FR2473737A1 - Multiple projector system for audiovisual presentation - has horizontally movable carriage for selectively bringing required projector into position - Google Patents

Abstract

The system has at least two projectors used selectively to project an image onto a common projection screen. All the projectors are supported by a carriage, which is moved in a horizontal plane transverse to the projection axis to bring the required projector into alignment with a projection window. Pref. the carriage has a clamping element, e.g. a spring pin, used to hold the carriage in at least one of these projection positions. Pref. the carriage supports a cine projector, adjusted in height by adjustable screw feet, together with two identical slide projectors mounted independently on respective supports above a casing containing a sound amplifier etc. Each of the supports pref. pivots about a vertical axis. The system is used for audio-visual presentations.

Description

Device for projecting images from at least
minus two devices
Modern installations for the projection of images on a screen commonly include several devices, in order to be adapted to a maximum of audiovisual possibilities.

 Thus a projection booth must at least be equipped with a cinema film projector and a fixed view projector. When you want to use the projection method known as "crossfade" you need at least two projectors rigorously rigged relative to each other and both relative to the screen.

 These installations exclude those which have only one destination, as is the case for cinemas intended for the public. In this case, you need only two devices at most and they are fixed fairly close to each other.

 On the contrary, congress or conference rooms, for example, must be adapted to the use of several different projection systems which can be used immediately one after the other.

 However, to date, we have great difficulty in moving from one type of projection to another because it is necessary, in each case, to adjust the devices and these adjustments are difficult.

 Thus, for example, for an installation with which the objective of a still projector is approximately 14 meters from the screen, a displacement of half a millimeter of the camera results in a displacement of 15 centimeters from the image on the screen (for a focal length of 250 millimeters) or a multiplier of 300.

 When using the crossfade, or the constitution of a single complete image from several partial projections, the devices must be calibrated with respect to each other with the greatest precision, in height, in width and in inclination lateral so that there is a perfect superposition of images. We can admit that the superimposition (or "rep erage") is correct to the nearest millimeter on the screen. With the installation defined above, this precision supposes that none of the devices is,;: adjusted by more than 1 / 300th of a millimeter and that in none of the three directions.

 This rigorous immobility is possible when the devices are stationary. It is impossible to keep when moving the devices.

 However, such displacements are inevitable with multipurpose installations because all the devices must be substantially placed in the axis of the screen (or, at least symmetrically arranged relative to this axis but, in the latter case, they do not d - must not be too far from said axis).

 Indeed, any significant shift causes distortions of the image, distortions which are further amplified when the observed image results from the combination of at least two images projected from two devices, because the images are in the form of reverse trapezoids. and the horizontal lines tend towards an increasing obliquity from the center to the upper and lower edges of the screen.

 The invention overcomes these drawbacks by simultaneously ensuring the mobility of the devices and their rigorous setting both with respect to each other and with respect to the screen.

 The invention will be better understood from the detailed description below made with reference to the accompanying drawing. Of course, the description and the drawing are only given by way of an indicative and nonlimiting example.

 FIGS. 1 and 2 are diagrammatic plan views showing two extreme positions of a device according to the invention and comprising a cinema film projector as well as two still view projectors.

 Figure 3 is a rear elevational view of the same device.

 Figure 4 is a side view of the side view projectors side.

 FIG. 5 is a partial view showing a support for a fixed view projector.

Referring to the drawing, it can be seen that a device according to the invention for projecting images onto a screen A from devices B, C and D which can be used selectively in a booth E, is characterized in that it includes a carriage l on which all the apparatuses 3, C and D are set in height, and which is mounted movable, in a horizontal plane, transverse to the projection axis x between two positions corresponding to the correct projection location of the device
B on the one hand and CD devices on the other.

 Camera B is a cinema film projector. It is placed directly on the carriage 1 and can be chocked in height by means of the usual adjustable feet with which it is provided.

 The cameras C and D are two identical projectors of fixed views. They are placed on supports 2 and 3 independent of each other and placed above a compartment 4 which is open on the rear face and which must contain an apparatus F of any known type such as a sound amplifier, synchronizer etc ...

