JPH10221598A - Projecting lens device and projection television device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projecting lens device which can reduce drift of focus performance caused by temperature or humidity change, and has wide view angle. SOLUTION: In order to prevent temperature and humidity change in paraxial system from decreasing focus performance, most of positive refracting force which entire projecting lens device possesses is assigned to glass lenses 3. Plastic non-spherical lenses 1, 2 which have low positive refracting force are arranged near an optical axis. This provides wide view angle for the lens device. On the other hand, aberration depending on aperture is corrected by using non- spherical shape on the lens' peripheral part. Local change of refracting force in the lens which is caused by temperature/humidity depending change of the non-spherical shape on the lens' peripheral part is offset by combination of plural plastic non-spherical lenses 1, 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection lens apparatus suitable for a projection television apparatus, and more particularly to a hybrid projection lens apparatus in which a glass lens and a plastic lens are mixed.

[0002]

2. Description of the Related Art In a so-called projection television apparatus in which an original image on a fluorescent screen of a cathode ray tube is projected on a screen by a projection lens apparatus, remarkable progress has been made in focus performance in recent years. The required performance of the lens device is increasing year by year.

In such a situation, a plastic lens having a large degree of freedom for aberration correction, a large aperture, and excellent mass productivity can be obtained by easily making the lens surface aspherical. It is becoming mainstream as a lens constituting the device. Initially, the projection lens device mainly composed of a plastic lens was mainly used, but now, a hybrid system using a glass lens (spherical lens) and an aspherical plastic lens in combination is mainly used.

[0004] The reason for this is that if a projection lens device is constituted only by a plastic lens, there is a problem that the refractive index and the shape change due to the temperature change, the focal position changes, and the focus performance deteriorates. (Hereinafter, such a decrease in focus performance is referred to as a focus temperature drift).

Japanese Patent Application Laid-Open (JP-A) No. 63-264716 is an example of a document that discloses specific technical means for solving this problem. The prior art disclosed herein is a projection lens apparatus having a five-group configuration, in which most of the positive refracting power of the entire lens system is borne by the third lens group. Temperature drift is significantly reduced. By using the first lens unit as a positive lens and the second lens unit as a negative lens, a change in the refractive power (due to a change in the refractive index) of the lens caused by a temperature drift is offset.

As described above, the conventional projection lens device described in the above-mentioned document can be said to be an excellent projection lens device in which the focus temperature drift is reduced by the optimal design of the lens configuration.

[0007]

In the above-mentioned prior art lens arrangement, the second group lens composed of a concave lens is replaced with a third group lens in order to reduce spherical aberration, astigmatism and coma aberration depending on the aperture. Is arranged in close proximity to the screen side. For this reason, the entrance pupil position of the entire lens system moves away from the center of the third lens unit to the screen side, which is the image point, and a wide angle of view (shortening of the projection distance) is achieved with the above-mentioned prior art projection lens device. If it is attempted to achieve the above, it is very difficult to correct distortion and astigmatism.

Further, in order to obtain a sufficient peripheral light amount ratio at the same time as increasing the aperture, the outer diameter of the constituent lens increases,
Production costs increase. For the reasons described above, it has been very difficult to achieve a wide angle of view (short projection distance) with the projection lens device according to the related art.

Furthermore, in the above-mentioned prior art, there is no disclosure about the deformation of the lens shape due to expansion and contraction of each lens due to the temperature change which still occurs and the solution therefor, and there is a lack of practicality. .

It is an object of the present invention to provide a projection lens device which can sufficiently reduce the drift of focus performance due to temperature and humidity and can widen the angle of view (shortening the projection distance). Another object of the present invention is to provide a projection television apparatus using the projection lens apparatus.

[0011]

To achieve the above object, the present invention takes the following measures. That is, in order to reduce the deterioration of the focus performance with respect to temperature and humidity changes in the paraxial system, most of the positive refractive power of the entire projection lens device is a glass lens (hereinafter referred to as a glass power lens).
To share. At this time, no concave lens is arranged near the glass power lens, and a plastic aspheric lens having a weak positive refractive power is arranged near the optical axis.

Thus, since the entrance pupil does not move to the screen side away from the glass power lens, a projection lens device having a wide angle of view can be realized.

