Occupant detection apparatus, operation device control system, seat belt system, and vehicle

0001The present invention relates to an occupant detection technology to be installed in a vehicle and; more particularly, a technology for detecting information about a rear-seat occupant sitting in a vehicle rear seat.

Background of the Invention

0002Conventionally, there are known various techniques for detecting an object occupying a vehicle seat by using a photographing means such as a camera. For example, disclosed in <patcit id="pcit0001" dnum="JP2003294855A"><text>JP-A-2003-294855</text></patcit> as listed below is a configuration of an occupant detection apparatus in which a camera capable of two-dimensionally photographing an object is arranged in front of a vehicle occupant to detect the position of the vehicle occupant by the camera.

Problems to be solved by the Invention

0003By the way, as to seat belt apparatuses to be attached to a vehicle rear seat among seat belt apparatuses for restraining an occupant by a seat belt, for example, there is a demand to increase the seat belt wearing rate by rear-seat occupants. To serve this demand, it is required to detect precisely information about a rear-seat occupant actually sitting in a vehicle rear seat. Such a technology for detecting precisely information about a rear-seat occupant is also effective for a seat belt apparatus for the rear-seat occupant, a drive assist apparatus, and the like.

0004However, it is difficult to precisely detect desired information about a rear-seat occupant in a case of using a camera to two-dimensionally photograph a vehicle occupant such as the detecting apparatus as disclosed in <patcit id="pcit0002" dnum="JP2003294855A"><text>JP-A-2003-294855</text></patcit>, for the following reasons. That is, when there is a small difference in color between the background and a rear-seat occupant or a small difference in color between the skin and the clothes, a problem arises that it is difficult to securely detect the rear-seat occupant.

0005A occupant detection device according to the preamble of claim 1 is known from <patcit id="pcit0003" dnum="WO03089277A"><text>WO 03/089277</text></patcit>.

0006The present invention is made in view of the aforementioned point and it is an object of the present invention to provide a technology which is effective for precisely detecting information about a rear-seat occupant sitting in a vehicle rear seat.

Means to solve the Problems

0007According to the invention, this object is achieved by an occupant detection apparatus as defined in claim 1, an operation device control system as defined in claim 2, a seat belt system as defined in claim 3 or 5 and a vehicle as defined in claim 6 or 7. The dependent claim defines a preferred and advantageous embodiment of the invention.

0008For achieving the object, the present invention is configured. Though the present invention is typically adapted to an occupant detection apparatus in an automobile for detecting information about a rear-seat occupant sitting in a vehicle rear seat, the present invention can be also adapted to an occupant detection apparatus in a vehicle other than the automobile.

0009An occupant detection apparatus of the present invention comprises at least: a photographing section, an information extracting section, a division processing section, and a derivation processing section.

0010The photographing section is a photographing means which is disposed to face to a vehicle rear seat in a vehicle cabin for taking three-dimensional images. As the photographing section, a 3-D type monocular C-MOS camera, a 3-D type pantoscopic stereo camera, or a laser scanner may be employed. As the mounting place for the photographing section, any place facing to the vehicle rear seat can be selected and an area around an inner rearview mirror is typically selected. Further, the number of the photographing section(s) mounted may be one or plural, if necessary. The "vehicle rear seat" used here widely includes various vehicle seats arranged in a rear-side portion of a vehicle. That is, the vehicle rear seat means a seat or seats in the second row from the front in case of vehicle seats of two row layout or all seats except seats in the first row from the front in case of vehicle seats of a plural row layout.

0011The information extracting section has a function of extracting only image information corresponding to an upper area of a seat back of the vehicle rear seat from the three-dimensional images taken by the photographing section. In the present invention, since the three-dimensional images containing distance information taken by the photographing section are used, it is possible to extract information according to the distance, thereby precisely extracting image information corresponding to the upper area of the seat back of the vehicle rear seat. The "upper area of a seat back" used here means an area corresponding to an upper area of the seat back among respective parts of the vehicle rear seat and is an area which is effective in obtaining information about rear-seat occupants sitting in the vehicle rear seat because this area is hardly interrupted by front-seat occupants sitting in the vehicle front seats, for example. The upper area of the seat back is typically an area defined by a horizontal plane extending through the shoulders of the occupant sitting in the vehicle rear seat, a horizontal plane extending above the head of the rear-seat occupant sitting in the vehicle rear seat, a vertical plane extending in front of the head of the rear-seat occupant sitting in the vehicle rear seat, a vertical plane extending behind the head of the rear-seat occupant sitting in the vehicle rear seat, and vertical planes extending on right and left sides of the seat back of the vehicle rear seat.

