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EP-4740028-A1 - POSITION DETECTION SYSTEM FOR LIGHT POINTS ON SURFACES AND IN SPACE

EP4740028A1EP 4740028 A1EP4740028 A1EP 4740028A1EP-4740028-A1

Abstract

The invention relates to a position detection system, having at least one position detection device (1) and at least one light source device (20 to 2N), which differs from the position detection device (1). Every light source device (20 to 20N) is designed to generate a light point at a distance from the at least one position detection device (1). The at least one position detection device (1) comprises at least two line scan image sensors (11, 11'), wherein directions of extent of sensor surfaces (12, 12') of the two line scan image sensors (11, 11') together enclose an angle greater than 0° and preferably 90°. Above each line scan image sensor (11, 11'), a slot aperture (13, 13') is provided such that the slot aperture (13, 13') and the associated sensor surface (12, 12') enclose an angle greater than 0° and preferably 90°. The at least one position detection device (1) and the at least one light source device (20 to 2N) each have interfaces for wireless communication via which the at least one position detection device (1) and the at least one light source device (20 to 2N) are temporally synchronised in order to enable the position of a light point generated by a respective light source device (20 to 2N) to be detected by a time-multiplex method during the emission of light by the at least one light source device (20 to 2N).

Inventors

  • HARALD, Sonntag

Assignees

  • Harald Sonntag und Elmar Will GbR

Dates

Publication Date
20260513
Application Date
20240705

Claims (20)

