Apparatus for image projecting having a matrix type of optical-switch

An image projecting apparatus having an optical switch of a non-square matrix structure, is provided. A light source emits a plurality of monochromatic lights having different wavelengths. A first light transmission unit includes of a plurality of optical fibers that allows monochromatic lights to be passed therethrough. An optical switch unit has a plurality of non-square matrix type reflecting mirrors to selectively reflect the monochromatic lights. The reflecting mirrors includes a first group placed at odd lines and a second group placed at even lines. A square-beam generation unit converts reflected monochromatic lights into square beams, and a panel transmits the monochromatic lights converted into square beams and forms monochromatic signals of a predetermined size.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for image projecting, and more particularly, to an apparatus for image projecting to form a plurality of R, G, B color signals on a panel by using an optical-switch having a non-square matrix type structure.

The present application is based on Korean Patent Application No. 2002-24209 filed on May 2, 2002, which is incorporated herein by reference.

2. Description of the Prior Art

A projector is an apparatus for image projecting that shows an image by projecting an input image signal on a screen. The image projecting apparatus is mainly used for presenting in a meeting room, in a projector in a cinema, and in a home theater.

A method for projecting an image on a screen after magnifying the image shown on a liquid crystal display (LCD) or a cathode ray tube (CRT) with a lens has been conventionally used to realize a big screen. However, this method only magnifies an image but does not provide a clear image. To solve the above problem, an image projecting apparatus applying a DMD (Digital Micro-mirror Device) panel is now used.

DMD is an optical-switch using a micro-mirror. The micro-mirror controls the reflection of light in accordance with an input image signal. Also, the DMD applies a digital method, thus color reproduction of the image signal is good and brightness is high. Moreover, it does not require A/D or D/A conversion, thus images are clearly realized.

FIG. 1is a view showing a basic structure of a conventional apparatus for image projecting using a color wheel.

Referring toFIG. 1, the apparatus for image projecting using the color wheel has a light source10, a color wheel20, a DMD panel30and a projecting lens40. InFIG. 1, an optical passage of white light is shown as one dotted line.

The light source10emits white light by using an arc lamp or a laser. The color wheel20rotates (shown as the direction of an arrow) by a rotating means (not shown), and it is divided into R(red), G(green) and B(blue) regions.

The white light emitted from the light source10is separated as R, G, B beams by the R, G, B region of the color wheel20. The DMD panel30is composed of a plurality of micro-mirrors30a. The R, G, B beams separated for each wavelength are projected to the DMD panel30and reflected at the micro-mirrors30a. Reflected R, G, B beams penetrate the projecting lens40and create an image on a screen.

FIG. 2is a view showing a basic structure of an apparatus for image projecting having an optical-switch of a 3×3 matrix structure.

The apparatus for image projecting200ofFIG. 2has been already invented by the inventor of the present invention that is discussed in this specification, but it has not been disclosed to the public yet.

Referring toFIG. 2, the apparatus for image projecting200has a light source110, a first light transmission unit120, an optical-switch unit130, a second light transmission unit140, square-beam generation units150, a panel160and a projecting lens unit170. Moreover, the optical passages of R, G, and B laser beams in the optical-switch unit130are shown by a one-dotted line, a two-dotted line and a three-dotted line respectively.

The light source110emits a plurality of monochromatic lights having different wavelengths from each other, and in this embodiment, R, G, and B laser beams will be used as the monochromatic lights. The light transmission unit120has a plurality of first optical fibers122a,122band122cand a plurality of first collimating lenses124a,124band124c. The first optical fibers122a,122band122callow R, G, and B laser beams to pass therethrough, and the first collimating lenses124a,124band124cfocus the laser beams transmitted through the optical fibers to the optical-switch unit130.

The optical-switch unit130has optical switches130ato130iarranged in the 3×3 matrix structure. Each of the optical switches130ato130iselectively reflects the focused laser beams to output ports135a,135band135c.

The laser beams reflected from the optical switches130ato130iof the optical-switch unit130are incident in second collimating lenses142a,142band142cthrough the output ports135a,135band135c, respectively.