0012The division processing section has a function of dividing the image information extracted by the information extracting section into areas relating to respective sitting areas of a plurality of rear-seat occupants sitting in the vehicle rear seat. Specifically, in case of a vehicle rear seat of which passenger capacity is two, the image information extracted by the information extracting section is divided into two areas. In case of a vehicle rear seat of which passenger capacity is three, the image information extracted by the information extracting section is divided into three areas.

0013The derivation processing section has a function of deriving, with regard to histogram showing frequency distribution of picture elements relative to distances from said photographing section, a first histogram corresponding to each image information divided by said division processing section and also obtaining a difference histogram by deducting a second histogram previously defined as a case where the vehicle rear seat is unoccupied from said derived first histogram. The "picture element" used here is sometimes called "pixel" which is a colored "point" as a unit composing a digital image, and may contain information about distance (depth), degree of transparency, and the like. A digital image is represented by a sheet of image composed of square or rectangular pixels which are aligned orderly lengthwise and crosswise. The histogram showing frequency distribution of picture elements relative to distances from the photographing section is made with an abscissa axis representing the distances from the photographing section and an ordinate axis representing the frequency (number) of picture elements corresponding to the distance from the photographing section.

0014Then, the derivation processing section derives information about each rear-seat occupant in each sitting area of said vehicle rear seat based on the difference histogram. Specifically, since the sum of differences in the difference histogram at a position where the rear-seat occupant is seated within a predetermined range from the photographing section, that is, the frequency of picture elements in the predetermined range from the photographing section corresponds to the volume of an object detected in the sitting area, it is determined whether or not there is a rear-seat occupant in each sitting area of the vehicle rear seat by comparing the volume of the detected object to a preset value which is previously set as the volume corresponding to an occupant. When the volume of the detected object exceeds the preset value or equal to or more than the preset value, it is determined that the detected object contains a rear-seat occupant, that is, the rear-seat occupant is seated. On the other hand, when the volume of the detected object is equal to or less than the preset value or is below the preset value, it is determined that the object does not contains a rear-seat occupant, that is, no rear-seat occupant is seated (the seat is unoccupied).

0015In the present invention, the function of obtaining the differential histogram may be conducted by another processing section besides the determination processing section.

0016According to the arrangement of the occupant detection apparatus of the present invention, it is possible to precisely detect whether or not there is a rear-seat occupant in each sitting area of the vehicle rear seat by conducting the respective processes based on three-dimensional images taken by the photographing section. The information extracting section extracts only image information corresponding to the upper area of the seat back of the vehicle rear seat from the three-dimensional images taken by the photographing section, thereby reducing the load for image processing.

0017The information about whether or not there is a rear-seat occupant previously determined by the determination processing section of the occupant detection apparatus may be used for controls of vehicular assist in a seat belt apparatus for restraining the rear-seat occupant by a seat belt in the event of a vehicle collision and/or an air bag apparatus for restraining the rear-seat occupant by an airbag in the event of a vehicle collision.

0018An operation device control system of the present invention comprises an occupant information detecting section for detecting information about a rear-seat occupant sitting in a vehicle rear seat; and an operation device which is actuated according to the detection result of the occupant information detecting section. In the operation device control system, the occupant information detecting section is composed of an occupant detection apparatus as mentioned above and the operation device is actuated according to the determination results determined by the determination processing section. Specifically, the operation device may be a component of a seat belt apparatus for restraining the rear-seat occupant by a seat belt in the event of a vehicle collision, a component of an airbag apparatus for restraining the rear-seat occupant by an airbag which deploys in front of or on a side of the rear-seat occupant in the event of a vehicle collision, and/or a component of a device which rises a seat cushion of the vehicle rear seat in the event of a vehicle collision in order to prevent a phenomenon that the rear-seat occupant tends to slide along the seat surface below the seat belt, so-called "submarine phenomenon".

