JP2009284470A - In-vehicle camera apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-vehicle camera apparatus for surely detecting whether a shutter signal is transferred from a control section to an imaging element. <P>SOLUTION: An in-vehicle camera apparatus includes: an imaging element; a vertical driver IC connected to the imaging element; a control section for controlling a shutter; a monitor circuit which acquires a monitor signal from wiring of the shutter signal between the imaging element and the vertical driver IC; and a microcomputer which is connected to the monitor circuit for monitoring whether or not the wiring of the shutter signal is normal, on the basis of the monitor signal. A bias voltage can also be applied to the shutter signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an in-vehicle camera device mounted on an automobile.

  An image sensor such as a CCD can adjust the amount of charge by discarding the charge with an electronic shutter. That is, the brightness is changed by controlling the opening time of the electronic shutter to be long or short (the screen is bright when the opening time is long, and dark when it is short). Here, there is a technique for detecting disconnection of a control signal in a circuit manner (see Patent Document 1).

Japanese Patent Application Laid-Open No. 7-141583

  According to Patent Document 1, the disconnection of the shutter signal wiring can be detected. However, in the case of a CCD in which a voltage bias is applied inside the imaging device, it cannot be detected if the CCD foot is disconnected or opened. There is.

  Therefore, an object of the present invention is to provide an in-vehicle camera device that reliably detects whether a shutter signal is transmitted from a control unit to an image sensor.

  In order to solve the above problems, one of the desirable embodiments of the present invention is as follows.

  The in-vehicle camera device includes an imaging device, a vertical driver IC connected to the imaging device, a control unit that controls a shutter, a monitor circuit that acquires a monitor signal from a wiring of a shutter signal between the imaging device and the vertical driver IC, A microcomputer is connected to the monitor circuit and monitors whether or not the shutter signal wiring is normal based on the monitor signal.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle-mounted camera apparatus which detects reliably whether the shutter signal is transmitted to the image pick-up element from a control part can be provided.

The figure which shows the structure of the functional module in a vehicle-mounted camera apparatus. The figure which shows the waveform of the shutter signal and monitor signal at the time of normal. The figure which shows the diagnostic method of the shutter signal in the microcomputer 105. FIG. The figure shown about the case where the shutter signal 1 is disconnected. The figure which shows the mode of the shutter signal 1 from the control part 103. FIG. The figure shown about the case where the vertical driver IC102 side of the line of the shutter signal 2 is disconnected. The figure which shows the operation | movement at the normal time of the shutter signal 1. FIG. The figure shown about the case where the CCD101 side of the line of the shutter signal 2 is disconnected. The figure which shows the operation | movement at the normal time of the shutter signal 1. FIG. The figure which shows a normal shutter control waveform and the image acquired in that case. The figure which shows the mode of a shutter signal maximum open state. The figure which shows the mode of a shutter signal minimum open state.

  Embodiments will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a functional module in an in-vehicle camera device.

  The in-vehicle camera device includes a CCD (imaging device) 101, a vertical driver IC 102, a control unit 103 that controls a shutter, a monitor circuit 104, and a microcomputer 105. The microcomputer 105 monitors the wiring of the shutter signal 2 between the CCD 101 and the vertical driver IC 102 through the monitor circuit 104.

  The shutter signal 1 from the control unit 103 is buffered and voltage-converted (boosted) by the vertical driver IC 102 and input to the CCD 101 as the shutter signal 2.

  The monitor circuit 104 takes out the signal of the line immediately before being input to the CCD 101 as the monitor signal 1, performs processing such as stepping down to a voltage that can be monitored by the microcomputer 105, converts it to the monitor signal 2, and transmits it to the microcomputer 105. . The microcomputer 105 monitors the monitor signal 2.

  FIG. 2 is a diagram illustrating the waveforms of the shutter signal and the monitor signal in a normal state (the state where there is no disconnection, ground fault, or sky fault of the shutter signal).

