Patent application EP20178163A (EP), filed 2020-06-04
Publication number: EP3748394A1
Title: LIDAR SYSTEM UTILIZING MULTIPLE NETWORKED LIDAR INTEGRATED CIRCUITS
Abstract: A ranging system includes a first ranging unit with a first laser driver, a first control circuit generating a first trigger signal, and a first data interface with a first trigger transmitter transmitting the first trigger signal over a first data transmission line and a first calibration receiver receiving a first calibration signal over a second data transmission line. A second ranging unit includes a second laser driver, a second data interface with a second trigger receiver receiving the first trigger signal and a second calibration transmitter transmitting the first calibration signal, and a second control circuit generating the first calibration signal in response to receipt of the first trigger signal. The first control circuit determines an elapsed time between transmission of the first trigger signal and receipt of the first calibration signal. The determined elapsed time is used to synchronize activation of the first and second laser drivers.
IPC codes: G01S  17/   931            A I
G01S   7/   481            A I
G01S   7/   497            A I
Claims: number: 1
text: A ranging system, comprising:
number: 2
text: The ranging system of claim 1,
wherein the first control circuit (21, 31, 41, ..., n1) generates a first control signal for the first laser driver (23, 33, 43, ..., n3) to cause delayed activation of the first laser driver, the delay of the activation of the first laser driver being a function of the elapsed time determined by the first control circuit;
wherein the second control circuit (32, 42, ..., n2) generates a second control signal for the second laser driver (33, 43, ..., n3) to cause activation of the second laser driver based upon receipt of the first trigger signal by the second trigger receiver.
number: 3
text: The ranging system of claim 2, wherein the delay is one half the elapsed time determined by the first control circuit (21, 31, 41, ..., n1), and wherein the second control circuit (32, 42, ..., n2) generates the second control signal to cause activation of the second laser driver (33, 43, ..., n3) substantially immediately upon receipt of the first trigger signal, such that the first and second control signals cause substantially simultaneous activation of the first and second laser drivers (23, 33, 43, ..., n3).
number: 4
text: The ranging system of any of claims 1 to 3, wherein the first and second data interfaces (21, 31, 41, ..., n1) are low voltage differential sensing (LVDS) data interfaces.
number: 5
text: The ranging system of any of claims 1 to 4, wherein the first control circuit (21, 31, 41, ..., n1) comprises a first elapsed time measurement circuit configured to activate upon generation of the first trigger signal and to determine an elapsed time between transmission of the first trigger signal by the first trigger transmitter and receipt of the first calibration signal by the first calibration receiver.
number: 6
text: The ranging system of claim 5, wherein the first control circuit (21, 31, 41, ..., n1) further comprises:
number: 7
text: The ranging system of any of claims 1 to 6, wherein the first control circuit (21, 31, 41, ..., n1) further comprises a multiplexer configured to selectively pass a master trigger signal as the first trigger signal in response to a master/slave selection signal.
number: 8
text: The ranging system of any of claims 1 to 7, wherein the first and second ranging units are integrated circuit chips (20, 30, 40,..., n).
number: 9
text: The ranging system of any of claims 1 to 8, wherein the first ranging unit further comprises a first laser unit driven by the first laser driver (23, 33, 43, ..., n3); wherein the second ranging unit further comprises a second laser unit driven by the second laser driver (33, 43, ..., n3); wherein the first and second ranging units are physically arranged with respect to one another such that a first aperture through which the first laser unit emits laser beams is spaced apart from a second aperture through which the second laser unit emits laser beams by a first spacing distance.
number: 10
text: The ranging system of claim 9, wherein the first spacing distance is no more than 1cm.
number: 11
text: The ranging system of claim 9 or 10, wherein the first laser unit:
number: 12
text: The ranging system of any of claims 1 to 11,
wherein the second data interface (31, 41, ..., n1) comprises a second calibration receiver configured to receive a second calibration signal over a fourth data transmission line, and a second trigger transmitter configured to transmit a second trigger signal over a third data transmission line;
wherein the second control circuit (32, 42, ..., n2) is further configured to generate the second trigger signal based upon receipt of the first trigger signal by the second trigger receiver over the first data transmission line, and to determine an elapsed time between transmission of the second trigger signal by the second trigger transmitter and receipt of the second calibration signal by the second calibration receiver;
further comprising a third ranging unit, the third ranging unit comprising:
number: 13
text: The ranging system of claim 12,
wherein the first control circuit (21, 31, 41, ..., n1) generates a first control signal for the first laser driver (23, 33, 43, ..., n3) to cause delayed activation of the first laser driver, the delay of the activation of the first laser driver being a function of the elapsed time determined by the first control circuit and the elapsed time determined by the second control circuit (32, 42, ..., n2);
wherein the second control circuit generates a second control signal for the second laser driver (33, 43, ..., n3) to cause delayed activation of the second laser driver, the delay of the activation of the second laser driver being a function of the elapsed time determined by the second control circuit;
wherein the third control circuit (42, ..., n2) generates a third control signal for the third laser driver (43, ..., n3) to cause activation of the third laser driver based upon receipt of the second trigger signal by the third trigger receiver ; and.
preferably:
wherein the delay of activation of the first laser driver (23, 33, 43, ..., n3) is equal to a sum of one half the elapsed time determined by the first control circuit (21, 31, 41, ..., n1) and one half the elapsed time determined by the second control circuit (32, 42, ..., n2); wherein the delay of activation of the second laser driver (33, 43, ..., n3) is equal to one half the elapsed time determined by the second control circuit; and wherein the third control circuit (42, ..., n2) generates the third control signal to cause activation of the third laser driver (43, ..., n3) substantially immediately upon receipt of the second trigger signal, such that the first, second, and third control signals cause substantially simultaneous activation of the first, second, and third laser drivers.
number: 14
text: The ranging system of claim 13, wherein the second control circuit (32, 42, .., n2) sends the elapsed time determined by the second control circuit to the first control circuit (21, 31, 41, ..., n1) over a data bus.
number: 15
text: A method of synchronizing light output of a number N of ranging chips within a ranging system, the method comprising:
determining light output activation delays for first through the (N-1)th ranging chips by performing steps of:
number: 16
text: The method of claim 15, further comprising:
activating the N ranging chips to output light in a synchronized fashion, by performing steps of:
Office action: search_report, dated 2020-12-09
Rejection reasons: inventive_step_epc_56
Prior art cited: ref_id: US2018106903A1
ref_type: patent
severity: background
ref_id: EP2189804A1
ref_type: patent
severity: background
ref_id: US8368876B1
ref_type: patent
severity: background
ref_id: EP2189804
ref_type: patent
severity: obviousness
ref_id: US8368876
ref_type: patent
severity: background
ref_id: US2018106903
ref_type: patent
severity: obviousness
Final disposition: pending (2020-12-09)