JPH09230284A - Projection display device - Google Patents

Abstract

(57) Abstract: An object of the present invention is to easily move a projection image projected on a screen. A projection display device (21) includes a light source (22), a condenser lens (23), and a liquid crystal light valve (24) for transmitting light from the condenser lens (23) in accordance with a predetermined image pattern.
And the light passing through the liquid crystal light valve 24 is passed through the screen 2
5 and a projection lens 26 for projecting. Projection lens 2
The projection lens position adjusting mechanism 27 adjusts the position 6 in the vertical direction. The condenser lens 23 is formed by a liquid crystal lens adjusted to have an arbitrary refractive index. A voltage from the refractive index control circuit 29 is applied to the condensing lens 23 according to the operation amount of the adjustment switch 28, and the magnitude of the voltage to which the liquid crystal molecules enclosed in the condensing lens 23 are applied. Accordingly, the refractive index in the up-down direction in the condenser lens 23 changes stepwise for each location, and the focal position of the condenser lens 23 is moved. As a result, the projection image projected on the screen 25 can be easily moved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device, and more particularly to a projection display device configured to move an image projected on a screen in a direction orthogonal to an optical axis. In the projection display device, when the optical axis of the projection lens is set to be perpendicular to the screen surface, the best image without image distortion is focused on the entire screen and is projected on the screen surface. Actually, even if the optical axis of the projection lens is slightly deviated from the direction perpendicular to the screen surface, the image display is gradually deteriorated, so that some deviation is allowed.

However, when installing the projection type display device, if the device is installed in a place where it does not disturb the user,
The direction of the optical axis of the projection lens with respect to the screen may deviate significantly. Even in that case, it is desirable that the image projected on the screen is not distorted into a trapezoid or the peripheral part is out of focus.

[0003]

2. Description of the Related Art A conventional projection display device has an overall structure as shown in FIG. 7, for example. In this projection display device 1, when the white light emitted from the light source 2 reaches the GR reflection dichroic mirror DM1, B light is transmitted and G,
The R light is reflected. The G and R lights reach the R reflection dichroic mirror DM2, the G light is transmitted, and the R light is reflected. As a result, the white light emitted from the light source 2 becomes R
It is split into light, G light, and B light.

The R light passes through the liquid crystal light valve 3 dedicated to the R light and is spatially modulated by the image reproduced on the liquid crystal light valve 3. The G light transmits through the liquid crystal light valve 4 dedicated to the G light and is spatially modulated by the image reproduced on the liquid crystal light valve 4. The B light is reflected by the total reflection mirror M1 and transmitted through the liquid crystal light valve 5 dedicated to the B light, and spatially modulated by the image reproduced by the liquid crystal light valve 5.

The spatially modulated R light and B light are combined by the R reflection dichroic mirror DM3, and BR
Heading towards the reflective dichroic mirror DM4. The spatially modulated G light is reflected by the total reflection mirror M2 and travels toward the BR reflection dichroic mirror DM4. At the portion of the BR reflection dichroic mirror DM4, the spatially modulated R light, G light, and B light are combined.

Then, the combined R light, G light and B light are
The image 8 projected on the screen 7 through the projection lens 6 and enlarged is displayed on the screen 7. In this way, the R light, G light, and B light spatially modulated by the image reproduced by the liquid crystal light valves 3 to 5 are
The light is combined by the BR reflection dichroic mirror DM4 and projected from the projection lens 6 onto the screen 7.

Since the R, G, and B light optical paths have substantially the same structure, only one optical path will be described below. FIG. 8 is a configuration diagram showing only one optical path out of the optical paths of R light, G light, and B light. A condenser lens 9 and a liquid crystal light valve 10 are arranged between the light source 2 and the projection lens 6. This liquid crystal light valve 10
Has a configuration in which polarizing plates 12 and 13 are arranged in front of and behind the liquid crystal panel 11.

The unpolarized white light beam emitted from the light source 2 is decomposed into the R, G, and B light beams by the above-mentioned dichroic mirror (see FIG. 7), and then the condenser lens 9 is used. Then, it becomes a light beam having a focus on the pupil of the projection lens 6 and enters the liquid crystal panel 11 through the polarizing plate 12. The incident-side polarization plate 12 extracts only the linearly polarized light component from the unpolarized light beam.

