KR20020016413A - Optical projection engine for monitor - Google Patents

Abstract

PURPOSE: An optical projection engine for a monitor is provided to reduce size and weight and to be applied to a rear projection monitor suitable for a high resolution, large-sized screen. CONSTITUTION: An optical projection engine for a monitor comprises a lamp consisting of a bulb to emit a light and a reflector to reflect the light emitted from the bulb, a heat glass to remove the regions of ultraviolet rays and infrared rays except the region of visible rays, a light pipe to make uniform the intensity of the light passing the heat glass, a relay lens to focus the light on a desired position, a mirror to change the path of the light, a polarizer to remove a polarized light of wave P or S, a retarder foil to rotate the light of a specific wavelength zone opposite to an incident light and output the rotated light, a color corner to split a light and output the split light to respective LCD(Liquid Crystal Display), and a projection lens to project an image reflected on the LCD on a screen without distortion.

Description

Optical projection engine for monitor

The present invention relates to an optical projection engine for a monitor, and more particularly, to an optical projection engine for a monitor applied to a monitor using a reflective micro LCD (μ-LCD) and a color corner.

Currently, the size of CRT monitor is gradually increasing in size from the existing 15 ', and many 19' and 21 'models are appearing. Increasing the size of the CRT monitor inevitably leads to an increase in the total volume, thereby increasing the weight. On the other hand, the increase in the size of the monitor in the situation that the office space is almost fixed, which leads to a reduction of the work space, and also difficult to move and store.

LCD monitors have emerged as a way to solve these problems. However, although the LCD monitor has many advantages in terms of volume and weight compared to the CRT monitor, it is difficult to popularize it yet because the price increases rapidly as the size increases.

According to the corresponding trend, we propose a new type of optical projection engine for rear projection monitor (RPM) that can meet both the low cost advantages of CRT monitors and the thin advantages of LCD monitors.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an optical projection engine for a monitor that can be used in a rear projection monitor suitable for a large screen with high resolution while being compact and lightweight.

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows schematically the structure of the optical projection engine for general monitors.

FIG. 2 is a diagram illustrating an arrangement state of a relay lens and a polarizing prism in FIG. 1. FIG.

3 is a view showing the structure and principle of the color corner according to the present invention

4 is a table showing illuminance measurement data of a rear projection monitor and a CRT monitor according to the present invention;

5 is a cross-sectional view illustrating a configuration of a monitor to which an optical projection engine is applied.

According to a feature of the present invention for achieving the above object, a lamp consisting of a bulb (bulb) for emitting light and a reflector (reflector) reflecting the light emitted from the bulb, and emitted from the lamp A heat filter that removes the UV and IR areas except visible light among the three areas of UV, visible light, and IR, a light pipe that makes the intensity of light passing through the heat filter uniform; A relay lens for connecting the uniform light passing through the light pipe to a desired position, a mirror for changing the light path for efficient space utilization of the entire system, and an incident on the LCD as an image source A polarization prism that removes one of P and S waves, and a delayed foil that rotates light of a predetermined wavelength band in a direction opposite to the incident polarization so that the light becomes a single polarization. (retarder foil), a combination of one polarizing beam splitter (PBS) and two dichroic prisms, a color corner that separates light and outputs it to each LCD, and is reflected from each LCD It is characterized by including a projection lens to enlarge the projected image on the screen without distortion of the image.

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

1 is a diagram schematically showing a configuration of a general optical projection engine for monitors.

Referring to FIG. 1, the basic principle of the rear projection monitor (RPM) uses a high resolution (SXGA: 1280 * 1024) micro LCD (μ-LCD) and a high output lamp to project a bright and clear image onto the screen, and the user On the other side you will see an image passing through the screen.

In FIG. 1, the names and roles of the parts are as follows.

First, a lamp can be divided into two parts, one of which is a bulb emitting light and the other of which is a reflector reflecting light emitted from the bulb. In this case, the lamp is classified into a parabolic lamp and an elliptic lamp according to the shape of the reflector.

The characteristics of each lamp are characterized in that parabolic lamps have light emitted from the bulb meeting the reflector, and the light reflected from the reflector becomes parallel light. In addition, the elliptic lamp is designed to reflect the light emitted from the bulb to focus at one point. After all, the lamp is a light source of the whole system, the brightness of the entire system is determined by the amount of light from the lamp.

On the other hand, the heat filter (heat glass), the light emitted from the lamp (lamp) can be divided into three parts, UV, visible light, IR. The wavelength range required by the system is the visible light wavelength band. Light in the UV wavelength range can degrade the performance of the system's optical components, plastic lenses and other optical components, polarization prisms, and LCDs, so light in this wavelength band must be removed. In addition, the light of the IR wavelength band does not directly damage the component, but when the optical component absorbs the light of the IR wavelength band, the temperature of the optical component rises, thereby preventing its performance. Therefore, the heat filter serves to reflect light toward the lamp which is not used as a filter whose transmittances of the UV and IR wavelength bands are smaller than those of the visible light wavelength band.

In addition, the reason why the light pipe is used is that the light emitted from the lamp is not uniform in intensity, so the intensity of light in the direction of the optical axis is strong, and the intensity of the light decreases as the distance from the optical axis increases. . When this light is reflected off the LCD, the brightness of the image on the screen is not uniform, and light pipes are used to make the uneven light from the lamp as uniform as possible. The type of lamp used in this system is an elliptic type, so the light emitted from the lamp focuses on a point. The first side of the light pipe will be at this focal point. The light passing through the first side of the light pipe is reflected several times inside the light pipe, and at the end of the light pipe, more uniform light is obtained.