  Normally, the voltage level of the shutter signal 1 is determined by the I / O voltage of the control unit 103, and the shutter opening time is determined according to the pulse period. In FIG. 2, the voltage of the shutter signal 1 is 0V to 3.3V. Thereafter, the shutter signal 1 is inverted and buffered and boosted by the vertical driver IC 102 to become the shutter signal 2 and enters the CCD 101. The voltage of the shutter signal 2 is 7V to 29V. Here, since the shutter signal 2 is normally biased by about 7V inside the CCD, the voltage is 7V. The voltage of the monitor signal 2 after entering the monitor circuit 104 as the monitor signal 1 from the shutter signal 2 line and being stepped down becomes a voltage that can be monitored by the microcomputer 105. Here, it is assumed that the I / O voltage of the microcomputer is 0 V to 3.3 V (eg, VIH = 2.0 V, VIL = 0.7 V), and the monitor signal line is about 0.6 V to 2.5 V (the voltage is It can be adjusted by the monitor circuit 104).

  FIG. 3 is a diagram illustrating a shutter signal diagnosis method in the microcomputer 105. FIG. 3 (A) diagnoses the count number of rising or falling edges for a certain period, and FIG. 3 (B) shows a diagnosis method for failing when the count number deviates from the intended count number. There is also a diagnosis method in which a failure is determined when the pulse period is measured and deviates from the intended period.

  FIG. 4 is a diagram illustrating a case where the shutter signal 1 is disconnected. When the shutter signal 1 is disconnected, as shown in FIG. 5, the shutter signal 1 from the control unit 103 is disconnected, so that the vertical driver IC 102 is in a constant voltage state near 0 V, and the shutter signal 2 is further transmitted by the vertical driver IC 102. Inverted buffering and boosting result in shutter signal 2, and the voltage is a constant voltage near 29V. The monitor signal 1 having the same potential as the shutter signal 2 is stepped down by the monitor circuit 104, and a constant voltage in the vicinity of 2.5 V is input to the microcomputer 105.

  Since the constant voltage is monitored by the microcomputer 105, the above-mentioned edge count becomes 0, or the pulse cycle becomes too long, so that the microcomputer can detect an abnormality.

  FIG. 6 is a diagram illustrating a case where the line of the shutter signal 2 is disconnected on the vertical driver IC 102 side. When the vertical driver IC 102 is disconnected from the branch of the monitor signal 1 in the shutter signal 2 line, the shutter signal 1 is normal (state before disconnection) as shown in FIG. On the input side of the CCD 101, the voltage is a constant voltage around 7V (because a bias voltage of about 7V is applied inside the CCD). Similarly, the monitor signal 1 has a constant voltage in the vicinity of 7V. Therefore, the monitor signal 2 after passing through the monitor circuit 104 is about 0.6V.

  Since the constant voltage is monitored by the microcomputer 105, the above-mentioned edge count becomes 0, or the pulse cycle becomes too long, so that the microcomputer 105 can detect an abnormality.

  FIG. 8 is a diagram showing a case where the CCD 101 side is disconnected from the branch of the line of the shutter signal 2 with the monitor signal 1.

  In this case, as shown in FIG. 9, the shutter signal 1 is normal (the state before disconnection), but the vertical driver IC 102 side of the shutter signal 2 line from the branch with the monitor signal 1 is inside the CCD 101. Since no bias is generated by the bias circuit, a voltage waveform of 0V to 22V is obtained by subtracting a voltage of 7V from the voltage waveform of 7V to 29V. Similarly, the monitor signal also has a voltage waveform of 0 V to 22 V, and is stepped down by the monitor circuit 104 to become the monitor signal 2, a voltage of 0 V to 1.8 V, and is input to the microcomputer 105.

  In the microcomputer 105, the constant voltage of the monitor signal 2 is not input, but 0V to 1.8V is input. However, if the HI and LO thresholds of the microcomputer 105 are VIH = 2.0V and VIL = 0.7V, the monitor signal 2 voltage of 0V to 1.8V cannot exceed the VIH threshold of the microcomputer 105. The fact that it is not recognized as HI can be used. That is, when viewed from the microcomputer 105, a constant voltage of LO is detected, and the above-mentioned edge count becomes 0, or the pulse cycle becomes too long, so the microcomputer can detect an abnormality. It becomes possible.