The light beam that has passed through the polarizing plate 12 and becomes linearly polarized is subjected to image modulation by the liquid crystal panel 11, is further imaged by the polarizing plate 13 on the emitting side, and then enlarged and projected by the projection lens 6. The light rays projected from the projection lens 6 form an image on the screen 7.

In order to project the best image on the screen 7, it is desirable to set the relative position so that the optical axis 14 of the projection lens 6 is perpendicular to the screen 7. However, when the projection display apparatus 1 is installed in an unobtrusive position, the angle deviation of the optical axis 14 of the projection lens 6 with respect to the screen 7 becomes large, and the projection image projected on the screen 7 deteriorates. There is a problem that (trapezoidal distortion, out-of-focus of the peripheral portion) occurs.

As a measure against such a problem, for example, when the projection source data to be displayed on the liquid crystal panel 11 is electrically processed and projected upward, the trapezoid has a long upper side, so that the data on the upper side is reduced. Then, there is a method of displaying on the liquid crystal panel 11. However, this method is a countermeasure against only the trapezoidal distortion and discards a part of the image information, so that the deterioration of the display quality when displaying characters and the like as a still image cannot be ignored and is not practical.

In order to solve such a problem, in the conventional projection display device 1, the light source position adjusting mechanism 15 for moving the light source 2 in the vertical or horizontal direction and the projection lens 6 for moving the projection lens 6 in the vertical or horizontal direction. A lens position adjusting mechanism 16 is provided. For example, when the screen 7 is above the projection display device 1, the light source position adjusting mechanism 15
The projection light source 2 is lowered by the projection lens position adjustment mechanism 16 and the projection lens 6 is raised by the projection lens position adjustment mechanism 16.
Is adjusted so that the center of is located on the optical axis 14. As a result, the image projected from the projection lens 6 is displayed on the screen 7.

[0013]

However, in the conventional projection display device 1 configured as described above, the light source 2
The light source position adjusting mechanism 15 for raising and lowering the projector and the projection lens position adjusting mechanism 16 for raising and lowering the projection lens 6 must be provided in the housing, which complicates the mechanism and increases the size of the entire apparatus, which hinders miniaturization. It was.

Moreover, in the conventional configuration, it is necessary to move the light source 2 and the projection lens 6 in an interlocking manner so that the center of the projection lens 6 is located on the optical axis 14, and the position of the light source 2 and the projection lens 6 is moved. Must be adjusted with high precision, and it was difficult to move the light source 2 and the projection lens 6 accurately.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a projection type display device whose structure can be simplified by gradually changing the refractive index of a condenser lens.

[0016]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized by taking the following various means. In the invention according to claim 1, a light source,
A condensing lens that collects the light from the light source, a light valve that transmits the light from the condensing lens according to a predetermined image pattern, and a projection lens that projects the light that has passed through the light valve onto a screen. In the projection display device having, the projection lens is provided so as to be movable in a direction orthogonal to the optical axis, and the condensing lens is formed by a liquid crystal lens whose refractive index is adjusted to an arbitrary value. The refractive index of the liquid crystal lens is adjusted so that the direction corresponds to the position after the movement of the projection lens.

According to a second aspect of the present invention, in the projection display device according to the first aspect, the refractive index of the liquid crystal lens is changed stepwise in the vertical direction or the horizontal direction. is there.

In the invention according to claim 3, a light source,
A condensing lens that collects light from the light source, a light valve that transmits the light from the condensing lens according to a predetermined image pattern, and a projection lens that projects the light that has passed through the light valve onto a screen. In the projection display device having the above, a wedge-shaped liquid crystal prism is arranged between the condenser lens and the light valve.

According to a fourth aspect of the present invention, in the projection display device according to the third aspect, the wedge-shaped liquid crystal prism refracts light from the condenser lens so as to bend the light vertically or horizontally. It is characterized in that the rate is adjusted.

According to a fifth aspect of the invention, in the projection display device according to the third aspect, the wedge-shaped liquid crystal prism is arranged on the other surface side opposite to the electrode arranged on the one surface side. The voltage is controlled so that the distance between the electrodes and the voltage applied to the electrode are proportional to each other.

