FIELD OF THE INVENTION The invention relates in general to picture projector called gobo projector and more particularly to a compact and low energy consumption picture projector providing dynamic pictures, colour changing or beam adjustment notably.

BACKGROUND OF THE INVENTION

It is well known gobo projectors comprising at least a thin metal template disk with cut-out patterns or etched glass and a light source, to project light patterns on surfaces. These gobo projectors are usually used in the entertainment industry, i.e night clubs, concerts, stage productions, and the like, and in the trade field to create or improve brand or shop identity.

For example, US 6,685,347 discloses such a picture projector called Gobo projector. The gobo projector includes a cylindrical body, a light source and reflector at a first end of the body for casting a beam of light toward the opposite end of the body, and a window housing attached to the opposite end of the body. The window housing includes a window opening covered with a transparent material in an airtight manner and a pivotal mirror adapted to reflect the beam of light outward through the window opening. The gobo projector further includes a pair of lenses, interposed between the light source and the mirror, slidably mounted in the housing for adjusting the size and focus of the projected image, a slot for receiving a gobo and a heat shield between the slot and the light source to protect the gobo.

Such gobo projector has the drawback to be fixed, expensive and bulky for dynamic picture projection. Moreover, this kind of gobo projector needs high power consumption.

To overcome above-mentioned limitation, a need exists for a compact and low energy consumption picture projector providing dynamic pictures, colour changing or beam adjustment notably.

SUMMARY OF THE INVENTION It is therefore an object of the invention to provide a picture projector comprising at least a light source emitting a parallel beam light, a first lens array dividing the parallel light beam into a plurality of unitary beams, a diaphragm comprising a plurality of holes through which unitary beams pass, a translucent screen comprising a plurality of optical elements wherein the optical elements receive unitary beams to form images of optical elements, a second lens array projecting the images of the optical elements to form one picture onto a projection screen, and at least one actuator moving the translucent screen with respect to the diaphragm and/or moving the diaphragm the first lens array 3 and the second lens array 10 with respect to the translucent screen wherein the translucent screen and/or the diaphragm, the first lens array and the second lens array are moved perpendicularly to the unitary beams.

Preferably, the light source includes a LED source and a collimator to emit a parallel beam light.

The translucent screen includes horizontal and vertical black lines forming a grid, each square of the grid including an optical element. Such black lines form killed area that improve the separation between optical elements

Moreover, holes of the diaphragm are arranged in front of squares of the translucent screen having the same optical element.

Advantageously, the actuator moves the translucent screen and/or the diaphragm relative to the diaphragm and/or respectively the translucent screen in a stepping manner with a pitch equal to squares dimensions.

The diaphragm comprises n holes and the translucent screen comprises X ² n optical elements, with X and n positive integers .

Each optical element is a picture, a symbol or a holographic lens or elementary optical components.

The actuator provides a vertical and/or horizontal displacement of the translucent screen with respect to the diaphragm.

Alternatively, the actuator provides a rotation of the translucent screen with respect to the diaphragm.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the objects and advantages of the present invention, references should be made to the following drawings in conjunction with the accompanying descriptions and operations, wherein:

- Figure 1 shows a schematic exploded perspective view of a picture projector according to the present invention,

- Figure 2 shows a schematic perspective view of a picture projector according to the invention,

- Figure 3 is a right hand end view taken from figure 1 ,

- Figure 4 is a front view of the translucent screen and the diaphragm of the picture projector according to the invention, - Figure 5 is a detailed view of the translucent screen of the picture projector according to the invention,

- Figures 6A to 6F are front views and back views of the translucent screen and the diaphragm of the picture projector according to the invention, during the different movement of the translucent screen with respect to the diaphragm for a dynamic picture projection,

- Figure 7 is a front view of another embodiment of the translucent screen and the diaphragm of the picture projector according to the invention. DETAILED DESCRIPTION OF EMBODIEMENTS

It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

For the purpose of promoting an understanding of the present invention, references are made in the text hereof to embodiments of a lamp, only some of which are depicted in the drawings. It is nevertheless understood that no limitations to the scope of the invention are thereby intended.

Furthermore, in the embodiments depicted, like reference numerals refer to identical structural elements in the various drawings.

Referring to figure 1 to 3, the picture projector according to the invention comprises a light source 1 emitting a parallel beam light 2 (figure 3), a first lens array 3 dividing the parallel light beam 2 into a plurality of unitary beams 20, a diaphragm 4 comprising a plurality of holes 5 through which unitary beams 20 pass, a translucent screen 6 comprising a plurality of optical elements 7 wherein the optical elements 7 receive unitary beams to form images of optical elements, two actuators 8 and 9 moving the translucent screen 6 with respect to the diaphragm 4 perpendicularly to the unitary beams 20 and a second lens array 10 projecting the images of the optical elements 7 to form one picture onto a projection screen; not shown on figures.

