Mitsubishi Denki Kabushiki Kaisha

Kazuo Tsukagoshi

Hiroshi Kawamura

Eiichi Toide

Hiroshi Tetsuda

Motoo Takahashi

Toshihide Kaneko

Naoki Kawamoto

A projection type display apparatus incorporating a light receiver or a light transmitter, in which the light signal is received or transmitted through a screen or condensing lens disposed in its vicinity, and hence the luminous flux utility efficiency is high. A projection type display apparatus capable of preventing deterioration of picture quality due to difference in color in the projection units, and the best picture quality is realized even when the projection lenses for different colors are composed of nearly same components.

Projection unit for projection type display apparatus

A transmission screen includes a screen material having a projection light incident surface on which a Fresnel lens is formed, and a projection light outside surface on which a lenticular lens is formed. The lenticular lens has a plurality of lenticular lens portions. Formed between adjacent pairs of the lenticular lens portions are black stripes. Images of the projection light are seen on an outer surface of the lenticular lens. Furthermore, a coating having a low refraction index and a predetermined thickness is formed only on the black stripes.

Transmission screen

In a projection type television apparatus, a first and a second color selecting device are located on an optical light path passing through a cathode ray tube and a series of projection lenses are disposed in front of the cathode ray tube without a color selecting device therein. The first color selecting device has a high refractive factor to light having a wavelength of 570nm or more and the second color selecting device has a high reflection factor or a high absorption factor to light having a wavelength of 520nm or less. With this color selecting device, the range of color reproduction can be much more improved. This thus causes an increased degree of color purity of green light at the central and peripheral areas of the cathode ray tube. Moreover, with this arrangement, it becomes easy to conserve the characteristic of the color selecting devices and to facilitate the manufacturing operation.

Projection type television apparatus

A projection television system having three cathode ray tubes one of which has a display window, a fluorescent material layer disposed on the innermost surface of the display window, and a multilayered interference filter disposed between the display window and the fluorescent material layer. The multilayer interference filter is composed of a number of alternate layers of high refractive index material and low refractive index material. At most, two of the cathode ray tubes have only the display window and the fluorescent material layer. Images are thereafter produced with high brightness wherein respective supplied beam currents are increased by an amount to compensate for a drop in luminance intensity caused by filter removal. The brightness attained is equal to that of a conventional projection system which includes cathode ray tubes which each utilize multilayer interference filters.

Three tube color projection television system having at least one tube

In a projection television apparatus, a color selecting device is located on an optical light path passing through a cathode ray tube and a series of projection lenses disposed in front of the cathode ray tube. This color selecting device has a high reflection factor or a high absorption factor to light having a wavelength of at most 520 nm. With this color selecting device, the range of color reproduction can be much more improved, thus causing an increased degree of color purity of green at the central and peripheral areas of the cathode ray tube.

Projection television apparatus

In a projection television set including red, green and blue CRTs, and red, green and blue projection lens systems, the green projection lens system is provided with a coating or a filter having a high reflecting coefficient against light below about 520 nm and above about 570 nm in wavelength. Therefore, unnecessary light, emitted from a green light source in the green projection lens system, can be reflected by the coating of filter so that only necessary light is passed. This allows for a projection television set which contains a color reproduction range closer to the color reproduction range of a standard television set.

Projection television set

A video projector includes a cabinet having a scren mounting opening, a projector unit housed within the cabinet, and a generally rectangular composite projection screen secured to the cabinet to cover the screen mounting opening and a picture is projected from the projector unit onto the screen. The composite screen includes a laminar structure of a Fresnel lens plate and a lenticular lens plate. The lenticular lens plate has a height smaller than the height of the Fresnel lens plate and an upper edge connected by adhesive tape with an upper edge of the Fresnel lens plate such than a lower edge of the lenticular lens plate opposite to the upper edge is offset in an upward direction relative to a lower edge of the Fresnel lens plate to provide a margin extending along the width of the composite screen for accommodating the expansion of the lenticular lens plate. The composite screen is secured to the cabinet and covers the screen mounting opening so that a gap can be formed between the upper clamping fixture and the top edge of the composite screen.

Growing community of inventors

Nagaokakyo, Japan

Kazuo Tsukagoshi