  1. 1. A position detection system has: at least one position detection device (1); and at least one light source device (20 to 2N) which is different from the position detection device (1); wherein each light source device (20 to 20N) is designed to generate a light spot spaced from the at least one position detection device (1); the at least one position detection device (1) comprises at least two line image sensors (11, 11'), each with sensor surfaces (12, 12') arranged along a line, wherein extension directions of the rows of sensor surfaces (12, 12') of the two line image sensors (11, 11') enclose an angle of greater than 0° and preferably 90° with one another; a slit diaphragm (13, 13') is provided above each line image sensor (11, 11') such that the slit diaphragm (13, 13') forms an angle of greater than 0° and preferably 90° with the associated line of sensor surfaces (12, 12'); the at least one position detection device (1) and the at least one light source device (20 to 2N) each have interfaces for wireless communication, via which the at least one position detection device (1) and the at least one light source device (20 to 2N) are synchronized in time in order to enable position detection of a light point generated by a respective light source device (20 to 2N) by means of a time-multiplex method when light is emitted by the at least one light source device (20 to 2N).
  2. 2. Position detection system according to claim 1, comprising a plurality of position detection devices (1) which are designed to detect light points generated by the at least one light source device (20 to 2N) from different angles, wherein the position detection system is designed to calculate the position of the at least one light source device (20 to 2N) in 3D space based on X-Y coordinates for the position of the light points output by the respective position detection device (1).
  3. 3. Position detection system according to claim 1 or 2, wherein the at least one light source device (20 to 2N) has keys and is designed to transmit the state of each key and/or status information as data bits modulated onto at least one light point emitted by the at least one light source device (20 to 2N), and wherein the at least one position detection device (1) has a photosensor (19) and is designed to receive the data bits sent by the at least one light source device (20 to 2N) in the at least one modulated light point, wherein an assignment of the data bits to an individual light source device (20 to 2N) takes place by the time-multiplex method.
  4. 4. Position detection system according to one of claims 1 to 3, wherein the at least one position detection device (1) is designed to send data packets to the at least one light source device (20 to 2N) via the interfaces for wireless communication, wherein the data packets are initially sent with low transmission power and then repeatedly sent with increasing transmission power, wherein a packet numbering of the data packets enables the at least one Light source device (20 to 2N) enables to determine whether a data packet has already been received with low transmission power, and the at least one light source device (20 to 2N) is designed to discard duplicates after receiving a data packet.
  5. 5. Position detection system according to one of claims 1 to 4, wherein the at least one position detection device (1) is designed to regularly send a command to this light source device via the interfaces for wireless communication when a light point of a light source device (20 to 2N) is detected, which command causes the light source device (20 to 2N) to set a number of light points per second to a maximum value, wherein the at least one light source device (20 to 2N) is designed to regulate the frequency of light points per second generated by the respective light source device (20 to 2N) down from a maximum value if no more command is received from the at least one position detection device (1) to set the number of light points generated per second to a maximum value.
  6. 6. Position detection system according to one of claims 1 to 5, wherein the at least one light source device (20 to 2N) has at least one vibration motor and/or at least one loudspeaker and/or at least one display, wherein the at least one position detection device (1) is designed to send commands for activating the at least one vibration motor and/or the at least one loudspeaker and/or the at least one display of a respective light source device (20 to 2N) via the interfaces for wireless communication, and wherein the at least one light source device (20 to 2N) is designed to receive commands received from the at least one position detection device (1) via the interfaces for wireless communication for activating the at least one vibration motor and/or the at least one loudspeaker and/or the at least one display and to activate the at least one vibration motor and/or the at least one loudspeaker and/or the at least one display accordingly.
  7. 7. Position detection system according to one of claims 1 to 6, wherein the at least one position detection device (1) is designed to block a channel by means of the wireless communication interface (17) by sending a first data packet, the transmission duration and thus end time of which is known in the at least one position detection device (1) and the transmission duration of which is known in the at least one light source device (20 to 2N), and which first data packet contains a current time of the position detection device (1) and is identified as a first data packet, and to send a second data packet directly after the end time of the first data packet, which second data packet contains a current time of the position detection device (1) and is identified as a second data packet, wherein the at least one light source device (20 to 2N) is designed to use the time of the position detection device (1) contained in the first data packet as a zero point for synchronization in the multiplex method, provided that the first data packet can be received, and the at least one light source device (20 to 2N), the time of the position detection device (1) contained in the second data packet minus the transmission time as the zero point to be used for synchronization in the multiplexing procedure, provided that the second data packet can be received.
  8. 8. Position detection system according to one of claims 1 to 7, wherein the at least one light source device (20 to 2N) is designed to generate an internal clock signal, to determine a clock deviation by comparison with a clock signal received from the at least one position detection device (1), and when a deviation is determined, to recalculate a time constant defined in the at least one light source device (20 to 2N) for switching the at least one light source device (20 to 2N) on and off based on the clock deviation and to use these newly calculated time constants for switching the at least one light source device (20 to 2N) on and off.
  9. 9. Position detection system according to one of claims 1 to 8, wherein the at least one interface for wireless communication (17) in the at least one position detection device (1) is designed to modulate a synchronous pattern started by a controller (18) of the position detection device (1) after a data packet on a carrier wave which is then still active without data, and wherein the interface for wireless communication (17) in the at least one light source device (20 to 2N) is designed to wait a short time after each data packet to see whether such a synchronous pattern appears on the carrier wave and to immediately store an internal timer value at the end of the synchronous pattern, which is read out after decoding and checking the actual data packet and used to synchronize the time multiplexing method.
  10. 10. Position detection system according to one of claims 1 to 9, wherein the sensor surface of each line image sensor of the at least one position detection device (1) is composed of several partial sensor surfaces (ZSO to ZS3), wherein the partial sensor surfaces (ZSO to ZS3) are arranged with overlap in mutually parallel rows.
  11. 11. Position detection system according to claim 10, wherein the overlaps of the line image sensors of the at least one position detection device (1) are determined by measuring by traveling over a total distance (L) of the respective line image sensor with an LED, are permanently stored in a non-volatile memory (18) of the at least one position detection device (1) and are taken into account in the position detection.
  12. 12. Position detection system according to one of claims 1 to 11, wherein a linear Fresnel lens is arranged above the line image sensors of the at least one position detection device (1).
  13. 13. Position detection system according to one of claims 1 to 12, wherein the position detection system comprises a plurality of position detection devices (1), and wherein, for the purpose of synchronization in the multiplex method, one position detection device of the plurality of position detection devices (1) is designed as a clock transmitter and the other position detection devices are designed as clock receivers.
  14. 14. Position detection system according to one of claims 1 to 12, wherein the position detection system comprises a plurality of position detection devices (1), and wherein, for the purpose of synchronization in the multiplexing process, each position detection device transmits at different times with specially marked data packets which allow the position detection device to be recognized as an additional timing transmitter.
  15. 15. Position detection system according to one of claims 1 to 14, wherein the at least one position detection device (1) further comprises an instrument operational amplifier which is designed to subtract another signal from its input signal, wherein the instrument operational amplifier receives as an input signal a signal output by the line image sensors (11, 11') of the at least one position detection device (1) and as a signal to be subtracted a subtract signal stored in a memory (18) of the at least one position detection device (1), wherein the subtract signal is obtained from an output signal of the line image sensors (11, 11') of the at least one position detection device (1) when none of the light source devices (20 to 2N) is active.
  16. 16. Position detection system according to one of claims 1 to 15, wherein the at least one position detection device (1) has internal light sources (14, 14') connected to a controller (15) of the position detection device (1), which are designed to irradiate the sensor surfaces (12, 12') of the line image sensors (11, 11') of the at least one position detection device (1) under the control of the controller (15).
  17. 17. Position detection system according to claim 16, wherein the internal light sources (14, 14') are designed, controlled by the controller (15), to cause a voltage amplitude of pixels of the line image sensors (11, 11') by irradiating the sensor surfaces (12, 12') of the line image sensors (11, 11'), the amount of which is lowest for pixels in the middle of the line image sensors (11, 11') and highest for pixels at the outermost edges of the line image sensors (11, 11') when no additional light is incident on the line image sensors (11, 11') through the slit diaphragms (13, 13'), and/or ... Voltage amplitude of pixels of the line image sensors (11, 11'), which voltage amplitude has a U-shaped curve with the bottom of the U in the middle of the respective line image sensor (11, 11 ') and the leg ends of the U at the outermost edges of the respective line image sensor (11, 11') when the pixels of the line image sensors (11, 11 ') are read out sequentially and the voltage values are plotted over the arrangement of the pixels.
  18. 18. Position detection system according to one of claims 16 or 17, wherein the internal light sources (14, 14') are either provided between the sensor surfaces (12, 12') of the line image sensors (11, 11') and the associated slit diaphragms (13, 13') and are directed directly onto the sensor surfaces (12, 12') of the line image sensors (11, 11'), or are provided next to the line image sensors (11, 11') on a board carrying the line image sensors (11, 11'), and are designed to radiate onto a plate (13P) in which the Slit diaphragms (13, 13') are formed, wherein the plate (13P) diffusely reflects the light emitted by the internal light sources (14, 14') onto the sensor surfaces (12, 12').
  19. 19. Position detection system according to claim 18, wherein the plate (13P) is provided with a white diffuse reflector (131) on its side facing the line image sensors (11, 11') next to the respective slit diaphragm (13, 13').
  20. 20. Position detection system according to one of claims 16 to 19, wherein the light emitted by the internal light sources (14, 14') has the same wavelength as the light emitted by the at least one light source device (20 to 2N).

