Abstract:
a photosensor structure; and switching means coupled between the photosensor structure and one of the plurality of signal lines, the switching means responsive to select signals on one or more of the plurality of select lines for conveying a photosensor signal between the photosensor structure and the one of the plurality of signal lines.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a novel image sensor device, herein referred to as a light emitting and image sensing device, and the apparatus in which it is used.  
         [0003]     2. Description of the Related Art  
         [0004]     An embodiment of a conventional image sensor, in this case a CMOS image sensor, is schematically illustrated in cross-section in  FIG. 1 . A microlens  30  focuses incident light, or photons  32 , on a plurality of photodiodes  34  in a silicon substrate  36 . Color filters  38  filter photons of specific wavelengths so that each of the photodiodes  34  collects photons within one of three ranges of wavelengths, corresponding to red, green and blue light.  
         [0005]     An embodiment of a conventional active pixel element in a CMOS image sensor is illustrated in schematic view in  FIG. 2 . The active pixel element comprises a photodiode and an active pixel circuit indicated generally by reference numerals  34 . 2  and  40  respectively. The photodiode  34 . 2  provides a photosensor signal on conductor  42 . The photosensor signal on conductor  42  is read out through a buffer transistor  44  onto a column bus  46  when a row select transistor  48  is activated. A reset transistor  50  operates to reset the photodiode  34 . 2  to a known state.  
         [0006]     A schematic plan view of the conventional image sensor is illustrated in  FIG. 3 . The conventional image sensor comprises a matrix of rows and columns of pixel elements indicated generally by reference numeral  52 . Each of the pixel elements contains a photosensing structure and corresponding support circuitry, such as the photodiode  34 . 2  and active pixel circuit  40 , respectively, illustrated in  FIG. 2 .  
         [0007]     There are many image sensor applications wherein a light source is required to illuminate a scene, or an object, so that the image sensor can capture one or more images. Examples of such applications include but are not limited to video surveillance, cell phones, digital cameras and digital video systems. During low ambient light level conditions the light source is necessary for an image to be captured at all.  
         [0008]     An example of a conventional infrared video surveillance camera is given by U.S. Pat. No. 6,642,955 by Brent Midgley et al. Midgley describes a CCD type image sensor in a camera system that switches electronically between infrared radiation sensing and visible light sensing depending on ambient conditions. Furthermore, the camera in Midgley makes use of either incandescent or LED type illuminators. These illuminators are located external to the camera system, but may be in a camera system enclosure along with the CCD image sensor.  
         [0009]     An example of a CMOS sensor used in cell phone is given by U.S. Pat. No. 6,730,900 by Hsish et al. in which is described a novel CMOS based active sensor array that, along with focusing optics, is preferably incorporated into a cellular phone camera for producing electronic images.  
         [0010]     A disadvantage of the prior art is the lack of integration of a light source for image illumination with the image sensor. This has resulted in excessively large image sensor products for the applications listed above. In the case of the video surveillance camera, the illuminator is either in a separate enclosure altogether, or is mounted inside the camera system enclosure thereby increasing the size.  
         [0011]     Another disadvantage of the lack of integration is the inability to take advantage of an illumination apparatus. In a cell phone, for example, where space is a constrained, it is often not feasible to include the illumination apparatus. In this situation, a cell phone camera can only be used in conditions where ambient light is sufficient for its operation.  
         [0012]     Furthermore, another disadvantage of the prior art is that by lack of integration the power consumption of the above mentioned products and applications is excessively large.  
       BRIEF SUMMARY OF INVENTION  
       [0013]     In one aspect of the present invention there is provided a light emitting and image sensing device for a scene. The device is formed in a semiconductor substrate and comprises a photosensor component for sensing an image of the scene. The photosensor component is responsive to incident light from the scene and provides an electrical signal representative of the image. There is also a photoemitter component for emitting a light signal representative of the electrical signal, and a coupling component connecting the photosensor component with the photoemitter component.  
         [0014]     In another aspect of the present invention there is provided a light emitting and image sensing device for a scene. The light emitting and image sensing device is formed in a semiconductor substrate and comprises a photoemitter means for illuminating the scene with light, and a photosensor means for sensing an image of the scene. The photosensor means is responsive to incident light from the scene.  
         [0015]     In another aspect of the invention there is provided a light emitting and image sensing device that includes a photosensor means. The photosensor means comprises a matrix of rows and columns of photosensor structures responsive to incident light upon the light emitting and image sensing device. For each row in the matrix there is row select circuitry connected to each of the photosensor structures in the row for selectively designating for outputting output signals representative of the light sensed by the photosensor structure. For each column in the matrix there is column select circuitry connected to each of the photosensor structures in the column for selectively designating for outputting output signals representative of the light sensed by the photosensor structures.  
         [0016]     In another aspect of the invention there is provided a light emitting and image sensing device having a photoemitter means. The photoemitter means includes an array of photoemitter structures operable to emit light from the device and a photoemitter control means for controlling an emission of the light from the array of photoemitter structures.  