Each of the above means operates as follows. According to the invention described in claim 1, since the refractive index of the liquid crystal lens is adjusted so that the direction of the light emitted from the liquid crystal lens corresponds to the position after the movement of the projection lens, the structure is simplified as compared with the conventional one. The size of the device can be reduced, and the image projected on the screen can be displayed at any position by adjusting the refractive index of the liquid crystal lens so that the optical axis of the liquid crystal lens follows the moving direction of the projection lens. Can be moved. Even if a projection lens having a small entrance pupil diameter is used, the light emitted from the condenser lens can be projected on the screen.

According to the second aspect of the invention, the image projected on the screen is moved to an arbitrary position by changing the refractive index of the liquid crystal lens stepwise in the vertical direction or the horizontal direction. Therefore, it is possible to prevent distortion of the projected image and defocus. According to the third aspect of the invention, since the wedge-shaped liquid crystal prism is arranged between the condenser lens and the light valve, the same action and effect as those of the first aspect can be obtained.

According to the fourth aspect of the invention, since the wedge-shaped liquid crystal prism has its refractive index adjusted so as to bend the light from the condenser lens in the vertical direction or the horizontal direction, it enters the light valve. The light beam can be moved to any position. According to the invention of claim 5, the inter-electrode distance between the electrode arranged on one surface side of the wedge-shaped liquid crystal prism and the electrode arranged on the other surface side facing the wedge-shaped liquid crystal prism, and the voltage applied to the electrode. Since the voltage is controlled so as to be proportional to, the light beam incident on the light valve can be moved to an arbitrary position, and the distortion and focus shift of the projected image can be prevented.

[0024]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing only one optical system path of a projection type display apparatus according to a first embodiment of the present invention. In FIG. 1, the optical paths of the R light, the G light, and the B light have substantially the same configuration, and the description of the other optical paths will be omitted.

The projection type display device 21 generally has a light source 22.
A condenser lens 23 formed of a liquid crystal lens, a liquid crystal light valve 24 for transmitting the light from the condenser lens 23 according to a predetermined image pattern, and a light passing through the liquid crystal light valve 24 is projected on a screen 25. Projection lens 26
And

The projection lens 26 is provided so as to be movable in the vertical direction orthogonal to the optical axis, and has a projection lens position adjusting mechanism 27.
The vertical position is adjusted by. When the adjustment switch 28 is operated, the projection lens position adjusting mechanism 27 moves the projection lens 26 up and down according to the amount of operation of the adjustment switch 28 to vertically move the image forming position where an image is formed on the screen 25.

The condenser lens 23 is formed by a liquid crystal lens whose refractive index is adjusted. A voltage from the refractive index control circuit 29 is applied to the condenser lens 23 according to the operation amount of the adjustment switch 28, and the refractive index of the liquid crystal lens is adjusted according to the applied voltage as described later.

The liquid crystal light valve 24 has a known structure in which polarizing plates 31 and 32 are arranged in front of and behind the liquid crystal panel 30, respectively. FIG. 2 is an enlarged configuration diagram showing the configurations of the condenser lens 23 and the liquid crystal light valve 24.

In the condenser lens 23, a convex surface 33 on the incident side and a flat surface 34 on the outgoing side, which are made of transparent glass (or a synthetic resin material), are integrally joined to each other to form a hemispherical convex surface 33.
The liquid crystal 35 is enclosed in a convex lens-shaped sealed space formed between the flat surface 34 and the flat surface 34. In the case of this embodiment,
As the liquid crystal 35, for example, a twisted nematic liquid crystal (also called “TN liquid crystal”) which is a nematic liquid crystal having a positive dielectric anisotropy is used.

Inside the convex surface 33 and the flat surface 34,
In order to make the liquid crystal molecules of the nematic liquid crystal move easily, a homogeneous alignment treatment (elongated liquid crystal molecules are flat
4 is a treatment method for the glass surface to be arranged in parallel with No. 4). Further, the transparent electrode 36 is provided on the entire inner surface of the convex surface 33, and the stripe-shaped transparent electrodes 37 (37 _{1 to} 37 _n ) are provided on the inner surface of the flat surface 34.

As shown in FIG. 3, the stripe-shaped transparent electrode 37 (37 ₁ ~37 _n) is a plurality of arranged at a predetermined pitch, disposed in parallel in a direction of each extends horizontally There is. The stripe transparent electrodes 37 provided on the inner surface of the transparent electrode 36 and the plane 34 on the internal surface of the convex surface 33 (37 ₁ ~37 _n) as described above are opposed to each other, farthest central portion doing.

