JP2011039352A - Projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection display device that satisfactorily compensates for defocus resulting from a temperature change even when a luminous flux from a light source is intense. <P>SOLUTION: A temperature detector is provided in one of positions T<SB>s1</SB>to T<SB>s4</SB>that is not directly irradiated with a luminous flux modulated by a light valve. Using information about a relation between the predetermined temperature change and the amount of movement of a defocus correction lens used for compensating for defocus of the projection lens, resulting from the temperature change, at least one of defocus correction lens groups of the projection lens 4 is moved in the direction of an optical axis Z on the basis of temperature information outputted from the temperature detector, so as to compensate for the defocus. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a projection display device that irradiates a light bulb with a light beam from a light source and enlarges and projects an image displayed on the light valve onto a screen. The present invention relates to a projection display device that is formed using a material that is significantly contracted by heat.

  Various light valves such as a transmissive liquid crystal display element, a reflective liquid crystal display element (LCOS), and a DMD (digital micromirror device) are known as light valves mounted on a projector.

  By the way, in recent projectors, high definition has progressed due to the progress of the light valve and the like, and the focus shift due to the temperature fluctuation in the optical system when irradiating the light flux from the light source becomes more conspicuous. In addition, with the demand for higher definition, the use of materials with a large Abbe number (for example, with an Abbe number of 75 or more) has been increasingly used to reduce chromatic aberration. It has become.

  As a technology to correct the focus shift due to temperature fluctuation, the lens barrel is configured by members with different expansion coefficients, and a method of appropriately selecting the lens power balance and material, even if there is a temperature fluctuation, It is known that mutual compensation is performed for thermal expansion and contraction.

However, these methods are also factors that hinder high performance, downsizing, weight reduction, and cost reduction.
Furthermore, when the temperature environment in the projection lens is not uniform, the design itself for obtaining the temperature compensation effect becomes difficult.

  In order to deal with such problems, in the field of photographing optical systems, those described in the following Patent Documents 1 and 2 are known as those in which a part of a lens is actively moved to perform focus adjustment accompanying a temperature change. It has been.

Japanese Patent No. 2762200 JP 2002-341243 A

  However, unlike a photographing optical system as described in the above publication, in the case of a projection lens, in order to introduce a light beam from an extremely strong light source into the projection lens, The temperature change is remarkable, the magnitude of the fluctuation, and the fluctuation over a long period of time (for example, 2 hours after lighting), cannot be considered in the same manner as in the photographing optical system.

  Further, as the above-described technique for correcting the focus movement accompanying the temperature fluctuation, a technique for moving a predetermined lens based on the temperature detected in the system can be considered. It was difficult to operate the temperature detector in the system with high accuracy.

  The present invention has been made in view of such circumstances, and provides a projection display device that can satisfactorily compensate for a focus shift caused by a detected temperature fluctuation even when a light beam from a light source is strong. .

The projection display device according to the present invention is
In a projection display device including a projection lens that modulates a light beam from a light source by a light valve and enlarges and projects the modulated light beam on a screen.
A temperature detector is provided at a position where the modulated light beam is not directly irradiated,
Based on the temperature information from the output from the temperature detector, information on the relationship between the temperature fluctuation and the amount of movement of the focus deviation compensation lens group that compensates for the focus deviation of the projection lens accompanying the temperature fluctuation is obtained in advance. And at least one focus deviation compensation lens group disposed in the projection lens so as to compensate for the focus deviation is configured to move in the optical axis direction. It is.

The defocus compensation lens group preferably satisfies the following conditional expression.
0.1 <Δdd / Δbf <10.0 (1)
here,
Δdd: Amount of movement of the lens group for compensating for the defocus (absolute value display)
Δbf: Focus movement amount with respect to Δdd movement (absolute value display)

  The projection lens preferably includes two or more positive lenses having an Abbe number of 75 or more.

  The projection lens preferably includes a plastic lens.

  Further, it is preferable that one temperature detector is arranged in the vicinity of the lens having the smallest effective diameter.

