JP2009038464A - On-vehicle optical communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-vehicle optical communication system capable of regularly executing communication without loss by keeping power input to a light reception device constant regardless of a light transmission device of an input source. <P>SOLUTION: This on-vehicle optical communication system is provided with a plurality of light transmission devices 100<SB>i</SB>, and a light reception device 200. The light reception device 200 is provided with a transmission means electrically transmitting light input intensity information showing intensity of the received light signal to the light transmission device having transmitted the light signal. The light transmission device 100<SB>i</SB>is provided with an adjustment means receiving the light input intensity information as an electric signal, and adjusting the output intensity of the output light signal to set the intensity of the light signal received by the light reception device at a set value based on the light input intensity information. In the on-vehicle optical communication system, when starting the system, the output intensity values of the light signals output by the plurality of light transmission devices 100<SB>i</SB>are sequentially adjusted to make the intensity values of the light signals received by the light reception device 200 from the respective light transmission devices 100<SB>i</SB>coincide with one another. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an in-vehicle optical communication system that transmits and receives information using an optical signal.

The in-vehicle optical communication system includes a plurality of devices (for example, the first to fifth cameras 100 _{1 to} 100 ₅ and the center ECU 200 in FIG. 8), and these devices transmit and receive information using optical signals. Are connected by an optical waveguide means such as an optical fiber. Further, in this system, as shown in FIG. 8, information (video information) from a plurality of optical transmission devices (cameras) is combined and collected in an optical reception device (center ECU (Electric Control Unit)) only in one direction. A communication method is also assumed. As the communication method, it is expected that a time division multiplexing (TDM) is adopted instead of a costly wavelength division multiplexing (WDM).

Here, in the conventional in-vehicle optical communication system of FIG. 8, the first to fifth cameras 100 _{1 to} 100 ₅ include laser diodes (LDs) for transmitting optical signals, and the LD is in a light emitting state. It is assumed that such an image is captured. FIG. 9 shows the intensity of an optical signal input from the _first to _fifth cameras 100 _{1 to} 100 ₅ to the center ECU 200 when TDM is used in a conventional in-vehicle optical communication system in such a state.

Even video information input to all cameras ₁₀₀ 1 to 100 _5, as in this state are the same, different output intensity of the LD to the camera ₁₀₀ 1 to 100 every _five, and each camera ₁₀₀ 1 to 100 ₅ 9 and the center ECU 200 are different from each other in the connection status, the input power to the center ECU 200 varies with time as shown in FIG. Since the optical receiver (center ECU 200) cannot receive correctly immediately after the input power fluctuates, in the conventional in-vehicle optical communication system, the information transmitted by the optical transmitter cannot be reproduced by the optical receiver. That is, communication cannot be performed normally.

  Similarly to the above, a PON system can be cited as a general system using TDM. In the PON system, the time from when the input power to the optical receiver is switched until the normal electrical output is output (settling). Since the communication is started after the time has elapsed, the communication can be normally performed. However, since it is necessary to wait until the time has elapsed, a time loss occurs accordingly.

  The present invention has been made in view of the above-described circumstances, and allows power to be input to the optical receiving device to be constant regardless of the input optical transmitting device, so that normal communication can be performed without time loss. An object is to provide an in-vehicle optical communication system.

  An in-vehicle optical communication system according to the present invention includes a plurality of optical transmission devices and an optical reception device that receives a plurality of optical signals output from the plurality of optical transmission devices in a time division manner. The apparatus includes transmission means for electrically transmitting optical input intensity information indicating the intensity of the received optical signal to the optical transmission apparatus that transmitted the optical signal, and the optical transmission apparatus uses the optical input intensity information as an electrical signal. An in-vehicle optical communication system comprising adjusting means for adjusting the output intensity of an optical signal to be received and set based on the optical input intensity information so that the intensity of the optical signal received by the optical receiver becomes a set value At the time of activation, the output intensity of the optical signals output from the plurality of optical transmission devices is sequentially adjusted, and the optical reception device matches the intensity of the optical signal received from each optical transmission device.

