The present invention relates to a vehicle-mounted camera device mounted on a vehicle.
In recent years, techniques using a vehicle-mounted camera device as an external recognition sensor have been advanced as a vehicle-mounted safety device. Particularly, a stereo camera technique having two imaging units has been developed.
A stereo camera has imaging units on both the right and left sides, and an image control unit thereof controls imaging timings and image data transmission timings of the right and left imaging units.
Image data signals transmitted from the right and left imaging units are transmitted to an image processing unit at the center of the camera to be subjected to an image processing. Thereafter, a recognition application or the like uses the images processed in the image processing unit to recognize an object, thereby performing vehicle control depending on the recognition result.
The signals transmitted from the right and left imaging units may be clock signals or image synchronization signals in addition to the image data signals. The image synchronization signal indicates a vertical synchronization signal or a horizontal synchronization signal for determining an aspect size of the screen.
The stereo camera needs to calculate a disparity based on the images shot in the right and left imaging units for calculating a distance. The right and left imaging units need to shoot images at the same time for calculating the disparity.
In a typical stereo camera, the image control unit sends an imaging instruction to the right and left imaging units at the same time such that the right and left imaging units shoot images at the same time. The image data shot at the same time is transmitted to the image processing unit at the same timing.
Thus, when the image data signals, the clock signals or the image synchronization signals are transmitted from the right and left imaging units to the image processing unit, there is a problem that switching easily occurs in many signal lines at the same time and unnecessary large radiation noises are generated.
The vehicle-mounted camera device such as a stereo camera is attached near the room mirror in the vehicle interior in many cases. The circumstances around the room mirror are disadvantageous for an attachment position of a TV antenna (attached to or embedded in the front glass), a GPS antenna (on or near the dashboard) or EMC (Electromagnetic Compatibility). That is, even unnecessary small radiation noises can be easily caught by the TV antenna or GPS antenna. Under the condition of the attachment around the room mirror, a vehicle-mounted camera has a laterally elongate structure such as antenna-like structure, so as not to break a view of the driver or the passenger, which is disadvantageous for EMC.
Against the problem, as described in PTL 1, there is disclosed a structure capable of reducing unnecessary radiation noises by offsetting a data signal from a clock signal.
However, with the structure in PTL 1, the stereo camera is less effective in reducing unnecessary radiation noises only by simply offsetting data from a clock, and consequently it employs a method for reducing a noise level by many noise canceling units (such as lug terminal, radio wave absorber and shield tape), which causes higher cost.
It is an object of the present invention to reduce unnecessary large radiation noises generated when image data signals, clock signals or image synchronization signals are transmitted from two imaging units to an image processing unit in a low-cost vehicle-mounted camera device.
Preferred aspects of the present invention for solving the above problem are as follows.
A vehicle-mounted camera device according to the present invention includes a first imaging unit for shooting an image and outputting an image data signal, a second imaging unit for shooting an image and outputting an image data signal, an image control unit for outputting imaging timing signals for controlling imaging timings of the first imaging unit and the second imaging unit to the first imaging unit and the second imaging unit, and outputting transmission timing control signals for controlling transmission timings of signals output from the first imaging unit and the second imaging unit to the first imaging unit and the second imaging unit, and an image processing unit for performing an image processing on the signals output from the first imaging unit and the second imaging unit, wherein the image control unit temporally offsets a timing of outputting the signal from the first imaging unit to the image processing unit from a timing of outputting the signal from the second imaging unit to the image processing unit based on the transmission timing control signals.
A vehicle-mounted camera device includes a first imaging unit for shooting an image and outputting an image data signal, a second imaging unit for shooting an image and outputting an image data signal, an image control unit for outputting imaging timing signals for controlling imaging timings of the first imaging unit and the second imaging unit to the first imaging unit and the second imaging unit, and outputting transmission timing control signals for controlling transmission timings of signals output from the first imaging unit and the second imaging unit to the first imaging unit and the second imaging unit, an image processing unit for performing an image processing on the signals output from the first imaging unit and the second imaging unit, a first circuit device provided between the first imaging unit and the image processing unit, and a second circuit device provided between the second imaging unit and the image control unit, wherein a constant of the first circuit device is different from a constant of the second circuit device.