When one transparent electrode 36 is connected to the ground side and the other stripe transparent electrode 37 moves the direction of the light emitted to the liquid crystal light valve 24, the voltage from the refractive index control circuit 29 is applied. Is applied. still,
Since the liquid crystal light valve 24 has the same structure as the conventional one, its description is omitted here.

Here, the light flux of unpolarized white light emitted from the light source 22 is the dichroic mirror (see FIG. 7).
(See (1)), the light is decomposed into R, G, and B light beams, and then the condensing lens 23 forms a converging light beam having a focus on the pupil of the projection lens 26, and passes through the polarizing plate 31 and the liquid crystal panel. It is incident on 30. The incident-side polarization plate 31 extracts only the linearly polarized light component from the unpolarized light beam.

The light beam which has passed through the polarizing plate 31 and becomes linearly polarized is subjected to image modulation by the liquid crystal panel 30 and further imaged by the polarizing plate 32 on the emission side, and then the projection lens 26.
Is enlarged and projected. The light rays projected from the projection lens 26 form an image on the screen 25.

The projection lens 26 is set such that the optical axis 38 of the projection lens 26 is in the center of the liquid crystal panel 30 in the initial state before the apparatus is installed, and the optical axis 3 of the projection lens 26 is set.
8 is the center of the image projected on the screen 25.
In this case, the stripe-shaped transparent electrodes 37 provided on the condenser lens 23 (37 ₁ to 37 _n) are no voltage is applied, light emitted from the light source 22, A line shown in FIG. 2 ( Following the trajectory (indicated by the solid line), the image is modulated by the liquid crystal panel 30 and is incident on the projection lens 26.

Here, when the projection image projected on the screen 25 is moved upward, the projection lens position adjusting mechanism 27 moves the projection lens 26 upward in accordance with the operation amount of the adjustment switch 28, and at the same time the light is condensed. stripe-shaped transparent electrodes 37 of the lens 23 (37 ₁ ~37 _n) to apply a voltage corresponding to the operation amount of the adjustment switch 28.

In this case, the refractive index control circuit 29
Yip-shaped transparent electrode 37 (37₁~ 37 _n) Applied voltage to
Adjust to a lower voltage at the top and a higher voltage at the bottom.
Adjust. That is, the uppermost striped transparent electrode 37
₁The voltage to
The stripe-shaped transparent electrode at the bottom by increasing the applied voltage to
37_nMaximize the voltage to.

Further, the refractive index control circuit 29 applies a voltage proportional to the distance between the electrodes. Therefore, as the stripe-shaped transparent electrode 37 (37 ₁ ~37 _n)
A voltage value according to the distance between the electrodes is added to the voltage applied to the. That is, the applied voltage is increased in a parabolic manner as the distance from the uppermost portion to the lower portion decreases, and the electric field strength applied to the liquid crystal molecules becomes constant.

Thus, the striped transparent electrode 37 (3
7 _{1 to} 37 _n ) is applied with a stepwise changed voltage, liquid crystal molecules arranged in parallel with the stripe transparent electrodes 37 (37 _{1 to} 37 _n ) are changed depending on the applied voltage. As a result, the effective refractive index at each position in the vertical direction of the liquid crystal 35 filled in the condenser lens 23 changes stepwise as it tilts in the direction of the electric field.

As a result, the upper portion of the condenser lens 23 is adjusted to a low refractive index, the lower portion of the condenser lens 23 is adjusted to a high refractive index, and the refractive index between the upper portion and the lower portion of the condenser lens 23 is adjusted. Is gradually changed. This is the condenser lens 23
The focus position of moves to the upper side as shown by the line B (indicated by the alternate long and short dash line) in FIG. In this way, the condenser lens 2
In order to adjust the refractive index of the condenser lens 23 so that the direction of the light emitted from 3 corresponds to the position after the movement of the projection lens 26, the focus position of the condenser lens 23 is adjusted to the vertical movement position of the projection lens 26. Can be matched exactly to
The projected image can be projected on the screen 25 without deterioration (trapezoidal distortion, out-of-focus of the peripheral portion).