0019According to the arrangement of the operation device control system of the present invention, the operation device can be actuated based on the precisely detected information about the presence or absence of a rear-seat occupant in the vehicle rear seat so that this arrangement is effective for suitably actuating the operation device.

0020A seat belt system which is installed in a vehicle comprises: at least an occupant detection apparatus as mentioned above; a seat belt which can be worn by a rear seat occupant sitting in a vehicle rear seat for restraining the rear-seat occupant, a seat belt buckle which is installed in each sitting area of the vehicle rear seat; a tongue which is attached to the seat belt and is latched with the seat belt buckle during the seat belt wearing state; and an informing section. The informing section has a function of informing of the position of at least either of the seat belt buckle and the tongue installed for each sitting area where an occupant is sitting, based on determination result by a determination processing section of the occupant detection apparatus. Specifically, the position of the seat belt buckle and/or the tongue corresponding to the rear-seat occupant sitting in the vehicle rear seat is informed by the informing section. As the arrangement of the informing section, means of lightening the seat belt buckle itself and/or the tongue itself, protruding the seat belt buckle, sending out the tongue, sliding the tongue up and down, or displaying on a monitor panel may be employed.

0021According to the arrangement of the seat belt system of the present invention, the rear-seat occupant sitting in the vehicle rear seat can be informed of the existence of the seat belt buckle and/or the tongue while using the precisely detected information about the presence or absence of a rear-seat occupant in the vehicle rear seat. This can increase the recognition of the existence of the seat belt buckle and/or the tongue and is thus effective in increasing the seat belt wearing rate by rear-seat occupants.

0022In a seat belt system of a further aspect of the present invention, the informing section has a function of informing of the positions of the seat belt buckle and the tongue which are correctly latched with each other during the normal seat belt wearing state.

0023According to the arrangement of the seat belt system of the present invention, it can prevent wrong buckling such as a case that the tongue for the left side rear-seat occupant is latched with the seat belt buckle for the right side rear-seat occupant, thereby exhibiting the original occupant restraining function of the seat belt.

0024A seat belt system of another aspect of the present invention comprises: at least an occupant detection apparatus as mentioned above; a seat belt which can be worn by a rear seat occupant sitting in a vehicle rear seat for restraining the rear-seat occupant; a seat belt buckle which is installed in each sitting area of the vehicle rear seat; a tongue which is attached to the seat belt and is latched with the seat belt buckle during the seat belt wearing state; a buckle detecting sensor for detecting that the tongue is latched with the seat belt buckle; and an output section. The output section in the seat belt system has a function of outputting the wearing completion of the seat belt installed in each sitting area where an occupant is sitting, based on determination result by a determination processing section of the occupant detection apparatus and the detection result by the buckle detecting sensor. The output section is composed of a monitor panel or a meter panel capable of displaying the detection result or a speaker for outputting voice guidance.

0025According to the arrangement of the seat belt system of the present invention, it can urge front-seat occupants including a driver and the rear-seat occupant(s) to wear the seat belt when the rear-seat occupant(s) sitting in the vehicle rear seat does not wear the seat belt while using the precisely detected information about the presence or absence of a rear-seat occupant in the vehicle rear seat. This is effective in increasing the seat belt wearing rate by rear-seat occupants.

0026A vehicle of the present invention comprises: at least an engine/running system; an electrical system; a vehicle control device; and an operation device control system as mentioned above.

0027The engine/running system is a system involving an engine and a running mechanism of the vehicle. The electrical system is a system involving electrical parts used in the vehicle. The vehicle control device is a device having a function of controlling the actuation of the engine/running system and the electrical system.

0028According to the arrangement of the vehicle of the present invention, the operation device is actuated based on the precisely detected information about the presence or absence of a rear-seat occupant in the vehicle rear seat. Therefore, this arrangement is effective in suitably actuating the operation device.

0029A vehicle of another aspect of the present invention comprises: at least an engine/running system; an electrical system; a vehicle control device, and a seat belt apparatus.