  In addition, it is preferable that one temperature detector is disposed outside the lens barrel at a position closer to the reduction side than the lens mount.

  Further, it is preferable that the defocus compensation lens group includes a lens arranged on the most reduction side in the projection lens.

  In this case, it is preferable that the defocus compensation lens group is composed of a single lens disposed on the most reduction side in the projection lens, and further, the defocus compensation lens group. It is preferable that one lens located closest to the reduction side is configured not to move by a zooming operation and a focusing operation.

  Here, the “position where the modulated light beam is not directly irradiated” means that the light beam from the light valve is blocked by a member in the apparatus or the temperature at which the light beam is emitted from the light valve. A position where the light does not enter the detector is designated.

  In the projection lens, an extremely strong light beam from the light source is introduced into the projection lens, so that the temperature change with the passage of time from the time of turning on the light source increases, and the focus shift due to the temperature change also increases.

  Therefore, it is important to perform an operation for compensating for the focus shift. However, if the light beam from the light source is directly applied to the temperature detector for this purpose, an appropriate compensation for the focus shift is required. It becomes difficult to obtain temperature information. The prior art described in the above publication relates to an imaging apparatus, and the temperature inside the apparatus is much lower than that of a projection display device, and there is a problem with the position of the temperature detector with respect to the incident light beam. There is no consideration for such a point.

  On the other hand, according to the projection display device of the present invention, a temperature detector is provided at a position where the modulated light beam is not directly irradiated, and temperature information is obtained from an output from the temperature detector. Since a powerful light beam from the light source in the projection display device does not directly irradiate the temperature detector, it is possible to obtain appropriate temperature information for compensating for the focus shift. In the projection display apparatus according to the present invention, the temperature variation obtained in advance based on the appropriate temperature information obtained thereby and the focus for compensating for the focus shift of the projection lens due to the temperature variation are compensated. Since the amount of movement of the projection lens is compensated using the information on the relationship between the displacement compensation lens group and the amount of movement, even in the case of a projection display device, the projection lens regardless of temperature fluctuations in the device. It is possible to maintain the in-focus state with high accuracy.

  Further, in the projection display device according to the present invention, if it is configured to compensate for the focus shift according to the temperature variation by moving one focus shift compensation lens group in the optical axis direction, the above-mentioned publication Compared with the described prior art, the compensation operation for defocusing is simpler and more advantageous in terms of cost.

It is a figure showing the structure of the projection type display apparatus which concerns on Example 1 (embodiment) of this invention. It is a block diagram which shows the notional structure of the projection type display apparatus which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the projection type display apparatus which concerns on embodiment of this invention. 2 is a cross-sectional view illustrating a configuration of a projection lens of the projection display apparatus according to Embodiment 1. FIG. It is a figure showing the structure of the projection type display apparatus which concerns on the comparative example 1. FIG. It is a figure showing the structure of the projection type display apparatus which concerns on Example 2 of this invention. 6 is a cross-sectional view illustrating a configuration of a projection lens of a projection display apparatus according to Embodiment 2. FIG. It is a figure showing the structure of the projection type display apparatus which concerns on the comparative example 2.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram for explaining a projection display apparatus according to an embodiment of the present invention.
The apparatus 1 includes a lens barrel portion 2 and a projector main body 3, and a plurality of lens groups (second lens group G ₂₎ among the lens groups housed in the cam barrel 2 b in the zoom lens barrel portion _2. To the fifth lens group G ₅ ) are configured to move along the optical axis Z independently of each other. On the other hand, the projector body 3 includes light valves corresponding to R, G, and B3 colors (not shown). A color synthesizing prism 5 for synthesizing the luminous fluxes is provided.

Further, the lens barrel portion 2 and the projector main body 3 are configured such that a part of the lens barrel portion 2 (the portion corresponding to the fifth lens group G ₅ and the sixth lens group G ₆ on the reduction side) is in the projector main body 3. They are combined so that they are inserted. The lens barrel portion 2 is provided with a flange portion 2a for holding the lens barrel portion 2 on the lens mount portion 3a of the projector main body 3.