On the other hand, the correction of the aberration depending on the aperture is corrected by the aspherical shape of the portion (peripheral portion of the lens) separated from the optical axis. Next, a local change in the refractive power of the lens surface due to a change in the temperature and humidity of the aspherical shape around the lens is offset by a combination of a plurality of plastic aspherical lenses. With the method described above, highly accurate temperature and humidity compensation of the focus performance can be realized.

In the mounted state, the shape of the two types of plastic aspherical lenses is forcibly deformed so that shape changes due to temperature and humidity do not occur freely, or even if they occur, they are easily offset. The above-mentioned object by making the lens barrel and the lens structure having such a structure
Can be achieved.

[0015]

The function of the technical means for solving the problems of the present invention will be described with reference to FIGS. 3, 4 and 5. FIG.

FIG. 3 is a longitudinal sectional view for explaining means for reducing the focus drift with respect to temperature and humidity of the projection lens apparatus according to the present invention. In the figure, 1 is a first group lens, 2 is a second group lens, 3 is a third group lens (however, the third group lens 3 is a glass lens formed by laminating a lens 3a and a lens 3b). ,
Reference numeral 4 denotes a fourth lens group, 5 denotes a single lens constituting a fifth lens group having a concave surface facing the screen side, 6 denotes a coolant, and 13 denotes a screen.

Referring to FIG. Effective imaging within the ray from the center point A of the cathode ray tube phosphor screen P ₁ (screen 13
) And the lower limit ray is RAY2. Further, among the rays from the object point B in the peripheral portion of the screen, the upper limit light of rays effective for image formation is RAY3 and the lower limit light is R
AY4.

For the sake of explanation, a six-lens projection lens system is used, and a hybrid system is used in which 3a and 3b are glass lenses and the other are plastic lenses.

First, means for reducing focus drift with respect to the temperature at the center of the screen will be described. The shapes of the first group lens 1 and the second group lens 2 which are plastic aspheric lenses in the vicinity of the optical axis are both formed to have a weak positive refractive power. As a result, it is possible to reduce the influence of a change in the refractive power of the two lenses due to the temperature on the refractive power of the entire projection lens system (mostly shared by glass lenses).

[0020] Next, as shown in FIG. 4 is an enlarged view of a portion A of FIG. 3, the shape of the peripheral portion of the lens refractive power of the first lens unit 1, a concave lens shape (local lens is -Pusai ₁ ), and the second group lens 2, a convex lens shape on the opposite (and ₄ the refractive power of the local lens [psi), approximately equal to local power therebetween. That is, the ψ ₁ ≒ ψ _4.

Next, the means for reducing the focus drift with respect to the temperature in the peripheral portion of the screen will be described. Returning to FIG. 3, among the image light from the off-axis object point B, the upper limit light RAY3 and the lower limit light RAY4 are the first plastic aspherical lenses as shown in FIG. 5, which is an enlarged view of the portion of FIG. 3A. In the group lens 1, the light passes above the optical axis.

The shape of the passing area is a concave lens shape centered on the position where the principal ray has passed. On the other hand, the shape of the light passage area of the second group lens 2 is a weak convex lens shape near the optical axis. The refractive power (−ψ ₅ ) of the local concave lens in the region between the principal ray of the first lens unit 1 and the upper limit light ray ₃ is substantially equal to the refractive power ψ ₇ of the local convex lens of the second lens unit 2. .

Similarly, the refractive power (−ψ ₆ ) of the local concave lens in the region between the principal ray of the first group lens 1 and the lower limit light ray 4 and the refractive power of the local convex lens of the second group lens 2 ψ Make ₈ approximately equal.

Although the meridional plane has been described above for convenience of explanation, it goes without saying that the same effect can be obtained for a sagittal plane.
As described above, in order to reduce the focus drift with respect to the temperature change, the first group lens 1 and the second group lens 2 may be designed so that the local lens shapes have substantially the same refractive power.

Further, in order to reduce the deterioration of the focus performance caused by the expansion and contraction of the lens caused by the change in humidity, as described above, the local lens shapes of the first lens group 1 and the second lens group 2 are required. It is preferable to make the refractive powers of the two substantially equal to cancel each other. Further, a means for restraining the first group lens 1 and / or the second group lens 2 or both of them other than the effective diameter of the lens from the radial direction is provided, and when the lens expands, it is forcibly deformed. It is even better to increase the local lens refractive power to enhance the canceling effect.

[0026]

Embodiments of the present invention will be described below. 1 and 2 are cross-sectional views each showing a main part of a lens of a projection lens device as one embodiment of the present invention.