  In addition, the optical transmitter includes a laser diode that outputs an optical signal, and adjusts the amount of current supplied to the laser diode based on the determination result of whether or not the value of the received optical input intensity information is within the set value. It is preferable to do this. Note that it is preferable that the optical transmission device retains the adjusted current amount after adjusting the amount of current supplied to the laser diode in each of the optical transmission devices when the on-vehicle optical communication system is activated. Further, at the time of steady operation after adjusting the amount of current that each optical transmission device supplies to the laser diode at the time of starting the on-vehicle optical communication system, the optical transmission device may, as needed, based on the received input intensity information The amount of current supplied to the diode may be adjusted.

  According to the present invention, by utilizing the fact that the system is a closed system, each optical transmission is performed based on the input power of the optical signal from each optical transmission device received by the optical reception device when the system is started. Since the output power of the apparatus is adjusted, the optical input power input to the optical receiver during communication is constant regardless of the input optical transmitter. As a result, in the in-vehicle optical communication system, communication can be normally performed without time loss.

The in-vehicle optical communication system according to the present invention includes, for example, a plurality of optical transmission devices that transmit information as optical signals, and an optical reception device that receives an optical signal transmitted by the optical transmission device, as in the related art. They are connected by optical waveguide means such as optical fibers. In the present specification, the in-vehicle optical LAN includes five cameras (first to fifth cameras 100 _{1 to} 100 ₅ ) as optical transmission devices, similarly to the conventional in-vehicle optical LAN shown in FIG. The center ECU 200 will be described as an optical receiver. The center ECU 200 is optically connected to the _first to fifth cameras 100 _{1 to} 100 ₅ via optical fibers, and receives optical signals from the cameras 100 _{1 to} 100 ₅ to the center ECU 200 in a time division manner. .

  First, an in-vehicle optical communication system (hereinafter referred to as an in-vehicle optical LAN (Local Area Network) system) according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram for explaining a connection relationship between each camera and the center ECU constituting the on-vehicle optical LAN system. FIG. 2 is a block diagram illustrating a configuration example of a light transmission module of each camera, and FIG. 3 is a block diagram illustrating a configuration example of a light reception module of the center ECU.

The _first to _n- th cameras 100 _{1 to} 100 _n constituting the in-vehicle optical LAN capture images of the outside and inside of the vehicle, respectively. During normal operation, for example, the captured moving image data is converted into an optical signal. Then, as shown in FIG. 1, the data is output to the center ECU 200 via the optical fiber O. Further, the output signals of the respective cameras 100 _i (i = 1 to n) are transmitted to the center ECU 200 by time division. That is, a time slot is assigned to each of the cameras 100 _{1 to} 100 _n , and a signal is output from one camera 100 _i for each time slot.

The center ECU 200 receives an optical signal of moving image data, and outputs a moving image based on the received image data to an application 300 (for example, a display device in a vehicle) during normal operation. When moving image data is received from a plurality of cameras 100 _i , the center ECU 200 selects one of them, or multiplexes two or more moving image data and outputs the multiplexed data to the application 300.

In such an in-vehicle optical LAN system, as shown in FIG. 1, the camera 100 _i includes an optical transmission module 111 for transmitting an optical signal, and the center ECU 200 receives an optical reception module 211 for receiving the optical signal. Is provided. The optical transmission module 111 and the optical reception module 211 are optically connected via an optical fiber O.

In addition, the in-vehicle optical LAN system can make the optical input power input to the optical receiver during communication (normal operation) constant regardless of the input optical transmitter. This is because the output power from the camera 100 _i (the optical transmission module 111) is adjusted in advance based on the input power of the optical signal to the center ECU 200 (the optical reception module 211) at the time of system startup before normal operation. Is achieved.

Therefore, the camera 100 _i and the center ECU 200, as the optical input power information indicating the input power (input power) of the optical signal center ECU 200 sends (light input intensity information) camera 100 _i can receive an electrical signal For example, they are connected via a controller area network (CAN) bus C. The camera 100 _i and the center ECU 200 are provided with CAN drivers / receivers 112 and 212 as information transmission / reception units, respectively, and in addition to the optical input power information via the CAN drivers / receivers 112 and 212 and the CAN bus C. Information such as a synchronization signal for time division transmission is transmitted as an electrical signal between the camera 100 _i and the center ECU 200.

