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Vehicular radar systemVehicular radar system description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070146684, Vehicular radar system. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] This application is based on and incorporates herein by reference Japanese Patent Application No. 2004-290482 filed on Oct. 1, 2004. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a vehicular radar device. [0004] 2. Description of Related Art [0005] JP-A-2004-177350 describes a vehicular radar system having a light emitter for emitting a laser light and a photoreceptor for receiving a reflected light of the laser light. The vehicular radar system is attempting to improve detection sensitivity of the reflected light reflected by a reflection object. [0006] The light emitter of the vehicular radar system generates the laser light with a laser diode and changes an emission direction of the laser light with a polygon mirror that is driven to rotate. Thus, the light emitter performs scanning over a predetermined angular range for each predetermined minute angle with the laser light. If the laser light is reflected by the reflection object, the photoreceptor receives the reflected light with a light receiving lens. The received light is introduced to photoreceptive elements. The photoreceptive elements output voltage signals corresponding to intensity of the received light. [0007] The vehicular radar system integrates a predetermined number of light reception signals, which are output based on a predetermined number of laser lights emitted contiguously, and outputs an integration signal, while ensuring angular resolution of the laser light. Thus, a light reception signal component corresponding to the reflected light is amplified by integrating the predetermined number of the light reception signals, and detection sensitivity of the reflected light can be improved. [0008] Another vehicular radar system has a light emitter for emitting a laser light over a predetermined angular range in one emission and a photoreceptor having photoreceptive elements of the number corresponding to necessary angular resolution. The photoreceptive elements are arranged into an array along a width direction of the vehicle. This vehicular radar system integrates light reception signals, which are output when the photoreceptive element repeatedly receives the light, for each photoreceptive element. Thus, this vehicular radar system attempts to improve the detection sensitivity of the reflected light. [0009] In such a case where the photoreceptor has multiple photoreceptive elements, usually, a structure shown in FIG. 11A having an integrator that integrates the light reception signals output by the photoreceptor is used. [0010] The structure shown in FIG. 11A includes an amplification circuit (AMP), an A/D conversion circuit (A/D), an integrator, and switches (SW). The amplification circuit AMP amplifies the light reception signals output by the photoreceptive elements (PD) such as photo diodes. The A/D conversion circuit A/D converts the analog light reception signals into digital signals. The integrator integrates the digital light reception signals. The switch SW switches the output of the light reception signal output by each photoreceptive element PD. The amplification circuit AMP, the A/D conversion circuit A/D and the integrator are commonly used for the respective photoreceptive elements PD and switches SW. [0011] The integration of the light reception signals is performed by switching each photoreceptive element PD. Therefore, the integration of the light reception signals output from the respective photoreceptive elements PD cannot be processed at the same time (in parallel). In such a case, the laser light needs to be emitted repeatedly for the time corresponding to the product of the number of the photoreceptive elements PD and the time of the integration. The laser diode will be degraded sooner as the time number of laser light emission increases. [0012] In order to overcome this problem, the amplification circuit AMP, the A/D conversion circuit A/D and the integrator may be disposed for each photoreceptive element PD, without employing the switches SW as shown in FIG. 11B. Thus, the integration of the light reception signals output from the respective photoreceptive elements PD can be performed in parallel, and the early degradation of the laser diode can be inhibited. However, the circuit structure becomes large in scale because the A/D conversion circuit A/D and the integrator have to be disposed for each photoreceptive element PD. SUMMARY OF THE INVENTION [0013] It is therefore an object of the present invention to provide a vehicular radar system capable of performing integration of light reception signals output from multiple photoreceptive elements in parallel by using a small-scale circuit structure. [0014] According to an aspect of the present invention, a radar system of a vehicle has a light emitter, a photoreceptor, a comparator, an integrator, and a sensor. The light emitter repeatedly emits laser light so that the laser light is emitted over a predetermined angular range at least along width direction of the vehicle in each light emission. The photoreceptor outputs light reception signals, which are output from photoreceptive elements in accordance with intensity of reflected laser light reflected by a reflection object. The photoreceptive elements are arranged at least along the width direction of the vehicle. The comparator compares the light reception signal output from each photoreceptive element with a standard signal and outputs for each photoreceptive element a comparison signal indicating two different states corresponding to a result of the comparison. The integrator samples the comparison signal and converts the comparison signal into one-bit digital data while a predetermined time passes after the laser light is emitted. The integrator integrates the digital data for each photoreceptive element based on emitting timing of the laser light every time the laser light is emitted. The integrator outputs the integrated data. The sensor compares the integrated data of each photoreceptive element with a predetermined integration standard value. The sensor senses the reflection object based on the integrated data equal to or greater than the integration standard value. [0015] The radar system of the present invention can be structured with one signal line for each channel unlike a conventional radar system that uses an eight-bit A/D converter requiring eight signal lines for each channel. The integrator integrates one-bit digital data for each channel. A counter can substitute for the integrator. Thus, the light reception signals output from the multiple photoreceptive elements can be integrated in parallel by using a small-scale circuit structure having the comparator and the integrator. [0016] Since the integrator integrates the light reception signals for each channel, the detection sensitivity of the reflected light can be improved. BRIEF DESCRIPTION OF THE DRAWINGS [0017] Features and advantages of embodiments will be appreciated, as well as methods of operation and the function of the related parts, from a study of the following detailed description, the appended claims, and the drawings, all of which form a part of this application. In the drawings: [0018] FIG. 1 is a block diagram showing a vehicle controller according to an example embodiment of the present invention; [0019] FIG. 2 is a schematic diagram showing a laser radar sensor according to FIG. 1 embodiment; [0020] FIG. 3 is a schematic diagram showing a photo IC of the laser radar sensor and a laser radar CPU according to FIG. 1 embodiment; Continue reading about Vehicular radar system... Full patent description for Vehicular radar system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Vehicular radar system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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