JP2008181046A - Reflection type screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-luminance reflection type screen that can reduce a loss of image light emitted from a projector, and that can be easily manufactured. <P>SOLUTION: The reflection type screen comprises a diffusing base material which comprises a transparent substrate and a light diffusing layer and whose refractive index is represented by 1.40 or more, a circular Fresnel lens whose optical center is deviated from a screen toward the side of the projector and pitch is ≤122 μm and height is ≤30 μm for instance, and a metal reflecting layer. In the reflection type screen, the light diffusing layer is configured in such a manner that one or more layers in which a transparent layer portion and a light diffusing layer portion are integrated and whose Hayes value is ≥70% are laminated. Further, the reflection type screen which is characterized by further giving a reflection preventing film layer to an observer surface can be provided. Further, a light absorbing layer can be given as well. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reflective screen that is a projection screen that is disposed on a projection side and observes reflected (imaged) image light with respect to various projection apparatuses.

  Equipment such as OHP (overhead projector) and projectors using 16mm and 8mm film are used in conferences and projection meetings, and in recent years, as the projector itself has become smaller and the price has decreased, The demand for home use such as the above has increased, and projection systems are increasingly used in ordinary homes.

  In this case, the projection system is often installed in a home living space or the like, but such a place is usually susceptible to ambient light such as outside light or illumination light. For this reason, a projection screen used in a projection system for home use is desired to be able to realize a good video display even under bright ambient light.

  There are various types of screens arranged on the projection side with respect to these projection devices, and they are selected and used according to the application. Of these, even if the screen is a flat plate that does not bend in a parabolic shape, even if the decrease in peripheral luminance is small and the direction of the projection light from the projection device is limited, there is no need to tilt the screen. In order to control the directivity of image light reflected and viewed as a type screen, a proposal related to a reflection type screen having a Fresnel lens surface as a reflection surface is known (see, for example, Patent Document 1).

  The invention described in Patent Document 1 is a reflective screen that projects an image projected from a projection device, and includes a reflection surface that reflects the projection light from the projection device, and the reflection surface is formed from the projection device. Are projected in parallel to each other and reflected in a certain direction. However, Patent Document 1 does not describe a detailed configuration.

Patent documents etc. are as follows.
JP 2005-134448 A

  The present invention has been made in view of such a background art, and an object of the present invention is to provide a reflective screen that can reduce loss of image light from a projector and can be easily manufactured with high brightness.

  In order to achieve the above object in the present invention, first, in the invention of claim 1, a diffusion base material composed of a transparent substrate and a light diffusion layer, a circular Fresnel lens whose optical center is shifted from the screen to the projector side, The reflective screen is made of a metal reflective layer, and the light diffusion layer is a reflection type screen in which a substantially transparent layer portion and a light diffusion layer portion are integrated and one or more layers having a haze value of 70% or more are laminated. .

  According to a second aspect of the present invention, there is provided a reflective screen according to the first aspect, wherein the circular Fresnel lens has a pitch of 122 μm or less and a height of 30 μm or less.

  According to a third aspect of the present invention, there is provided a reflective screen according to the first aspect, wherein the refractive index of the diffusing substrate is 1.40 or more and the height of the circular Fresnel lens is 30 μm or less. Is.

  According to a fourth aspect of the present invention, there is provided a reflective screen characterized in that an antireflection film layer is further provided on the viewer side of the reflective screen according to any one of the first to third aspects.

  According to a fifth aspect of the present invention, there is provided a reflective screen characterized in that a light absorbing layer is further added to the reflective screen according to any one of the first to fourth aspects.

  According to a sixth aspect of the present invention, there is provided the reflective screen according to any one of the first to fifth aspects, wherein the light diffusion layer has a half-value viewing angle of 20 degrees or more.

  According to a seventh aspect of the present invention, there is provided the reflective screen according to any one of the first to sixth aspects, wherein a rise angle of the circular Fresnel lens is 85 degrees or more in each annular zone.

  According to the first aspect of the present invention, it is possible to increase the mass productivity and the quality because the time for replacing the jig used for the mold can be saved by making the apex angle constant. In addition, since the apex angle is limited to 121 ° or less and the rise angle is limited to 90 ° or less, it is possible to design a lens suitable for a reflective screen that can be manufactured with high brightness in consideration of loss of image light. Therefore, the invention of claim 1 has the effect of reducing the loss of image light from the projector and providing a reflective screen that is easy to manufacture with high brightness.

  The invention of claim 2 limits the pitch of the circular Fresnel lens to 122 [mu] m or less and makes the height of this lens 30 [mu] m or less. Therefore, there is an effect that it is possible to provide a reflective screen with further excellent mass productivity.

