JP2008290545A - In-cabin photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-cabin photographing device capable of precisely capturing the head part of an occupant and increasing the ratio of an object in a photographing image. <P>SOLUTION: An angle sensor 9 of the in-cabin photographing device 5 detects an angle of a mirror surface 4a of a room mirror 1 relative to a vehicle, and presumes a position of the head part of the occupant in the cabin based on the detection result of the angle sensor 9. Further, a photographing direction change mechanism 8 changes a photographing direction of a camera 6 relative to the mirror surface 4a such that the head part of the occupant is arranged on an optical axis of the camera 6 based on the presumption result. Thereby, the photographing direction of the camera 6 is automatically preferably set so as to be fitted to a position of the head part of the occupant. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle interior imaging device provided in a vehicle interior to image a passenger's head.

Conventionally, some vehicles have a drowsiness prevention system that detects a passenger's drowsiness state and gives an alarm, and an emergency stop system that detects a passenger's abnormal state and safely stops the vehicle. In order to image a passenger's head (face), the vehicle is provided with a vehicle interior imaging device as disclosed in Patent Document 1, for example. This vehicle interior imaging apparatus includes a camera built in a rearview mirror. The mirror surface of this room mirror is constituted by a half mirror. The camera is fixed to the back side of the half mirror, and images the occupant's head through the half mirror.
Japanese Utility Model Publication No. 6-12199

  By the way, the rearview mirror is provided so that the occupant can visually recognize the rear of the vehicle with the mirror surface. The angle of the rearview mirror is such that light from the rear of the vehicle reflects on the mirror surface. It is set according to the position of the head (eyes) of the occupant so as to enter the head (eyes). That is, the angle of the mirror surface of the room mirror is set so that the normal of the mirror surface is always between the vehicle front-rear direction and the direction of the position of the passenger's head as viewed from the room mirror. For this reason, when the conventional camera is fixed to the back side of the half mirror, the camera imaging direction may not match the head position direction with respect to the mirror surface, and how the mirror surface angle is set. However, it is necessary to set a wide imaging range of the camera so that the head of the passenger can be accurately imaged. In addition, it is conceivable that the camera imaging direction can be adjusted by the passenger so that the passenger's head can be accurately imaged, but for the passenger to accurately grasp the imaging range of the camera. In the end, it is necessary to set a wide imaging range of the camera. However, when the imaging range is set wide as described above, the proportion of the head image of the passenger in the captured image becomes small.

  On the other hand, in order to capture the passenger's facial expression in detail in image processing, it is desirable that the proportion of the passenger's head image in the captured image is large. However, in order to increase the ratio of the object in the captured image in this way, the imaging range must be narrowed.

  In other words, if the imaging range is narrowed to analyze the passenger's facial expression in detail, it becomes difficult to grasp the passenger's head, and if the imaging range is widened to accurately capture the head, the passenger's facial expression is analyzed in detail. It becomes difficult.

  The present invention has been made in view of such circumstances, and an object of the present invention is to accurately capture the passenger's head in the vehicle interior imaging device that images the passenger's head, and in the captured image. An object of the present invention is to provide a vehicle interior imaging device capable of increasing the proportion of an object.

  The invention according to claim 1 is an in-vehicle imaging device that includes imaging means provided on a rearview mirror, and images the passenger's head with the imaging means, wherein the angle of the mirror surface of the rearview mirror with respect to the vehicle is set. An angle detecting means for detecting, a head position estimating means for estimating the position of the head of the occupant in the passenger compartment based on a detection result of the angle detecting means, and an estimation result of the head position estimating means The gist of the invention includes an imaging direction changing unit that changes an imaging direction of the imaging unit with respect to the mirror surface so that the head of the passenger is disposed on the optical axis of the imaging unit.

  According to the present invention, the position of the passenger's head in the passenger compartment is estimated based on the angle of the mirror surface detected by the angle detection means. Based on the estimated head position, the imaging direction changing means changes the imaging direction of the imaging means relative to the mirror surface so that the head of the passenger is placed on the optical axis of the imaging means. For this reason, the imaging direction of the imaging means is automatically and suitably set according to the position of the passenger's head. Therefore, it is possible to capture the passenger's head accurately without setting the imaging range of the imaging means wide. Therefore, in the vehicle interior imaging device that images the passenger's head, the passenger's head can be accurately captured and the proportion of the object in the captured image can be increased. As a result, the passenger's facial expression can be analyzed in detail regardless of the position of the passenger's head.