When the projected image projected on the screen 25 is moved downward, the voltage applied to the stripe transparent electrodes 37 (37 _{1 to} 37 _n ) may be changed contrary to the above. That is, the stripe-shaped transparent electrode 3
7 (37 _{1 to} 37 _n ) the higher the voltage is adjusted,
Adjust to a lower voltage toward the bottom.

Further, in this embodiment, since it is not necessary to move the light source 22 in accordance with the movement of the projection lens 26, a mechanism for moving the light source 22 is unnecessary, and the structure can be simplified more than that of the conventional one. Has been planned. Therefore, the projection display device 21 can be made smaller than the conventional one, and the installation work can be easily performed.

When the projection lens 26 is moved, the angle of light emitted from the flat surface 34 of the condenser lens 23 changes upward due to the change in the refractive index of the condenser lens 23, and the light is emitted from the condenser lens 23. All the light is on the entrance pupil 39 of the projection lens 26.
Adjusted to fit inside. Therefore, even if the projection lens 26 having a small entrance pupil diameter is used, the light emitted from the condenser lens 23 can be projected onto the screen 25, so that the image projected on the screen 25 does not become dark. It can be projected in the center of 25.

FIG. 4 is a schematic configuration diagram showing only one optical system path of the projection type display apparatus according to the second embodiment of the present invention. In FIG. 4, the optical paths of the R light, the G light, and the B light have substantially the same configuration, and the description of the other optical paths will be omitted. Further, the same parts as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The projection type display device 41 has a stripe transparent electrode 42 (42 ₁ to 42 _{1-) on} the inner surface of the convex surface 33 of the condenser lens 23.
42 _n ) are provided. As shown in FIG. 5, the transparent electrode 42 (42 ₁ ~42 _n) is a plurality of arranged at a predetermined pitch are provided in parallel in a direction of each extends in a vertical direction. Thus, stripe-shaped transparent electrodes 42 provided on the inner surface of the convex surface 33 (42 ₁ ~42 _n) with the plane 34
Striped transparent electrode 37 (37 ₁
.About.37 _n ) are arranged in a matrix so as to face each other and extend in a direction orthogonal to each other.

In the projection display device 41, the condenser lens 23
Striped transparent electrodes 37 (3
7 _{1 to} 37 _n ) adjusts the vertical refractive index, and stripe-shaped transparent electrodes 42 (42 ₁ to 42 ₁
42 _n ) adjusts the refractive index in the left-right direction. Therefore, when the projection image projected on the screen 25 is moved in the vertical direction, the projection lens position adjusting mechanism 27 moves the projection lens 26 up and down in accordance with the operation amount of the adjustment switch 28 as in the case of the first embodiment. And the stripe-shaped transparent electrode 37 (37) of the condenser lens 23.
_{1 to} 37 _n ) is applied with a voltage that is changed stepwise according to the operation amount of the adjustment switch 28.

When the projection image projected on the screen 25 is moved to the right, the refractive index control circuit 29
Striped transparent electrodes 42 (42 ₁
The voltage applied to ˜42 _n ) is adjusted to a smaller voltage on the right side and a larger voltage on the left side. That is, the voltage to the rightmost striped transparent electrode 42 ₁ is minimized, and the applied voltage is gradually increased toward the left to maximize the voltage to the leftmost striped transparent electrode 42 _n .

Thus, the striped transparent electrode 42 (4
2 ₁ If through 42 _n) to thereby apply a gradually changed voltage, depending on the magnitude of the voltage the liquid crystal molecules is applied, which were arranged in parallel in a stripe-shaped transparent electrode 42 (42 ₁ ~42 _n) As a result, the effective refractive index at each position in the left-right direction of the liquid crystal 35 filled in the condensing lens 23 changes stepwise.

As a result, the right side of the condenser lens 23 is adjusted to a low refractive index, the left side of the condenser lens 23 is adjusted to a high refractive index, and the refractive index between the right side and the left side of the condenser lens 23 is adjusted. Is gradually changed. This is the condenser lens 23
The focus position of moves to the right as indicated by the line C (indicated by the alternate long and short dash line) in FIG. Therefore, the condenser lens 23
Can be accurately adjusted to the vertical and horizontal movement positions of the projection lens 26, and the projection image is projected on the screen 25 so that the projection image does not deteriorate (trapezoidal distortion, out-of-focus of the peripheral portion). be able to.