In these figures, P ₁ is a CRT fluorescent screen, 7 is a CRT panel, 6 is a coolant, and 5 is a single lens having a concave surface facing the screen. The fifth lens group includes a CRT panel 7, a cooling liquid 6, and a single lens 5, 4 is a fourth lens group, 3 is a third lens group, 2 is a second lens group, and 1 is a first lens group. It is.

The first to fourth lens units 1 to 4 are assembled into the inner lens barrel 8 and fixed to the outer lens barrel 9 with fixing screws 11. Furthermore, it is screwed and fixed to the bracket 10 via the fixing plate 12 by the outer lens barrel 9.

The optical system of the present embodiment has a CRT fluorescent screen P
_The configuration is such that the best performance is obtained when a 5.4 inch raster on ₁ is enlarged and projected on the screen.
Table 1 (A), (B) and Table 2
In the optical system constituted by the lens data shown in (A) and (B), the magnification is 8.4 times, and Table 3 (A) and (B)
In the optical system constituted by the lens data shown in Tables 5A and 5B, the magnification is 9.3 times.

The angle of view of the lens is 72 degrees in an optical system constituted by the lens data shown in Tables 1 (A) and (B) and Tables 2 (A) and 2 (B), and Table 3 ( A), (B) or Table 5 (A), the optical system constituted by the lens data shown in each of (B) is 78 degrees, realizes a high angle of view, and one folding mirror is sufficient. A compact set can be realized.

The first lens group 1 has an aspherical shape in order to eliminate spherical aberration based on the aperture. Second lens group 2
Has an aspherical shape to eliminate astigmatism and coma. The third lens group 3 is a glass lens and has as much power as possible to reduce focus drift due to temperature change.

The fourth lens unit 4 has an aspherical shape in order to eliminate high-order coma aberration, and its power is made as small as possible. The fifth group lens is composed of a single lens 5 having a concave surface facing the screen side as a lens for correcting the curvature of field, a CRT panel 7 and a coolant 6.

Further, in order to correct off-axis sagittal aberration, the air-side (screen-side) interface of the single lens 5 is made aspheric. Further, cathode ray tube phosphor surface P ₁ is Motashi a curvature in order to correct the field curvature. In particular, if an aspherical surface is used to correct higher-order field curvature, more excellent correction can be performed.

Generally, the fluorescent screen P ₁ of the CRT panel 7
Is manufactured by press molding without post-processing. Therefore, whether the molded shape is spherical or aspherical,
The manufacturing method itself does not change.

On the other hand, the lens of the present lens system is designed to minimize the power of the plastic lens and is thin, and the thickness difference between the central portion and the peripheral portion is reduced, thereby improving the moldability. I'm trying.

In the embodiment of the present invention, as an optical system having data as shown in Table 6, the focal length of the entire projection lens system is set to 8
The focus is shortened to about 0 mm to reduce chromatic aberration. In addition, as shown in FIG.
The two lenses a and 3b are laminated lenses (corresponding to Tables 1 (A), 2 (A) and 4 (A) in the embodiment). The lens 3b is a concave lens made of a high-dispersion material, and the lens 3a is a convex lens made of a low-dispersion material.

Tables 1 to 5 show specific lens data that can be taken by the projection lens apparatus according to the present invention described above.

Next, how to read the lens data will be described based on Table 1. Table 1 shows the data divided into a spherical system (Table 1 (A)) mainly dealing with the lens area near the optical axis and an aspheric system (Table 1 (B)) on the outer periphery thereof.
First, the screen has a radius of curvature of ∞ (that is, a plane), the distance (surface interval) on the optical axis from the screen to the surface S ₁ of the _first lens unit 786.09 mm, and the refraction of the medium (air) between them. The rate is shown to be 1.0.

The radius of curvature of the S ₁ surface of the first lens unit 1 is 97.898 mm (the center of curvature is on the fluorescent screen side).
The distance between the lens surfaces S ₁ and S _{2 on} the optical axis (surface distance) is 8.8.
74 mm, and the refractive index of the medium between them is 1.4933.
4 is shown. In the same manner the end has a radius of curvature of the fluorescent face P ₁ of the CRT panel 7 341.2
8 mm, the thickness on the optical axis of the CRT panel 7 is 13.4
mm and a refractive index of 1.56232.