In the present embodiment, a temperature detector is provided at any one or two or more of the positions Ts _{1 to} Ts ₄ where the light beam modulated by the light valve is not directly irradiated. Further, based on the temperature information based on the output from the temperature detector, the temperature fluctuation obtained in advance and the amount of movement of the focus deviation compensation lens group that compensates for the focus deviation of the projection lens accompanying the temperature fluctuation. By using a data table representing the relationship, at least one focus deviation compensation lens group in the projection lens 4 is moved in the optical axis direction so as to compensate for the focus deviation.

  Such a focus deviation compensation lens group preferably includes a lens disposed on the most reduction side in the projection lens 4.

In this case, the lens unit for compensating for the defocus is constituted by a single lens (the fifteenth lens L ₁₅ constituting the sixth lens group G _{6 in} the first embodiment) arranged on the most reduction side in the projection lens. Further, it is preferable that one lens located on the most reduction side constituting the lens group for compensating for the defocus is configured not to be moved by a zooming operation and a focusing operation. Accordingly, it is possible to easily and at low cost compensate for out-of-focus due to temperature fluctuation.

In FIG. 1, the movement locus of the moving lens groups G ₂ , G ₃ , G ₄ , and G ₅ that moves from the wide-angle end to the telephoto end during zooming is depicted.

Further, the position of the temperature detector may be a position in the projection display device where the light beam modulated by the light valve is not directly irradiated, but in particular, the temperature detector Ts shown in FIG. ₁ is preferably disposed in the vicinity of the lens having the smallest effective diameter (in the first embodiment, the lens L ₁₁ on the most enlarged side of the fifth lens group G ₅ ). Alternatively, like the temperature detector Ts ₂ in FIG. 1, it is preferable that the lens barrel portion 2 is disposed outside (on the outer wall surface) at a position closer to the reduction side than the lens mount portion 3a.

The defocus compensation lens group preferably satisfies the following conditional expression (1).
0.1 <Δdd / Δbf <10.0 (1)
here,
Δdd: Amount of movement of the lens group for defocus compensation (absolute value display)
Δbf: Focus movement amount corresponding to the movement of Δdd (absolute value display)

  Conditional expression (1) is intended to simplify the optical adjustment of the moving lens group and shorten the amount of movement of the moving lens group. That is, if the lower limit is not reached, it is difficult to adjust the alignment of the lens group to be moved. On the other hand, if the upper limit is exceeded, the amount of movement of the lens group to be moved becomes too large.

  If the projection lens 4 includes two or more positive lenses having an Abbe number ν of 75 or more, chromatic aberration can be favorably corrected. In addition, it is preferable to include a plastic lens in the projection lens 4 in order to reduce the cost.

  FIG. 2 is a block diagram showing main elements in the apparatus of this embodiment. In other words, the temperature information output from the temperature detection sensor 21 is read by the CPU 22, and the temperature information is obtained from a correspondence table in which the temperature fluctuation amount and the moving lens group compensation movement amount are associated with each other and created in advance and stored in the memory 23. The lens drive motor 24 (which can be shared with the focus lens drive motor can be used as a motor drive signal corresponding to the move lens group compensated move amount. The lens group 25 for defocus compensation is moved to a predetermined position on the optical axis Z in response to this. As a result, after the light source is turned on, it is possible to satisfactorily correct the focus shift based on the temperature fluctuation that occurs in the projection display device. Instead of the above table, the moving lens group compensation movement amount can be obtained from the temperature fluctuation amount using a relational expression between the temperature fluctuation amount and the movement lens group compensation movement amount. Also in this case, the relational expression is stored in the memory 23 in advance.

Further, the CPU 22 drives a zoom lens group (in the first embodiment, the lens groups G ₂ , G ₃ , G ₄ , and G ₅ ) or a focus lens group (in the first embodiment, the lens group G ₁ ). A drive signal is transmitted.