When the projected image projected on the screen 25 is moved to the left, the voltage applied to the stripe-shaped transparent electrodes 42 (42 _{1 to} 42 _n ) may be changed contrary to the above. . That is, the stripe-shaped transparent electrode 4
The applied voltage 2 (42 ₁ ~42 _n) is adjusted to a voltage greater extent right, adjusted to a small voltage as the left.

Further, in the present embodiment, since it is not necessary to move the light source 22 in accordance with the movement of the projection lens 26, a mechanism for moving the light source 22 in the vertical direction and the horizontal direction is unnecessary, which is more than that of the conventional one. Also simplifies the configuration. Therefore, the projection display device 21 can be made smaller than the conventional one, and the installation work can be easily performed.

Further, when the projection lens 26 is moved to the right, the focusing lens 23 changes due to the change in the refractive index of the focusing lens 23.
The angle of the light emitted from the plane 34 changes to the right,
It is adjusted so that all the light emitted from the condenser lens 23 enters the entrance pupil 39 of the projection lens 26. Therefore, even if the projection lens 26 having a small entrance pupil diameter is used, the condenser lens 23
Since the light emitted from the screen can be projected on the screen 25, the image projected on the screen 25 can be projected on the center of the screen 25 without becoming dark.

FIG. 6 is a schematic structural view showing only one optical system path of the projection type display apparatus according to the third embodiment of the present invention. In FIG. 6, the optical paths of the R light, G light, and B light have substantially the same configuration, and the description of the other optical paths will be omitted. Further, the same parts as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the projection display device 51, a wedge-shaped liquid crystal prism 53 is provided between the condenser lens 52 and the liquid crystal light valve 24. This wedge-shaped liquid crystal prism 5
3 is a vertical plane 54 on the incident side formed of transparent glass (or a synthetic resin material), an inclined plane 55 on the emission side,
The upper spacer 56 and the lower spacer 57 are integrally joined, and both side surfaces are closed by side walls (not shown). The emission-side inclined plane 55 is inclined at an angle θ with respect to the vertical direction.

A TN liquid crystal (twisted nematic liquid crystal) 58 is enclosed in the wedge-shaped space formed between the vertical plane 54 and the inclined plane 55. for that reason,
The light incident from the vertical plane 54 is refracted according to the refractive index of the TN liquid crystal 58 and the inclination angle θ of the inclined plane 55 and is emitted to the liquid crystal light valve 24. In this embodiment, since the wedge-shaped liquid crystal prism 53 is inserted between the condenser lens 52 and the liquid crystal light valve 24, it is easy to assemble the wedge-shaped liquid crystal prism 53 into the existing one. Can be modified.

Of the vertical plane 54 and the inclined plane 55,
On the side, in order to allow the TN liquid crystal molecules to move easily,
Homogeneous alignment treatment (long and narrow liquid crystal molecules are vertical plane 54
Glass surface treatment method that is arranged in parallel with
Have been. Further, on the inner surface of the vertical plane 54 on the incident side,
Striped transparent electrodes 59 (59) extending in the horizontal direction ₁
~ 59_n) Is provided. Also, the inclined plane on the output side
A transparent electrode 60 is provided on the entire inner surface of 55.
You.

Striped transparent electrodes 59 (59 _{1 to} 59)
_n ) are arranged at a predetermined pitch and are arranged in parallel with each other in the direction in which they extend in the horizontal direction. As described above, the stripe-shaped transparent electrodes 59 (59 _{1 to} 59 _n ) provided on the inner surface of the vertical plane 54 and the transparent electrode 60 provided on the inner surface of the inclined plane 55 have their upper portions closest to each other and their lower portions They face each other so that they are most apart from each other, and the separation distance increases as they move downward.

Then, one transparent electrode 60 is connected to the ground side, and the other striped transparent electrode 59 (59 ₁ -59 _1- ).
59 _n ) is applied with a voltage from the refractive index control circuit 29 when moving the direction of the light emitted to the liquid crystal light valve 24. Striped transparent electrode 59 (59 _{1 to} 59)
_The voltage applied to _n ) is a voltage value proportional to the distance between the transparent electrode 60 and each of the stripe-shaped transparent electrodes 59 _{1 to} 59 _n so that the electric field strength applied to the liquid crystal molecules at each location is constant. Is set.