  When the monitor circuit 104 is constituted by a voltage dividing resistor, the resistance value is increased so that the original shutter signal 2 is not affected. However, if the value is too large, the output impedance of the monitor signal 2 is lowered, so several kΩ to several hundred Ω is desirable.

  When the monitor circuit 104 is composed of a comparator or the like, the voltages of HI and LO can be arbitrarily set by the constants of the comparator. Further, there is an advantage that the output impedance of the monitor signal 2 can be lowered.

  The monitor circuit 104 preferably includes a Zener diode or a clamp diode for circuit protection in order to step down a high voltage. However, it is desirable that the parasitic capacitance is small so that the waveform of the monitor signal 1 is not affected by the parasitic capacitance such as a Zener diode or a clamp diode.

  Next, a method for detecting disconnection of a shutter signal only by software processing in an existing in-vehicle camera system, instead of arranging a monitor circuit in the in-vehicle camera in hardware, will be described.

  Here, when disconnection of the shutter signal wiring occurs, an image captured with a certain electronic shutter has an open time halfway. That is, if the shutter time is too short, a dark image is captured, and if it is too long, a bright image is captured. Comparing the brightness of the screen imaged by the microcomputer that is processing the image, if the image is clearly too bright or clearly too dark, it can detect the shutter abnormality because the shutter cannot be controlled. However, when the shutter time is halfway, it is determined that the screen to be picked up appears to be normal, so an abnormality cannot be detected. Also, even in an environment where the surroundings are slightly bright, or conversely, such as tunnels, where the surroundings are slightly dark, images are captured with unintended shutter values, so the acquired image may be too bright or too dark. is there.

  In particular, in the case of an in-vehicle camera device that recognizes a three-dimensional object such as a vehicle, a pedestrian, or a lane, it is necessary to perform optimum shutter control for recognition. If this shutter control does not function, an unintended acquired image may be too bright or too dark, which may result in misrecognizing a three-dimensional object, or a three-dimensional object that the user originally wants to see cannot be recognized. There is a problem of erroneous control.

  FIG. 10 is a diagram illustrating a normal shutter control waveform and an image acquired at that time. When taking an image, the image is intentionally set with the shutter fully open. Then, as shown in FIG. 11, the number of pulses of the shutter signals 1 and 2 decreases, and the captured image is captured brightly. The average brightness of the screen at this time is calculated. Theoretically, when the image becomes brighter than the image captured in FIG. 10, the shutter function is functioning normally, indicating that the shutter signals 1 and 2 are transmitted from the control unit 103 to the CCD 101.

  In addition, when taking an image, the image is intentionally set to a minimum open state (a state in which the shutter is closed to the maximum). Then, as shown in FIG. 12, the number of pulses of the shutter signals 1 and 2 increases, and the captured image is captured darkly. The average brightness of the screen at this time is calculated. Theoretically, the image is darker than the image captured in FIG. Of course, it can be said that the image is darker than the image captured in FIG.

  As a method for detecting the disconnection of the shutter signal only by software processing, it is preferable to insert the above-mentioned diagnosis because the disconnection can be detected instantaneously if the above diagnosis can be performed while the application of the in-vehicle camera is being executed.

  However, if it is difficult to put the above diagnosis in the middle of the application of the in-vehicle camera (if it affects the load or performance of the application), it can be performed when the camera is started or stopped. it can.

  If the surrounding environment is completely dark, even if the shutter signal is intentionally opened to the maximum open state, the brightness of the screen to be captured does not change, and the average luminance may not increase. In that case, when the driver turns on the headlight, the diagnosis may be performed when the surrounding environment becomes bright to some extent.

  If the environment of the cycle is too bright (backlight from the sun, etc.), even if the shutter signal is intentionally in the minimum open state, the brightness of the screen to be imaged does not change significantly, and the average luminance may not be lowered. In that case, the diagnosis may be performed when the driver starts driving and no backlight is emitted.