Next, Table 1 (B) shows the surfaces S ₁ and S ₂ of the _first lens unit 1, the surfaces S ₃ and S ₄ of the second lens unit 2, and the surfaces S ₇ and S ₄ of the fourth lens unit 4. _The aspheric coefficients are shown for ₈ , the surface S ₁₀ of the fifth lens unit 5, and the fluorescent surface P ₁ . here,
The aspheric coefficient is a coefficient when the surface shape is expressed by the following equation.

[0041]

(Equation 1)

However, as shown in FIGS. 7 and 8 which are explanatory diagrams of the definition of the lens shape, Z takes the optical axis direction as the Z axis.
Represents the height of the lens surface when r is taken in the radial direction of the lens (a function of r), where r is the distance in the radial direction and R _D
Indicates a radius of curvature.

Therefore, if the coefficients CC, AE, AF, AG, and AH are given, the height of the lens surface, that is, the shape, is determined according to the above equation.

FIG. 8 is an explanatory view of an aspherical surface. By substituting respective values for the above-mentioned aspherical surface, a lens shifted from the lens surface of the spherical system only by S _{S (r)} −A _{S (r).} The surface is obtained.
Further, the surface S ₁₁ of Table 1 (B) in the fifth lens group 5 shows that aspherical coefficients are all a zero spherical.

The above is how to read the data shown in Tables 1 (A) and (B). Tables 2 to 5 show specific examples of lens data of other examples, and the reading method is the same.

FIG. 1 is a side sectional view of a projection lens device corresponding to the lens data shown in Tables 1 (A) and (B).
3 is a side sectional view of the projection lens device corresponding to the lens data in Tables 4 (A) and (B).

Next, using the projection lens apparatus according to the present invention described above, an MTF (Modul) is obtained by enlarging and projecting a 5.4-inch image on a phosphor screen onto a screen.
FIGS. 9 to 13 show the evaluation results of the focus characteristics based on the operation transfer function. At this time, the phosphor emission spectrum shown in FIG. 6 was used.

FIG. 9 is a characteristic diagram corresponding to Tables 1 (A) and (B), FIG. 10 is a characteristic diagram corresponding to Tables 2 (A) and (B), and FIG. 11 is Table 3 (A). , (B), and FIG. 12 shows Table 4 (A),
FIG. 13 is a characteristic diagram corresponding to Table 5 (A) and FIG. 13 (B), respectively. Note that a case where 300 TV lines are taken as white and black stripe signals on the screen is shown.

FIG. 9 to FIG. 13 show good MTF characteristics. Regarding the embodiment constituted by the lens data shown in Tables 1 to 5, the focal length of the entire lens system is f0, the focal lengths of the first lens group 1, the second lens group 2, and the third lens group 3 are f1, Assuming f2 and f3, Table 6
The relationship shown in FIG. That is,

0.14 <f0 / f1 <0.24 0.02 <f0 / f2 <0.25 0.63 <f0 / f3 <0.83 In the present embodiment, most of the positive refractive power of the entire lens system is shared by the third lens unit, which is a glass lens, so that the focus temperature drift is reduced.

Next, the shape of the lens surface will be described. The first lens group 1 screen side lens surface S _1, the second group lens surface S _2, the second group lens first group side lens surface S ₃ 2,
For non-spherical shape of the second lens group 2 of the third group lens surface S ₄ the following can be said. This will be described below with reference to FIG.

FIG. 8 is an explanatory diagram showing the shape of the aspherical lens, as described above. S _{S (r)} , CC, AE, AF, A when the height of the lens surface when taking the optical axis direction as the Z axis and taking the lens in the radial direction is a spherical system, ie, only _RD.
Assuming that each of the aspherical coefficients of G and AH is substituted in the above equation (1) is A _{S (r).} If the crap radius is substituted for r, the above-mentioned screen-side lens surface S ₁ of the first group lens ₁ is obtained. A _{S (r)}
And the ratio of S _{S (r)} is as shown in Table 8.

The relationship of -0.08 <A _s / S _s <0.05 is established, and the second lens unit 1
In the group-side lens surface S _2, 0.20 <are composed relationship A _S / _{S S} <0.52.

As shown in Table 9, the first lens unit lens surface S ₃ of the second lens unit 2 satisfies the relationship of −1.26 <A _S / S _S <0.06. Similarly, the relationship of −0.11 <A _S / S _S <0.75 is satisfied on the third lens surface S ₄ of the second lens unit 2.