  The gist of the invention described in claim 2 is that it includes a light projecting unit that is provided integrally with the image capturing unit and that changes the light projecting direction with respect to the mirror surface by the image capturing direction changing unit.

  According to the present invention, since the head of the passenger is illuminated by the light projecting unit provided integrally with the imaging unit, the state of the head of the passenger can be captured in detail at night or in a dark place such as a tunnel. Can do. Further, as described above, the imaging direction changing unit changes the imaging direction of the imaging unit with respect to the mirror surface so that the head of the passenger is disposed on the optical axis of the imaging unit. For this reason, the light projection direction of the light projection means provided integrally with the imaging means is set in accordance with the position of the head of the passenger. Therefore, the passenger's head can be accurately illuminated.

  The invention according to claim 3 includes image processing means for determining a center position of a passenger's head in a captured image captured by the imaging means, wherein the imaging direction changing means is a determination result of the image processing means. And changing the imaging direction of the imaging means relative to the mirror surface so that the center position of the head of the occupant is located at the center position of the captured image.

  According to the present invention, since the imaging direction of the imaging unit with respect to the mirror surface is adjusted so that the center position of the passenger's head is located at the center position of the captured image, the imaging range of the imaging unit is set to be narrower Can do. Therefore, the ratio of the object in the captured image can be increased.

  According to the present invention, in a vehicle interior imaging device that images a passenger's head, a vehicle interior imaging device that can accurately capture the passenger's head and increase the proportion of an object in a captured image. Can be provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In this embodiment, the vehicle interior imaging device of the present invention is applied to a drowsy driving prevention system that detects a drowsiness state of a vehicle occupant and gives an alarm.

  As shown in FIG. 1, a room mirror 1 is provided at the front end of a roof R in the vehicle interior. As shown in FIG. 2, the rearview mirror 1 includes a case 3 fixed to a vehicle roof R via a support member 2 and a half mirror 4 fixed to the case 3. The case 3 is formed in a thin, substantially rectangular parallelepiped box having one side opened. The half mirror 4 is formed in a substantially rectangular shape that closes the opening 3 a of the case 3, and transmits part of the light incident on the mirror surface 4 a or the surface opposite to the mirror surface 4 a (back surface). The rearview mirror 1 is supported so that the longitudinal direction of the case 3 and the half mirror 4 is in the vehicle width direction, and the mirror surface 4a of the half mirror 4 is on the vehicle rear side.

  A connecting portion 3 b that is connected to the support member 2 is provided at the bottom center portion of the case 3. The connecting portion 3b is connected to the support member 2 via the spherical joint 2a. For this reason, the room mirror 1 can be tilted in a three-dimensional direction with respect to the vehicle.

  In the hollow part of the room mirror 1 (inside the case 3), a camera 6 as an imaging unit constituting a vehicle interior imaging device 5 that images a passenger's head H seated on the seat S, and a light projecting unit A plurality of light projecting elements 7, an imaging direction changing mechanism 8 as an imaging direction changing unit, and an angle sensor 9 as an angle detecting unit are accommodated. The camera 6, the light projecting element 7, the imaging direction changing mechanism 8, and the angle sensor 9 are connected to a control circuit 10 of the vehicle interior imaging device 5 provided outside the room mirror 1. Connected to the control circuit 10 are a system control device M1 of the drowsy driving prevention system and an in-vehicle device M2 such as an audio device, an air bag device, and an outer mirror driving device.

  The imaging direction changing mechanism 8 is fixed inside the case 3 on the left side (one side) of the vehicle with respect to the connecting portion 3b. A camera 6 is connected to the imaging direction changing mechanism 8. On the outer surface 6a of the camera 6, a collar 6b extends in a direction perpendicular to the imaging direction of the camera 6, and six light projecting elements 7 are fixed to the surface of the collar 6b on the half mirror 4 side. ing. The angle sensor 9 is provided in the connecting portion 3 b inside the case 3.