Description

Position detection system for light points on surfaces and in space Systems that can detect the position of a light point (usually the light point of a laser beam) on a projection surface (e.g. screen or wall) have been known for more than 20 years. The detected position is then sent in the form of X and Y coordinates to a computer, which then processes these X and Y coordinates. For example, the computer can set the position of a mouse cursor to these X and Y coordinates. If keystrokes are also transmitted, these can also be received and taken into account by the computer. These systems, as described in WO 00/38102, for example, generally work as follows: A digital camera for generating spatially resolved images (e.g. a webcam) with, for example, a resolution of 1920 x 1080 pixels (picture elements) is aimed at a projection surface, and the image data output by the camera is searched for the pixel with the highest brightness value. This is usually the point of light being sought, since the point of light is brighter than the rest of the projection surface (otherwise the point of light in the projection surface would not be visible to a user). The position of the pixel found in this way within a receiving surface (e.g. a CCD sensor) of the camera is determined by its construction and is therefore known. As a result, the position of the point of light on the projection surface can be deduced from the position of the pixel within the receiving surface of the camera. For this purpose, a calibration between the camera and the projection surface may have taken place beforehand. If a light source/light source device for the light point (e.g. a laser pointer) also has buttons, their status can also be transmitted (wired or wirelessly) to the camera or a computer connected to the camera. As a result, the projection surface can be used, for example, with With a laser pointer with a radio module, everything that can be controlled with a computer mouse, for example, can be controlled. When using multiple light source devices and thus multiple light points at the same time, it is not sufficient to simply look for the pixel that outputs the highest brightness value. To distinguish between different light points, the use of (laser) light with different wavelengths in combination with several cameras, each with adapted filters, has been proposed. However, this is a very expensive solution due to the use of several cameras. It was further proposed to use a time-multiplexing method in which the individual light source devices are each switched on synchronously with the camera in predefined different time windows on the time axis T, but are switched off in the other time windows. This is illustrated in Figure 1. In the example of Figure 1, the camera sends a synchronization signal S at regular time intervals on the time axis T, which is received by the light source devices, so that all light source devices work synchronously with the camera. The light source device with the number 0 emits light in the time window F00 (e.g. by switching on a laser) and stops the light output again at the end of the time window (e.g. by switching off a laser). Then the light source device with the number 1 emits light in the time window F01 and stops the light output again at the end of the time window, etc. After the light output by the light source device 99, all light source devices wait for the next synchronization signal S and this process is repeated endlessly (e.g. 20 times per second) so that the position of the light points on the projection surface attributable to the light source device 1 to 99 can be captured without excessive jumps. Due to the short light output by the individual light source devices, the light points generated by the individual light source devices on the projection surface are generally not or only poorly perceptible to a user. To better orient the user, an individual cursor (e.g. in different colors) can be displayed on the projection surface for each light source device using the computer, so that each user of a particular light source device knows where he or she is pointing. The synchronization signal S can be transmitted to the light source device using a cable or wireless, electrical, light-based or radio-based method. However, these previously known systems also have severe limitations with regard to the number of light source devices that can be used simultaneously (due to the time-division multiplexing method, only one light source device emits light at a time). The reason for this is that (as with any camera) it is not only the brightness of the light point that determines whether the light point can still be detected by the camera, but also the time, because the light energy (power times time) determines which output voltage a sensor generates for each individual pixel. The more light source devices are used, the shorter the period of time during which a respective light source device emits light du