In addition, as shown in FIG. 1, the camera 100 _i has an imaging unit 120 that is configured to take an image of a situation outside the vehicle (for example, a CCD element), and a moving image captured by the imaging unit 120 is converted into an optical signal, and the center ECU 200 A camera main body 110 for transmitting to the camera.
In addition to the optical transmission module 111 and the CAN driver / receiver 112 described above, the camera body 110 performs analog / digital conversion on the moving image input from the imaging unit 120 in order to transmit the moving image data captured by the imaging unit 120. An input / output circuit 113 that outputs the same is provided. Moreover, a microcomputer (hereinafter referred to as a microcomputer) 114 for controlling the camera body 110 and a PHY chip 115 that generates an electrical input signal indicating the data based on the data are provided.

  In addition, as shown in FIG. 2, an optical transmission module 111 that converts an electrical input signal from the PHY chip 115 into an optical output signal and emits it, a laser diode (LD) 111a, an LD drive circuit 111b, A bias current control circuit 111c and a control unit 111d are provided.

The LD 111a is driven by a drive current (modulation current) from the LD drive circuit 111b based on an electrical input signal indicating data and a bias current. The LD 111a emits an optical output signal corresponding to the modulation current. Since the drive current corresponds to the electrical input signal input from the PHY chip 115 to the LD drive circuit 111b, the optical output signal from the LD 111a shows the same data as the electrical input signal. The light output signal from the LD 111a is input to the center ECU 200 via the optical fiber O.
Incidentally, the center ECU200, as described below, the optical input power information of the optical signals transmitted from the respective LD111a camera 100 _i, via the CAN bus C, so that it can electrically transmit to each of the camera 100 _i It has become.

The bias current control circuit 111c controls the LD drive circuit 111b according to the control of the control unit 111d, and controls the bias current that the LD drive circuit 111b passes through the LD 111a.
The control unit 111d receives optical input power information transmitted from the center ECU 200 via the microcomputer 114 or the like. The control unit 111d is a calculation device that performs calculation to adjust the optical output power of the LD 111a based on the received optical input power information, and controls the bias current control circuit 111c based on the calculation result. Note that the control unit 111d can also control the LD drive circuit 111b based on the received optical input power information and control the modulation current that the LD drive circuit 111b passes through the LD 111a.

When adjusting the optical output power of the LD 111a, the optical transmission module 111 including the control unit 111d and the like has optical input power information (that is, the intensity of the optical signal received by the center ECU 200) transmitted from the center ECU 200 as a set value. Thus, the output current of the optical signal to be output is adjusted by controlling the bias current flowing through the LD 111a.
In the camera 100 _i , the optical transmission module 111 receives the optical input power information transmitted from the center ECU 200, and sequentially adjusts the output intensity of the optical signal, so that the center ECU 200 receives from each camera _i . The intensity of the optical signal can be matched. That is, the optical input power to the center ECU 200 can be prevented from changing for each camera 100 _i .

  In the in-vehicle optical LAN system, the adjustment of the optical output power of the LD 111a based on the optical input power information from the center ECU 200 may be performed at the time of system startup as described above. The optical input power may change due to, for example, a shift of the connector joint due to the like. In such a case, it may be performed at any time during normal operation.

  Next, the center ECU 200 will be described with reference to FIG. In addition to the optical receiver module 211 and the CAN driver / receiver 212 described above, the center ECU 200 outputs the electrical output signal from the optical receiver module 211 as moving image data in response to the electrical output signal from the optical receiver module 211. A PHY chip 213 that performs analog / digital conversion and the like. The center ECU 200 receives the moving image data from the microcomputer 214 for controlling the ECU and the microcomputer 214, converts the data into a format that can be processed by the external application (for example, display device) 300, and the external application And an input / output circuit 215 for outputting to 300.

  As shown in FIG. 3, an optical reception module that receives an electrical signal that is a source of moving image data output to the external application 300 as an optical signal includes a PD 211a, a transimpedance amplifier (TIA) 211b, A limiting amplifier 211c, a PD current detection circuit 211d, an A / D converter 211e, and an arithmetic device 211f are provided.

PD211a detects an optical signal transmitted from LD111a camera 100 _i through the optical fiber of O, it generates an output current signal corresponding to the intensity of the optical signal. The output current signal from the PD 211a is amplified by the TIA 211b and further limit-amplified by the limiting amplifier 211c. The limit-amplified electric signal is subjected to analog / digital conversion or the like by the PHY chip 213. Data is output as an electrical output signal to the microcomputer 214 (see FIG. 1).

