JP2584742B2 - Projection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection apparatus in which a display means using a liquid crystal panel is arranged in a microfilm projection optical path.

[Prior Art] As a conventional microfilm projector, there is known a system which projects an optical image of a microfilm formed on a screen by an imaging lens.

[Problems to be Solved by the Invention] The above-described conventional projection apparatus has a disadvantage that information other than the information displayed by the microfilm cannot be displayed on the display screen. To add a display other than information,
It has been considered to provide a display means by a liquid crystal panel on the projection screen.

However, generally used liquid crystal panels are
A display pattern to be displayed is in a dark state, and a bright background is formed on a display surface other than the display pattern. However, when such a liquid crystal panel is provided on the screen of the above-described projection device, a negative pattern is formed. On the other hand, when the microfilm is projected, the display surface is displayed as a negative image. On the other hand, when the display is performed by the above-described liquid crystal panel, a display pattern in a dark state appears under a background in a bright state. It turned out that there was a problem. Also, when displaying a display pattern such as a character or a numeral in a dark state on a bright background with a projection display surface, the visibility of the display pattern by the observer is reduced, and furthermore, the observer may not be able to observe the observer visually. It has been found that there is a problem of increasing the fatigue of the tire.

[Means for Solving the Problems] and [Operation] Accordingly, an object of the present invention is to provide a projection apparatus that solves the above-mentioned problems, and particularly to a display pattern for displaying on a liquid crystal panel. An object of the present invention is to provide a projection device for a microfilm in which visibility is improved and fatigue of an observer's eyes is reduced.

That is, according to the present invention, a table on which a microfilm is placed, a liquid crystal panel, and information recorded on the microfilm placed on the table or information displayed on the liquid crystal panel are projected in the optical path. A screen, an imaging lens that forms information recorded on the microfilm as an optical image on the screen, and a light source, and the information displayed on the microfilm is projected on the screen. Means for setting a display portion of the liquid crystal panel to a light transmitting state when the information displayed on the liquid crystal panel is projected onto the screen, and setting a portion corresponding to the display pattern of the liquid crystal panel to a light state when the information is displayed on the screen. And a means for setting a portion that does not correspond to a dark state to a dark state.

In particular, the apparatus has a pair of polarizers on the incident side and the output side of the liquid crystal panel in the optical path, and has means for detaching one of the pair of polarizers from the optical path. Is preferred.

Further, it is preferable that the liquid crystal panel is a twisted nematic liquid crystal panel.

Further, the liquid crystal panel comprises a first twisted nematic liquid crystal panel and a second twisted nematic liquid crystal panel, and the first twisted nematic liquid crystal panel is used when information displayed on the liquid crystal panel is projected on the screen. It is also a preferable embodiment to have a voltage applying means for forming a display pattern and a voltage applying means for applying a voltage over the entire predetermined area of the second twisted nematic liquid crystal panel. In that case, it is preferable that the polarization axes of the polarizing plates are parallel to each other.

In addition, the liquid crystal panel comprises a first twisted nematic liquid crystal panel and a second twisted nematic liquid crystal panel, and the information displayed on the liquid crystal panel is projected on the screen when the first twisted nematic liquid crystal is projected. It is also a preferable embodiment to have a voltage applying means for forming a display pattern on the panel and a voltage applying means for applying no voltage over the entire predetermined area of the second twisted nematic liquid crystal panel. It is preferable that the polarization axes of the plates are orthogonal to each other.

Embodiment FIG. 1 is an explanatory view schematically showing a projection device of the present invention. In FIG. 1, reference numeral 10 denotes the direction of the observer's line of sight, 11 denotes a polarizing plate, 12 denotes a liquid crystal panel, 18 denotes a diffusing screen, 13 denotes an optical path bending mirror, 14 denotes an imaging lens, 15 denotes a movable slide table, 16 Is a condenser lens for illumination, and 17 is a halogen lamp for illumination. In a liquid crystal panel, twisted nematic liquid crystal is disposed between a glass or plastic substrate on which a pair of opposed transparent electrodes are wired. This twisted nematic liquid crystal is used, for example, in M. Schadt.
"Applied Physics Letters" by W. Helfrich and W. Helfrich
Letters ") Volume 18, Issue 4 (issued February 15, 1971),
“Voltage D Pendant Optical Activity of a Twisted Nematic Liquid Crystal” on pages 127-128 (“Voltage D
ependent Optical Activity of a Twisted Nema
tic Liquid Crystal "). This twisted nematic liquid crystal has a rotatory power that rotates the polarization axis of incident polarized light by 90 ° when no voltage is applied.
When an AC voltage of a certain level is applied, this optical rotation is canceled. Further, as one of a pair of transparent electrodes used in the liquid crystal panel 12, for example, a transparent electrode pattern 22 as shown in FIG. The other substrate (not shown)
For example, a predetermined numerical display can be performed by forming one surface of the transparent electrode pattern 22 with a transparent electrode and switching each predetermined segment of the transparent electrode pattern 22.
Further, in the present invention, it is also possible to use a time-division driving electrode structure disclosed in, for example, Japanese Patent Publication No. 51-14360.