0030The engine/running system is a system involving an engine and a running mechanism of the vehicle. The electrical system is a system involving electrical parts used in the vehicle. The vehicle control device is a device having a function of controlling the actuation of the engine/running system and the electrical system. The seat belt apparatus has a function of restraining a rear-seat occupant sitting in a vehicle rear seat by a seat belt and is composed of a seat belt system as mentioned above.

0031According to the arrangement of the vehicle of the present invention, a vehicle can be provided which is provided with a seat belt apparatus capable of conducting controls using precisely detected information about the presence or absence of a rear-seat occupant in the vehicle rear seat by conducting respective processes based on three-dimensional images taken by the photographing section.

Effects of the Invention

0032As described in the above, the present invention enables precise detection of information about a rear-seat occupant sitting in a vehicle rear seat.

Brief Explanation of the drawings

0033<ul id="ul0001" list-style="none"><li><figref idref="f0001">Fig. 1</figref> is an illustration showing a system configuration of an occupant detection apparatus 100, which is installed in a vehicle, according to an embodiment.</li><li><figref idref="f0002">Fig. 2</figref> is an illustration showing an example of image taken by the 3D camera 112 of the embodiment</li><li><figref idref="f0003">Fig. 3</figref> is an illustration showing an area A1 defined as an upper area of a seat back by an information extracting section 152 of this embodiment.</li><li><figref idref="f0004">Fig. 4</figref> is an illustration showing aspects in the information extracting process by the information extracting section 152 of this embodiment.</li><li><figref idref="f0005">Fig. 5</figref> is an illustration showing aspects in the process by a division processing section 154 of this embodiment.</li><li><figref idref="f0006">Fig. 6</figref> is an illustration showing aspects in the process for deriving the difference histogram in a histogram computing section 156 of this embodiment.</li><li><figref idref="f0007">Fig. 7</figref> is an illustration showing a structure of a vehicle on which the occupant detection apparatus 100 shown in <figref idref="f0001">Fig. 1</figref> is mounted.</li></ul>

Best Modes for carrying out the Invention

0034Hereinafter, embodiments of the present invention will be described with reference to drawings. First, an occupant detection apparatus 100 as an embodiment of "occupant detection apparatus" of the present invention will be described with reference to <figref idref="f0001">Fig. 1</figref>.

0035The system configuration of an occupant detection apparatus 100, which is installed in a vehicle, of this embodiment is shown in <figref idref="f0001">Fig. 1</figref>. As shown in <figref idref="f0001">Fig. 1</figref>, the occupant detection apparatus 100 of this embodiment is installed in an automobile as the "vehicle" of the present invention for detecting information about occupants and mainly comprises a photographing means 110 and a control means 120. Further, the occupant detection apparatus 100 cooperates together with an ECU 200, as an actuation control device for the vehicle, and an operation device 210 to compose a certain vehicular assist system (corresponding to "operation device control system" and "seat belt system" of the present invention). The vehicle comprises, but not shown, an engine/running system involving an engine and a running mechanism of the vehicle (corresponding to "engine/running system" of the present invention), an electrical system involving electrical parts used in the vehicle (corresponding to "electrical system" of the present invention), and a vehicle control device (ECU 200) for conducting the actuation control of the engine/running system and the electrical system. In this case, the vehicle control device corresponds to "vehicle control device" of the present invention.

0036The photographing means 110 of this embodiment includes a 3D camera 112 as the photographing device and a data transfer circuit. The 3D camera 112 is a 3-D (three-dimensional) camera (sometimes called "monitor") of a C-MOS or CCD (charge-coupled device) type in which light sensors are arranged into an array (lattice) structure. By this camera, three-dimensional images can be taken from a single view point. Thus, distance relative to the occupant is measured a plurality of times to detect a three-dimensional surface profile, thereby identifying the presence or absence, the size, the position, and the attitude of the occupant. As the 3D camera 112, a 3-D type monocular C-MOS camera or a 3-D type pantoscopic stereo camera may be employed. The photographing means 110 (the 3D camera 112) corresponds to "photographing section which is disposed to face to a vehicle rear seat in a vehicle cabin for taking three-dimensional images" of the present invention. Instead of the 3D camera 112, a laser scanner capable of obtaining three-dimensional images may be employed.