         [0017]     In another aspect of the invention there is provided a light emitting and image sensing device having a photosensor means. The photosensor means comprises a plurality of select lines, a plurality of signal lines, and a plurality of pixel elements. The pixel elements include a photosensor structure, and a switching means coupled between the photosensor structure and one of the plurality of signal lines. The switching means is responsive to select signals on one or more of the plurality of select lines for conveying a photosensor signal between the photosensor structure and the one of the plurality of signal lines.  
         [0018]     In another aspect of the present invention there is provided a light emitting and image sensing device for a scene. The light emitting and image sensing device includes a photosensor means for sensing an image of the scene and a photoemitter means for illuminating the scene with light. The photosensor means is formed in a first semiconductor substrate and is responsive to incident light from the scene. The photoemitter means is formed in a second semiconductor substrate. The second semiconductor substrate is attached to the first semiconductor substrate.  
         [0019]     In another aspect of the present invention there is provided a light emitting and image sensing device for a scene. The light emitting and image sensing device includes a photosensor means for sensing an image of the scene and a photoemitter means for illuminating the scene with light. The photosensor means is formed in a first semiconductor substrate and is responsive to incident light from the scene. The photoemitter means is formed in a second semiconductor substrate. The second semiconductor substrate is attached to the first semiconductor substrate. The light emitting and image sensing device further includes a photoemitter control circuit operable to control an emission of the light from the photoemitter means. The photoemitter control circuit is formed in the first semiconductor substrate.  
         [0020]     In another aspect of the present invention there is provided a light emitting and image sensing device for a scene. The light emitting and image sensing device includes a photosensor means for sensing an image of the scene and a photoemitter means for illuminating the scene with light. The photosensor means is formed in a first semiconductor substrate and is responsive to incident light from the scene. The photoemitter means is formed in a second semiconductor substrate. The second semiconductor substrate is attached to the first semiconductor substrate. The photosensor means includes a matrix of rows and columns of photosensor structures responsive to incident light upon the device. For each row in the matrix there is row select circuitry connected to each of the photosensor structures in the row for selectively designating for outputting output signals representative of the light sensed by said photosensor structure. For each column in the matrix there is column select circuitry connected to each of the photosensor structures in said column for selectively designating for outputting output signals representative of the light sensed by said photosensor structures.  
         [0021]     In another aspect of the invention there is provided a light emitting and image sensing device that is formed in a semiconductor substrate. The light emitting and image sensing device comprises a photoemitter operable to emit electromagnetic radiation from the device, and a photosensor responsive to electromagnetic radiation incident upon the device.  
         [0022]     In another aspect of the invention there is provided a lens housing for an image sensor type camera, the camera for generating an image of a scene. The lens housing comprises a first light channel for guiding an emission of light from the image sensor to illuminate the scene, and a second light channel for guiding light from the scene towards the image sensor.  
         [0023]     In another aspect of the invention there is provided a housing for a light emitting and image sensing device. The housing comprises a first light channel for emitted light from the light emitting and image sensing device to illuminate a scene, and a second light channel for incident light from the scene towards the light emitting and image sensing device.  
         [0024]     In another aspect of the invention there is provided a housing for a light emitting and image sensing device. The housing comprises a first light channel for emitted light from the light emitting and image sensing device to illuminate a scene, and a second light channel for incident light from the scene towards the light emitting and image sensing device. The second light channel has an outer surface. The first and second light channels have a common axis. The first light channel being formed around the outer surface of the second light channel.  
         [0025]     In another aspect of the invention there is provided, in combination, a light emitting and image sensing device and a housing. The housing has a first end where the light emitting and image sensing device is disposed.  
         [0026]     In another aspect of the invention there is provided a method of illuminating a scene and sensing an image. The method comprises the steps of emitting light from a light emitting and image sensing device, channelling the emitted light along a first channel, dispersing the light with a first lens towards the scene, focusing incident light from the scene with a second lens, channelling the focused light along a second channel towards the light emitting and image sensing device, and sensing the image of the scene with the focused light upon the light emitting and image sensing device.  
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0027]     The invention will be more readily understood from the following description of preferred embodiments thereof given, by way of example only, with reference to the accompanying drawings, in which:  
         [0028]      FIG. 1  is a schematic view in cross-section of a conventional CMOS image sensor.  
         [0029]      FIG. 2  is a schematic view of a conventional active pixel element.  
         [0030]      FIG. 3  is a schematic plan view of a conventional image sensor.  
         [0031]      FIGS. 4   a - h  are schematic plan views of embodiments of light emitting and image sensing devices.  
         [0032]      FIG. 5  is a schematic view in cross-section of an embodiment of the light emitting and image sensing device in a silicon substrate.  
         [0033]      FIG. 6  is a schematic view in cross-section of another embodiment of the light emitting and image sensing device in a silicon substrate.  
         [0034]      FIG. 7  is a broken-away schematic view in cross-section of an embodiment of the light emitting and image sensing device wherein a photoemitter is in a first semiconductor substrate and a pixel element is in a second semiconductor substrate.  