In addition, relay lenses 1 and 2 are lenses used to connect the uniform light passing through the light pipe to a desired position, and a mirror is a light path for efficient space utilization of the entire system. It is a role to change.

In addition, the polarizer, the light from the lamp can be divided into P wave and S wave, one of the P wave or the S wave should be removed because the light incident on the LCD as the image source should be a single polarized light. . For this purpose a polarizing prism is used. In the system of the present invention, two film-type polarizing prisms were used because the efficiency of the polarizing prism was not 100%, so that the second polarizing prism eliminated light of constant polarization that was not removed from the first polarizing prism. . In the optical projection engine for the monitor, as shown in FIG. 2, a film type polarizing prism was attached to the surface of the relay lens to minimize other components or spaces for fixing the polarizing prism.

In addition, in the retarder foil, the light passing through the polarizing prism is a single polarized light. However, in order to separate the path using PBS, light of two different polarizations is required. For this purpose, a delay thin film is required. The role of the delay thin film is to rotate and output light having a predetermined wavelength in polarized light in the opposite direction to the incident polarized light. In this system, the polarization of light in the green wavelength range is returned. When passing through the PBS, the green wavelength light goes straight and the remaining wavelength light is reflected. And the light reflected on the LCD is synthesized in PBS again. In this case, because the waveform of the green wavelength band is different from the polarization of the green and blue bands of other wavelengths, one more delay film is placed on the exit side to return the polarization of the green wavelength band again. It is necessary.

In addition, a color corner is composed of a combination of one PBS 31 and two dichroic prisms 32 as shown in FIG. When the white light incident by the delay thin film meets the PBS 31, the green wavelength band is transmitted and the remaining blue and red wavelength bands are reflected. The green that has passed through the PBS 31 meets the LCD 33, is reflected, enters the PBS 31 again, and is then reflected. Blue and red reflected from the PBS 31 meet the dichroic prism 32 and are separated into blue and red. The two separated lights are reflected by the LCDs 34 and 35 and are incident on the dichroic prism 32 again, and are transmitted through the PBS 31. The light passing through the PBS 31 is white light such as incident light and the light is projected onto the screen through the projection lens.

Further, as shown in FIG. 1, the light reflected from the LCD enters the projection lens through the color corner. The role of the projection lens is to enlarge and project the image reflected from the LCD onto the screen without image distortion.

In the present invention having the above-described configuration, the rear projection monitor (RPM) and the general CRT monitor using the optical projection engine for the monitor were measured using the illuminance measuring equipment called CA-120, and the results as shown in FIG. 4 were obtained. . As shown in the result of FIG. 4, the RPM has a value more than twice that of the conventional CRT. The black state value is much different from the ANSI value compared to the CRT, but the sequential value is not much different. In contrast, the RPM shows less contrast than CRT in ANSI, but the sequential shows better performance than CRT. This shows that the results may differ depending on the measurement method. In addition, there are many things that can be compared in terms of performance, but if you look at the white level, the black level, and the contrast side, which are considered the most important factors, I can see the performance that is comparable to the existing CRT. In addition, the monitor using the optical projection engine can minimize the electromagnetic problems from the existing CRT, and by using the digital input, the circuit technology can realize various screens that cannot be seen on the conventional monitor. .

In terms of non-performance aspects, conventional CRT monitors are rapidly increasing in price as their size increases, and their volume and weight increase accordingly. PBM, on the other hand, needs to increase the optical throw distance even as the monitor size increases, so the volume will increase slightly, but the increase and price will not be much different.

5 is a 25 "monitor using an optical projection engine. In order to minimize the thickness, a reflection mirror is used to optimize the thickness to 373mm. Since the current 19" CRT monitor is about 400mm thick, it is 500mm when it is about 25 "by CRT. It takes up a lot of office space, so it will be difficult to use it in a narrow office space.A monitor using an optical projection engine has sufficient advantages in terms of performance, price, and volume compared to conventional CRT monitors. In this case, reference numeral 51 denotes an optical projection engine, 52, 53 and 54 denote mirrors, and 55 denotes a screen.

While the invention has been shown and described in connection with specific embodiments thereof, it is well known in the art that various modifications and changes can be made without departing from the spirit and scope of the invention as indicated by the claims. Anyone who owns it can easily find out.

As described above, the optical projection engine for a monitor of the present invention can be made smaller and lighter than conventional CRT monitors, and has the effect of bright and clear brightness and low electromagnetic waves.

In addition, the thickness and weight can be reduced by 40% compared to the CRT monitor, and the screen size can be changed without changing the engine model.

Claims (1)

Lamp consisting of a light emitting bulb (bulb) and a reflector (reflector) reflecting the light emitted from the bulb, and UV, except visible light of the three areas of UV, visible light and IR emitted from the lamp And a heat filter for removing an IR region, a light pipe for making the intensity of light passing through the heat filter uniform, and a uniform light passing through the light pipe to a desired position. A relay lens, a mirror that changes the path of light for efficient space utilization of the entire system, and one of P-wave and S-wave to ensure that the light incident on the LCD, the image source, is a single polarized light. A polarizer that removes polarization, a retarder foil that rotates and outputs light of a certain wavelength band in a direction opposite to the incident polarization, a polarizing beam splitter (PBS) and two dies It consists of a combination of roic prisms and includes a color corner that separates light and outputs it to each LCD, and a projection lens that enlarges and projects the image reflected from each LCD onto the screen without image distortion. An optical projection engine for monitors.