1. Field of the Invention
The present invention relates to an imaging device with a plurality of imaging elements mounted thereon, and more particularly to a flexible imaging device in which shooting directions of a plurality of imaging elements can be set to arbitrary directions.
2. Description of the Related Art
Vehicle-mounted cameras for shooting images of such as a front side, a lateral side, a back side, or an interior a motor vehicle such as an automobile, and monitoring cameras for ensuring security are becoming widespread. As solid-state imaging elements which are mounted on these cameras, those which afford a high aspect ratio and a wide view angle are suitable. However, such solid-state imaging elements have a problem in that their production yield is low, resulting in a high production cost. Further, there is an additional problem in that when a moving image of an object is shot, it is impossible to increase the frame rate.
Accordingly, conventionally, as disclosed in, for example, JP-A-62-10988 and JP-A-62-11264, a plurality of solid-state imaging elements are accommodated in one package, and images shot by the respective solid-state imaging elements are synthesized to thereby shoot images with a high aspect ratio and a wide view angle and increase the frame rate of the moving images.
By mounting a plurality of solid-state imaging elements and by synthesizing images shot by the individual solid-state imaging elements, it is possible to obtain images of a wide view angle and improve the frame rate of the moving picture.
However, in a case where it is desired to install a monitoring camera at, for instance, a corner of a house and obtain both a monitoring image in a frontal direction of the house and a monitoring image in a lateral direction of the house, i.e., a 90-degree direction to the front side, two monitoring cameras would be required. Hence, there is a problem in that the number of monitoring cameras required increases, resulting in a higher cost.
An object of the invention is to provide a flexible imaging device with a plurality of imaging elements mounted thereon which is capable of shooting video pictures in an arbitrary number of directions with one imaging device.
According to the invention, there is provided a flexible imaging device comprising: a flexible substrate; and a plurality of imaging elements mounted on the flexible substrate.
According to the invention, there is provided the flexible imaging device, wherein said plurality of imaging elements are at least three imaging elements, and at least two of said at least three imaging elements are accommodated in one common package.
According to the invention, there is provided the flexible imaging device, wherein the at least two imaging elements accommodated in the one common package are imaging elements which are formed adjacently on an identical semiconductor wafer and are diced out as an integral piece.
According to the invention, there is provided the flexible imaging device, wherein the package is a laminated ceramic package.
According to the invention, there is provided the flexible imaging device, further comprising: a lens array fitted to the package; and imaging lenses respectively provided for said plurality of imaging elements inside the package.
According to the invention, there is provided the flexible imaging device, further comprising: a timing generator that imparts an identical drive signal to each of said plurality of imaging elements.
According to the invention, there is provided the flexible imaging device, further comprising a first substrate on which (i) the timing generator, (ii) preprocessing sections, provided in correspondence with the imaging elements respectively, each of which preprocesses an output signal from corresponding one of the imaging elements, (iii) digital signal processing sections, provided in correspondence with the imaging elements, each of which image processes an output signal from corresponding one of the preprocessing sections, and (iv) arithmetic processing sections that integratedly processes output image data from the digital signal processing sections are mounted, wherein the first substrate is provided continuously to the flexible substrate.
According to the invention, there is provided the flexible imaging device, which has a connection configuration such that said plurality of imaging elements and the timing generator are connected by a common wiring, wherein an identical drive signal is branched from the common wiring to each of the imaging elements.
According to the invention, there is provided the flexible imaging device, wherein said plurality of imaging elements comprise filters having different transmission characteristics, the filters being provided in front of light receiving surfaces of the imaging elements respectively.
According to the invention, there is provided the flexible imaging device, wherein the imaging elements are of a CCD type.
According to the invention, there is provided the flexible imaging device, wherein the arithmetic processing section comprises a section that, when two of the imaging elements are shooting an identical object, calculates a distance to the object from a distance between the two imaging elements and images shot by the imaging elements.
According to the invention, there is provided the flexible imaging device, wherein the arithmetic processing section comprises a section that outputs an alarm upon detecting that the calculated distance to the object has reached a threshold distance or less.
According to the invention, there is provided the flexible imaging device which is a vehicle-mounted camera.
According to the invention, there is provided the flexible imaging device which is a monitoring camera.
Referring now to the accompanying drawings, a description will be given of an embodiment of the invention.