  According to the invention of claim 3, since the refractive index of the light diffusion layer is set to 1.40 or more and the height of the lens is set to 30 μm or less, there is an effect that it is possible to provide a design with a margin.

  According to a fourth aspect of the present invention, an antireflection film layer is provided on the viewer's surface of the reflective screen, and the influence of external light can be reduced.

  The invention of claim 5 is characterized in that a light absorption layer is provided on the reflective screen, and an image with high contrast can be created even in a bright room.

  The invention according to claim 6 is characterized in that the half-value viewing angle is 20 degrees or more in the light diffusion layer, and a reflective screen having a high luminance and a high viewing angle can be realized.

  The invention according to claim 7 is characterized in that the rise angle of the circular Fresnel lens is 85 degrees or more in each annular zone, so that it is possible to reduce the external light and produce a high-contrast image. It becomes.

In the present invention, the image light from the projector is incident from the viewer side opposite to the projector side, and the image light is reflected by the reflecting element surface provided on the projector side of the screen, thereby allowing the viewer to view the image. A reflection type screen that serves to supply light, and is provided with a diffusion base material having at least a diffusion function, and a metal reflection layer having a function of making incident light substantially parallel to the viewer side This forms a circular Fresnel lens whose center is shifted from the screen toward the projector.

  A schematic cross-sectional schematic view of a reflective screen of the present invention is shown in FIG. This reflective screen is composed of a transparent substrate 0, a light diffusing layer 11, a transparent layer portion 1 in the light diffusing layer 11, a light diffusing layer portion 2, a circular Fresnel lens 3, and a metal reflecting layer 4, and is incident from a projector. The light beam first passes through the transparent substrate 0 and then first-order diffuses in the light diffusing layer portion 11, then passes through the circular Fresnel lens 3, and is attached to the metal reflection layer 4 associated with a lens surface that differs for each circular Fresnel radius. , And then secondarily diffuses in the light diffusion layer portion 11 and then passes through the transparent substrate 0.

  The term “transparent” in this case does not mean that it is completely transparent, it is sufficient that the transparency required for the reflective screen is maintained, and it is not necessary to be completely transparent in terms of the characteristics of additives and materials.

  At that time, the light beam reflected by the metal reflection layer 4 attached to the lens surface that differs for each circular Fresnel radius is scattered by the light diffusion layer, and the maximum peak of the light beam is approximately in the direction of the optical axis of the circular Fresnel lens. Injected in parallel, it reaches the observer.

  FIGS. 2 and 3 show the case where there are a plurality of the light diffusion layer portions 11. In this case as well, the light rays reflected by the metal reflection layer 4 attached to the lens surface that differs for each circular Fresnel radius are each light. After repeating scattering at the diffusion layer, the vicinity of the maximum peak of the light beam is emitted substantially parallel to the optical axis direction of the circular Fresnel lens and reaches the observer.

  In FIG. 4, in order to reduce the influence of external light, for example, by adding an antireflection film layer 5 attached to the transparent substrate 0, the influence of external light can be reduced and a high contrast screen can be realized. It becomes possible.

  In FIG. 5, by arranging the light absorption layer 6, it is possible to adjust the amount of external light absorbed and the amount of light from the projector, which can be used for contrast adjustment.

  Hereinafter, the best mode of the present invention will be described by showing examples of the present invention.

  Table 1 shows Example 1 of the half-value viewing angle in the change of the haze value and the number of stacked layers of the light diffusion layer portion of the present invention. It can be seen that the half-value viewing angle increases as the haze value and the number of stacked layers increase. However, looking at the half-value viewing angle of Hz 65% or less, it can be seen that even if the number of stacked layers is increased, the increase in Hz value is not so much. On the contrary, when the frequency is 70% or more, it can be seen that a considerable half-value viewing angle increase can be seen by increasing the Hz value. Thus, it can be seen that an efficient diffusion value is 70% or higher.

  By making the apex angle constant in producing the mold, it is possible to eliminate the trouble of replacing the jig to be used, so that mass productivity and quality can be improved. As the apex angle increases, the height of the circular Fresnel lens can be reduced. In Example 1, the apex angle is set to 120 °, so that the height of the lens is about 14.8 μm in the case of the incident angle Θ1 = 70 °. In Example 2, by setting the apex angle to 100 °, the height of the circular Fresnel lens is about 17.3 μm when the incident angle Θ1 is 70 °, which is about 2.5 μm higher than that of Example 1. .

  Moreover, when Example 1 and Example 2 of Table 2 are specifically compared, the loss becomes almost zero by changing the apex angle from 120 ° to 100 °.

  If the apex angle is further reduced and the apex angle is set to 70 ° as in Example 3 in Table 3, the incident angle Θ1 = 30 °, and no loss occurs even at a location where the incident angle Θ1 is small. However, if the rise angle exceeds 90 ° as in Example 3, a circular Fresnel lens cannot be manufactured. Therefore, it is desirable to set the apex angle so that the rise angle is 90 degrees or less and the rise angle is 85 degrees or less when the intersection is viewed.

