Image projection device with optimised image change

Abstract

The invention relates to an image projection device comprising: at least one LED that emits an illumination light beam, and at least one image change module comprising different images to be projected, said images being mounted on a disc coupled to a stepper motor. The device comprises an electrical control circuit configured to control the motor so as to rotate the disc in order to change the projected image, by controlling the motor with a step-change control frequency (f) which is greater than or equal to a given target frequency (fc) during a main phase (Pp), and then decreases gradually down to zero during a controlled deceleration phase (Pd).

Claims

DEMANDS

1. Image projection device (2) comprising: - at least one LED (60) emitting a beam of light (F) for illumination, - an image-changing module (7) comprising different images (Im1, Im2, Im3, Im12) to be projected, mounted on a disk (5) coupled to a stepper motor (4), and - an electrical control circuit (8), connected to the stepper motor (4) and configured to control the motor (4) according to a given control sequence (Sc), so as to rotate the disk (5): o from a first angular position (ccl), in which a first of said images (Im1) is present on the path of the light beam (F), o to a second angular position (a2), in which a second of said images (Im2) is present on the path of the light beam (F), with stopping in the second angular position, - characterized in that the electrical control circuit (8) is configured to, during the control sequence (Sc), control the motor (4) with a step change control frequency (f) which, o during a main phase (Pp), is greater than or equal to a given target frequency (fc), then o during a controlled deceleration phase (Pd), gradually decreases to zero.

2. Device (2) according to claim 1, wherein the first image (Im1) and the second image (Im2) are not consecutive, on the disk (5), at least one other of said images (Im7; Im5, Im9) being interleaved between the first image (Im1) and the second image (Im2).

3. Device (2) according to claim 2, wherein the number of images interleaved between the first image (Im1) and the second image (Im2) is less than or equal to four.

4. Device (2) according to claim 2 or 3, wherein the electrical control circuit (8) is configured to control the motor (4) so ​​as to successively project the images (Im1, Im2, Im3, Im12) of the disk (5) in accordance with a pre-established projection sequence, said images being distributed on the disk so that, for each pair grouping two of said images (Im1, Im2) which follow each other immediately in the projection sequence, the two images (Im1, Im2) of the pair are non-consecutive on the disk, at least one other of said images (Im7; Im5, Im9) being intercalated between the two images of the pair.

5. Device (2) according to the preceding claim, wherein the disk (5) rotates more than one turn, or even more than one and a half turns, to successively project said images (Im1, Im2, Im3, Im12) in accordance with said projection sequence.

6. Device (2) according to any one of the preceding claims, wherein the control sequence (Sc) includes, prior to the main phase (Pp), a controlled acceleration phase (Pa), during which the step change control frequency (f) gradually increases (from zero) until it reaches said target frequency (fc).

7. Device (2) according to any one of the preceding claims, wherein, during the control sequence (Sc), the motor (4) exerts a given motor torque (CM), and wherein the electrical control circuit (8) is configured such that said target frequency (fc) is greater than a pull-in frequency (fpi) of the motor, the pull-in frequency (fpi) being a limit frequency beyond which the motor (4) misses some steps of the control signal, if it is commanded to move from a first stop position to a second stop position at a constant angular velocity corresponding to said step change control frequency (f) and exerting said motor torque (CM).

8. Device (2) according to the preceding claim, wherein the electrical control circuit (8) is configured such that said target frequency (fc) is lower than a pull-out frequency (fpo) of the motor, the pull-out frequency (fpo) being a limiting frequency for which, when the motor exerts said motor torque (CM) and the motor is already rotating at an angular velocity corresponding to said step change control frequency (f), then, if the control frequency is increased beyond the pull-out frequency (fpo), the motor misses some steps of the control signal.

9. Device (2) according to any one of the preceding claims, wherein the first angular position (a1) and the second angular position (a2) are angularly offset from each other by at least 45 degrees, or even by at least 60 degrees.

10. Device (2) according to any one of the preceding claims, wherein the first angular position (a1) and the second angular position (a2) are angularly offset from each other by less than 120 degrees, or even less than 90 degrees. [Claim 1 1 ] Device (2) according to any one of the preceding claims, further comprising an optical projection system (21 ) arranged to project onto the ground, from a motor vehicle (1 ), the image (Im1 ) placed on the path of the light beam (F).

12. Device (2) according to the preceding claim, wherein the electrical control circuit (8) is configured to: - receive a signal (or signals) for the opening or unlocking of an opening (10, 1 1) of the vehicle (1), and for - in response to said signal, control the motor (4) in accordance with said control sequence (Sc).

13. A method for controlling an image projection device (2) comprising: at least one LED (60) emitting a light beam (F) of illumination, an image change module (7) comprising different images (Im1, Im2, Im3, Im12) to be projected mounted on a disc (5) coupled to a stepper motor (4), and an electrical control circuit (8) connected to the stepper motor (4), the method comprising a control sequence (Sc) during which the electrical control circuit (8) commands the motor (4) so ​​as to rotate the disc (5): o from a first angular position (a1), in which a first of said images (Im1) is present on the path of the light beam (F), o to a second angular position (a2), in which a second of said images (Im2) is present on the path of the light beam (F), with stopping in the second angular position, - the process being characterized in that, during the control sequence (Sc), the electrical control circuit (8) controls the motor (4) with a step change control frequency (f) which, o during a main phase (Pp), is greater than or equal to a given target frequency (fc), then o during a controlled deceleration phase (Pd), gradually decreases to zero.

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