Infrared cut filters 3a, 3b, 3c, and 3d are respectively provided in front of the solid-state imaging elements 2a, 2b, 2c, and 2d, and imaging lenses 4a, 4b, 4c, and 4d are further provided in preceding stages thereof.
Emitter followers 5a, 5b, 5c, and 5d are provided at output stages of the respective solid-state imaging elements 2a, 2b, 2c, and 2d. Provided at rear stages of the respective emitter followers 5a, 5b, 5c, and 5d are known preprocessing units (correlational double sampling (CDS) processing units, gain control unit analog-to-digital conversion (ADC) portions, etc.) 6a, 6b, 6c, and 6d which are known in the CCD type solid-state imaging elements. It should be noted that there are cases where the emitter followers 5a, 5b, 5c, and 5d are omitted depending on the initial stage characteristics of the preprocessing units.
Outputs of the preprocessing units 6a, 6b, 6c, and 6d are connected to digital signal processing (DSP) units 7a, 7b, 7c, and 7d, outputs from the respective are connected to a microprocessor unit (MPU) 8 for integratedly controlling the imaging device 1, and an output from the microprocessor 8 is connected to a memory 9 for image recording. It should be noted that a configuration may be provided such that four microprocessors 8 and four memories 9 are provided in correspondence with the CCD type solid-state imaging elements 2a, 2b, 2c, and 2d.
The driving of the respective CCD type solid-state imaging elements 2a, 2b, 2c, and 2d is controlled by V drive signals (a read pulse signal, a vertical transfer pulse, and an electronic shutter pulse) for driving the vertical charge transfer paths (VCCD) and H drive signals (a horizontal transfer pulse and a reset pulse) for driving the horizontal charge transfer paths (HCCD).
In addition, the preprocessing units 6a, 6b, 6c, and 6d are controlled by drive signals including, for example, a sampling pulse signal for determining the feedthrough level in the correlational double sampling processing, a sampling pulse signal for determining the data level, and a sampling pulse of the analog-to-digital conversion portions.
In this embodiment, these drive signals are configured to be generated by one timing generator (TG) 10 provided in common to the four solid-state imaging elements 2a, 2b, 2c, and 2d and the four preprocessing units 6a, 6b, 6c, and 6d.
Namely, in response to an instruction from the microprocessor 8, the timing generator 10 generates and outputs drive signals for the preprocessing units, H drive signals, and V drive signals. The drive signals for the preprocessing units are branched into four signals, which are respectively supplied to the preprocessing units 6a, 6b, 6c, and 6d.
In addition, the H drive signals generated by the timing generator 10 are branched into four signals, which are respectively supplied to the horizontal charge transfer paths (HCCD) and the like of the respective CCD type solid-state imaging elements 2a, 2b, 2c, and 2d through buffers 11a, 11b, 11c, and 11d. It should be noted that the buffers 11a to 11d are not essentially required circuit elements, and may not be used.
Further, the V drive signals generated by the timing generator 10 are branched into four signals, which are respectively supplied to the vertical charge transfer paths (VCCD) and the like of the respective CCD type solid-state imaging elements 2a, 2b, 2c, and 2d through drivers 12a, 12b, 12c, and 12d.
As a result, the four CCD type solid-state imaging elements 2a, 2b, 2c, and 2d perform respective operations (exposure, readout, transfer, and output) completely identically and simultaneously, and the four preprocessing units 6a, 6b, 6c, and 6d also perform sampling processing and the like in a completely identical operational state. Accordingly, differences among the picked-up image signals which are outputted from the four CCD type solid-state imaging elements 2a, 2b, 2c, and 2d are those which are ascribable only to differences among the positions of layout of the four CCD type solid-state imaging elements 2a, 2b, 2c, and 2d.
A device with a plurality of imaging elements mounted in one camera conventionally exists. For example, a three-plate type camera is so configured that three imaging elements for imaging a red-color image, imaging a green-color image, and imaging a blue-color image are accommodated in one camera, and incident light is divided into three components, which are made incident upon the respective imaging elements. With the conventional three-plate type camera, timing generators are separately provided in correspondence with the respective imaging elements, and the three timing generators are adapted to generate horizontal transfer pulses and vertical transfer pulses separately on the basis of common horizontal synchronizing signals HD and vertical synchronizing signals to drive the respective imaging elements.