The projection lens 26 is set so that the optical axis 38 of the projection lens 26 is located above the center line 61 of the liquid crystal panel 30 in the initial state before installation of the apparatus. In this state, the wedge-shaped liquid crystal prism 53 has the condenser lens 52.
It is provided to effectively guide the light beam that has passed through the entrance pupil 39 to the entrance pupil 39.

At this time, the stripe-shaped transparent electrodes 59 (59 _{1 to} 5 1-5) provided in the wedge-shaped liquid crystal prism 53.
9 _n ), no voltage is applied, and the light emitted from the light source 22 follows the locus of the line A (shown by the solid line) shown in FIG. 2 and is image-modulated by the liquid crystal panel 30 to be projected on the projection lens 26. It is incident.

Here, when the projection image projected on the screen 25 is moved upward, the projection lens 26 is moved upward by the projection lens position adjusting mechanism 27 according to the operation amount of the adjustment switch 28, and the wedge-shaped image is formed. Striped transparent electrodes 59 (59 _{1 to} 5) of the liquid crystal prism 53
9 _n ) is applied with a voltage corresponding to the operation amount of the adjustment switch 28.

In this case, since the refractive index control circuit 29 applies a voltage proportional to the distance between the electrodes, the refractive index control circuit 29 adjusts the voltage so that the upper portion with a smaller distance is a smaller voltage and the lower portion with a larger distance is a larger voltage. That is, the voltage applied to the uppermost striped transparent electrode 59 ₁ is minimized, and the applied voltage is increased stepwise as it moves to the lower part to maximize the voltage applied to the lowermost striped transparent electrode 59 _n . The electric field strength applied to the molecule is made constant.

Thus, the striped transparent electrode 59 (5
9 _{1 to} 59 _n ) is applied with a stepwise changed voltage, liquid crystal molecules arranged in parallel to the stripe-shaped transparent electrodes 59 (59 _{1 to} 59 _n ) are changed depending on the applied voltage. And tilts in the direction of the electric field.
The effective refractive index at each position in the vertical direction of the liquid crystal 58 filled therein changes stepwise.

As a result, the upper part of the wedge-shaped liquid crystal prism 53 is adjusted to have a low refractive index, the lower part of the wedge-shaped liquid crystal prism 53 is adjusted to have a high refractive index, and the upper part of the wedge-shaped liquid crystal prism 52 is moved to the lower part thereof. The refractive index of is changed stepwise. As a result, the focal position of the condenser lens 52 moves upward as shown by the line B (indicated by the alternate long and short dash line) in FIG. Therefore, the focus position of the condenser lens 52 can be accurately adjusted to the vertical movement position of the projection lens 26, and at the same time, the projected image on the screen 25 is prevented from being deteriorated (trapezoidal distortion, peripheral focus deviation). Can be projected on.

To move the projection image projected on the screen 25 downward, the voltage applied to the stripe transparent electrodes 58 (58 _{1 to} 58 _n ) may be changed contrary to the above. Further, in this embodiment, the projection lens 2
Since it is not necessary to move the light source 22 in accordance with the movement of 6, the mechanism for moving the light source 22 is not necessary, and the structure is simplified more than that of the conventional one. Therefore, the projection display device 51 can be made smaller than the conventional one, and the installation work can be easily performed.

Further, when the projection lens 26 is moved, the angle of the light emitted from the wedge-shaped liquid crystal prism 53 changes upward due to the change in the refractive index of the wedge-shaped liquid crystal prism 53, and the light emitted from the condenser lens 52. Are all adjusted so as to enter the entrance pupil 39 of the projection lens 26. Therefore, even if the projection lens 26 having a small entrance pupil diameter is used, the light emitted from the condenser lens 52 can be projected onto the screen 25, so that the image projected on the screen 25 does not become dark. It can be projected in the center of 25.

Further, when the light emitted from the condenser lens 52 is moved in the left-right direction, a wedge-shaped liquid crystal prism inclined laterally is arranged between the liquid crystal light valve 24 and the condenser lens 52. Just do it.

[0068]

According to the present invention as described above, the following various effects can be realized. According to the invention described in claim 1, since the refractive index of the liquid crystal lens is adjusted so that the direction of the light emitted from the liquid crystal lens corresponds to the position after the movement of the projection lens, the focus position of the condenser lens can be easily adjusted. It can be adjusted and a mechanism for moving the light source is not required, and the structure can be simplified more than that of the conventional one. Therefore, the device can be miniaturized to facilitate installation work, and even if a projection lens with a small entrance pupil diameter is used, the light emitted from the condenser lens can be projected onto the screen and projected onto the screen. The projected image can be projected in the center of the screen without darkening.