The camera 6 is a CCD camera or the like, and images the passenger's head H through the half mirror 4. The camera 6 outputs a captured image including the passenger's head H to the control circuit 10.
The light projecting element 7 is an infrared light emitting diode or the like, and the light projecting direction (optical axis) of each light projecting element 7 is set parallel to the imaging direction of the camera 6. The light projecting element 7 irradiates light in a direction parallel to the imaging direction of the camera 6 based on a control signal from the control circuit 10.

  The imaging direction changing mechanism 8 includes an actuator 8 a fixed to the bottom of the case 3 and a driving mechanism 8 b that is driven by the actuator 8 a and changes the imaging direction of the camera 6. The actuator 8 a is, for example, a stepping motor, and drives the drive mechanism 8 b based on a control signal from the control circuit 10 to change the imaging direction of the camera 6 with respect to the mirror surface 4 a of the half mirror 4. When the imaging direction of the camera 6 is changed by the actuator 8a, the light projecting direction of the light projecting element 7 with respect to the mirror surface 4a of the half mirror 4 is also changed.

  The angle sensor 9 detects the angle α of the mirror surface 4 a with respect to the vehicle width direction as the angle of the mirror surface 4 a with respect to the vehicle based on the angle of the room mirror 1 with respect to the support member 2, and outputs the detection result to the control circuit 10. To do.

  As shown in FIG. 3, the control circuit 10 includes a CPU, a RAM, a ROM, and the like (not shown), a camera control unit 11 that controls the camera 6 and each light projecting element 7, and an image processing unit 12 as an image processing unit. And an imaging direction control unit 13 as a head position estimating means.

  The camera control unit 11 analyzes the captured image output from the camera 6 and adjusts the luminance of each captured image by adjusting the illuminance of each light projecting element 7. In addition, the camera control unit 11 outputs the captured image output from the camera 6 to the system control device M1 of the doze driving prevention system. The system control device M1 analyzes the output captured image to detect the passenger's dozing state. When the passenger is in the dozing state, the system control device M1 drives an alarm device (not shown) to generate an alarm sound. In addition, the camera control unit 11 outputs the captured image output from the camera 6 to the image processing unit 12. The image processing unit 12 determines the center position Ph (see FIGS. 5A and 5B) of the passenger's head H in the captured image G by using an image processing method such as a neural network or illumination difference, for example. Head center position information including Ph is output to the imaging direction control unit 13.

  The imaging direction control unit 13 estimates the position of the passenger's head in the vehicle interior based on the detection result of the angle sensor 9, and the passenger's head H is on the optical axis of the camera 6 based on the estimation result. A control signal for changing the imaging direction of the camera 6 with respect to the mirror surface 4a is output to the actuator 8a. Further, the imaging direction control unit 13 mirrors the center position Ph of the occupant's head H at the center position Pg of the captured image G based on the head center position information output from the image processing unit 12. A control signal for changing the imaging direction of the camera 6 with respect to the surface 4a is output to the actuator 8a (imaging direction changing process based on the captured image). Further, the imaging direction control unit 13 outputs head center position information to the in-vehicle device M2 such as an audio device or an airbag device.

  Next, a process for estimating the head position of the passenger and a process for calculating the imaging direction of the camera 6 will be described with reference to FIG. FIG. 4 shows the positional relationship between the passenger's head H, the position of the rearview mirror 1, and the camera 6 in the horizontal direction (on the horizontal plane) in the passenger compartment.