  In order to provide a high-brightness reflective screen, it is preferable to reduce the loss at the lens portion, and specifically, it is desirable to reduce the loss to 10% or less. Example 4 of Table 4 shows the form when the apex angle is 121 °. If the incident angle Θ1 = 70 ° only increases by 1 ° from 120 ° in the first embodiment, the loss becomes about 10%. Therefore, it is desirable to set the apex angle to an upper limit of 121 °.

  By the way, as for mold fabrication and lens molding using the mold, fabrication becomes easier as the height of the circular Fresnel lens is lower. The height of the circular Fresnel lens in the reflective screen increases when the incident angle Θ1 is large. For example, in Example 1, the height of the circular Fresnel lens when the incident angle Θ is 70 ° is about 14.8 μm, whereas when the incident angle Θ1 is 30 °, the height is about 8.9 μm. In order to facilitate the fabrication of the mold and the molding of the circular Fresnel lens, a material suitable for mass production can be obtained by setting the height of the circular Fresnel lens to 30 μm or less.

  Various factors can be considered to change the height of the circular Fresnel lens. First, it is possible to cope by making the pitch fine. Specifically, when the incident angle Θ1 = 70 ° and the lens pitch is changed from 60 μm in Example 1 to 122 μm in Example 5 in Table 5, the height of the circular Fresnel lens is about 14.8 μm to about 30 μm. Become. Therefore, as in Examples 1 and 5, it is desirable to set the pitch to 122 μm or less when the apex angle is 120 ° and the refractive index n2 of the diffusion base material is 1.53.

  The height of the circular Fresnel lens can also be lowered by increasing the refractive index of the diffusion base material used. For example, in Example 5, the pitch is 122 μm, and when the incident angle Θ1 = 70 °, the height of the circular Fresnel lens is about 30 μm. Here, when the pitch is kept at 122 μm as in Example 6 and the refractive index is changed from 1.53 to 1.40, the height of the circular Fresnel lens is about 31.8 μm. In order to provide a wide design range, it is preferable that the refractive index be as high as possible. If it is 1.40 or more, it is possible to provide a sufficient design space.

  Table 6 shows the observer's evaluation when observing from 30 degrees in front of the screen at each half-value viewing angle. The number of observers is 15, and the evaluation result is 3 points. The average value is 3 points, 2 points are △, and 1 point is ×. The evaluation was performed from the viewpoint of whether or not the brightness of the screen when viewed from 30 degrees front is appropriate with respect to the brightness in the front direction. At this time, the evaluation differs at a half-value viewing angle value of 20 degrees. Therefore, it can be seen that the half-value viewing angle value is desirably more than 20 degrees as a reference.

  The table is as follows.

It is a schematic cross section of the reflective screen of the present invention. It is a schematic cross-sectional schematic diagram of a reflective screen when there are a plurality of light diffusion layer portions of the present invention. FIG. 3 is a schematic cross-sectional schematic diagram of a reflective screen when there are a plurality of light diffusion layer portions of the present invention different from FIG. 2. It is a schematic cross-sectional schematic diagram of the reflective screen which provided the antireflection film layer 5 of this invention. It is a schematic cross-sectional schematic diagram of the reflective screen which provided the light absorption layer of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 0 Transparent substrate 11 Light-diffusion layer 1 Transparent layer part 2 Light-diffusion layer part 3 Circular Fresnel lens 4 Metal reflective layer 5 Antireflection film layer 6 Light absorption layer

Claims (7)

  A diffusing substrate composed of a transparent substrate and a light diffusing layer, a circular Fresnel lens whose optical center is shifted from the screen to the projector side, and a metal reflecting layer, the light diffusing layer comprising a transparent layer portion and a light diffusing layer portion And a reflection type screen in which one or more layers having a haze value of 70% or more are laminated.   2. The reflective screen according to claim 1, wherein the pitch of the circular Fresnel lens is 122 [mu] m or less and the height is 30 [mu] m or less.   2. The reflective screen according to claim 1, wherein the refractive index of the diffusing substrate is 1.40 or more and the height of the circular Fresnel lens is 30 [mu] m or less.   4. A reflection type screen, further comprising an antireflection film layer provided on the viewer's surface of the reflection type screen according to claim 1.   A reflection type screen, further comprising a light absorption layer added to the reflection type screen according to claim 1.   6. The reflection type screen according to claim 1, wherein a half-value viewing angle of the light diffusion layer is 20 degrees or more.   The reflective screen according to any one of claims 1 to 6, wherein a rise angle of the circular Fresnel lens is 85 degrees or more in each annular zone.

Images