Assuming that the surface distance between the first lens unit 1 and the second lens unit 2 is I23, the ratio of I23 to the focal length f0 of the whole projection lens system is 0.15 <0.15 as shown in Table 7. The relationship of (I23 / f0) <0.25 holds.

To maintain the peripheral light quantity ratio while maintaining the force performance, it is necessary to satisfy 0.15 <(I23 / f0).

On the other hand, as this ratio increases, the amount of light in the middle area of the screen tends to decrease, so that (I23 / f0) <0.25 is preferable.

Table 7 shows the ratio of the surface distance I23 between the first group lens 1 and the second group lens 2 and the surface distance I45 between the second group lens 2 and the third group lens 3. Thus, the relationship of 23.0 <(I23 / I45) <40.0 holds.

[0059] Preferably in order to secure the edge thickness of the lens pressing the sag of the first lens group side lens surface S ₃ of the second lens unit 2 needs to be (I23 / I45) <40.0.

On the other hand, if the above value is reduced while securing the brightness at the center of the screen, it is necessary to increase the effective diameter of the second group lens 2. Therefore, it is desirable that 23.0 <(I23 / I45).

Tables 1 to 5 show the phosphor screen shapes.
The center of curvature is a surface shape that exists on the screen side and has a larger radius of curvature from the center to the periphery as shown in FIG.

The projection lens device according to the present invention has 45
The projection distance is 787.6 mm in inch projection and 790.0 mm in 50 inch projection, which is sufficiently short and requires only one folding mirror, so that a compact set can be achieved.

The features of the projection lens apparatus according to the embodiment of the present invention have been described based on the lens data. Next, the effect of this embodiment will be specifically described.

FIGS. 14 and 15 show a projection lens apparatus (Tables 1 (A) and 1 (B)) as an embodiment of the present invention shown in FIG.
The first group lens 1 alone, the second group lens 2 alone, and the first group lens 1 and the second lens
M of 300 TV lines when the lens shape is changed by simultaneously expanding and contracting the group lens 2 by 0.1% and 0.1%.
FIG. 4 is a characteristic diagram showing a change in TF characteristic.

In both figures, the average of the MTFs of meridional and sagittal are calculated and plotted at the respective image heights. The condition 1 in both figures is that the first group lens 1
Condition 2 indicates a case where only the second group lens 2 is used alone. Condition 3 is that the first group lens 1 and the second
The case where the group lens 2 is expanded or contracted at the same time is shown.

As can be seen from these figures, in the present embodiment, a decrease in focus performance caused by a change in the lens surface shape caused by expansion or contraction is offset by a change in the shape of the first lens unit 1 and the second lens unit 2. I understand.

Next, FIGS. 16 and 17 are characteristic diagrams showing a change in the MTF characteristic of 300 TV with respect to a change in the refractive index of the lens caused by a temperature change in the same embodiment as the above-described embodiment. In the figure, the averages of MTFs of meridional and sagittal are calculated and plotted at respective image heights.

FIG. 16 is a characteristic diagram when the lens temperature is 40 ° C. FIG. 17 shows that the lens temperature is 65 ° C.
FIG. 6 is a characteristic diagram in the case of ° C.

The condition 1 in both figures indicates a case where only the first group lens 1 is used alone, and the condition 2 indicates a case where only the second group lens 2 is used alone. Condition 3 indicates a case where the refractive indexes of the first group lens 1 and the second group lens 2 are changed at the same time.

In both figures, when the condition 2 is satisfied, that is, when the refractive index is changed only by the second group lens 2 alone, the focus performance is most greatly reduced. As in the case of the focus reduction due to the expansion and contraction of the lens described above, in the case of condition 3, that is, when the refractive index changes of the first group lens 1 and the second group lens 2 occur simultaneously, the focus performance is reduced. It turns out to be offset.

As described above, the projection lens apparatus according to the present embodiment can prevent the focus performance from being lowered by the temperature and humidity.
This can be offset by the lens surface shapes of at least two plastic aspheric lenses in the constituent lenses.

[0072]

[Table 1 (A)]

[0073]

[Table 1 (B)]

[0074]

[Table 2 (A)]

[0075]

[Table 2 (B)]

[0076]

[Table 3 (A)]

[0077]

[Table 3 (B)]

[0078]

[Table 4 (A)]

[0079]

[Table 4 (B)]

[0080]

[Table 5 (A)]

[0081]

[Table 5 (B)]

[0082]

[Table 6]

[0083]

[Table 7]

[0084]

[Table 8]

[0085]

[Table 9]

[0086]

According to the present invention, the shape of at least two plastic aspherical lenses in the projection lens device makes it possible to control the temperature and the temperature even when the diameter of the projection lens device is increased.
It is possible to offset a decrease in focus performance with respect to humidity.