The above-mentioned liquid crystal panel 12 has a polarizing plate 11 fixedly disposed in the optical path. When displaying a predetermined number or character using the liquid crystal panel 12, another polarizing plate is used. It is arranged on the opposite side of the plate 11, and its respective polarization axes are parallel to each other.

In a preferred embodiment of the present invention, the other polarizing plate described above is mounted on a micro-film film 31, for example, as shown in FIG. FIG. 3 is a plan view schematically showing the microfilm 31 placed on the slide movable table 15, and reference numerals 2 to 24 denote each of the microfilms on which predetermined images are recorded. Screen 33
The number 1 is provided with a polarizing plate 32. Therefore, when performing display using the liquid crystal panel 12, predetermined display can be performed by moving the movable slide table 15 and disposing the polarizing plate 32 in the optical path.

Next, an operation method of the projection device of the present invention will be described.

First, as a first step, a case where the microfilm reader is used as a microfilm reader will be described.

In this case, images 2 to 24 of the microfilm 31 appear in the optical path.
Is placed on the second polarizing plate 32.
Has been removed from the light path. Therefore, the liquid crystal panel 12
Is transparent and colorless, so that an observer can easily read a micro image of the micro film 31 formed on the diffusing screen 18. FIG. 4A shows this state as an image on the screen 18. FIG. Here, a map is drawn as a microfilm image as if projected on a screen (18).

Next, as a second step, a case where the present device is used as a liquid crystal display will be described.

In this case, the micro-film is removed from the optical path by moving the movable slide table 15, and the movable slide table 15 is moved so that the second polarizing plate 32 is inserted into the optical path.
At this time, the polarization axes of the first polarizing plate 11 and the second polarizing plate 32 are
They are parallel to each other.

Here, when an appropriate voltage is applied to the transparent electrode pattern (reference numeral 22 in FIG. 2) of the liquid crystal panel 12, the portion where no voltage is applied is caused by the optical rotation of the twisted nematic liquid crystal.
The polarization axis of the incident polarized light transmitted through the polarizing plate 32 is rotated by 90 degrees and cut off by the first polarizing plate 11 to be black (dark state).
Polarized light passing through the area where voltage is applied
Since it does not receive the optical rotation of 90 degrees, it passes through the polarizing plate 11 and looks white (bright state). The display state at this time is shown in FIG. According to FIG. 4 (b), white characters emerge on a black background. Here, an example is shown in which a voltage is applied to the electrode corresponding to the number “193” to perform display.

In the above-described embodiment, as a driving method of the liquid crystal, a case is shown in which numerical display is performed by 7 segments using static driving. However, in the present invention, various display forms using a dot matrix electrode using time division driving are used. A possible liquid crystal driving method can be used.

The second polarizer 32 may be inserted at any position on the optical path between the liquid crystal panel 12 and the movable slide table 15 shown in FIG. Absent.

FIG. 5 illustrates another preferred embodiment of the present invention. 5, the same components as those in FIG. 1 represent the same members. In the figure, reference numeral 51 denotes a first liquid crystal panel;
Denotes a second liquid crystal panel, on both sides of which a first polarizing plate 11 and a second polarizing plate 53 are fixedly arranged. First liquid crystal panel
Both the liquid crystal panel 51 and the second liquid crystal panel 52 are twisted nematic liquid crystal, but the first liquid crystal panel 51 is formed with a transparent electrode pattern 22 as shown in FIG. The second liquid crystal panel 52 is provided with a pair of non-pattern electrodes each having one surface formed of a transparent electrode. The polarization axes of the first polarizing plate 11 and the second polarizing plate 53 are parallel to each other.

 Next, the operation of the projection device shown in FIG. 5 will be described.

First, a case where the microfilm reader is used in the first step will be described.

In this case, if both the voltages applied to the two liquid crystal panels 51 and 52 are set to OV, the optical axes of the liquid crystal panels 51 and 52 cause the polarization axes of the polarized light passing through the second polarizing plate 53 to be two. LCD panels 51 and 52, 90 degrees each, for a total of 180
Accordingly, the incident polarized light can pass through the first polarizing plate 11, so that the liquid crystal panels 51 and 52 are simply colorless and transparent, and the microfilm image formed on the diffusing screen 18 can be easily viewed by the observer. You can read it. FIG. 4A shows this state as an image on the screen 18. FIG. Here, the map of the microfilm is drawn as if projected on the screen.