0037The camera 112 of this embodiment is mounted to an area around an inner rearview mirror, an area around a side mirror, a central portion in the lateral direction of a dashboard, or the like in the automobile in such a manner as to face to a predetermined movement range in a vehicle rear portion. The "predetermined movement range" used here may be typically defined as a range including at least an area where the head and the upper body of a rear-seat occupant sitting in the rear seat may exist (an upper area of a seat back) in the passenger room of the vehicle cabin. This range may include a front-seat occupant and a front seat. By using the 3D camera 112, therefore, at least information about the rear-seat occupant sitting in the rear seat is measured periodically a plurality of times.

0038Image taken by the 3D camera 112 is shown in <figref idref="f0002">Fig. 2</figref> as a reference. <figref idref="f0002">Fig. 2</figref> shows an example of image taken by the 3D camera 112 of this embodiment. The example shown in <figref idref="f0002">Fig. 2</figref> is an image showing partially rear-seat occupants 12a sitting in a vehicle rear seat 12 behind front-seat occupants 10a sitting in vehicle front seats 10.

0039Mounted on the occupant detection apparatus 100 of this embodiment is a power source unit for supplying power from a vehicle battery to the 3D camera 112, but not particularly shown. The camera 112 is set to start its photographing operation when the ignition key is turned ON or when a seat sensor (not shown) installed in the driver seat detects an occupant sitting in the driver seat.

0040The control means 120 of this embodiment further comprises at least an image processing unit 130, a computing unit (MPU) 150, a storing unit 170, an input/output unit 190, and peripheral devices (not shown). The control means 120 is structured as an occupant information processing system (CPU) for processing information about the occupant based on images taken by the 3D camera 112.

0041The image processing unit 130 is a means for controlling the camera to obtain good quality images and for controlling the image processing for processing images taken by the 3D camera 112 to be used for analysis. Specifically, as for the control of the camera, the adjustment of the frame rate, the shutter speed, and the sensitivity, and the accuracy correction are conducted to control the dynamic range, the brightness, and the white balance. As for the control of the image processing, the spin compensation for image, the correction for distortion of the lens, the filtering operation, and the difference operation as image preprocessing operations are conducted and the configuration determination and the trucking as image recognition processing operations are conducted.

0042The computing unit 150 of this embodiment comprises at least an information extracting section 152, a division processing section 154, a histogram computing section 156, and a determination processing section 158. As for the computing unit 150, some of the information extracting section 152, the division processing section 154, the histogram computing section 156, and the determination processing section 158 may be combined.

0043The information extracting section 152 as a component of the computing unit 150 carries out a process of extracting information about the rear-seat occupant sitting in the rear seat based on the information form the image processing unit 130. Specifically, only image information corresponding to the upper area of the seat back of the vehicle rear seat is extracted (derived) from three-dimensional images of the image processing unit 130 by the information extracting section 152. The upper area of the seat back of the vehicle rear seat is shown in <figref idref="f0003">Fig. 3</figref> as a reference. <figref idref="f0003">Fig. 3</figref> shows an area A1 defined as the upper area of the seat back in the information extracting section 152 of this embodiment. The area A1 shown in <figref idref="f0003">Fig. 3</figref> is an area defined by a horizontal plane S1 extending through the shoulders of the occupant sitting in the vehicle rear seat 12, a horizontal plane S2 extending above the head of the rear-seat occupant sitting in the vehicle rear seat 12, a vertical plane S3 extending in front of the head of the rear-seat occupant sitting in the vehicle rear seat 12, a vertical plane S4 extending behind the head of the rear-seat occupant sitting in the vehicle rear seat 12, and vertical planes S5, S6 extending on right and left sides of the seat back of the vehicle rear seat 12. The information extracting section 152 corresponds to "image extracting section" of the present invention.

0044The information extracting process will be understood with reference to <figref idref="f0004">Fig. 4. Fig. 4</figref> shows aspects in the information extracting process by the information extracting section 152. As shown in <figref idref="f0004">Fig. 4</figref>, in the information extracting process, an image corresponding to the area A1 is extracted from the photographed image D1. For example, an extraction processed image D3 may be derived through a semi-processed image D2.