Here, the operation of the above-described embodiment apparatus will be described with reference to FIG.
First, when the main switch of the apparatus is turned on, the lens barrel 2 is extended to the wide-angle end position (S1). Thereafter, a plurality of lens groups (in the first embodiment, the lens groups G ₂ , G ₃ , G ₄ , G ₅ ) move along the optical axis Z in accordance with an operation of a zoom operation unit / focus operation unit (not shown). Then, a zooming operation and a focusing operation are performed (S2). In the case of a fixed focus lens as shown in Example 2, the zooming operation is not performed. Thereafter, the CPU 22 takes in temperature information from the temperature detection sensor 21 (S3). Based on the temperature information, the CPU 22 calculates the temperature fluctuation amount-moving lens group compensation movement correspondence table stored in advance in the memory 23 (or the temperature fluctuation amount and moving lens group compensation movement previously stored in the memory 23). The moving lens group compensation movement amount for compensating for the focus shift is derived using the relational expression between the amounts (S4). Then, the CPU 22 sends a motor drive signal corresponding to the obtained moving lens group compensation movement amount to the drive motor 24 (S5), and the drive motor 24 responds to the motor drive signal and the focus deviation compensation lens group 25. In the first embodiment, the lens group G ₆ is moved along the optical axis Z to compensate for the focus shift (S6).

  The operation of the above-described apparatus shown in FIG. 3 shows an example, and it is needless to say that other various operations can be adopted.

  For example, a zooming operation or a focusing operation may not be performed in response to an instruction from the CPU 22, but an operation for directly driving the drive motor 24 may be performed.

  Also, a correspondence table in which the three components of the temperature fluctuation amount, the zoom position, and the moving lens group compensation movement amount are associated is stored in the memory 23, and the value of the temperature fluctuation amount depends on the zoom position in combination with the zoom operation information. It is also possible to change the value of the moving lens group compensation movement amount according to the above.

  Specific examples of the projection display device according to the present invention will be described below. In addition, in each Example, the same code | symbol is attached | subjected about the member which makes mutually the same effect.

The projection lens of the projection display apparatus according to Example 1 is a zoom lens, and as shown in FIGS. 1 and 4, the first lens group G ₁ , the second lens group G ₂ , and the third lens are sequentially arranged from the enlargement side. It consists of a lens group G ₃ , a fourth lens group G ₄ , a fifth lens group G ₅ , and a sixth lens group G ₆ , of which the second lens group G ₂ , the third lens group G ₃ , and the fourth lens group G _4, and the fifth lens group G _5, at the time of zooming, and is configured to move independently of each other. The first lens group _{G 1} is composed of four lenses _(L 1 ~L _4), the second lens group _{G 2} is composed of two lenses _(L 5, L _6), the third lens group _{G 3} Consists of two lenses (L ₇ , L ₈ ), a mask 7 and a diaphragm 8, the fourth lens group G ₄ consists of two lenses (L ₉ , L ₁₀ ), and the fifth lens group G ₅ has 4 consists lenses _(L 11 _{~L 14),} the sixth lens group _{G 6} composed of one lens _{(L 15).} The sixth lens group G ₆ is configured so as not to move by zooming and focusing.

Further, as described above, zooming is performed by moving the _{second to} fifth lens groups G ₂ , G ₃ , G ₄ , and G ₅ independently of each other. Focusing moves the first lens group G ₁ . Is to be done.

Further, the reduction side of the sixth lens group G _6, the color synthesizing prism 5 and the light valve (transmissive liquid crystal, a reflective liquid crystal or DMD, etc.) 6 is disposed. In general, three light valves are provided for each color light of R, G, and B, but in the drawing of the present application, only one light valve is displayed for convenience of viewing.

The temperature detector is disposed in any _{one of} positions Ts _{1 to} Ts _{4 in} the projection display apparatus where the light beam modulated by the light valve is not directly irradiated. . That is, the position Ts ₁ is an arrangement in the vicinity of the lens L ₁₁ on the most magnifying side of the fifth lens group G _{5 having} the smallest effective diameter in the entire system. Further, the position Ts ₂ is a position on the outer side (on the outer wall surface) of the lens barrel portion 2 and on the reduction side with respect to the lens mount portion 3a. The position Ts ₃ are inside the lens barrel 2 (on the inner wall surface of the outer cylinder), the position of the reduction side than the lens mount portion 3a. The position Ts ₄ is an inner wall surface of the projector body 3 and is a position where the light beam from the color synthesis prism 5 is not directly irradiated. Providing a temperature detector at such a position prevents a strong light beam from the light source in the projection display device from being directly applied to the temperature detector, so appropriate temperature information to compensate for the focus shift Can be obtained.