The PD current detection circuit 211d detects the magnitude of the current corresponding to the intensity of the optical signal from the LD 111a detected by the PD 211a, and the detected magnitude of the current is digitally converted by the A / D converter 211e. It is converted into a signal and input to the arithmetic device 211f. The arithmetic device 211f converts the optical input power from the input value and transmits it to the microcomputer 214 as a monitor value (optical input power information). The microcomputer 214 electrically transmits optical input power information to the camera 100 _i via the CAN driver / receiver 212 and the CAN bus C. As described above, the camera 100 _i adjusts the optical output power based on the optical input power information.

  In this specification, the in-vehicle optical LAN system is described as being configured to use the CAN protocol as a communication protocol, but may be configured to use the IEEE 1394 protocol, the FlexRay protocol, or the like. The on-vehicle optical LAN system may be configured to use a PLC (Power Line Communications) protocol using a power line.

Next, a process for adjusting the optical output power of the optical transmission module at the time of starting the in-vehicle optical LAN system having the above configuration will be described with reference to FIG. In this processing example, the camera 100 _i determines whether the value of the received optical input power information matches the set value so that the intensity of the optical signal received by the center ECU 200 matches a predetermined set value. Based on the determination result, the amount of current supplied to the LD (here, the amount of bias current passed through the LD) is adjusted, and the output intensity of the optical signal output from the LD is adjusted. The determination as to whether or not the value of the received optical input power information matches the set value is based on the determination as to whether or not the value of the received optical input power information is within a predetermined range including the set value. Done.

  First, in the in-vehicle optical LAN system of the present invention, after activation, the microcomputer 214 of the center ECU 200 determines whether or not the light receiving module 211 is turned on (step S1). When the optical receiver module 211 is turned on (in the case of YES), the microcomputer 214 selects a camera (optical transmission module) for adjusting the optical output power (step S2), and the camera adjusts to the selected camera. A selection signal indicating that the selection has been made is transmitted via the CAN bus C. The order of cameras to be adjusted is arbitrary and may be set in advance.

  In the selected camera, that is, the camera that has received the selection signal, the microcomputer 114 transmits information indicating that the adjustment signal has been received to the optical transmission module 111, and an electric signal indicating data for optical output adjustment (test data). Control is performed so as to input from the PHY chip 115 to the optical transmission module 111. In the optical transmission module 111, the control unit 111d controls the bias current control circuit 111c so that the bias current of the initial setting value flows to the LD 111a. Further, the LD drive circuit 111b passes a drive current to the LD 111a based on the control from the bias current control circuit 111c and the electric signal indicating the test data from the PHY chip 115 (step S3).

Thereafter, the camera 100 _i stands by until the light output of the LD 111a is stabilized (step S4). This standby (wait) time is set in advance.
At this time, the center ECU 200 receives (receives) an optical signal from the LD 111 a of the camera 100 _i via the optical fiber O by the PD 211 a of the optical receiving module 211. The camera 100 _i receives the optical input power information by requesting the center ECU 200 to transmit the optical input power information after the standby time has elapsed (step S5).

The camera 100 control unit 111d of the _i of the optical transmission module 111 based on the optical input power information acquired via the microcomputer 114 and the like, input power of the received optical signal PD211a of the optical receiver module 211 is within a predetermined range (Step S6).
If not within the specified range (in the case of NO), the control unit 111d of the optical transmission module 111 determines whether or not the input power of the optical signal received by the optical reception module 211 is greater than a predetermined range. (Step S7).

When larger than the predetermined range (in the case of YES), the control unit 111d of the optical transmission module 111 controls the bias current control circuit 111c so that the bias current flowing through the LD 111a is reduced by one step (step S8). .
After changing the magnitude of the bias current flowing through the LD 111a, it waits for a predetermined time (step S9). After a predetermined time has elapsed, the process returns to step S5.

On the other hand, when the intensity of the optical signal received by the optical receiving module 211 is smaller than the specified range (NO) in step S6, it is determined whether or not the bias current value is equal to or less than the limit value (step S10). . The limit value is a value that may cause damage to the LD 111a when exceeding this value.
If it does not exceed the limit value (in the case of YES), the control unit 111d of the camera 100 _i of the optical transmission module 111, a bias current applied to LD111a to what one step larger, controls the bias current control circuit 111c (Step S8).
After changing the magnitude of the bias current applied to LD111a, the processing by the camera 100 _i, the process goes to the process in step S9 described above, the process returns to step S5.