 Each support 2-3 is pivotally mounted on a vertical axis 5 and includes an operating index 6. Near this latter, the support is notched with a light in an arc of circle 7 through which passes a threaded rod 8 made integral with the upper wall 4 a of the compartment 4 and having to receive by screwing a locking button 9.

 The assembly which has just been described is movable owing to the fact that the carriage 1 is provided with wheels 10 which cooperate with rails 11 fixed on a fixed base 12.

 This base 12 is arranged in such a way that the rails 11 are indeed horizontal and well perpendicular to the x axis and that the objectives of the apparatuses B, C and D can be located at the right of a projection window G formed in the wall front of cabinet E.

The operation of this device is as follows
To wedge the apparatuses C and D, the carriage 1 is placed in its extreme right position, as shown in FIG. 1. One then acts on the adjustable feet H of known type with which they are provided so that their objectives are at good height relative to screen A and in a good orientation relative to the edges of said screen A. Then after having unlocked the button 9 of one of the supports 2-3, this support is pivoted about its axis 5 by acting on index 6 to adjust the horizontal angular position of the device. When this is obtained, the button 9 is blocked to immobilize the support.

 We act in the same way for the second support and, if necessary by successive approximations, we perform the perfect setting of the two devices C and D.

 This done, the carriage l is moved to its extreme left position (FIG. 2) in which the objective of the projector B must be in the projection axis x. The projector is moved and the adjustable feet of known type are acted upon with it until the perfect setting is obtained.

 We can then, at any time, in a few seconds and without any additional adjustment, switch from the projection of films by projector B to the projection of still views with only one of the CD projectors or with both at the same time, by moving the carriage 1 on the rails ll The only condition to be observed is that the fixed base 12 is suitably placed relative to the screen A so that the rails ll are parallel to the lower and upper edges of the screen. Naturally, as with any projection installation, the screen A must itself be in a plane that is suitably oriented relative to the booth E, in such a way that the x axis is normal to this plane.

 According to a characteristic of the invention, the device comprises at least one member 13 capable of immobilizing 1 carriage 1 in at least one of the two positions corresponding to FIGS. 1 and 2.

 This member 13 is, for example, a pin biased by a spring and capable of penetrating selectively into one of two bowls 14 formed in the base 12 at suitable locations.

 Referring to Figure 4, we see that the supports 2 and 3 are arranged in a plane inclined downwards and towards the screen A so that the projectors C and D placed on each of them are substantially horizontal when the feet adjustable H with which they are fitted at the front are in partial lifting position.

 This arrangement is advantageous since the projection booths are almost always placed in height, so that in order to be in the projection position through window G, the devices are rather inclined downwards. Thus the extreme high position (horizontal projection axis) is obtained when the feet H are in the partial lifting position and it is possible to obtain an adjustment over a relatively long stroke by lowering the devices and no longer, as is commonly the case. case, by raising them.

 To ensure very fine adjustment of the supports 2 and 3, it is possible to provide, instead of a simple index 6, a micrometric screw mechanism (not shown) for example.

 The invention is not limited to the single embodiment described and shown but embraces, on the contrary, all variants. In particular, the carriage 1 can receive a larger number of juxtaposed or superimposed devices.

Claims (4)

 1 - Device for projecting images on a screen (A) from at least two devices (BCD) which can be used selectively in a cabin (E), characterized in that it comprises a carriage (1) on which all the devices (BCD) are fixed in height and which is mounted mobile-, in a horizontal plane. transversely to the projection axis (x) between at least two positions corresponding to the correct projection location of the device (s) (B-C-D) desired.  2 - Device according to claim 1, characterized in that it comprises at least one member (13) capable of immobilizing the carriage (1) in at least one of the positions corresponding to a correct projection location.  3 - Device according to claim 1, characterized in that the carriage (1) carries at least one support (2-3) on which must be wedged in height at least one device (CD) and which is pivotally mounted relative to the carriage (1) along a vertical axis (5), means (7-8-9) being provided for immobilizing the support (2-3) in pivoting.  4 - Device according to claim 3, characterized in that the support (2-3) is arranged in a plane inclined downward and towards the screen (A) so that the device (CD) to be placed on the i is substantially horizontal when an adjustable foot (H) with which it is provided at the front, as is known per se, is in the partial lifting position.