Next, as a second step, a case where the present device is used as a liquid crystal display will be described.

In this case, the microfilm on the slide movable table 15 is removed from the optical path, and the second liquid crystal panel 52
The optical rotation is removed over the entire surface of the panel by applying an appropriate AC voltage to the panel. Here, when an AC voltage is applied to an appropriate segment of the transparent electrode pattern (22 in FIG. 2) of the first liquid crystal panel 51, the polarization axis of the incident polarized light is rotated by 90 degrees in a portion where no voltage is applied, and Since the incident polarized light is not rotated in the portion where the voltage is applied, the optical rotation of the second liquid crystal panel 52 is eliminated.
The polarized light that can pass through the first polarizing plate 11 is transmitted to the first liquid crystal panel 51.
Is the portion to which the voltage is applied. The display state at this time is shown in FIG.

According to FIG. 4 (b), white characters emerge on a black background. Here, an example is shown in which a voltage is applied to the segment corresponding to the number “193” and displayed.

In the above-described embodiment, the case of numerical display by 7 segments using static driving is shown as a driving method of the liquid crystal. However, in the present invention, various display forms by dot matrix electrodes using time division driving are possible. Various driving methods can be used.

In addition, the two liquid crystal panels 51 and 52 may be switched back and forth, and the polarization axes of the two polarizing plates are parallel to each other in the above-described embodiment, but the polarization axes are orthogonal to each other. As for the direction, if the voltage applied to the second liquid crystal panel 52 is changed to be turned on when using the microreader and turned off when using the liquid crystal display, the same display state can be obtained. it can. Further, the positions of the diffusing screen 18 and the second polarizing plate 53 can be interchanged.

According to the present invention, when used as a liquid crystal panel display, characters appear bright in a dark background, so that the visibility of the user is improved, and as a result, eye fatigue can be reduced. In addition, when used as a microfilm reader, it is possible to produce a favorable result that it can be used without any difference from a normal microfilm reader.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a projection device of the present invention. FIG. 2 is a plan view showing a transparent electrode pattern. FIG. 3 is a plan view showing an example of a microfilm with a polarizing plate. FIG. 4A is an explanatory diagram showing a display state at the time of projection, and FIG. 4B is an explanatory diagram showing a display state at the time of display on a liquid crystal panel. FIG. 5 is an explanatory view schematically showing another projection apparatus of the present invention.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-147890 (JP, A) JP-A-52-40996 (JP, A) JP-A-52-121352 (JP, A) 38422 (JP, U) Fully open Showa 60-152191 (JP, U) Really open Showa 61-188122 (JP, U)

Claims (7)

(57) [Claims] 1. A mounting table on which a microfilm is mounted, a liquid crystal panel, and information recorded on the microfilm mounted on the mounting table or information displayed on the liquid crystal panel is projected into an optical path. A screen, an imaging lens that forms information recorded on the microfilm as an optical image on the screen, and a light source,
Means for causing a display portion of the liquid crystal panel to be in a light transmitting state when information displayed on the microfilm is projected on the screen; and a liquid crystal panel when information displayed on the liquid crystal panel is projected on the screen. Means for setting a portion corresponding to the display pattern to a bright state and a portion not corresponding to the display pattern to a dark state. 2. A liquid crystal panel having a pair of polarizing plates on an incident side and an emitting side of the liquid crystal panel in the optical path, and one of the pair of polarizing plates is separated from the optical path. 2. The projection apparatus according to claim 1, further comprising means. 3. The projection apparatus according to claim 2, wherein said liquid crystal panel is a twisted nematic liquid crystal panel. 4. The liquid crystal panel comprises a first twisted nematic liquid crystal panel and a second twisted nematic liquid crystal panel, and the first twisted nematic liquid crystal panel is used when the information displayed on the liquid crystal panel is projected onto the screen. 4. The device according to claim 3, further comprising: voltage applying means for forming a display pattern on the nematic liquid crystal panel; and voltage applying means for applying a voltage over a predetermined area of the second twisted nematic liquid crystal panel. Item 3. The projection device according to Item 1. 5. The projection apparatus according to claim 2, wherein the polarization axes of said pair of polarizing plates are parallel to each other. 6. A liquid crystal panel comprising a first twisted nematic liquid crystal panel and a second twisted nematic liquid crystal panel, wherein said first twisted nematic liquid crystal panel is used when said information displayed on said liquid crystal panel is projected onto said screen. A voltage applying means for forming a display pattern on the nematic liquid crystal panel, and a voltage applying means for applying no voltage over a predetermined area of the second twisted nematic liquid crystal panel. 4. The projection device according to claim 3. 7. The projection device according to claim 6, wherein the polarization axes of said pair of polarizing plates are orthogonal to each other.