According to the second aspect of the invention, the image projected on the screen is moved to an arbitrary position by gradually changing the refractive index of the liquid crystal lens in the vertical direction or the horizontal direction. Therefore, it is possible to prevent distortion of the projected image and defocus. Further, according to the invention described in claim 3, since the wedge-shaped liquid crystal prism is arranged between the condenser lens and the light valve, the existing one can be easily modified and the same action as that of the above-mentioned claim 1 is achieved. , The effect is obtained.

According to the fourth aspect of the invention, since the wedge-shaped liquid crystal prism has its refractive index adjusted so as to bend the light from the condenser lens in the vertical direction or the horizontal direction, it enters the light valve. The light beam can be moved to any position. According to the invention of claim 5, the inter-electrode distance between the electrode arranged on one surface side of the wedge-shaped liquid crystal prism and the electrode arranged on the other surface side facing the wedge-shaped liquid crystal prism, and the voltage applied to the electrode. Since the voltage is controlled so as to be proportional to, the electric field strength applied to the liquid crystal molecules can be kept constant and the refractive index of the wedge-shaped liquid crystal prism can be adjusted stably. In addition, it is possible to move the light beam incident on the light valve to an arbitrary position, and it is also possible to prevent distortion and focus shift of the projected image.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing only one optical system path of a projection type display apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged configuration diagram showing a configuration of a condenser lens and a liquid crystal light valve.

FIG. 3 is a front view of a condenser lens showing an array of horizontal stripe-shaped transparent electrodes.

FIG. 4 is a schematic configuration diagram showing only one optical system path of a projection type display apparatus according to a second embodiment of the present invention.

FIG. 5 is a front view of a condenser lens showing a state in which horizontal and vertical stripe transparent electrodes are arranged in a matrix.

FIG. 6 is a schematic configuration diagram showing only one optical system path of a projection type display apparatus which is a third embodiment of the present invention.

FIG. 7 is a diagram showing an overall configuration of a conventional projection display device.

FIG. 8 is a schematic configuration diagram showing only one optical system path of a conventional projection display device.

[Explanation of symbols]

 21, 41, 51 Projection display device 22 Light source 23 Condenser lens 24 Liquid crystal light valve 25 Screen 26 Projection lens 27 Projection lens position adjusting mechanism 28 Adjustment switch 29 Refractive index control circuit 30 Liquid crystal panel 31, 32 Polarizing plate 33 Convex surface 34 Plane 35,58 Liquid crystal 36,60 Transparent electrode 37,42,59 Striped transparent electrode 53 Wedge liquid crystal prism

Claims (5)

[Claims] 1. A light source, a condenser lens that collects light from the light source, a light valve that transmits the light from the condenser lens according to a predetermined image pattern, and a light that passes through the light valve. In a projection display device having a projection lens for projecting on a screen, the projection lens is movably provided in a direction orthogonal to an optical axis, and the condenser lens is formed of a liquid crystal lens adjusted to an arbitrary refractive index, A projection type display device, wherein the refractive index of the liquid crystal lens is adjusted so that the direction of light emitted from the liquid crystal lens corresponds to the position of the projection lens after the movement. 2. The projection display device according to claim 1, wherein the refractive index of the liquid crystal lens is changed stepwise in a vertical direction or a horizontal direction. 3. A light source, a condenser lens that collects light from the light source, a light valve that transmits the light from the condenser lens according to a pattern of a predetermined image, and a light that passes through the light valve. A projection type display device having a projection lens for projecting on a screen, wherein a wedge-shaped liquid crystal prism is arranged between the condenser lens and the light valve. 4. The projection display device according to claim 3, wherein the wedge-shaped liquid crystal prism has a refractive index adjusted so as to bend the light from the condenser lens in a vertical direction or a horizontal direction. And a projection display device. 5. The projection type display device according to claim 3, wherein the wedge-shaped liquid crystal prism has an inter-electrode distance between an electrode arranged on one surface side and an electrode arranged on the other surface side facing the other surface. A projection display device, characterized in that the voltage is controlled so as to be proportional to the voltage applied to the electrode.