  Next, a description will be given of processing in the case where NG is output by a diagnosis in which the shutter signal is monitored in hardware or a diagnosis in which the shutter is set to the maximum open state or the minimum open state and the change in the average luminance of the screen is observed.

  When vehicle control is performed in the in-vehicle camera device, control from the camera is stopped (acceleration, deceleration, steering, lamp lighting, wiper, defroster, etc.). This increases the possibility of misrecognition due to an abnormal shutter signal. Therefore, even if misrecognition is made, the highest priority is given to ensuring safety to prevent erroneous control due to misrecognition.

  Next, the recognition process of the determination part at the time of vehicle control is stopped. Since control is impossible, it is desirable to operate with a minimum hardware / software configuration by stopping the recognition process.

  Thereafter, the vehicle side is notified via the in-vehicle network such as CAN that the shutter signal is abnormal, and the driver is alerted.

  According to the present embodiment, it is possible to realize a fail-safe function that reliably detects whether a shutter signal is transmitted from the control side to the image sensor with a low-cost and simple configuration that does not occupy a comparator or two ports.

  When the shutter signal is monitored by hardware as shown in FIG. 1, if the monitor circuit 104 fails, the monitor circuit 104 becomes abnormal and the microcomputer 105 may detect the abnormality. This is because even if the shutter signal 2 originally monitored moves without disconnection or the like, the microcomputer 105 determines that it is abnormal. Therefore, it is easier to detect the faulty part if the fault of the monitor circuit 104 can be detected. Therefore, the failure of the monitor circuit 104 can also be detected by using a method of detecting the disconnection of the shutter signal only by software processing as shown in FIG. 10, FIG. 11, and FIG.

  During normal operation, it is often difficult to put in a diagnosis that detects disconnection of the shutter signal only by software processing while the application for the in-vehicle camera is being executed. Therefore, during normal operation, the hardware monitor circuit 104 as shown in FIG. 1 is inserted and the microcomputer 105 detects the disconnection of the shutter signal. When the microcomputer 105 detects an abnormality, first, the application of the in-vehicle camera is temporarily stopped, and the software for detecting the disconnection of the shutter signal is started only by the software processing as shown in FIGS. Diagnose whether the shutter signal is broken. If it is judged here that it is disconnected in software, it can be said that it is actually disconnected.

  On the other hand, if the disconnection cannot be detected by software, there is a high possibility that the monitor circuit 104 has failed. The application of the in-vehicle camera may be stopped in consideration of safety or the like on the in-vehicle camera system, or may continue to move from the performance aspect.

  As a result, by combining the two hardware diagnosis and the software diagnosis, it becomes possible to more reliably detect the disconnection of the shutter signal with the minimum application stop time of the in-vehicle camera even during the operation of the camera.

101 CCD
102 Vertical driver IC
103 Control Unit 104 Monitor Circuit 105 Microcomputer

Claims (5)

An image sensor;
A vertical driver IC connected to the image sensor;
A control unit for controlling the shutter;
A monitor circuit for obtaining a monitor signal from a wiring of a shutter signal between the image sensor and the vertical driver IC;
An in-vehicle camera device comprising a microcomputer connected to the monitor circuit and monitoring whether or not the shutter signal wiring is normal based on the monitor signal.   The in-vehicle camera device according to claim 1, wherein a bias voltage is applied to the shutter signal. A control unit for controlling the shutter;
A monitor unit is provided to monitor whether the shutter signal wiring is normal,
The control unit calculates a first average luminance when imaged with the shutter in the maximum open state, and a second average luminance when imaged with the shutter in the maximum closed state,
The monitor unit is an in-vehicle camera device that determines whether the wiring is normal based on the first and second average luminances.   The in-vehicle camera device according to claim 3, wherein the monitor unit determines whether or not the wiring is normal when the in-vehicle camera is activated or stopped.   The in-vehicle camera device according to claim 1 or 2, further comprising a function of stopping recognition processing of the in-vehicle camera and notifying the driver that an abnormality has occurred when an abnormality in wiring is detected.

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