The present specification encompasses the contents described in the specification and/or the drawings in Japanese Patent Application No. 2011-047079 on which the priority of the present application is based.
It is possible to reduce unnecessary large radiation noises generated when image data signals, clock signals or image synchronization signals are transmitted from two imaging units to an image processing unit in a low-cost vehicle-mounted camera device.
An embodiment will be described below with reference to the drawings.
The stereo camera as a vehicle-mounted camera device has two imaging units (cameras) including a first imaging unit 101 and a second imaging unit 102 at the right and left sides thereof. An image control unit 100 outputs imaging timing signals via a control line 111 (first control line) and a control line 112 (second control line) to control imaging timings of the first imaging unit 101 and the second imaging unit 102. Typically, the imaging timing signals for controlling the imaging timings of the control line 111 and the control line 112 are shutter control signals, or register setting signals for imaging devices or AFE (Analog Front End: A/D converter).
Image data (left image and right image) shot by the first imaging unit 101 and the second imaging unit 102 is transmitted to an image processing unit 103 via a signal line 113 (first signal line) and a signal line 114 (second signal line) together with image data signals, clock signals or image synchronization signals. The transmission timings of the signal line 113 and the signal line 114 are controlled by the transmission timing control signals output from the image control unit 100 via a transmission timing control signal line 115 (first transmission timing control signal line) and a transmission timing control signal line 116 (second transmission timing control signal line). Herein, the transmission timing control signal line 115 and the transmission timing control signal line 116 are clock lines for reference clock, and the like.
The image processing unit 103 calculates a disparity by use of the right and left image data shot by the first imaging unit 101 and the second imaging unit 102. A recognition unit 104 performs a recognition processing to perform an object recognition processing or to calculate a distance based on the result of the image processing. A vehicle control unit 105 makes calculations for vehicle control and issues a vehicle control instruction based on the processing result of the recognition unit 104.
For the stereo camera, the image data shot by the first imaging unit 101 and the second imaging unit 102 has to be shot at the same time for calculating a disparity. Thus, the image control unit 100 controls, based on the signals output via the control line 111 and the control line 112, such that the first imaging unit 101 and the second imaging unit 102 shoot images at the same time.
The image data shot by the first imaging unit 101 and the second imaging unit 102 is transmitted to the image processing unit 103 through the signal line 113 and the signal line 114 together with the image data signals, the clock signals or the image synchronization signals by the transmission timing signals controlled by the transmission timing control signal line 115 and the transmission timing control signal line 116 in the image control unit 100.
The present invention is characterized in that the timings of transmitting the image data signals, the clock signals or the image synchronization signals shot by the first imaging unit 101 and the second imaging unit 102 via the signal line 113 and the signal line 114 are temporally offset.
The image control unit 100 can control the timings of transferring the image data shot by the first imaging unit 101 and the second imaging unit 102 to the image processing unit 103 by use of the transmission timing control signal line 115 and the transmission timing control signal line 116. That is, the image control unit 100 can offset the temporal timings of the signal line 113 and the signal line 114 through which the image data signals, the clock signals or the image synchronization signals shot by the first imaging unit 101 and the second imaging unit 102 are transmitted.
The image data shot by the first imaging unit 101 and the second imaging unit 102 is transmitted to the image processing unit 103 via the signal line 113 and the signal line 114 together with the image data signals, the clock signals or the image synchronization signals, but the transmission paths are arranged as long as the base line length (length between the first imaging unit 101 and the second imaging unit 102) illustrated in
Further, as can be seen from the transmission paths of the signal line 113 and the signal line 114 in
Therefore, the temporal timings of the signal line 113 and the signal line 114 through which the image data signals, the clock signals or the image synchronization signals shot by the first imaging unit 101 and the second imaging unit 102 are transmitted are offset, and thus the current change amount di/dt per unit time can be restricted for the entire substrate, thereby preventing unnecessary radiation.