The light source 1 comprises a support 11 holding a LED source 12 and a collimator

13 to emit a parallel beam light 2 (figure 3). The LEDs 7 have a power supply which is not illustrated. LEDs are a good alternative to standard light sources. A large number of LEDs may be mounted on the LED source 12 to provide sufficient lighting. One of the advantages of LEDs is miniaturization. This allows for reduced thickness of the picture projector with miniaturized lens arrays. Another advantage of LEDs is low energy consumption. Nevertheless, the LED source 12 can be substituted by any suitable light source such as such as halogen or HID lamps for example without departing from the scope of the invention.

Moreover, the first lens array 3 has a square shape and is arranged at the outlet of the collimator 13. The diaphragm 4 has also a square shape and comprises a plurality of holes 5 through which unitary beams emitted at the outlet of the first lens array 3 pass. Holes 5 of the diaphragm are arranged in horizontal and vertical rows and uniformly spaced apart. Each hole has a round shape ; nevertheless, holes 5 can have any shape such as square, triangular, octagonal, etc...without departing from the scope of the invention.

The translucent screen 6, referring to figures 1 to 5, includes horizontal 14 and vertical black lines 14 and 15 forming a grid 16, each square of the grid including an optical element 7. It should be noted that horizontal and vertical black lines 14 and 15 form killed area that improve the separation between the optical elements 7. Each optical element 7 is a picture, colour filter, a symbol or a holographic lens for example. In this particular embodiment, optical elements 7 are coloured squares, each color being indexed by the same number; for example Blue=l, light green=2, purple=3, yellow= 4, green=5, red=6, light blue=7, pink=8 and orange=9. These nine colours are put together in a primary square of 3x3 colored squares and the translucent screen 6 includes 16 primary squares. Therefore, the diaphragm 4 comprises 16 holes 5 and the translucent pictures 6 comprises 144 optical elements 7. Holes 5 of the diaphragm 4 are arranged in front of squares of the translucent screen 6 having the same optical element 7 in such a manner that all unitary beams 20 would light on only squares of the translucent screen with the same optical element, i.e. the same color, at the same time.

It is obvious that the translucent screen 6 can comprise more squares, i.e. more optical element 7, each optical element being smaller. In this way, the diaphragm 4 may comprise n holes and the translucent screen 6 may comprise 9n or more generally X ² n optical elements 7, wherein X and n are positive integers.

Furthermore, the translucent screen 6 is arranged on sliding channels, not shown on figures, and cooperate with actuators 8 and 9 providing a vertical and/or horizontal displacement of the translucent screen 6 with respect to the diaphragm 4. Preferably, each actuator 8,9 moves the translucent screen 6 in a stepping manner with a pitch equal to the squares dimensions, i.e. to the optical elements 7 dimensions. Considering the small amplitude of movement by optical element 7, it is possible to use any low energy, low dimensions and low noise actuator 8,9 well known by the man skilled in the art such as finger touch, dent, cam, electrical piezzo, and the like. Said actuators 8,9 can be piloted by any suitable control unit, not shown on figures, in such a manner that vertical and horizontal displacement of the translucent screen 6 are synchronized or alternate. An example of alternate vertical and horizontal displacement of the translucent screen 6 are shown on figure 6 A to 6F.

In another embodiment, the translucent screen 6 is fixed and the diaphragm 4, the first lens array 3 and the second lens array 10 are arranged on sliding channels, not shown on figures, and cooperate with actuators 8 and 9 providing a vertical and/or horizontal displacement of the diaphragm 4, the first lens array 3 and the second lens array 10 with respect to the translucent screen 6. In the same way as preceding, each actuator 8,9 moves the diaphragm 4, the first lens array 3 and the second lens array 10 in a stepping manner with a pitch equal to the squares dimensions, i.e. to the optical elements 7 dimensions.

In yet another embodiment, depicted in figure 7, the translucent screen 6 can be rotated with respect to the diaphragm 4 by at least one actuator around the optical axis of the light source 1. Nevertheless, the actuator may also be arranged such that this rotation is performed around an axis parallel to the optical axis or any other axis. In this particular embodiment, the translucent screen 6 includes radial and concentric black lines 17 and 18 forming a grid 16, each area of the grid 16 including an optical element 7. Said radial and concentric black lines 17 and 18 form killed area that improve the separation between the optical elements 7. Moreover, as preceding, each optical element 7 is a picture, colour filter, a symbol or a holographic lens for example. The diaphragm 4 has a disc shape and comprises a plurality of holes 5 through which unitary beams emitted at the outlet of the first lens array 3 pass. Holes 5 of the diaphragm are arranged in radial rows and uniformly spaced apart. Each hole has a round shape ; nevertheless, in same manner as preceding, holes 5 can have any shape such as square, triangular, octagonal, etc... without departing from the scope of the invention.

Furthermore, the picture projector according to the invention can comprise at least one lens, not shown on figures, arranged at the outlet of the second lens array to enlarge and/or reduce the projected image.

Although embodiments of the present disclosure have been described in detail, those skilled in the art should understand that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure. Accordingly, all such changes, substitutions and alterations are intended to be included within the scope of the present disclosure as defined in the following claims.