  The room mirror 1 is provided so that a passenger can visually recognize the rear of the vehicle with the mirror surface 4a. The angle α of the mirror surface 4a of the rearview mirror 1 with respect to the vehicle is such that light from the rear of the vehicle is applied to the mirror surface 4a. The position is set according to the position of the head (eyes) H of the passenger so as to be reflected and incident on the head (eyes) H of the passenger. For this reason, the angle α formed by the vehicle center line Lm extending in the front-rear direction of the vehicle and passing through the rotation center Pm of the rearview mirror 1 and the normal line Nm of the mirror surface 4a is the center position of the passenger's head H and the seat S Is approximately half of the angle formed by the vehicle center line Lm and the line segment Lm2 passing through the rotation center Pm of the rearview mirror 1 and the center position Ph of the passenger's head H. . The angle α formed by the vehicle center line Lm and the normal line Nm of the mirror surface 4a is formed by a line segment l extending in the vehicle width direction through the mirror surface 4a of the rearview mirror 1 and the rotation center Pm of the rearview mirror 1. It is substantially equal to the angle (that is, the angle of the mirror surface 4a with respect to the vehicle width direction) α. Accordingly, the distance L from the line segment l to the center position Ph of the passenger's head H, the distance W between the vehicle center line Lm and the seat center line Lh, and the angle α of the mirror surface 4a of the rearview mirror 1 are as follows: (1) is satisfied. The imaging direction control unit 13 includes a distance W between the vehicle center line Lm and the seat center line Lh on which the passenger is seated, a rotation center Pm of the rearview mirror 1 and a rotation center Pc of the camera 6. The distance D between them is stored in advance. Then, the imaging direction control unit 13 acquires the angle α of the mirror surface 4a of the room mirror 1 through the angle sensor 9, and calculates the distance L from the line segment l to the passenger's head H from the following equation (Equation 1). calculate. In this way, the position (center position Ph) of the passenger's head H based on the position of the room mirror 1 (rotation center Pm) is estimated.

  Next, the imaging direction control unit 13 sets the estimated position of the occupant's head H so that the center position Ph of the occupant's head H estimated as described above is positioned on the optical axis Lc of the camera 6. Accordingly, the imaging direction of the camera 6 is calculated.

  As shown in FIG. 4, when the center position Ph of the occupant's head H is arranged on the optical axis Lc of the camera 6, the optical axis Lc of the camera 6 is related to the rotation center Pc of the camera 6 and the occupant's center. It substantially coincides with a straight line connecting the center position Ph of the head H. Therefore, as shown in FIG. 4, the angle β formed by the optical axis Lc of the camera 6 and the normal line Nc of the mirror surface 4a passing through the rotation center Pc of the camera 6, the angle α of the mirror surface 4a, the vehicle center line Lm The distance W between the seat center line Lh, the distance D between the rotation center Pm of the rearview mirror 1 and the rotation center Pc of the camera 6, and the distance L to the passenger's head H are expressed by the following formula ( Satisfies the relationship shown in Equation 2).

  Therefore, from the above formulas (Formula 1) and (Formula 2), the angle β formed by the optical axis Lc of the camera 6 and the normal line Nm of the mirror surface 4a is expressed as the following formula (Formula 3). The imaging direction control unit 13 calculates the angle β of the camera 6 from the following equation (Equation 3).

  Then, the imaging direction control unit 13 controls the actuator 8a so that the angle formed by the optical axis Lc of the camera 6 and the normal line Nm of the mirror surface 4a is the calculated angle β. Thus, the imaging direction of the camera 6 is automatically and suitably set according to the position of the passenger's head H. Similarly, the imaging direction control unit 13 executes processing for estimating the head position in the vertical direction and processing for calculating the imaging direction of the camera 6. In the present embodiment, descriptions of the process of estimating the head position in the vertical direction and the process of calculating the imaging direction of the camera 6 are omitted.

  As illustrated in FIG. 5, the imaging direction control unit 13 causes the center position Ph of the passenger's head H in the captured image G to deviate from the center position Pg of the captured image G (see FIG. 5A). Based on the determination result of the center position Ph of the occupant's head H by the image processing unit 12, the center position Ph of the occupant's head H is arranged at the center position Pg of the captured image G (so as to match). ) The imaging direction of the camera 6 with respect to the mirror surface 4a is changed (see FIG. 5B). Therefore, even if the position of the head H of the passenger is calculated on the assumption that the head H of the passenger is in the center of the seat S in the process of estimating the head position, It is possible to suitably prevent the center position Ph of the passenger's head H in the captured image G that is shifted from the center of the seat S from being shifted from the center position Pg of the captured image G.