The image control unit 100 illustrated in
As illustrated in
As illustrated in
As illustrated in
Typically, in consideration of a setup/hold time of the reception-side IC or a delay time such as waveform rise/fall dullness, the cycle T is desirably set in the range of about |Td|<T-delay time (several nsec to several tens nsec). With the setting, data can be accurately obtained even when the signals are offset.
An internal logic is incorporated such that the image processing unit 103 in
Particularly in the parallel communication, a plurality of signal lines through which the image data signals are transmitted are present in many cases (the number of bits also increases when the bus width is large), and the current change di/dt on the simultaneous switching easily increases. Thus, unnecessary radiation noises are easily problematic.
As illustrated in
As illustrated in
As illustrated in
As illustrated in
Similarly as in the serial communication, typically, in consideration of a setup/hold time on the reception-side IC or a delay time such as waveform rise/fall dullness, the cycle T is desirably set in the range of about |Td|<T-delay time (several nsec to several tens nsec). With the setting, data can be accurately obtained even when the signals are offset.
An internal logic is incorporated such that the image processing unit 103 in
Typically, the circuit device 201 and the circuit device 202 are inserted for maintaining the signal quality (restricting signal reflections) in the signal line 113 and the signal line 114 from the first imaging unit 101 and the second imaging unit 102 to the image processing unit 103, respectively, in many cases. Typically, for the circuit device 201 and the circuit device 202, dumping resistors, ferrite beads, coils, capacitors or buffer circuits are inserted in many cases.
Also in the system in which the signal timings of the signal line 113 and the signal line 114 from the first imaging unit 101 and the second imaging unit 102 to the image processing unit 103 cannot be offset, a constant of the circuit device 201 and a constant of the circuit device 202 are intentionally changed so that the properties of the waveforms of a signal line 123 (third signal line) and a signal line 124 (fourth signal line) can be changed after passing the circuit device 201 and the circuit device 202, thereby offsetting the signal timings.
A signal transmitted via the signal line 123 after the signal transmitted from the first imaging unit 101 to the image processing unit 103 passes the circuit device 201 inserted in the signal line 113 is offset by a predetermined time Td1. Similarly, a signal transmitted via the signal line 124 after the signal transmitted from the second imaging unit 102 to the image processing unit 103 passes the circuit device 202 inserted in the signal line 114 is offset by a predetermined time Td2.
Consequently, the signals transmitted via the signal line 123 and the signal line 124 are offset by a predetermined time Td3, thereby reducing noises due to the temporally simultaneous switching. Therefore, unnecessary radiation noises can be reduced.
Particularly in the parallel communication, a plurality of signal lines through which the image data signals are transmitted are present in many cases (the number of bits also increases when the bus width is large), and the current change di/dt on the simultaneous switching easily increases. Therefore, unnecessary radiation noises are easily problematic.
A signal (clock signal, image data signal, or image synchronization signal) transmitted via the signal line 123 after the signal transmitted from the first imaging unit 101 to the image processing unit 103 passes the circuit device 201 inserted in the signal line 113 is offset by a predetermined time Td1 from the signal line 113 (clock signal, image data signal or image synchronization signal).
Similarly, a signal (clock signal, image data signal or image synchronization signal) transmitted via the signal line 124 after the signal transmitted from the second imaging unit 102 to the image processing unit 103 passes the circuit device 202 inserted in the signal line 114 is offset by a predetermined time Td2 from the signal (clock signal, image data signal, or image synchronization signal) transmitted via the signal line 114.
Consequently, the signals transmitted via the signal line 123 and the signal line 124 are offset by a predetermined time Td3, thereby reducing noises due to the temporally simultaneous switching. Therefore, unnecessary radiation noises can be reduced.
As described above, according to the present invention, it is possible to reduce unnecessary large radiation noises occurring when the image data signals, the clock signals or the image synchronization signals from the two imaging units are transmitted to the image processing unit 103 at low cost in the vehicle-mounted camera device having the two imaging units.
All of the publications, patents and patent applications cited in the present specifications are incorporated herein by reference.
Number | Date | Country | Kind |
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2011-047079 | Mar 2011 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2012/055253 | 3/1/2012 | WO | 00 | 8/23/2013 |