In contrast, in the imaging device in accordance with this embodiment, since the plurality of imaging elements are driven by the output signal of one timing generator, the plurality of imaging elements perform not mere synchronous operation but completely identical and simultaneous operation.
Namely, timings at which detection signals of pixels (light receiving elements) located at the same coordinate positions on the respective light receiving surfaces are outputted from the respective imaging elements are identical, timings at which preprocessing is carried out are also identical, timings at which image processing is carried out are identical, and timings at which data are stored in the memory 9 are also identical. In a case where four memories 9 are provided, timings of storage of data which are stored at the same address in the memories are also identical.
The second substrate 14 is constituted by a flexible substrate, and the four solid-state imaging elements 2a to 2d are mounted on this flexible substrate 14. In the illustrated example, the solid-state imaging elements 2a and 2b are accommodated in a common package 16, and the solid-state imaging elements 2c and 2d are accommodated in another common package 16. These packages 16 are fixed on the flexible substrate 14.
As shown in
After accommodating the solid-state imaging elements in the package 16, a package opening serving as a plane of incidence of the light is closed by a transparent glass lid 18. The glass lid 18 is adhered to the package opening portion by an adhesive 19 such as an ultraviolet (UV) curing resin or the like.
The wiring 21 is laid on the flexible substrate 14 further to a further distance, the package 16 accommodating the solid-state imaging elements 2a and 2b accommodated therein is connected to this wiring 21 in the same way as in
The solid-state imaging elements 2a and 2b (or 2c and 2d) which make up a pair are sufficient if they have the same dimensions and the same number of pixels, and it is preferable to use solid-state imaging elements which are formed in the same manufacturing process. In a most preferable form, as shown in
This diced unit is accommodated in the package 16, as shown in
In the imaging device 1 in accordance with this embodiment, the MPU 8 integratedly processes images picked up by the four solid-state imaging elements 2a, 2b, 2c, and 2d. At the time of this integrated processing, it is necessary to ascertain the mutual positional relationships among the four solid-state imaging elements 2a to 2d and the respective shooting directions (directions in which the light receiving surfaces are oriented) with high accuracy. In particular, it is necessary to control with high accuracy the mounting positions in the package 16 of the two solid-state imaging elements 2a and 2b (or 2c and 2d) making up a pair. In this sense as well, the embodiment described with reference to
A description will be given of the operation when an object image is shot by the flexible imaging device 1 having the above-described configuration. For example, the imaging devices 1 are installed at positions of various parts of an automobile as vehicle-mounted cameras, as shown in
In the flexible imaging devices 1′ and 1″, the respective solid-state imaging elements are so adapted as to be capable of being oriented in different directions since they are respectively accommodated in separate packages.
Each of the solid-state imaging elements of the flexible imaging device converts into an electrical signal the field light formed into an image through each focusing lens, and outputs the shot image to each corresponding preprocessing unit, the corresponding DSP effects image processing, and the MPU effects integral processing the shot images obtained by the respective solid-state imaging elements.
For example, since the video picture of the two solid-state imaging elements 2a and 2b facing the front side serves as that of a stereo camera, when a video picture of a pedestrian or an oncoming vehicle is shot, this video picture is displayed on a monitor screen provided in the vehicle compartment. A distance to the object can then be determined from a distance between the solid-state imaging elements 2a and 2b and from the respective shot images as in the manner described in, for example, JP-A-2006-318062, and can be notified to the driver.
Similarly, also from the video picture of the two solid-state imaging elements 3c and 2d facing one side, a video picture of, for example, a pedestrian or the like advancing from a by-road which cannot be seen from the driver's seat can be displayed on a monitor screen, and the distance can be notified. Preferably, the MPU 8 is adapted to output an alarm upon detecting that an object to be alarmed, such as a pedestrian, has approached to within a threshold distance.
To calculate the distance to the object with high accuracy, the simultaneity of the two shot images is required, but since the simultaneity of the two shot images is ensured in this embodiment, the calculation of the distance with high accuracy becomes possible.
In addition, when the images shot by the four solid-state imaging elements are synthesized and displayed on the monitor screen, the simultaneity of the four shot images is ensured, so that the driver is able to simultaneously view an image of the lateral side at exactly the same instant as that of an image of the front side, thereby making it possible to improve the safety of driving.