0045The division processing section 154 as a component of the computing unit 150 has a function of dividing the image information extracted by the information extracting section 152 into sections for respective occupants sitting in the vehicle rear seat. Specifically, in case of a vehicle rear seat of which passenger capacity is two, the image information extracted by the information extracting section 152 is divided into two areas. In case of a vehicle rear seat of which passenger capacity is three, the image information extracted by the information extracting section 152 is divided into three areas. It should be understood that the information about the passenger capacity of the vehicle rear seat of the subject vehicle is previously stored in the storing unit 170.

0046The process by the division processing section 154 will be further described with reference to <figref idref="f0005">Fig. 5. Fig. 5</figref> shows aspects in the process by the division processing section 154 of this embodiment. As shown in <figref idref="f0005">Fig. 5</figref>, in case of a process for dividing the image information extracted by the information extracting section 152 into two areas, the area A1 is divided into two areas, i.e. divided areas B1 and B2. In case of a process for dividing the image information extracted by the information extracting section 152 into three areas, the area A1 is divided into three areas, i.e. divided areas C1 through C3. The divided areas formed by dividing the area A1 are assumed as detection areas where features of a rear-seat occupant can be detected. The division processing section 154 corresponds to "division processing section" of the present invention.

0047The histogram computing section 156 as a component of the computing unit 150 derives, with regard to the image information in each divided area obtained in the division processing section 154, an occupied-state histogram during the seat is occupied and also derives a difference histogram showing a difference between the occupied-state histogram and an unoccupied-state histogram. The occupied-state histogram is a histogram showing frequency distribution of picture elements relative to distances from the 3D camera 112 with regard to the image information in each divided area during the seat is actually occupied. On the other hand, the unoccupied-state histogram is a histogram showing frequency distribution of picture elements relative to the distances from the 3D camera 112 during the seat is unoccupied. The information about the unoccupied-state histogram is previously stored in the storing unit 170. The "picture element" used here is sometimes called "pixel" which is a colored "point" as a unit composing a digital image, and may contain information about distance (depth), degree of transparency, and the like. A digital image is represented by a sheet of image composed of square or rectangular pixels which are aligned orderly lengthwise and crosswise. The histogram showing frequency distribution of picture elements relative to distances from the 3D camera 112 is made with an abscissa axis representing the distances from the 3D camera 112 and an ordinate axis representing the frequency (number) of picture elements corresponding to the distance from the 3D camera 112.

0048The deriving process of the difference histogram will be further described with reference to <figref idref="f0006">Fig. 6. Fig. 6</figref> shows aspects in the process for deriving the difference histogram in the histogram computing section 156 of this embodiment. As shown in <figref idref="f0006">Fig. 6</figref>, in the process for deriving the difference histogram, the difference histogram is derived by deducting the unoccupied-state histogram from the occupied-state histogram. As for the derived difference histogram, the sum of differences in the difference histogram at a position where a rear-seat occupant is seated within the predetermined range from the 3D camera 112, that is, the frequency of picture elements within the predetermined range from the 3D camera 112 corresponds to the volume of an object detected in the divided area. The predetermined range from the 3D camera 112 is previously stored in the storing unit 170.

0049The determination processing section 158 as a component of the computing unit 150 determines, based on the information derived by the histogram computing section 156, whether or not the object detected in each divided area contains a rear-seat occupant. Specifically, when the volume of the detected object computed by the histogram computing section 156 exceeds a preset value or is equal to or more than the preset value, the determination processing section 158 determines that the object contains a rear-seat occupant, that is, the rear-seat occupant is seated. On the other hand, when the volume of the detected object computed by the histogram computing section 156 is equal to or less than the preset value or is below the preset value, the determination processing section 158 determines that the object does not contains a rear-seat occupant, that is, no rear-seat occupant is seated (the seat is unoccupied). The determination process and the process for deriving the difference histogram as a pretreatment of the determination process are conducted for every divided area of the two or three divided areas obtained by the division processing section 154. The determination processing section 158 and the aforementioned histogram computing section 156 cooperate together to compose "derivation processing section" of the present invention.

0050The storing unit 170 of this embodiment is a means for storing (recording) data for correction, buffer frame memory for preprocessing, defined data for recognition computing, reference patterns, and the computed results of the computing unit 150 as well as an operation control software.