In step S6, if it is within the prescribed range (in the case of YES), the camera 100 _i selected to be adjusted holds the register value of the bias current at that time and ends the adjustment of the optical signal. (Step S12), the fact that the adjustment is completed is transmitted to the center ECU 200. The register value of the held bias current is used when an optical signal transmission instruction is given to the camera (the optical transmission module) after the adjustment of all the cameras is completed.

The center ECU 200 that has received the notification that the adjustment of the camera 100 _i has been completed records which camera has completed the adjustment, and determines whether there is an unadjusted camera based on the record (step S13). . When there is an unadjusted camera (in the case of YES), the center ECU 200 returns the process to step S2 so that the camera to be adjusted is selected from the center ECU 200. On the other hand, if there is no unadjusted camera in step S12 (NO), the process in the in-vehicle optical LAN system ends.

Further, (case of YES) when the bias current value exceeds the limit value in step S10, the control unit 111d of the camera 100 _i of the optical transmission module 111 is incomplete adjustment of the optical output of the camera 100 _i A message such as this is transmitted to the microcomputer 214 of the center ECU 200 (step S14). Further, in this step, the control unit 111d of the camera 100 _i of the optical transmission module 111 terminates the light output adjustment process, the fact that the adjustment is completed, via the microcomputer 114 of the camera 100 _i, the microcomputer 214 of the center ECU200 Send to.

Then, in the center ECU 200 that has received that the adjustment of the light output in the camera 100 _i is incomplete, the microcomputer 214 displays error display information for the display device to display that the output adjustment has not been performed in the camera. The data is output to the display device (external application) 300 (step S15). And the process in a vehicle-mounted optical LAN system transfers to step S12.

  In step S1, if the optical receiving module 211 is not turned on (in the case of NO), the microcomputer 214 of the center ECU 200 displays error display information for displaying the fact on the display device (display application (external application)). It outputs to 300 (step S16). Thereafter, the processing in the in-vehicle optical LAN system ends.

  In step S15 or step S16, when error display information is output so that an error is displayed on the display device 300, the alarm sound ringing information for the display device 300 to sound an alarm sound is replaced with the error display information. Alternatively, it may be output together with error display information.

  In addition, it is preferable that the magnitude of the bias current at each stage flowing through the LD 111a, the standby time in step S4 and step S9, and the limit value of the bias current are set in advance. Further, the magnitude of the bias current between the stages is not limited to a constant value, and the magnitude of the bias current may change according to the current value of the bias current. The preset standby time is the same as that in step S4 described above. The waiting time may be different or the same.

After adjusting the optical output at the time of system startup as described above, for example, when predetermined data is input to the optical transmission module 111 of the _first to _fifth cameras 100 _{1 to} 100 ₅ , the optical reception module of the center ECU 200 The state of the light output received at 211 is shown in FIG. Here, data that causes the LD 111a to emit light is input as the predetermined data. Since the above adjustment is performed at the time of starting the system, even when there are a plurality of cameras, the optical input power to the optical reception module 211 of the center ECU 200 can be made constant as shown in FIG. It becomes possible.

  In the above, the optical output power of the LD 111a is adjusted by changing the current passed through the LD 111a step by step based on the optical input power information. However, the adjustment method is not limited to the above method, and the bias current for making the target optical input power is calculated from the information on the current optical input power and bias current, and the bias current flowing through the LD 111a is changed (adjusted). You may make it do.

  In this method, for example, when the current light input value (P [now]) is smaller than the target value (usually having a width) (than the minimum value (P [min]) within the width). When it is small, a bias current value ((P [min] −P [now] = ΔP) × A) further necessary for obtaining the target optical input power is calculated, added to the current bias current value, Change the supplied bias current value. The multiplier A has a dimension of [mA / P]. When the current optical input value is larger than the maximum value (P [max]) of the predetermined width, the bias current value ((P [now] −P [max] = ΔP) × A) is calculated and subtracted from the current bias current value to change the bias current value supplied to the LD.

  In this way, the bias current to be supplied for the target optical input power is calculated based on the input power to the receiver (center ECU 200) in a certain slot and the information on the bias current flowing in the LD 111a, It may be reflected in the output power of the next slot. The slot here refers to one time of a series of flows in which the optical input power information is acquired, the optical input value is compared / determined with the target value, the adjustment current value is calculated, and the supply current is increased or decreased.

