Abstract: A rear projection type display system with a transmissive screen. A transparent reinforcing plate is coupled to a lenticular sheet of the screen on the light output side by a connective member to broaden the horizontal diverging angle by 60 degrees or more to the right and left sides. The duty factor of a black stripe formed on the lenticular sheet is set to 60% or more so improve the contrast of an image. The diverging angle at each point of a vertically-diffusing lens for diverging light in the vertical direction is modulated in accordance with the height of each point to offer a proper visual angle range in the vertical direction.

Abstract: The amount of generation of heat per unit time due to combustion reaction of particulate matter is suppressed, and is made lower than the amount of heat radiation per unit time. By doing so, an abrupt temperature rise called "ignition" is prevented, and a temperature gradient in a filter is made small, thereby preventing unduly-high temperatures from developing. Therefore, the cracking of the filter as well as damage of the filter due to melting can be perfectly prevented, thereby enhancing the reliability. To achieve this, the whole of the filter is heated in such a manner that a temperature rise rate is not more than 10.degree. C./minute when the temperature in the filter is in the range of between 400.degree. C. and 600.degree. C. In the case where the filter carries an oxidizing catalyst, the heating is effected in such a manner that the temperature rise rate is not more than 10.degree. C./minute in the range of between 200.degree. C. and 400.degree. C.

Abstract: A rear projection type display system with a transmissive screen. A transparent reinforcing plate is coupled to a lenticular sheet of the screen on the light output side by a connective member to broaden the horizontal diverging angle by 60 degrees or more to the right and left sides. The duty factor of a black stripe formed on the lenticular sheet is set to 60% or more so improve the contrast of an image. The diverging angle at each point of a vertically-diffusing lens for diverging light in the vertical direction is modulated in accordance with the height of each point to offer a proper visual angle range in the vertical direction.

Abstract: A multi-screen projector having unit module projectors stacked at two higher and lower stages, each unit module projector having a screen with a Fresnel sheet unit, a prism sheet unit, and a lenticular sheet unit. By the functions of the Fresnel sheet unit and the prism sheet unit, main output light from higher and lower screens is converged to substantially the same target point. Only one type of metal molds is required for the Fresnel sheet unit as well as the prism sheet unit, thereby reducing the manufacturing cost of the multi-screen projector.

Abstract: A screen is constituted by one sheet of Fresnel lens and two sheets of lenticular lenses, and the following relationships are fulfilled: 0.9 To<vy.multidot.dy/n and 0.9 To<vx.multidot.dy<3 To where vx and vy denote respectively angles, which are obtained when viewing a projection lens from the side of the lenticular lenses through the Fresnel sheet, dx and dy denote respectively distances between a surface of the Fresnel lens and focal planes of the lenticular lenses, n denotes a refractive index of a medium, and To denotes a pitch of the Fresnel lens, whereby radial two dimensional moire disturbance appearing in a rear projection display can be reduced to one-fifth the amplitude of the prior art one.

Abstract: A support member for supporting a plurality of vertically-arranged Fresnel sheets is fixedly mounted on a lower end portion of a reinforcing sheet. A hanging mechanism hangs the reinforcement sheet and the Fresnel sheets vertically adjustably. An elongated screen is constituted by a plurality of vertically-arranged unit screens, and the overall screen is constituted by a plurality of elongated screens arranged horizontally. A mechanism for preventing the relative displacement of the opposed edges of the elongated screens from each other in a direction perpendicular to the plane of the elongated screen is provided at an effective projection light-absent region where the light projected from projectors onto the screen is not hindered. A mechanism for limiting the absolute displacement of the elongated screens in a direction perpendicular to the plane of the elongated screen is provided at the right and left edges of the elongated screens and is disposed at the effective projection light-absent region.

Abstract: Unit projectors whose number is n.times.m are arranged in n rows and m columns like a matrix. Unit screens whose number is n.times.m are arranged so that they as a whole form an enormous transmissive screen. Each unit screen is composed of the three layers of a front sheet on a Fresnel sheet on a re-inforcing sheet facing an observer. A front sheet is provided with the shape having a one-dimensional curvature which causes the peripheries of the front sheet and a re-inforcing sheet to be apart from each other when the center of the front sheet is brought in touch with that of the re-inforcing sheet in the unloaded state. Wires smaller in diameter than the pixel size are connected to the left and right sides of the front sheet, springs provide the wires with tension with support members as their support, and the force of the springs is thus provided by way of the wires for the front sheet so that the left and right sides of the front sheet are pressed on the re-inforcing sheet by way of the Fresnel sheet.