Further, other effects are as follows: (1) No concave lens is arranged on the screen side of the lens having positive refracting power of the entire projection lens system, so that distortion and astigmatism are corrected even if the angle of view is widened. It is possible to achieve both high focus and wide angle of view.

(2) As described above, since no concave lens is provided, light rays from the periphery of the screen are not diverged. Therefore, the height of the light beam can be reduced. Therefore, a favorable peripheral light amount ratio can be realized.

Further, in order to reduce the deterioration of the focusing performance with respect to temperature and humidity, means for restraining the movement of the plastic aspherical lens from the radial direction at a portion (edge) other than the effective diameter of the plastic aspherical lens is provided. In addition, the local shape of the lens is forcibly deformed by expansion due to a change in humidity, and the above-described canceling effect can be further enhanced.

Further, depending on the shape of the lens, holding means having no binding force may be required, and the above-described holding can be realized by the plastic lens of the present invention and the lens barrel.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a projection lens device as one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a projection lens device as one embodiment of the present invention.

FIG. 3 is a schematic view of a lens for explaining the operation principle of the projection lens device according to the present invention.

FIG. 4 is a schematic view of a lens for explaining the operation principle of the projection lens device according to the present invention.

FIG. 5 is a schematic view of a lens for explaining the operation principle of the projection lens device according to the present invention.

FIG. 6 is an emission spectrum characteristic diagram of a green phosphor.

FIG. 7 is an explanatory diagram used to explain the definition of a lens shape.

FIG. 8 is an explanatory diagram used to explain the definition of the lens shape.

FIG. 9 is an MTF characteristic diagram of the projection lens device shown as an example of the present invention.

FIG. 10 is an MTF characteristic diagram of the projection lens device shown as an embodiment of the present invention.

FIG. 11 is an MTF characteristic diagram of the projection lens device shown as an example of the present invention.

FIG. 12 is an MTF characteristic diagram of the projection lens device shown as an example of the present invention.

FIG. 13 is an MTF characteristic diagram of the projection lens device shown as an example of the present invention.

FIG. 14 is a characteristic diagram illustrating MTF characteristics with respect to a change in lens shape of the projection lens device as one embodiment of the present invention.

FIG. 15 is a characteristic diagram showing MTF characteristics with respect to a change in lens shape of the projection lens device as one embodiment of the present invention.

FIG. 16 is a graph showing the relationship between a change in the refractive index of a lens caused by a change in temperature of a projection lens apparatus according to an embodiment of the present invention and M
FIG. 4 is a characteristic diagram showing TF characteristics.

FIG. 17 is a graph showing a relationship between a change in refractive index of a lens caused by a change in temperature of a projection lens apparatus according to an embodiment of the present invention and a change in M;
FIG. 4 is a characteristic diagram showing TF characteristics.

[Explanation of symbols]

1 ... first group lens, 2 ... second group lens, 3 ... third group lens, 4 ... fourth group lens, 5 ... single lens, P ₁ ... phosphor screen,
6 ... Coolant, 7 ... CRT panel, 8 ... Inner barrel, 9 ...
Outer lens barrel, 10: bracket, 11: fixing screw, 12: fixing plate, 13: screen

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[Procedure amendment]

[Submission date] March 31, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyoshi Wada 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref.

Claims (12)