The second light transmission unit140has the plurality of second collimating lenses142a,142band142cand a plurality of second optical fibers144a,144band144c. The R, G and B laser beams focused to the second optical fibers144a,144band144cby the second collimating lenses142a,142band142care respectively transmitted to light tubes154a,154b, and154cof square-beam generation unit150.

The square-beam generation unit150has a plurality of first lenses152a,152band152c, a plurality of light tubes154a,154band154c, and a second lens156. The light tubes154a,154band154cconvert laser beams split by the first lenses152a,152band152cinto a square beam. The second lens156re-splits the converted laser beam.

The panel160is a DMD panel. The panel160receives the split R, G and B laser beam thereby respectively forming R, G and B color strips at one section among three sections of the panel160.

The three R, G and B color strips on the panel160are formed by the manipulation of the optical-switch unit130, and one image is created as the same color strip is formed three times at different positions that are upper, middle and lower sections of the panel160.

The panel160digitalizes and time-divides the R, G and B color strips and reflects them at a predetermined angle. The reflected image of the entire panel is projected onto a screen through the projecting lens170and the image is realized. The projecting lens170is installed facing the panel160.

The described conventional apparatus for image projecting100creates an image by using the color wheel20, and in this case, the amount of light used in DMD panel30is one third of the entire amount. This is because the R beam passed through the R region of the color wheel20is evenly projected to the entire DMD panel30but G and B beams are blocked by a color filter and not used. It is the same when G and B beams are projected.

The color wheel method can use one third of incident white light, and thus the luminance of the image is lowered to one third. In other words, the entire amount of the light is decreased as the white light emitted from the light source is projected to DMD panel30after passing through the color wheel and as a result, light efficiency is lowered as well. Furthermore, the luminance of the created image cannot be maximized.

In addition, the apparatus for image projecting200ofFIG. 2already proposed by the inventor of the present invention creates an image by using an optical switch of a 3×3 matrix structure, thus the light efficiency of the apparatus200is greater than that of an optical system using a color wheel. However, in the apparatus for image projecting200, the ends of each color strip formed at an upper, middle and lower layer of the panel160, are overlapped, and thus the boundary of the color signals are not clear. In this case, an image realized on a screen has an extra line.

SUMMARY OF THE INVENTION

The present invention has been made to overcome the above-mentioned problem of the prior art. Accordingly, it is the object of the present invention to provide an image projecting apparatus capable of improving the utilization of light that is deteriorated to one-third of a signal panel.

Another object of the present invention is to provide an image projecting apparatus using an optical switch of a (3×6) matrix, or a (6×3) matrix structure capable of preventing edge lines of monochromatic strips from being overlapped when a plurality of monochromatic strips are formed on a panel by using an optical switch.

An image projecting apparatus of the present invention has: a light source to emit a plurality of monochromatic lights having different wavelengths; a first light transmission unit comprising a plurality of optical fibers that the monochromatic lights pass through; an optical switch unit comprising a plurality of reflecting mirrors of non-square matrix structure to selectively reflect the monochromatic lights, the reflecting mirrors of non-square matrix structure comprising a first group placed at an odd row and a second group placed at an even row; at least one square-beam generation unit to convert the reflected monochromatic lights to square beams; a panel to form a monochromatic strip with a predetermined size by being transmitted the monochromatic lights converted to square beams; and a projecting lens unit installed opposing to the panel. The first group and the second group of the optical switch unit reflect the monochromatic lights in an alternate order.

More specifically, the reflecting mirrors move between a first position to reflect the monochromatic lights and a second position to allow the monochromatic lights to be passed therethrough. The optical switch unit allows only one reflecting mirror to be placed at the first position at one row and one column.

One screen is created on the panel as the plurality of reflecting mirrors reflect the monochromatic lights at least one time in accordance with a predetermined order. The non-square matrix of the optical switch unit is either a (3×6) matrix or a (6×3) matrix. The reflecting mirrors are MEMS (Micro Electro Mechanical System) mirrors.