In a case where fully covering video pictures of the front side of a house are to be shot by lenses each having one solid-state imaging element, super wide angle lenses are required, and four super wide angle lenses would be required in the illustrated example, so that the installation cost of the monitoring cameras becomes high. With the flexible imaging device 1 in accordance with this embodiment, however, a fully covering video picture of the front side can be shot by mounting three solid-state imaging elements on a curved portion at tilted angles to each other in one flexible imaging device without using super wide angle lenses. Hence, by installing a total of four flexible imaging devices, the 360° monitoring of the surroundings of a house becomes possible.
In
The synthesis processing of this 360° monitoring video picture is more facilitated than that in the case of the monitoring camera shown in
In the synthesis processing of the 360° monitoring video picture, since the simultaneity of the eight shot images is ensured, the integration processing of shot images which is executed by the MPU, i.e., such as retrieval processing of superimposed portions of images shot by adjacent solid-state imaging elements, is facilitated.
In addition, although the eight shot images are respectively fetched into the imaging device as moving pictures, since the acquisition timings of the respective moving pictures are completely identical among the eight solid-state imaging elements, when a video picture being captured by the solid-state imaging element 2a enters the shooting range of the adjacent solid-state imaging element 2b, the moving pictures can be recognized as an utterly identical moving picture. Hence, it is possible to obtain moving images which does not impart a sense of discomfort.
It should be noted that although in the embodiment shown in
If shooting ranges of a plurality of solid-state imaging elements using filters having different transmission characteristics are set to an identical range, and the respective shot images are integratedly processed and are displayed on a monitor, for example, when the light has become dim and a pedestrian in the advancing direction is difficult to see, a thermal image of the pedestrian shown in the infrared image can be displayed by being superimposed on the visible light image. Even in such a case, in the imaging device 1 in accordance with this embodiment, the plurality of solid-state imaging elements operate utterly identically, and output timings of detection signals of the respective pixels from the solid-state imaging elements, A/D conversion processing timings, and timings of storage into the frame memory within the MPU 8 are identical, so that the integration processing of the respective shot images can be effected in a short time and with ease.
It should be noted that although in the embodiment described with reference to
In addition, although in the above-described embodiment laminated ceramic packages are used, the invention is not limited to the same, and plastic packages, for example, may be used. Still alternatively, it is also possible to further miniaturize the imaging device by using chip size packages such as those described in Japanese Patent No. 3827310.
The semiconductor substrate 41, the transparent substrate 43, and the like are made thin so as to be provided with flexibility in themselves, and are adhered to the flexible substrate 14, as shown in
Connection pads 45 are provided at an end portion of the semiconductor substrate 41, and these pads 45 and the respective imaging elements 2a and 2b are connected by a common wiring 46 formed on the semiconductor substrate. In addition, the pads 46 and the timing generator (TG) 10 of the electronic circuitry 17 are connected by a wiring 47.
There are cases where the flexible substrate 14 is used by being bent by about 90 degrees. In this case, as shown in
Further, although in the above-described embodiment one lens is used for each individual solid-state imaging element as shown in
Furthermore, although in the above-described embodiment a description has been given of the case in which the solid-state imaging elements are of the CCD type, the above-described embodiment is also applicable to a plurality of CMOS type solid-state imaging elements which are driven by one timing generator.
According to the invention, since the shooting directions of the plurality of imaging elements can be set to arbitrary directions, it is possible to reduce the number of imaging devices required. In addition, since one timing generator is used for driving the respective imaging elements, it is possible to ensure the simultaneity of images shot by the respective imaging elements, so that integration processing of the shot images is facilitated.
Since the flexible imaging device in accordance with the invention makes it possible to set shooting directions of the plurality of solid-state imaging elements to arbitrary directions, it easily becomes possible to obtain video pictures in which the shooting directions are 90 degrees different. Therefore, the flexible imaging device in accordance with the invention is useful in application to a vehicle-mounted camera, a monitoring camera, and the like.
The entire disclosure of each and every foreign patent application from which the benefit of foreign priority has been claimed in the present application is incorporated herein by reference, as if fully set forth.
Number | Date | Country | Kind |
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P2007-222780 | Aug 2007 | JP | national |