0051The input/output unit 190 of this embodiment inputs information about the vehicle, information about traffic conditions around the vehicle, information about weather condition and about time zone as well as the determination results by the determination processing section 158 to the ECU 200 for conducting controls of the entire vehicle and outputs recognition results. As the information about the vehicle, there are, for example, collision prediction information of the vehicle by a radar or camera, the state (open or closed) of a vehicle door, the wearing of the seat belt, the operation of brakes, the vehicle speed, and the steering angle. In this embodiment, based on the information outputted from the input/output unit 190, the ECU 200 outputs actuation control signals to the operation device 210. The input/output unit 190 may be of any structure capable of outputting a control signal to the operation device 210. As shown in <figref idref="f0001">Fig. 1</figref>, the input/output unit 190 may output a control signal to the operation device 210 indirectly through the ECU 200 or may directly output a control signal to the operation device 210. The operation device 210 corresponds to "operation device" of the present invention.

0052According to the occupant detection apparatus 100 of this embodiment, as mentioned above, it is possible to precisely detect information about the rear-seat occupant(s) sitting in the vehicle rear seat 12 by conducting the respective processes based on three-dimensional images taken by the 3D camera 112. That is, in case of using three-dimensional images, it ensures high degree of precision in detection as compared to the case of using two-dimensional images because information can be extracted according to distances even when there is a small difference in color between the background and the rear-seat occupant or a small difference in color between the skin and the clothes.

0053As the operation device 210 of this embodiment, any component of seat belt apparatuses of the following embodiments or an airbag apparatus may be employed. The seat belt apparatus and the airbag apparatus used here correspond to "operation device control system" of the present invention. Especially, the seat belt apparatus corresponds to "seat belt system" of the present invention. Specific embodiments of the seat belt apparatus and the airbag apparatus will be described with reference to <figref idref="f0007">Fig. 7. Fig. 7</figref> shows a structure of a vehicle on which the occupant detection apparatus 100 shown in <figref idref="f0001">Fig. 1</figref> is mounted.

0054As a first embodiment, a first seat belt apparatus is provided which has an informing function of informing the rear-seat occupant of the positions of a seat belt buckle 21 and a tongue 22 for a seat belt 20 worn by the rear-seat occupant or the selection of the seat belt buckle 21 and the tongue 22, using information about the rear-seat occupant (the presence or absence of occupant, the seated position of the occupant) or information about boarding of the occupant and the information about opening or closing of a vehicle door. The informing action may be carried out by lightening the seat belt buckle 21 itself and the tongue 22 itself, protruding the seat belt buckle 21, sending out the tongue 22, sliding the tongue 22 up and down, or displaying on a monitor panel 13. The informing function used here can compose the "informing section" of the present invention. It should be noted that the information about opening or closing of the vehicle door is detected by a vehicle door sensor 14.

0055By using the seat belt apparatus having the aforementioned structure, the rear-seat occupant sitting in the vehicle rear seat can be informed of the existence of the seat belt buckle and the tongue. This can increase the recognition of the existence of the seat belt buckle and the tongue and is thus effective in increasing the seat belt wearing rate by rear-seat occupants.

0056As a second embodiment, a second seat belt apparatus is provided which has an informing function of informing a driver of the seat belt wearing completion (wearing state) of the rear-seat occupant, using information about the rear-seat occupant (the presence or absence of the occupant, the seated position of the occupant). The informing action may be carried out by displaying on the monitor panel 13 or a meter panel 15 or outputting voice guidance from a speaker. The informing function used here can compose the "informing section" of the present invention.

0057By using the seat belt apparatus having the aforementioned structure, it can urge front-seat occupants including the driver and the rear-seat occupant(s) to wear the seat belt when the rear-seat occupant(s) sitting in the vehicle rear seat does not wear the seat belt.

0058As a third embodiment, a third seat belt apparatus is provided which has an informing function of informing the driver or the rear-seat occupant of whether or not a tongue 22 is latched with a right seat belt buckle 21, using information about the rear-seat occupant (the presence or absence of the occupant, the seated position of the occupant). The informing action may be carried out by displaying on the monitor panel 13 or a meter panel 15 or voice output, or lightening or vibrating a certain portion. The informing function used here can compose the "informing section" of the present invention.