Next, the operational effects of the above embodiment will be described below.
(1) The angle sensor 9 of the vehicle interior imaging device 5 detects the angle of the mirror surface 4a of the room mirror 1 with respect to the vehicle, and the imaging direction control unit 13 is boarded in the vehicle interior based on the detection result of the angle sensor 9. The position of the person's head H is estimated. Then, the imaging direction changing mechanism 8 changes the imaging direction of the camera 6 with respect to the mirror surface 4 a based on the estimation result of the imaging direction control unit 13 so that the head H of the occupant is arranged on the optical axis of the camera 6. To do. For this reason, the imaging direction of the camera 6 is automatically and suitably set according to the position of the head H of the passenger. Therefore, the passenger's head H can be captured accurately without setting the imaging range of the camera 6 wide. Therefore, in the vehicle interior imaging device 5 that captures the passenger's head H, the passenger's head H can be accurately captured and the proportion of the object in the captured image G can be increased. As a result, the passenger's facial expression can be analyzed in detail regardless of the position of the passenger's head H.

  (2) Since the occupant's head H is illuminated by the light projecting element 7 provided integrally with the camera 6 of the vehicle interior imaging device 5, the occupant's head H can be detected even in a dark place such as at night or in a tunnel. The situation can be captured in detail. Further, as described above, the imaging direction changing mechanism 8 changes the imaging direction of the camera 6 with respect to the mirror surface 4a so that the passenger's head H is disposed on the optical axis of the camera 6. For this reason, the light projecting direction of the light projecting element 7 provided integrally with the camera 6 is set according to the position of the head H of the passenger. Therefore, the passenger's head H can be accurately illuminated.

  (3) Since the imaging direction control unit 13 adjusts the imaging direction of the camera 6 with respect to the mirror surface 4a so that the center position Ph of the passenger's head H is arranged at the center position Pg of the captured image G, The imaging range can be set narrower. Therefore, the ratio of the target object (passenger's head H) in the captured image G can be further increased.

  (4) The camera 6 of the vehicle interior imaging device 5 images the passenger's head H via the half mirror 4. Therefore, the position of the passenger's head H can be accurately estimated based on the position of the passenger's eyes. Therefore, even if the imaging range is set to be narrower, it is possible to capture the passenger's head H accurately, and to increase the ratio of the object (passenger's head H) in the captured image G. Can do.

  (5) The angle sensor 9 detects the angle of the mirror surface 4a based on the angle of the room mirror 1 with respect to the support member 2 fixed to the vehicle side, thereby improving the detection accuracy of the angle of the mirror surface 4a with respect to the vehicle. Can do.

  (6) Since the position information of the occupant's head H estimated by the imaging direction control unit 13 based on the angle of the mirror surface 4a is output to the outside, the occupant's head H is based on the position information. Therefore, it is possible to suitably perform the acoustic setting of the audio, the adjustment of the airbag deployment speed, and the adjustment of the mirror surface of the outer mirror.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the camera 6 is fixed inside the room mirror 1, but the camera 6 may be fixed outside the room mirror 1.

  In the above embodiment, the light projecting element 7 is fixed to the surface on the half mirror 4 side in the flange portion 6b that extends in a direction orthogonal to the imaging direction of the camera 6, but is limited to such a mode. However, the arrangement of the light projecting elements 7 can be changed as appropriate as long as the light projecting direction with respect to the mirror surface 4a is changed by the actuator 8a provided integrally with the camera 6. In the above embodiment, the light projecting element 7 is provided integrally with the camera 6 so that the light projecting direction of the light projecting element 7 is changed by the actuator 8a. However, the light projecting element 7 is projected by the actuator 8a. For example, the light projecting element 7 may be fixed to the case 3 of the room mirror 1 so that the direction is not changed. Even in this case, the head H of the passenger can be illuminated. Further, the light projecting element 7 may be omitted.

In the above embodiment, the six light projecting elements 7 are provided as the light projecting means of the vehicle interior imaging device 5, but the number of the light projecting elements 7 can be changed as appropriate.
-In above-mentioned embodiment, although the angle sensor 9 shall detect the angle of the mirror surface 4a with respect to a vehicle based on the angle of the room mirror 1 with respect to the supporting member 2, it is not limited to such an aspect. For example, as the angle sensor 9, a triaxial angle sensor may be attached to the support member 2 and the case 3, and the difference between them may be taken. In the case of a mirror that adjusts the mirror angle electrically, the actuator 8 a Angle information may be extracted.