Note that the multiplier A used for obtaining the adjustment current value may be a predetermined constant, or the optical input power information and the bias current value information for one or a plurality of slots are stored and stored. You may decide based on the information etc. which did. In the first slot, a predetermined value is used as the multiplier A. In the second slot, the multiplier A is determined based on the optical input power information and the bias current value in the first and second slots, and is adjusted. The current value may be obtained.
Further, in the above, the addition / subtraction current value is obtained based on the minimum value or maximum value within the allowable range (width) of the optical input power value. The adjustment current value may be obtained based on the target value.

By adjusting as described above, communication can be normally performed immediately after the system is started, but the input power from each camera 100 _i to the center ECU 200 is shifted during driving due to some factor (for example, displacement of the connector joint due to vibration). there is a possibility. Therefore, as the input power to the optical receiving module 211 of the center ECU200 is constant, the amount of current supplied to LD111a in all camera 100 _i during steady operation after adjusting at startup, the amount of current supplied to LD111a The transmission output may be constantly controlled based on the optical input power information to always control the transmission output.

FIG. 6 is a flowchart for explaining processing for constantly adjusting the optical output power of the optical transmission module in the in-vehicle optical LAN system of the present invention.
The center ECU 200 switches the camera 100 _i to be operated at certain intervals, and the switching is performed by inputting an enable signal from the center ECU 200 to the camera 100 _i . In other words, the Enable signal is input only to the camera 100 _i to be operated, and the disable signal is input to the other camera 100 _i (even if the Disable signal is input, the output of the optical signal is turned off). The internal arithmetic unit etc. is operating just by becoming). As will be described below, the camera 100 _i performs automatic power control (APC) control only when an Enable signal is input to the camera 100 _i .

The microcomputer 114 of the camera 100 _i determines whether an Enable signal is input from the center ECU 200 (step S21). If it contained (YES), the control unit 111d of the camera 100 _i of the optical transmission module 111 receives the optical input power information through the microcomputer 114 and the like (step S22). Then, based on the received optical input power information, it is determined whether or not the input power of the optical signal received by the PD 211a of the optical receiving module 211 is within a predetermined range (step S23).

When not in the predetermined range (in the case of NO), the control unit 111d of the optical transmission module 111 determines whether or not the input power of the optical signal received by the optical reception module 211 is larger than the predetermined range. (Step S24).
When larger than the predetermined range (in the case of YES), the control unit 111d of the optical transmission module 111 controls the bias current control circuit 111c so that the bias current flowing through the LD 111a is reduced by one step (step S25). . After changing the magnitude of the bias current flowing through the LD 111a, it waits for a predetermined time (step S26).

After a predetermined time has elapsed, the microcomputer 114 of the camera 100 _i determines whether or not an Enable signal is input from the center ECU 200 (step S27). If yes (YES), the process returns to step S23.
On the other hand, when the intensity of the optical signal received by the optical receiver module 211 is smaller than the predetermined range in step S24 (in the case of NO), it is determined whether or not the bias current value is equal to or less than the limit value (step S28). . This limit value is set in advance.

If it does not exceed the limit value (in the case of YES), the control unit 111d of the camera 100 _i of the optical transmission module 111, a bias current applied to LD111a to what one step larger, controls the bias current control circuit 111c (Step S29). After changing the magnitude of the bias current applied to LD111a, the processing by the camera 100 _i, the process proceeds to step S26 described above.

In step S23, when it is within the specified range (in the case of YES), the process proceeds to step S27.
In step S27, (the case of NO) when it is determined not to contain the Enable signal from the center ECU holds the register value of the bias current (step S30), and finishes the process the camera 100 _i.

Further, in step S28, (the case of NO) if the bias current value is determined to more than the limit value, the control unit 111d of the camera 100 _i of the optical transmission module 111 may effect can not be adjusted in the light output of the camera 100 _i like Is transmitted to the microcomputer 214 of the center ECU 200 (step S31). When the center ECU 200 receives that the light output cannot be adjusted in the camera 100 _i , the microcomputer 214 displays error display information for the display device to display that the output cannot be adjusted in the camera. You may output to 300.
Then, processing in the in-vehicle optical LAN system, the process proceeds to step S30, and terminates the processing for the camera 100 _i.