Furthermore, the image projecting apparatus further has an output port unit having a plurality of output ports to output the monochromatic lights reflected from the reflecting mirrors of the optical switch unit. The monochromatic light reflected from the first reflecting mirror among the plurality of reflecting mirrors is output to the output port corresponding to the first reflecting mirror.

In addition, the image projecting apparatus further has a second light transmission unit comprised of the plurality of optical fibers to transmit the monochromatic lights emitted from the output ports to the square-beam generation unit. The panel is a DMD (Digital Micromirror Device) that modulates a plurality of monochromatic strips to digital signals and reflects the signals to the projecting lens unit for a predetermined angle.

According to the present invention, as monochromatic strips are formed by using optical switches of a (3×6) matrix, or a (6×3) matrix structure, the overlap of the edge lines of the monochromatic strips can be prevented.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinbelow, the present invention will be described in greater detail by referring to the appended drawings.

FIG. 3is a view showing an apparatus for image projecting according to the preferred embodiment of the present invention.

Referring toFIG. 3, the apparatus for image projecting300according to the present invention includes a light source210, a first light transmission unit220, an optical-switch unit230, an output port240, a second light transmission unit250, a square-beam generation unit260, a panel270and a projecting lens unit280. In the optical-switch unit230ofFIG. 3, the light passages of R, G, and B laser beams are indicated as a one-dotted line, a two-dotted line and a three-dotted line, respectively.

The light source210emits a plurality of monochromatic light having different wavelengths. Laser, an arc lamp, a metal halide lamp, a halogen lamp and a xenon lamp can be applied for the light source210. In the present invention, a plurality of monochromatic lights of R, G, and B laser beams will be applied.

The first light transmission unit220has a plurality of optical fibers222a,222band222cand a plurality of first collimating lenses224a,224band224c. The first optical fibers222a,222band222ctransmit each of the R, G and B laser beams to the first collimating lenses224a,224band224c. The first collimating lenses224a,224band224cconcentrate the transmitted R, G and B laser beams to the optical-switch unit230.

The optical-switch unit230reflects the R, G and B laser beams at a predetermined angle or permits the R, G and B laser beams to pass therethrough, and has a plurality of optical-switches arranged in a non-square matrix structure. In other words, the plurality of optical switches is arranged in the m×n (n is an integer that is more than 3, m>n) matrix structure or m×n (m is an integer that is more than 3, m<n) matrix structure. In this case, the optical-switch unit230has m×n number of the optical switches.

It is preferable that a high-reflection mirror manufactured by applying MEMS (Micro Electro Mechanical System) is used for the optical switches. The optical switches directly output the R, G and B laser beams as they are without converting the input optical signals into electrical signals. Therefore, the speed of switching on or off becomes fast by tens of thousands of times more than conventional switching speed required for converting optical signals into electric signals.

The optical switches have a reflecting mirror and a driving unit. One side of the reflecting mirror is a high reflecting mirror of a MEMS and it reflects a laser beam. The reflecting mirror is moved by the driving unit between the first position (on position) where the R, G, and B laser beams input into the optical switch are reflected to a certain section of the panel and the second position (off position) where the R, G, and B laser beams input into the optical switch travel straight.

In the first position (on), the optical switch is sloped (for example, the position of the optical switch indicated as230a,230hand230oin FIG.3), reflecting the input laser beam. In the second position (off), the optical switch lies down (for example, the position of the optical switch indicated as230bto230g,230ito230nand230pto230rin FIG.3).

Referring toFIG. 3again, the optical switch unit230having 18 optical switches230ato230rformed in the 6×3 matrix structure will be described. The optical switches230ato230rof the optical switch unit120are divided into a first group provided at odd number lines (230a,230b,230c,230g,230h,230h,230m,230nand230o) and a second group provided at even number lines (230d,230e,230f,230j,230k,2301,230p,230qand230r).