[Claims] 1. A projection lens device for enlarging and projecting an original image projected on a screen display unit of an image display device onto a screen, wherein first, second and third lenses are arranged in order from the screen side to the image display device side. , A fourth group lens, and a fifth group lens are arranged. The first group lens has a central portion including an optical axis that is convex with respect to the screen side, and a peripheral portion that is radially away from the optical axis with respect to the screen. A first plastic lens having a concave surface with respect to the first group lens, wherein the second group lens has a predetermined positive refractive power at a center portion including an optical axis thereof, and is separated from the optical axis in a radial direction. A projection lens device, comprising: a second plastic lens having a surface having a shape having a positive refractive power larger than the predetermined positive refractive power in a peripheral portion, and satisfying the following relationship. 0.14 <f0 / f1 <0.24 0.02 <f0 / f2 <0.25 0.63 <f0 / f3 <0.83 where f0 is the fluorescent screen which is the screen display unit of the image display device. F1: focal length of first lens group f2: focal length of second lens group f3: focal length of third lens group 2. The projection lens apparatus according to claim 1, wherein an aspherical amount As / Ss of a screen-side lens surface of the first plastic lens satisfies the following relationship. Lens device. −0.08 <(As / Ss) <0.05, where As: Aspherical sag amount Ss: Spherical sag amount 3. The projection lens device according to claim 1, wherein an aspherical amount As / Ss of a lens surface on a display screen side of the first plastic lens satisfies the following relationship. Lens device. 0.2 <(As / Ss) <0.52 where, As: Aspheric sag amount Ss: Spherical sag amount 4. The projection lens device according to claim 1, wherein an aspherical amount As / Ss of a screen-side lens surface of the second plastic lens satisfies the following relationship. Lens device. Note: 1.26 <(As / Ss) <0.06, where As: Aspherical sag amount Ss: Spherical sag amount 5. The projection lens device according to claim 1, wherein an aspheric amount As / Ss of a lens surface on a display screen side of the second plastic lens satisfies the following relationship. Lens device. Note: −0.11 <(As / Ss) <0.75, where As: Aspherical sag amount Ss: Spherical sag amount 6. The projection lens device according to claim 1, wherein a surface interval between the first group lens and the second group lens is I23, and all lens systems including a fluorescent screen serving as a display screen are provided. When the focal length is f0, the following relationship is satisfied. 0.15 <(I23 / f0) <0.25 7. The projection lens device according to claim 1, wherein a surface distance between the first group lens and the second group lens is I23, and a distance between the second group lens and the third group lens is I23. Wherein the ratio of the two (I23 / I45) satisfies the following relationship, where I45 is the surface spacing of the projection lens device. Note 23 <(I23 / I45) <40 8. The projection lens device according to claim 1, wherein one or both of the first plastic lens and the second plastic lens are constrained in a radial direction at a portion other than the lens effective diameter. A projection lens device, comprising: 9. The projection lens device according to claim 8, wherein the restraining means sets the lens outer diameter of the plastic lens in a dry state to L.
And the inner diameter L ′ having the following relationship
Having a higher rigidity than plastic and holding the plastic lens of the lens barrel,
A projection lens device comprising a ring which is previously screwed, fitted, or insert-molded into a portion to be fixed. Note L '<(1.001 × L) 10. The projection lens device according to claim 8, wherein the restraining means sets the outside diameter of the plastic lens in a dry state to L.
And the inner diameter L ′ having the following relationship
A ring formed of a material having a higher rigidity than plastic and comprising the lens barrel previously screwed, fitted, or insert-molded in a portion for holding and fixing the plastic lens of the lens barrel. A projection lens device. Note L '<(1.001 × L) 11. The projection lens device according to claim 8, wherein at least one of the first and second plastic lenses or both lens barrels hold and fix the plastic lens. The plastic lens is supported and fixed in a radial direction by drilling at least three fixing holes in the hole and projecting the elastic body from the outside to the inside of the hole to connect the vertexes of the protrusions of the elastic body. When the diameter of the tangent circle is D and the diameter of the plastic lens in a dry state is L, D
> (1.001 × L) using a lens barrel having a relationship of (1.001 × L). 12. A projection television apparatus comprising: a screen; an image display device for projecting an original image; and a projection lens device for enlarging and projecting the original image projected on the image display device onto the screen. , The projection lens device includes, in order from the screen side to the image display device side,
Second, third, fourth, and fifth lens groups are arranged, and the first lens group has a central portion including an optical axis that is convex toward the screen side and has a periphery that is radially away from the optical axis. The first group includes a first plastic lens having a concave surface with respect to the screen side, and the second group lens has a predetermined positive refractive power at a center portion including an optical axis thereof, and has a predetermined positive refractive power. A projection lens device including a second plastic lens having a surface having a shape having a positive refractive power larger than the predetermined positive refractive power at a peripheral portion separated in a radial direction, and satisfying the following relationship. A projection television device characterized by the above-mentioned. 0.14 <f0 / f1 <0.24 0.02 <f0 / f2 <0.25 0.63 <f0 / f3 <0.83 where f0 is the fluorescent screen which is the screen display unit of the image display device. F1: focal length of first lens group f2: focal length of second lens group f3: focal length of third lens group