0059By using the seat belt apparatus having the aforementioned structure, it can prevent wrong buckling such as a case that the tongue for the left side rear-seat occupant is latched with the seat belt buckle for the right side rear-seat occupant, thereby exhibiting the original occupant restraining function of the seat belt.

0060As a fourth embodiment, a fourth seat belt apparatus is provided which has a seat belt load reducing function for reducing the seat belt load acting on the rear-seat occupant via the seat belt 20, using information about the rear-seat occupant (the presence or absence of the occupant, the seated position of the occupant). The seat belt load reducing function may be carried out by protruding the seat belt buckle 21, sending out the tongue 22, or driving another member (seat belt reacher) acting on the seat belt 20 by a driving device 30 or 31. By using the seat belt apparatus having the aforementioned structure, the seat belt load acting on the rear-seat occupant via the seat belt 20 can be reduced, thereby suitably restraining the rear-seat occupant by the seat belt 20.

0061The seat belt 20, the seat belt buckle 21 and the tongue 22 of each of the seat belt apparatuses as mentioned above correspond to "seat belt", "seat belt buckle" and "tongue" of the present invention, respectively.

0062As a fifth embodiment, a fifth seat belt apparatus is provided which actuates a pretensioner 23 for winding up the seat belt 20 to remove any slack of the seat belt 20 in the event of a vehicle collision, using information about the rear-seat occupant (the presence or absence of the occupant, the seated position of the occupant) and, as another information, information about buckling between the seat belt buckle and the tongue. By using the seat belt apparatus as mentioned above, the pretensioner 23 can be suitably actuated to wind up the seat belt 20 to remove the slack of the seat belt 20 in the event of a vehicle collision, thereby improving the occupant restraining property by the seat belt.

0063As a sixth embodiment, an operation device is provided which has a function of actuating an airbag for restraining a rear-seat occupant, using information about the rear-seat occupant (the presence or absence of the occupant, the seated position of the occupant). The operation device may be composed of an airbag 40 which is disposed in a portion under the vehicle front seat 10 or in a cabin ceiling and can be deployed in front of the rear-seat occupant in the event of a vehicle collision, a side airbag 41 which can be deployed at a door side of the rear-seat occupant in the event of a vehicle collision, or an intermediate airbag 42 which can be deployed between the rear-seat occupants in the event of a vehicle collision. Further, the operation device may be composed of a limiting device 43 which rises a seat cushion of the vehicle rear seat 12 by an airbag or another actuating mechanism in order to prevent a phenomenon that the rear-seat occupant tends to slide along the seat surface below the seat belt, so-called "submarine phenomenon", or a device which provides a curtain-like member between the vehicle front seats 10 and the vehicle rear seat 12 to partition them in order to prevent the rear-seat occupant and/or an object such as baggage from moving forward. By using the operation device as mentioned above, an occupant restraining means such as the airbag 40 and a side airbag 41 can be properly actuated in the event of a vehicle collision, thereby improving the occupant restraint property.

0064As another embodiment, there may be provided a device for locking the seat belt when a child seat is attached or a device for informing thereof, using information about the rear-seat occupant (the presence or absence of the occupant, the seated position of the occupant), and/or a device for locking a door when a small-size occupant such as a child is seated or when a child seat is attached or a device for informing thereof, using the aforementioned information about the rear-seat occupant.

0065According to the occupant detection apparatus 100 of this embodiment as mentioned above, there can be provided a seat belt apparatus and/or an airbag apparatus capable of controlling using information about the rear-seat occupant in the vehicle rear seat 12 precisely detected by the respective processes based on the three-dimensional images taken by the 3D camera 112. In addition, there can also be provided a vehicle to which such a seat belt apparatus and/or such an airbag apparatus are mounted.

Another embodiments

0066The present invention is not limited to the aforementioned embodiments and various applications and modifications may be made. For example, the following respective embodiments based on the aforementioned embodiments may be carried out.

0067Though the aforementioned embodiments have been described with regard to the arrangement of the occupant detection apparatus 100 to be installed in an automobile, the present invention can be adopted to occupant detection apparatuses to be installed in various vehicles such as an automobile, an airplane, a boat, a bus, and a train.