The first group and the second group of the optical switch unit230alternately reflect monochromatic light. Moreover, the first group (first line, third line and fifth line in (3×3) matrix) of the optical switch unit230operates with only one optical switch being placed at the first position (on) for one row and one column. In addition, the first group operates with the three optical switches being placed at the first position simultaneously or all of the (3×3) optical switches being placed at the first position in a predetermined order. This is identically applied to the second group (second line, fourth line and sixth line in a (3×3) matrix).

For example, when R, G, and B laser beams incident in the optical switch unit230are reflected by the first group, the second group is placed on the second position (off) for a predetermined time. When the predetermined time is passed, the first group is placed at the second position (off) and R, G, and B laser beams are reflected by the second group. The first group and the second group reflect R, G and B laser beams or allow them to be alternately penetrated at a predetermined temporal interval.

The predetermined temporal interval is the time maintained before the first group turns to the second group or the second group turns to the first group. The temporal interval is the time required for realizing60scenes of image per one second. Real temporal interval can differ based on a driving method.

Referring toFIG. 3, reflection of R, G and B laser beams by the first group will be described. When a certain optical switch230aof the first group is placed at the first position (on), optical switches230b,230c,230gand230mplaced at the same row and column as the certain optical switch230aare placed at the second position (off). When a certain optical switch230his placed at the first position (on), optical switches230iand230nplaced at the same row and column as the certain optical switch230hare placed at the second position (off), and the remained optical switch230ois placed at the first position (on).

In the above case, a R laser beam is reflected at an optical switch indicated as230a, a G laser beam is reflected at an optical switch indicated as230h, and a B laser beam is reflected at an optical switch indicated as230o. When the above process is completed, the second group reflects laser beams in the same manner.

Furthermore, one image is created as a (6×3) number of optical switches (230ato230r) are placed at the first position (on) at least one time. That is, three optical switches at different rows and columns in one group are placed at the first position (on) after three optical switches at different rows and columns in a predetermined group are placed at the first position (on) is operated three times. In the above process, the same optical switch is not placed at the first position (on).

Laser beams reflected at the optical switches230ato230rof the optical switch unit230are transmitted to the second light transmission unit250by the output port unit240.

The output port unit240has a plurality of output ports P1, P2, P3, P4, P5and P6. The output ports P1to P6are installed at an output end of the optical switch unit230in order to be respective aligned with each row of the optical switch unit230.

The second light transmission unit250has a plurality of second optical fibers250ato250f. In addition, a plurality of second collimating lenses (not shown) can be provided at front ends of the second optical fibers250ato250f. The second optical fibers250ato250ftransmit R, G and B laser beams concentrated by the second collimating lenses (not shown) to the square-beam generation unit260.

The square-beam generation unit260is provided at output ends of the second optical fibers250ato250f, and it converts transmitted R, G and B laser beams into square beams having a predetermined ratio of width to height. The square-beam generation unit260has a plurality of first lenses262ato262f, a plurality of light tubes264ato264fand a second lens266.

The first lenses262ato262fdisperse each laser beam in order to allow the laser beams to be incident into the light tubes264ato264fcorresponding to the first lenses262ato262f.

The light tubes264ato264fare formed to have a cubic shape and the inside of the tubes is hollowed. The four inner sides of the light tubes264ato264fare made of mirror. The laser beams incident into the inside of the hollowed light tubes264ato264ffrom the first lenses262ato262fare converted into square beams.

The second lens266disperses the laser beams converted into the square beams and allows the dispersed laser beams to be incident into the panel270. The panel270is composed of one DMD (Digital Micro Mirror) panel or one LCD (Liquid Crystal Display) panel. DMD panel is a reflective panel and LCD panel is a penetrable panel. When a LCD panel is used, the position of a projecting lens and a screen can be changed.

Hereinbelow, the present invention will be described by using DMD panel. Yet,FIG. 3shows a DMD panel excluding the optical passage of laser beams reflected at the DMD panel.

The panel270is a DMD panel of a single plate. R, G and B laser beams converted into square beams are formed as R, G and B monochromatic strips at one end of the panel270. The R strip is indicated by slant lines, the G strip by vertical lines, and B strips by inversed slant lines.