On the other hand, as shown in FIG. 5, for example, positions Tx ₁ and Tx ₂ where the light beam modulated by the light valve is directly irradiated (if the light beam is directly irradiated without any intervening, or a lens is interposed between them). When the temperature detector is disposed in a case where the light beam is directly irradiated via the light source, it is difficult to obtain appropriate temperature information for compensating for the focus shift.

Further, the value of Δdd / Δbf corresponding to the conditional expression (1) described above is moved integrally with the lenses L _{1 to} L ₄ of the first lens group G ₁ on the most enlargement side as the lens group 25 for defocus compensation. In this case, 1.33 at the wide-angle end and 0.52 at the telephoto end, satisfying the conditional expression (1). In this embodiment, the first lens group G ₁ is because the function as a focusing lens group, which is advantageous in terms of cost becomes a defocusing compensation well without providing a separate lens driving unit due to temperature variations .

On the other hand, when moving the most reduction side of the sixth lens group lens L ₁₅ in G ₁ as defocusing compensation lens group 25, at the wide angle end 1.21, even at the telephoto end is 1.21, the condition Expression (1) is satisfied (see FIG. 1).

The radius of curvature R of each lens surface of the projection lens according to Example 1 (normalized by setting the focal length at the wide-angle end to 1.00: the same as in Example 2), the center thickness of each lens, and the air space between each lens (hereinafter referred to as "axial surface distance") D (is normalized focal length at the wide angle end as 1.00: same in example 2), the refractive index N _d and the Abbe number [nu _d of each lens at d-line The values are shown in the upper part of Table 1. In Tables 1 and 2, the surface numbers represent the order from the enlargement side.

In this embodiment, two positive lenses (L ₁₄ , L ₁₅ ) having an Abbe number ν of 75 or more are provided.

The projection lens of the projection display apparatus according to Example 2 is a fixed focus lens, and as shown in FIGS. 6 and 7, in order from the enlargement side, the first lens group G ₁ , the second lens group G ₂ , and consisting the third lens group _{G 3.} The first lens group _{G 1} is composed of two lenses _(L 1, _{L 2),} the second lens group _{G 2} becomes one lens and _{(L 3)} from the mask 7, the third lens group _{G 3} Consists of _four lenses (L _{4 to} L ₇ ).

Focusing is adapted to be effected by moving the entire first lens group G _1, lens L ₇ on the most reduction side in the third lens group G ₃ is configured so as not to move by focusing .

In addition, the color synthesizing prism 5 and the light valve (transmission type liquid crystal, reflection type liquid crystal, DMD, etc.) 6 are disposed on the reduction side of the third lens group G ₃ on the most reduction side. Is the same as

The temperature detector is disposed in any one of the positions Ts _{5 to} Ts _{7 in} the projection display device where the light beam modulated by the light valve is not directly irradiated. . That is, the position Ts ₅ is a position in the vicinity of the lens L ₄ on the most magnifying side of the third lens group G _{3 having} the smallest effective diameter in the entire system. Further, the position Ts ₆ is a position (a position on the inner wall surface of the projector main body 3) on the reduction side of the lens mount portion 3a outside the lens barrel portion 2. Further, the position Ts ₇ is on the outer wall surface of the lens barrel portion 2. By providing a temperature detector at such a position, a strong light beam from the light source in the projection display device is not directly applied to the temperature detector, so appropriate temperature information to compensate for the focus shift Can be obtained.

On the other hand, for example, as shown in FIG. 8, positions Tx ₃ and Tx ₄ (directly irradiated with a light beam without any intervening or a lens between them as shown in FIG. When the temperature detector is disposed in a case where the light beam is directly irradiated via the light source, it is difficult to obtain appropriate temperature information for compensating for the focus shift.