In the above embodiment, the head center position information is output from the imaging direction control unit 13 to the in-vehicle device M2, but such a function may be omitted.
In the above embodiment, the image processing unit 12 is provided in the control circuit 10, and the imaging direction of the camera 6 with respect to the mirror surface 4a so that the center position Ph of the passenger's head H is arranged at the center position Pg of the captured image G. However, such a function may be omitted.

  In the above embodiment, the control circuit 10 is provided outside the case 3 of the room mirror 1, but these may be provided inside the case 3 of the room mirror 1. Further, the camera control unit 11, the image processing unit 12, and the imaging direction control unit 13 may be provided separately.

  In the above embodiment, the angle sensor 9 determines the angle of the mirror surface 4a with respect to the vehicle. However, on the control circuit 10 side, the angle of the room mirror 1 with respect to the support member 2 output from the angle sensor 9 is determined. Thus, the angle of the mirror surface 4a with respect to the vehicle may be determined.

  In the above embodiment, the angle α of the mirror surface 4a with respect to the vehicle width direction is detected by the angle sensor 9, but the angle of the mirror surface 4a with respect to the vehicle extends in the front-rear direction of the vehicle and the room mirror 1 rotates. The angle α formed by the vehicle center line Lm passing through the center Pm and the normal line Nm of the mirror surface 4a may be directly detected.

Next, the technical idea that can be grasped from the embodiment will be described below.
(A) In the vehicle interior imaging device according to any one of claims 1 to 3, the mirror surface of the room mirror is a half mirror that transmits a part of light incident on the mirror surface, and the imaging The means for imaging the passenger's head through the half mirror is a vehicle interior imaging device.

  (B) In the vehicle interior imaging device according to any one of claims 1 to 3, the angle detection means is based on an angle of the room mirror with respect to a support member fixed to the vehicle side and supporting the room mirror. A vehicle interior imaging device characterized by detecting an angle of the mirror surface.

  (C) The vehicle interior imaging device according to any one of claims 1 to 3, further comprising an output unit that outputs an estimation result of the head position estimation unit to the outside. .

The perspective view inside a vehicle. The schematic block diagram of the vehicle interior imaging device of this Embodiment. The functional block diagram of the vehicle interior imaging device of this Embodiment. Explanatory drawing of the process which estimates the head position, and the process which calculates an imaging direction. (A) (b) Explanatory drawing of the imaging direction change process based on a captured image.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Room mirror, 2 ... Support member, 4 ... Half mirror, 4a ... Mirror surface, 5 ... Car interior image pick-up device, 7 ... Projection element as light projection means, 8 ... Imaging direction change mechanism as imaging direction change means , 9... Angle sensor as angle detection means, 12... Image processing section as image processing means, 13... Imaging direction control section as head position estimation means, α. Head, Lc: Optical axis of camera, Pg: Center position of captured image, Ph: Center position of passenger's head in captured image.

Claims (3)

A vehicle interior imaging device that includes an imaging means provided in a room mirror, and images the passenger's head with the imaging means,
Angle detection means for detecting the angle of the mirror surface of the room mirror with respect to the vehicle;
Head position estimation means for estimating the position of the head of the passenger in the passenger compartment based on the detection result of the angle detection means;
An imaging direction changing unit that changes an imaging direction of the imaging unit with respect to the mirror surface so that the head of the occupant is arranged on an optical axis of the imaging unit based on an estimation result of the head position estimating unit; A vehicle interior imaging device comprising: In the vehicle interior imaging device according to claim 1,
A vehicle interior imaging apparatus comprising: a light projecting unit that is provided integrally with the image capturing unit and that changes a light projecting direction with respect to the mirror surface by the image capturing direction changing unit. In the vehicle interior imaging device according to claim 1 or 2,
Image processing means for determining the center position of the head of the passenger in the captured image captured by the imaging means;
The imaging direction changing means changes the imaging direction of the imaging means relative to the mirror surface so that the center position of the occupant's head is located at the center position of the captured image based on the determination result of the image processing means. A vehicle interior imaging device characterized by being changed.

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