device 102 Main body 103
Imaging unit, 104 EVF, 105 LCD panel, 1
06 finder, 200 liquid crystal, 500 2nd substrate

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tokio Koma             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. (72) Inventor Makoto Shimizu             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. F-term (reference) 2H049 BA05 BA43 BB61 BC22                 2H088 EA22 HA08 HA20 HA28 MA01                 2H091 FA10X FA14Y FA45X FD13                       HA05 LA16 MA10                 2H092 GA29 HA05 JA24 JB07 JB58                       JB63 JB68 NA01 QA05 RA10

Claims (9)

[Claims] 1. A display device having a light source, an active matrix type liquid crystal display panel having a thin film transistor in each pixel, and a reflection section for reflecting light from the light source to the liquid crystal display panel, wherein the reflection section has a predetermined length. And a polarization separation film that selectively reflects another light component and selectively transmits another light component, and a polarization film disposed on the opposite side of the liquid crystal display panel of the polarization separation film. And display device. 2. The polarizing film is arranged so as to transmit a light component selectively transmitted by the polarization separation film and block a light component selectively reflected by the polarization separation film. The display device according to claim 1. 3. The display device according to claim 1, wherein the polarization separation film has a transmission axis and a reflection axis that are orthogonal to each other. 4. The display device according to claim 1, wherein the polarizing film has a transmission axis and an absorption axis that are orthogonal to each other. 5. An electronic viewfinder having a light source, an active matrix type liquid crystal display panel having a thin film transistor in each pixel, and a reflection section for reflecting light from the light source to the liquid crystal display panel, wherein the reflection section is A polarization separation film that selectively reflects a predetermined light component and selectively transmits another light component, and a polarization film disposed on the opposite side of the liquid crystal display panel of the polarization separation film. A characteristic electronic viewfinder. 6. The polarization film is arranged so as to transmit a light component selectively transmitted by the polarization separation film and block a light component selectively reflected by the polarization separation film. The electronic viewfinder according to claim 5. 7. The electronic viewfinder according to claim 5, wherein the polarization separation film has a transmission axis and a reflection axis which are orthogonal to each other. 8. The electronic viewfinder according to claim 5, wherein the polarizing film has a transmission axis and an absorption axis which are orthogonal to each other. 9. An image pickup apparatus comprising the display device or the electronic viewfinder according to claim 1. Description: