FR3086489A1 - COLOR IMAGE PROJECTION AND / OR ACQUISITION SYSTEM - Google Patents

Abstract

The present description relates to a system for projecting or acquiring a color image, comprising: - a first matrix display (101R) or acquisition device adapted to emit or acquire a first chromatic component of the image; - a second matrix display (101G) or acquisition device adapted to transmit or acquire a second chromatic component of the image; and - a controllable mechanical actuation device for alternately placing the first (101R) and second (101G) matrix devices in the same projection (P) or acquisition position.

Description

TITLE: System for projecting and / or acquiring a color image

Technical Field This description relates to optoelectronic systems in general, and more particularly relates to a system for projecting a color image. It also relates to a system for acquiring a color image.

PRIOR ART [0002] Many systems for projecting color images have already been proposed. However, these systems have various drawbacks, in particular in terms of space, energy efficiency, complexity and / or manufacturing cost.

Similarly, known color image acquisition systems have various drawbacks, also in terms of size, energy efficiency, complexity and / or manufacturing cost.

SUMMARY OF THE INVENTION An object of an embodiment is to overcome all or part of the drawbacks of known projection and / or acquisition systems for color images.

For this, one embodiment provides a system for projecting a color image, comprising:

- a first matrix emissive display device adapted to emit a first chromatic component of the image;

- a second matrix emissive display device adapted to emit a second chromatic component of the image; and

- a controllable mechanical actuation device for alternately placing the first and second matrix display devices at the same projection position.

B17455- DD19000 [0006] According to one embodiment, the projection system further comprises a control circuit configured for, during a phase of projection of a color image, successively:

control the mechanical actuation device to place the first matrix display device in the projection position, and display the first chromatic component of the color image by means of the first matrix display device; and controlling the mechanical actuation device to place the second matrix display device in the projection position, and display the second chromatic component of the color image by means of the second matrix display device.

According to one embodiment, each of the first and second matrix display devices is suitable for transmitting directly in a specific wavelength range corresponding to the chromatic component to be displayed.

According to one embodiment, each of the first and second matrix display devices comprises an array of diodes.

Another embodiment provides a system for acquiring a color image, comprising:

- a first matrix acquisition device adapted to acquire a first chromatic component of the image;

- a second matrix acquisition device adapted to acquire a second chromatic component of the image; and

- a controllable mechanical actuation device for alternately placing the first and second matrix acquisition devices at the same acquisition position.

According to one embodiment, the acquisition system further comprises a control circuit configured for, during

B17455- DD19000 of a phase of acquisition of a color image, successively:

order the mechanical actuation device to place the first acquisition matrix device in the acquisition position, and acquire the first chromatic component of the color image by means of the first acquisition matrix device; and control the mechanical actuation device to place the second acquisition matrix device in the acquisition position, and acquire the second chromatic component of the color image by means of the second acquisition matrix device.

According to one embodiment, the mechanical actuation device comprises a mobile support on which the first and second matrix devices are mechanically fixed, and a motor adapted to drive the mobile support so as to alternately arrange the first and second devices acquisition matrixes at said position.

According to one embodiment, the mobile support is a polyhedron-shaped support, mobile in rotation about an axis passing through the polyhedron, the first and second matrix devices being arranged on two separate faces of the polyhedron.

According to one embodiment, the mobile support is a cube-shaped support, mobile in rotation about a diagonal axis of the cube, the first and second matrix devices being arranged on two separate faces of the cube, adjacent to the 'rotation axis.

According to one embodiment, the first and second matrix devices are electrically connected to a fixed control circuit by means of a connection structure with sliding contacts.

B17455- DD19000

BRIEF DESCRIPTION OF THE DRAWINGS These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments made without implied limitation in relation to the attached figures among which:

[Fig. 1] Figure 1 schematically shows an example of an embodiment of a color image projection system;

[Fig. 2] Figure 2 is a diagram representing, in the form of blocks, an example of an operating mode of the projection system of Figure 1;

[Fig. 3] Figure 3 is a partial view showing in more detail an embodiment of the projection system of Figure 1;

[Fig. 4] Figure 4 shows schematically and partially an alternative embodiment of the projection system of Figure 1;

[Fig. 5] Figure 5 shows schematically and partially another alternative embodiment of the projection system of Figure 1; and [0021] [Fig. 6] Figure 6 schematically shows an example of an embodiment of an image acquisition system at different wavelengths.

Description of the embodiments The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the various embodiments may have the same references and may have identical structural, dimensional and material properties.

B17455- DD19000 For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, the production of matrix emissive display devices and matrix acquisition devices of the systems described has not been detailed, the embodiments described being compatible with all or most of the matrix emissive display devices or 'known acquisition. In addition, the production of the control circuits of the systems described has not been detailed, the detailed production of these circuits being within the reach of those skilled in the art from the functional indications of the present description.

Unless otherwise specified, when reference is made to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when reference is made to two elements connected or coupled together, this means that these two elements can be connected or be linked or coupled via one or more other elements.

In the following description, when reference is made to qualifiers of absolute position, such as the terms front, rear, top, bottom, left, right, etc., or relative, such as the terms above, below, upper, lower, etc., or to orientation qualifiers, such as the terms horizontal vertical, etc., reference is made unless otherwise specified in the orientation of the figures, it being understood that, in practice, the devices described may be oriented differently.

Unless otherwise specified, the expressions approximately, approximately, substantially, and of the order of mean to within 10%, preferably to within 5%.

B17455- DD19000 [0027] Figure 1 schematically shows an example of an embodiment of a system for projecting color images. In FIG. 1, three views (A), (B) and (C) corresponding respectively to three distinct operating configurations of the system have been shown.

A color image can be broken down into several sub-images of a single color, called chromatic components of the image. In the example of FIG. 1, the color image to be projected is broken down into three chromatic components corresponding respectively to each of the three primary colors in additive synthesis, namely red, green and blue. The system of Figure 1 is designed to successively project the three chromatic components of the image, via separate matrix display emissive devices.

More particularly, the system of Figure 1 comprises three matrix emissive display devices 101R, 101G and 101B configured respectively for the emission of the red component, the green component, and the blue component of an image color to be projected. Each emissive display matrix device is adapted to emit mainly in a specific wavelength range corresponding to the color of the chromatic component to be displayed. Thus, the device 101R is adapted to emit mainly red light, for example in a range of wavelengths between 600 and 700 nm, the device 101G is adapted to emit predominantly green light, for example in a range wavelengths between 490 and 550 nm, and the device 101B is adapted to emit mostly blue light, for example in a range of wavelengths between 400 and 480 nm.

B17455- DD19000 Preferably, provision is made to use matrix emissive display devices adapted to directly supply signals at the desired wavelengths. This eliminates the losses linked to filtering, which makes it possible to obtain a projection system exhibiting good energy efficiency. By way of example, each of the emissive matrix display devices 101R, 101G and 101B comprises a matrix of identical or similar light emitting diodes, adapted to emit directly in the desired wavelength range and individually controllable in intensity to allow the display of an image. For example, in each of the matrix display devices 101R, 101G and 101B, the elementary light-emitting diodes are made from an inorganic semiconductor material, for example a III-V type semiconductor material, for example nitride of gallium. The distribution pitch of the elementary diodes and the dimensions of the array of elementary diodes are preferably substantially identical in the three display devices 101R, 101G and 101B. By way of example, the distribution pitch of the elementary diodes in each of the display devices 101R, 101G and 101B is less than 10 μm, for example of the order of 5 μm.

The projection system of Figure 1 comprises an electrically controllable mechanical actuating device for successively placing the matrix display devices 101R, 101G and 101B at the same position P, hereinafter called the projection position. When a matrix display device is located at the projection position P, an image displayed by this device can be viewed by an observer, possibly via an optical projection system, not shown. To project a color image, the system in Figure 1 successively displays the three components

B17455- DD19000 chromatic of the image at the projection position P, via the three display devices 101R, 101G and 101B respectively. FIG. 1 shows an arrow 115 diagramming the projection direction of the system, that is to say the main emission axis of the display devices 101R, 101G and 101B when the latter are placed in the projection position P. In the example of FIG. 1, at the projection position P, the display devices 101R, 101G and 101B are substantially orthogonal to the direction of projection 115.

In the example of Figure 1, the mechanical actuation device comprises a cubic support 103 mounted movable in rotation about a diagonal axis 105 of the cube, that is to say an axis not parallel to a face of the cube, passing through two vertices of the cube. The actuation device further comprises a motor 107 arranged to drive the support 103 in rotation about the axis 105.

The display devices 101R, 101G and 101B are mechanically secured to the support 103 and are respectively arranged on three adjacent faces 103R, 103G and 103B of the support 103. The faces 103R, 103G and 103B meet at the same vertex of the cube, located on the axis of rotation 105. In this example, each of the display devices 101R, 101G and 101B is mounted so that the display plane of the device is substantially parallel to the corresponding face 103R, 103G or 103B of the cube.

The projection system of Figure 1 further comprises a control circuit 109 (CTRL) adapted to control the matrix display devices 101R, 101G and 101B to display respectively the red, green and blue chromatic components of each image color to be projected. The control circuit 109 is connected to the display devices 101R, 101G and 101B respectively by a link 111R, a

B17455- DD19000 link 111G, and a link 111B. The links 111R, 111B and 111G are for example wired links each comprising several conductive wires adapted to supply to the corresponding matrix display device electrical supply signals and electrical data signals representative of the images to be displayed.

The control circuit 109 is further adapted to control the motor 107. For this, in the example of FIG. 1, the control circuit 109 is connected to the motor 107 by a link 113. The link 113 is by example a wired connection comprising several conducting wires adapted to supply to the motor 107 electrical supply signals and electrical control signals of the motor 107.

Figure 2 is a diagram illustrating, in the form of blocks, an example of an operating mode of the projection system of Figure 1. Figure 2 illustrates more particularly a display phase of a color image at using the system of FIG. 1. In this example, the display phase of a color image comprises five successive steps 201, 202, 203, 204 and 205.

During step 201 (DISPLAY R), the support 103 is arranged so that the matrix display device 101R is located in the projection position P, as illustrated by the view (A) of FIG. 1 , and the control circuit 109 controls the ignition of the display device 101R and the display of the red component of the image by the device 101R during a projection period TR. At the end of the projection period TR, the display device 101R is switched off.

In step 202 (ROTATE R -> B), after switching off the display device 101R, the control circuit 109 controls the motor 107 to rotate the cubic support 103 by an angle of 120 ° around axis 105. At the end of this

B17455- DD19000 rotation, the face 103B of the support 103 takes the place previously taken by the face 103R. Thus, the matrix display device 101B replaces the device 101R in the projection position P, as illustrated by view (B) of FIG. 1. The rotation of the support 103 is then interrupted.

In step 203 (DISPLAY B), after stopping the engine 107, the control circuit 109 controls the ignition of the display device 101B and the display of the blue component of the image by the device 101B during a TB projection period. At the end of the projection period TB, the display device 101B is switched off.

In step 204 (ROTATE B -> G), after switching off the display device 101B, the control circuit 109 controls the motor 107 to rotate the cubic support 103 by an angle of 120 ° around of the axis 105, in the same direction of rotation as in step 202. At the end of this rotation, the face 103G of the support 103 comes to take the place previously taken by the face 103B. Thus, the matrix display device 101G replaces the device 101B at the projection position P, as illustrated by view (C) of FIG. 1. The rotation of the support 103 is then interrupted.

In step 205 (DISPLAY G), after stopping the engine 107, the control circuit 109 controls the ignition of the display device 101G and the display of the green component of the image by the device 101G during a TG projection period. At the end of the projection period TG, the display device 101G is switched off.

At this point, a full color image has been displayed.

To display the following image, the method of FIG. 2 can be repeated in the opposite direction, by reversing the direction of rotation of the support 103 during steps 204 and 202. By doing so, that is to say by inverting the 'order

B17455- DD19000 for displaying the chromatic components and by reversing the direction of rotation of the motor 107 with each new image, the number of 120 ° rotations required to display a sequence of several successive color images is limited, and avoids the winding of the connection cables 111R, 111G and 111B around the shaft of the motor 107. It will be noted that the display order of the different chromatic components of the images may be different from that described above.

By way of example, the projection times TR, TB and TG of the different chromatic components all have the same value T, and the duration of rotation and stabilization of the engine during step 202 and the duration of rotation and motor stabilization in step 204 have the same value At. To obtain good quality video streams and taking into account the retinal persistence of the human eye, one will choose for example a display frequency of the images greater than or equal to 25 Hz and preferably greater than or equal to 60 Hz. Note that a frequency of 60 Hz corresponds to a period of the order of 16.7 ms. By setting the projection time T of each chromatic component to 5 ms and assuming that the ignition and extinction phases of the display devices 101R, 101B and 101G are almost instantaneous, there are approximately 1.7 ms left to perform the two 120 ° rotations of steps 202 and 204. This can be achieved by means of existing servos, electronically controlled to perform precise angular rotations at high speeds, for example brushless DC motors, for example type marketed by the company PORTESCAP under the commercial reference 26BC 6A. If necessary, the frequency of display of the images and / or the duration T of projection of each chromatic component may be reduced so as to reduce the speed of rotation of the motor.

B17455- DD19000 It will be noted that in the example in FIG. 1, only three faces of the cubic support 103 are occupied by matrix display devices. However, the three other faces of the support 103 have the same rotation path relative to the axis 105. Thus, provision may be made to mount on these three free faces three additional display matrix devices adapted to display the three chromatic components respectively. of a color image. Thus, it will be possible to carry out a double projection in two distinct directions, it being understood that the images projected in the two directions can be distinct or identical, and that the two directions of projection can be parallel or orthogonal.

Figure 3 is a partial view showing in more detail an embodiment of the projection system of Figure 1. Figure 3 shows more particularly an embodiment of a connection structure with wireless contact between the circuit 109 and the matrix display devices 101R, 101G and 101B, making it possible to overcome the need to reverse the direction of rotation of the motor 107 between two successive phases of projection of a color image. For simplicity, the cubic support 103 and the display devices 101R, 101G and 101B have not been shown in FIG. 3.

The connection structure of Figure 3 comprises a movable support 301 mechanically integral with the rotation shaft of the motor 107. In the example shown, the movable support 301 has the general shape of a tube centered on the motor rotation shaft 107. The connection structure of FIG. 3 further comprises, for each of the display devices 101R, 101G and 101B, a plurality of connection metallizations 303R, respectively 303G, respectively 303B, mechanically secured to the support

B17455- DD19000 mobile 301. The connection metallizations 303R, 303B and 303G are connected respectively to the display devices 101R, 101B and 101G by means of conductors or wires not shown. Insofar as the cubic support 103, the display devices 101R, 101B and 101G, the mobile support 301 and the connection metallizations 303R, 303G and 303B are all mechanically integral with the motor shaft 107, the rotation of the motor 107 does not lead to winding of the tracks or connecting wires connecting the connection metallizations 303R, 303G and 303B to the display devices 101R, 101G and 101B.

The connection structure of Figure 3 further comprises a fixed support 305. In the example shown, the fixed support 305 has the general shape of a plate substantially parallel to the central axis of the tube 301. The structure of connection further comprises, for each of the display devices 101R, 101G and 101B, a plurality of connection metallizations 307R, respectively 307G, respectively 307B, mechanically integral with the fixed support 305. The connection metallizations 307R, 307B and 307G are connected to the control circuit 109 via conductive tracks or wires.

In operation, each time one of the display devices 101R, 101G and 101B is in the projection position P of the device, the corresponding mobile connection metallizations 303R, respectively 303G, respectively 303B, are in contact with the corresponding fixed connection metallizations 307R, respectively 307G, respectively 307B, which makes it possible to ensure the electrical connection between the control circuit 109 and the display device. The metallizations 303R, respectively 303G, respectively 303B are however not mechanically integral with the metallizations 307R, respectively 307G,

B17455- DD19000 respectively 307B, so as not to prevent rotation of the motor 107. In other words, the mobile metallizations 303R, respectively 303G, respectively 303B form sliding contacts with the fixed metallizations 307R, respectively 307G, respectively 307B.

For example, the mobile connection metallizations 303R, 303G and 303B have the form of curved ribbons matching the outside wall of the tube 301, and the fixed connection metallizations 307R, 307G and 307B have the form of bosses or of spring blades bearing against the external wall of the tube 301 without rigid mechanical fixing with the tube 301 or with the metallizations 307R, 307G and 307B so as not to prevent rotation of the tube 301.

In the example of Figure 3, the mobile connection metallizations 303R, 303G and 303B are arranged so that only the matrix display device disposed at the projection position P of the device is connected to the control circuit 109 For this, in this example, the connection tapes 303R extend only in a first angular sector of 120 ° from the periphery of the tube 301, the connection tapes 303G extend only in a second angular sector of 120 ° from the periphery of the tube 301, and the connection strips 303B extend only in a third angular sector of 120 ° from the periphery of the tube 301. As a variant (not shown), the mobile connection metallizations 303R, 303G and 303B can be arranged so that the three matrix display devices 101R, 101G and 101B remain permanently connected to the control circuit 109. This can for example be obtained by extending c each of the mobile connection tapes 303R, 303G and 303B on all of the three angular sectors of the tube 301.

B17455- DD19000 Figure 4 shows schematically and partially another alternative embodiment of the projection system of Figure 1. The system of Figure 4 differs from the system of Figure 1 mainly by the shape and by the arrangement of the mobile support 103. For the sake of simplification, the motor 107 and the control circuit 109 have not been shown in FIG. 4.

In the example of Figure 4, the support 103 has the shape of a rectangular parallelepiped, not necessarily cubic, movable in rotation about an axis 105 passing through the centers of two opposite faces of the parallelepiped. The matrix display devices 101R, 101G and 101B are arranged respectively on three faces 103R, 103G and 103B of the parallelepiped parallel to the axis of rotation 105. In this example, the rotations of the support 103 around the axis 105 to pass from one display device to the next are performed in 90 ° steps.

Figure 5 shows schematically and partially another alternative embodiment of the projection system of Figure 1. The system of Figure 5 differs from the system of Figure 1 mainly by the shape and the arrangement of the support mobile 103. For the sake of simplification, the motor 107 and the control circuit 109 have not been shown in FIG. 5.

In the example of Figure 5, the support 103 has the shape of a right triangular prism movable in rotation about an axis 105 passing through the centers of the two opposite triangular faces of the prism. The matrix display devices 101R, 101G and 101B are arranged respectively on the three rectangular faces 103R, 103G and 103B of the prism. In this example, the rotations of the support 103 around the axis 105 to pass from one display device to the next are carried out in steps of 120 °.

B17455- DD19000 More generally, the embodiments described can be adapted to various forms of the mobile support 103, for example, but not necessarily, polyhedral forms. For example, the mobile support 103 can take the form of 'a rotating disc, the various matrix emissive display devices being mounted on the same face of the disc, in different angular sectors of the disc.

Various embodiments and variants have been described. Those skilled in the art will understand that certain features of these various embodiments and variants could be combined, and other variants will be apparent to those skilled in the art. In particular, the embodiments described are not limited to the examples described above in which the image to be projected is broken down into three chromatic components. More generally, the embodiments described can be adapted whatever the number of chromatic components of the image to be displayed, and therefore whatever the number, greater than or equal to two, of matrix display devices distinct from the system. Of course, the embodiments described are not limited either to the examples of ranges of emission wavelengths of the various matrix display devices mentioned above.

Furthermore, the embodiments described are not limited to the examples mentioned above in which each matrix display device comprises an array of individually controllable inorganic light emitting diodes. Alternatively, each matrix display device may include an array of organic light emitting diodes. In another variant, each matrix display device can be a liquid crystal display device using a

B17455- DD19000 backlight light source emitting directly in the desired wavelength range.

Furthermore, the examples detailed in connection with Figures 1 to 5 relate to color image projection systems. However, the principle described above of sequential projection of the different chromatic components of a color image from the same projection position P can be transposed to the acquisition of an image. In other words, the acquisition of an image can, similarly to what has been described above, be implemented by sequential acquisition of the different chromatic components of the image from the same acquisition position. Thus, color image acquisition systems can be produced by replacing, in the examples described above, the emissive display matrix devices 101R, 101G and 101B with matrix acquisition devices 101R ', 101G' and 101B ', each matrix acquisition device comprising for example a matrix of pixels (for example photodiodes) sensitive in a specific wavelength range corresponding to a chromatic component of the image to be acquired, and the control circuit 109 being adapted to read image data supplied by the sensors 101R ', 101G' and 101B '. An exemplary embodiment of such an acquisition system is illustrated in FIG. 6.

As an example, an acquisition system could be produced comprising a first acquisition matrix device adapted to acquire the red component of a color image, a second acquisition matrix device suitable for acquiring the green component of a color image, and a third matrix acquisition device adapted to acquire the blue component of a color image. As an alternative, an acquisition system may be produced

B17455- DD19000 comprising a first acquisition matrix device adapted to acquire a visible image, a second acquisition matrix device suitable for acquiring an infrared image, and a third acquisition matrix device suitable for acquiring an ultraviolet image.

Note also that projection and acquisition can be combined in the same optoelectronic system. Thus, a projection system of the type described above may include one or more matrix acquisition devices (for example on one or more of the free faces of the cube 103 in the example of FIG. 1). Similarly, a sequential acquisition system of the type described above may include one or more matrix emissive display devices making it possible to project an image. In this case, the projection and the acquisition can be implemented either sequentially, from the same position, or simultaneously from distinct positions.

Claims (10)

1. System for projecting a color image, comprising: a first emissive display matrix device (101R) adapted to emit a first chromatic component of the image; a second emissive display matrix device (101G) adapted to emit a second chromatic component of the image; and - a controllable mechanical actuation device for alternately placing the first (101R) and second (101G) matrix display devices at the same projection position (P). 2. A projection system according to claim 1, further comprising a control circuit (109) configured for, during a phase of projection of a color image, successively: - control the mechanical actuation device to place the first matrix display device (101R) in the projection position, and display the first chromatic component of the color image by means of the first matrix display device (101R); and - control the mechanical actuation device to place the second matrix display device (101G) in the projection position, and display the second chromatic component of the color image by means of the second matrix display device (101G). 3. projection system according to claim 1 or 2, wherein each of the first (101R) and second (101G) matrix display devices is adapted to transmit directly in a specific wavelength range corresponding to the chromatic component to display. B17455- DD19000 4. A projection system according to any one of claims 1 to 3, wherein each of the first (101R) and second (101G) matrix display devices comprises an array of diodes. 5. Acquisition system of a color image, comprising: - a first matrix acquisition device (101R ') adapted to acquire a first chromatic component of the image; - a second matrix acquisition device (101G ') adapted to acquire a second chromatic component of the image; and - a controllable mechanical actuation device for alternately placing the first and second matrix acquisition devices at the same acquisition position (P). 6. Acquisition system according to claim 5, further comprising a control circuit (109) configured for, during an acquisition phase of a color image, successively: - controlling the mechanical actuation device to place the first matrix acquisition device (101R ') at the acquisition position, and acquiring the first chromatic component of the color image by means of the first matrix acquisition device (101R '); and - controlling the mechanical actuation device to place the second matrix acquisition device (101G ') in the acquisition position, and acquiring the second chromatic component of the color image by means of the second matrix acquisition device (101G '). 7. System according to any one of claims 1 to 6, in which the mechanical actuation device comprises a mobile support (103) on which are mechanically fixed. B17455- DD19000 the first (101R; 101R ') and second (101G; 101G') matrix devices, and a motor (107) adapted to drive the mobile support (103) so as to alternately arrange the first and second matrix devices of acquisition at said position (P). 8. The system of claim 7, wherein the movable support (103) is a polyhedron-shaped support, movable in rotation about an axis (105) passing through the polyhedron, the first (101R; 101R ') and second ( 101G; 101G ') matrix devices being arranged on two distinct faces of the polyhedron. 9. The system as claimed in claim 7, in which the mobile support (103) is a cube-shaped support, mobile in rotation about a diagonal axis (105) of the cube, the first (101R; 101R ') and second ( 101G; 101G ') matrix devices being arranged on two distinct faces (103R, 103G) of the cube, adjacent to the axis of rotation (105). 10. System according to any one of claims 1 to 9, in which the first (101R; 101R ') and second (101G; 101G') matrix devices are electrically connected to a control circuit (109) fixed by means of a connection structure with sliding contacts.