Furthermore, the panel270can be temporally divided into an upper end1(up_1), upper end2(up_2), middle end1(mid_1), middle end2(mid_2), down end1(down_1) and down end2(down_2). When the optical switch unit230is operated as shown inFIG. 3, an R beam is reflected at a predetermined optical switch230a, a G beam is reflected at a predetermined optical switch230h, and a B beam is reflected at a predetermined optical switch230o.

In the above case, the R beam is projected to the upper end1(up_1) of the panel270after passing through the first output port P1, second optical fiber250a, first lens262a, light tube264aand second lens266. The G beam is projected to the middle end1(mid_1) and the B beam is projected to the down end1(down_1) of the panel270.

The panel270has numerous fine driving mirrors. The driving mirrors divide each R, G and B strip over time after modulating R, G and B strips formed at the panel270into a digital type, and reflect them at a predetermined angle. An image is created as the image of the entire panel reflected from the driving mirrors of the panel270is projected to a screen through the projecting lens unit280. The projecting lens unit280is installed facing the panel270.

FIG. 4is a view showing single strips formed at a DMD panel by a (6×3) optical switch unit.

InFIG. 4, the upper end1(up_1), upper end2(up_2) and middle end1(mid_1) of the panel270are shown. A first monochromatic strip (1 color) with respect to the laser beam reflected at the first line of the optical switch unit230is indicated as slant lines at the upper end1(up_1). A second monochromatic strip (2 color) with respect to the laser beam reflected at the second line of the optical switch unit230is indicated as reversed slant lines at the upper end2(up_2).

The part where the slant lines and the reversed slant lines are overlapped is to show the part where the edge area of the first monochromatic strip (color) and the second monochromatic strip (2color) are overlapped. The first monochromatic strip (1color) is formed first and the second monochromatic strip (2color) is formed at the lower end of the first monochromatic strip (1color) to be overlapped for the distance of d.

However, monochromatic strips formed at the panel270are not overlapped due to the driving mirrors of the panel270. Explaining more specifically, even when laser beams are incident to form the first monochromatic strip (1color) as much as the area of w×a (w is the width of the panel270and a is the height of the first monochromatic strip (1color) input into the panel270), the driving mirrors installed at the area of w×d″/2 (d″/2 is the half distance of overlapped area of d) of the panel270is driven not to form the first monochromatic strip (1color) at the area of w×d″/2. In other words, the first monochromatic strip (1color) is formed only at the upper end1(up_1) as the driving mirror is driven not to reflect laser beams incident into the area of w×d″/2 of the panel270.

The above method of forming the monochromatic strip is applied to the second monochromatic strip (2color) in the same manner. The second monochromatic strip (2color) is formed only at the upper end2(up_2). Therefore, the monochromatic strips can be formed in the way that the edge lines of the monochromatic strips are not overlapped due to the above driving manner of the optical switch unit230and the panel270.

FIGS. 5Ato5F are views showing the preferred embodiment of an image created based on the operation order of the optical switch unit according to the present invention. One screen is realized by applying the processes fromFIGS. 5Ato5F. These processes can be changed.FIGS. 5A,5C and5E show the operation of the optical switch placed at the first group, andFIGS. 5B,5D and5F show the operation of the optical switch placed at the second group.

Referring toFIGS. 5Ato5F, R, G and B laser beams transmitted through the first light transmission unit220are reflected at one of the optical switches230a,230gand230mplaced at the first column, one of the optical switches230b,230hand230nplaced at the second column, and one of the optical switches230c,230iand230oplaced at the third column of the first group. In the above case, only one optical switch reflects a monochromatic laser beam at the first position (on) for the same row and column.

Furthermore, the laser beam reflected at one optical switch of the optical switches230ato230cplaced at the first line of the first group forms a monochromatic strip at the upper end1(up_1) of the panel270through the first output port P1. The laser beam reflected at one optical switch of the optical switches230gto230iof the third line of the first group forms a monochromatic strip at the middle end1(mid_1) of the panel270through the third output port P3. The laser beam reflected at one optical switch of the optical switches230mto230oof the fifth lines of the first group forms a monochromatic strip at the down end1(down_1) of the panel270through the fifth output port P5.