Further, the value of Δdd / Δbf corresponding to the conditional expression (1) described above is moved integrally with the lenses L ₁ and L ₂ of the first lens group G ₁ on the most enlarged side as the lens group 25 for defocus compensation. In this case, it is 1.20, which satisfies the above conditional expression (1). Incidentally, when configured this way defocusing compensation lens group 25, in this embodiment, the first lens group G ₁ is because the function as a focusing lens group, separate for defocus compensation due to temperature variations There is no need to provide a lens driving unit, which is advantageous in terms of cost.

On the other hand, when the lenses L _{1 to} L ₄ of the third lens group G ₃ closest to the reduction side are moved as the focus deviation compensating lens group 25 (see FIG. 6), 0.99 is obtained, and the conditional expression (1 ) Is satisfied.

Further, both surfaces of the second lens L ₂ and the fourth lens L ₄ is an aspheric surface, the aspherical shape is defined by the following aspheric expression.

Table 2 shows the values of the radius of curvature R of each lens surface, the axial top surface distance D, the refractive index N _d of each lens at the d-line, and the Abbe number ν _d of the projection lens according to Example 2. In Table 2, the surface marked with * on the right side of the surface number is an aspherical surface. The aspheric coefficients representing these aspheric surfaces are shown in the lower part of Table 2.

In this embodiment, two plastic lenses (L ₂ and L ₄ ) are provided.

  The projection display device of the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the position of the temperature detector (temperature detection sensor), the projection lens It is possible to appropriately change the radius of curvature R and the lens interval (or lens thickness) D of each lens.

  Also, as the illumination optical system, an appropriate configuration corresponding to the type of light valve can be adopted.

DESCRIPTION OF SYMBOLS 1 Projection type display apparatus 2 Lens barrel part 2a Flange part 3 Projector body 3a Lens mount part 4 Projection lens 5 Color composition prism 21 Temperature detection sensor 22 CPU
23 memory 24 the lens driving motor 25 defocusing compensation lens group G ₁ ~G ₆ lens group L ₁ ~L ₁₅ lens R ₁ to R of curvature such as ₃₁ lens surface radius D ₁ to D ₃₀ axial distance Z optical axis

Claims (9)

In a projection display device including a projection lens that modulates a light beam from a light source by a light valve and enlarges and projects the modulated light beam on a screen.
A temperature detector is provided at a position where the modulated light beam is not directly irradiated,
Based on the temperature information from the output from the temperature detector, information on the relationship between the temperature fluctuation and the amount of movement of the focus deviation compensation lens group that compensates for the focus deviation of the projection lens accompanying the temperature fluctuation is obtained in advance. And at least one defocus compensation lens group disposed in the projection lens so as to compensate for the defocusing is configured to move in the optical axis direction. Type display device. The projection display device according to claim 1, wherein the lens group for compensating for the defocus satisfies the following conditional expression.
0.1 <Δdd / Δbf <10.0 (1)
here,
Δdd: Amount of movement of the lens group for compensating for the defocus (absolute value display)
Δbf: Focus movement amount with respect to Δdd movement (absolute value display)   3. The projection display device according to claim 1, wherein the projection lens includes two or more positive lenses having an Abbe number of 75 or more.   The projection display apparatus according to claim 1, wherein the projection lens includes a plastic lens.   The projection display device according to claim 1, wherein one temperature detector is disposed in the vicinity of a lens having the smallest effective diameter.   5. The projection display device according to claim 1, wherein one of the temperature detectors is disposed outside the lens barrel at a position closer to the reduction side than the lens mount. .   7. The projection display device according to claim 1, wherein the lens unit for compensating for a focus deviation includes a lens arranged closest to the reduction side in the projection lens.   8. The projection display device according to claim 7, wherein the focus deviation compensation lens group is constituted by a single lens arranged closest to the reduction side in the projection lens. 9. The projection display device according to claim 8, wherein one lens located on the most reduction side constituting the focus deviation compensation lens group does not move by a zooming operation and a focusing operation.

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