FIG. 7 shows the state of the light output received by the light receiving module 211 of the center ECU 200 when the transmission output is constantly controlled so that the light input power to the center ECU 200 is constant as described above. Here, it is assumed that data that causes the LD 111a to enter a light emitting state is input. In the example of FIG. 7, when switched to the second camera 100 ₂ and the fourth camera 100 ₄ time slots, and, in the middle of the fifth camera 100 ₅ time slots, in the in-vehicle optical LAN system, each light for some reason The input power from the transmitter to the optical receiver is shifted. However, as described above, since the optical output power of the LD 111a is constantly controlled, the input power to the optical receiver can be corrected to be constant, so that normal communication can be performed.

  In the above-described in-vehicle optical LAN system, the camera is provided as the optical transmission device. However, the application is not limited to the camera, and may be another application.

It is a block diagram explaining the connection relation of each camera and center ECU which comprise the vehicle-mounted optical LAN system of this invention. It is a block diagram which shows the structural example of the optical transmission module of each camera. It is a block which shows the structural example of the optical receiver module of center ECU. It is a flowchart explaining the process which adjusts the optical output power of an optical transmission module at the time of starting of the vehicle-mounted optical LAN system of this invention. It is a figure which shows the state of the light output light-received by center ECU, when predetermined data is input into a some camera after adjusting light output at the time of system starting. It is a flowchart explaining the process which always adjusts the optical output power of the optical transmission module in the vehicle-mounted optical LAN system of this invention. It is a figure which shows the state of the optical output light-received by center ECU when transmission output is always controlled so that the optical input power to center ECU becomes fixed. It is a figure which shows the structural example of a vehicle-mounted optical LAN system. It is a figure which shows the intensity | strength of the optical signal input into a center ECU from a some camera at the time of using TDM for the conventional vehicle-mounted optical LAN system.

Explanation of symbols

100 1 _... first camera, 100 2 _... second camera, 100 3 _... third camera, 100 4 _... fourth camera, 100 5 _... fifth camera, 110 ... camera body, 111 ... optical transmission module, 111a ... LD 111b ... LD drive circuit, 111c ... bias current control circuit, 111c ... control unit, 111d ... control unit, 112 ... CAN driver / receiver, 113 ... input / output circuit, 114 ... microcomputer, 115 ... PHY chip, 120 ... imaging unit 200 ... center ECU, 211 ... light receiving module, 211a ... PD, 211b ... TIA, 211c ... limiting amplifier, 211d ... PD current detection circuit, 211e ... A / D converter, 211f ... arithmetic unit, 212 ... CAN driver / Receiver 213... PHY chip, 214... Microcomputer, 215.

Claims (4)

An in-vehicle optical communication system comprising: a plurality of optical transmitters; and an optical receiver that receives, in a time division manner, a plurality of optical signals output from the plurality of optical transmitters,
The optical receiving device includes transmission means for electrically transmitting optical input intensity information indicating the intensity of the received optical signal to the optical transmitting device that transmitted the optical signal,
The optical transmitter receives the optical input intensity information as an electrical signal, and outputs light based on the optical input intensity information so that the intensity of the optical signal received by the optical receiver becomes a set value. An adjustment means for adjusting the output intensity of the signal;
When the on-vehicle optical communication system is activated, output intensities of optical signals output from the plurality of optical transmission devices are sequentially adjusted, and the optical reception devices receive the optical signals received from the optical transmission devices at the same intensity. In-vehicle optical communication system.   The optical transmission device includes a laser diode that outputs the optical signal, and an amount of current supplied to the laser diode based on a determination result of whether the value of the received optical input intensity information is within the set value The in-vehicle optical communication system according to claim 1, wherein the in-vehicle optical communication system is adjusted.   3. The optical transmission device holds the adjusted current amount after adjusting an amount of current supplied to the laser diode in each of the optical transmission devices when the on-vehicle optical communication system is activated. The on-vehicle optical communication system described.   At the time of steady operation after adjusting the amount of current that each optical transmission device supplies to the laser diode at the time of startup of the in-vehicle optical communication system, the optical transmission device, as needed, based on the received input intensity information, The in-vehicle optical communication system according to any one of claims 1 to 3, wherein the amount of current supplied to the laser diode is adjusted.

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