When the optical switch unit230is realized as Table 1, the monochromatic strips formed at the panel270are shown in5A-2of FIG.5A.

In Table 1, RED means R beam, GREEN means G beam, BLUE means B beam, Port1to Port6mean a plurality output ports, ON means the first position where the laser beam is reflected, OFF means the second position where the laser beam passes through, and230ato230rmean optical switches.

When the optical switches230ato230rof the optical switch unit230are driven for only the first group as shown in5A-1inFIG. 5A, a monochromatic strip like5A-2ofFIG. 5Ais formed at the panel270. P1:R of5A-1means that R beam is input from the optical switch230ainto the first output port P1. P3:G means that G beam is input from the optical switch230hinto the third output port P3. Lastly, P5:B means that B beam is input from the optical switch230ointo the fifth output port P5.

Additionally, when the optical switch unit230is driven as shown in Table 2, the single strips formed at the panel270are as shown in5B-2of FIG.5B.

When the optical switches230ato230rof the optical switch unit230are driven as shown in Table 2, that is, when only the second group is driven like in5B-1ofFIG. 5B, monochromatic strips as shown in5B-2are formed at the panel270.

Moreover, when the optical switch unit230is driven as shown in Table 3, the monochromatic strips formed at the panel270are as shown in5C-2of FIG.5C.

When the optical switches230ato230oof the optical switch unit230are driven as shown in Table 3, that is, when only the first group is driven as shown in5C-1ofFIG. 5, monochromatic strips as shown in5C-2are formed at the panel270.

In addition, when the optical switch unit230is driven as shown in Table 4, monochromatic strips formed at the panel270are as shown in5D-2of FIG.5D.

When the optical switches230ato230rof the optical switch unit230are driven as shown in Table 4, that is, when only the second group is driven as shown in5D-1ofFIG. 5D, monochromatic strips as shown in5D-2are formed at the panel270.

Furthermore, when the optical switch unit230is driven as shown in Table 5, monochromatic strips formed at the panel270are as that which is shown in5E-2of FIG.5E.

When the optical switches230ato230rof the optical switch unit230are driven as shown in Table 5, that is, when only the first group is driven as shown in5E-1ofFIG. 5E, monochromatic strips as shown in5E-2are formed at the panel270.

Moreover, when the optical switch unit230is driven as shown in Table 6, monochromatic strips are formed at the panel270as shown in5F-2of FIG.5F.

When the optical switches230ato230rof the optical switch unit230are driven like shown in Table 6, that is, when only the second group is driven like5F-1ofFIG. 5F, monochromatic strips as shown in5F-2are formed at the panel270.

As described so far, an image is realized by performing the processes ofFIGS. 5Ato5F in a predetermined order. Yet, the first group and the second group can be operated in an alternate order. Moreover, anamolphic lenses can be used as the square-beam generation unit260instead of the light tubes264ato264fused in the present invention. The anamolphic lenses have different curvatures for the length and the width and realize bar-typed beams of color strips on a panel.

According to the present invention, as optical switches of a (3×6) or a (6×3) matrix structure are applied, the edges of monochromatic strips formed on a panel are not overlapped. Especially, the optical switches are operated in an alternate order for a predetermined time interval, thus the overlap of the edge lines of the monochromatic strips does not occur. Furthermore, since the monochromatic strips are formed in consecutive order on the panel by using the MEMS method, the efficiency of light utilization on the panel can be increased. Accordingly, as the amount of the light and the utilization of the light increase, the luminance of a realized image can be improved.

Although the preferred embodiment of the present invention has been described, it will be understood by those skilled in the art that the present invention should not be limited to the described preferred embodiment, but various exchanges and modifications can be made within the spirit and the scope of the present invention. Accordingly, the scope of the present invention is not limited within the described range, but are defined by the following claims.