         [0035]      FIG. 8  is a schematic view in cross-section of another embodiment of the light emitting and image sensing device wherein a photoemitter is in a first semiconductor substrate and a pixel element is in a second semiconductor substrate.  
         [0036]      FIG. 9  is a partial schematic view of a matrix of active pixel elements of the light emitting and image sensing device of  FIG. 5 .  
         [0037]      FIG. 10  is a schematic view of an active pixel element of the light emitting and image sensing device of  FIG. 5 .  
         [0038]      FIG. 11   a - b  are schematic views of embodiments of light emitting and image sensing devices wherein an array of photoemitters is connected to a photoemitter control means.  
         [0039]      FIG. 12  is a schematic view in perspective of the light emitting and image sensing devices of the embodiments of  FIGS. 4   a - c.    
         [0040]      FIG. 13  is a schematic view in perspective of the light emitting and image sensing devices of the embodiments of  FIGS. 4   e - g.    
         [0041]      FIG. 14  is a partial schematic view in perspective of the light emitting and image sensing device of the embodiment of  FIGS. 4   h.    
         [0042]      FIG. 15  is a schematic view in perspective of an embodiment of a housing for the light emitting and image sensing device of  FIG. 4   h.    
         [0043]      FIG. 16  is a cross-sectional schematic view of an embodiment of the invention including the housing of  FIG. 15  taken along line  16 - 16 ′, the light emitting and image sensing device of  FIG. 4   h,  and a substrate.  
         [0044]      FIG. 17  is a schematic view in perspective of an embodiment of a housing having adjacent light channels.  
         [0045]      FIG. 18  is a cross-sectional schematic view of an embodiment of the invention including the housing of  FIG. 17  taken along line  18 - 18 ′, either one of the light emitting and image sensing devices of  FIGS. 4   e - g,  and a substrate.  
         [0046]      FIG. 19  is a schematic view in perspective of an embodiment of a housing having light channels with a common axis.  
         [0047]      FIG. 20  is a cross-sectional schematic view of an embodiment of the invention including the housing of  FIG. 19  taken along line  20 - 20 ′, either one of the light emitting and image sensing devices of  FIGS. 4   a - d,  and a substrate. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0048]     Referring to  FIG. 4   a,  a light emitting and image sensing device, indicated generally by reference numeral  60 , is formed in a semiconductor and has a light emitting region  62  and an image sensing region  64 . The light emitting region  62  has a photoemitter  68 . The photoemitter  68  operates to emit light, from a surface  66 , to illuminate a scene, or an object. The emitted light is in a range of wavelengths, which can be in an infrared band, a visible light band or an ultraviolet band of the electromagnetic spectrum. Other bands of the electrical magnetic spectrum are, however, possible as well.  
         [0049]     The image sensing region  64  has a plurality of pixel elements indicated generally by reference numeral  70 . The pixel elements  70  are responsive to incident light from the scene, or the object. Each of the pixel elements  70  provides a photosensor signal representative of the incident light in the area of the respective pixel element. The plurality of pixel elements  70  can be arranged in a matrix having rows and columns. An image sensor resolution is determined by a first number of pixel elements in each row and by a second number of pixel elements in each column.  
         [0050]     Two further embodiments of the invention similar to the embodiment shown in  FIG. 4   a  are illustrated in  FIGS. 4   b  and  4   c  wherein like parts have like reference numerals with an additional suffix. The embodiment illustrated in  FIG. 4   b  includes a plurality of photoemitters  68 . b  positioned in a photoemitter region  62 . b  around an image sensing region  64 . b.  The embodiment illustrated in  FIG. 4   c  includes a plurality of photoemitters  68 . c  having a photoemitter density comparable to a pixel element density.  
         [0051]     Another embodiment of the invention is illustrated in  FIG. 4   d  wherein like parts have like reference numerals with an additional suffix. The light emitting and image sensing device  60 . d  has a circular image sensing region  64 . d  surrounded by a ring-shaped light emitting region  62 . d.  The light emitting region  62 . d  has a plurality of photoemitters  68 . d.  The image sensing region  64 . d  has a plurality of pixel elements  70 . d.    
         [0052]     Three further embodiments of the invention are illustrated in  FIGS. 4   e,    4   f  and  4   g  wherein like parts have like reference numerals with an additional suffix. The embodiment illustrated in  FIG. 4   e  includes a light emitting region  62 . e  adjacent an image sensing region  64 . e.  The light emitting region  62 . e  includes a photoemitter  68 . e  and the image sensing region  64 . e  includes a plurality of pixel elements  70 . e.  The plurality of pixel elements  70 . e  can be arranged in a matrix having rows and columns. The embodiments illustrated in  FIGS. 4   f  and  4   g  are similar to that of  FIG. 4   e,  both including a plurality of photoemitters  68 . f  and  68 . g  respectively. The plurality of photoemitters  68 . g  has a photoemitter density comparable to a pixel element density.  
         [0053]     Another embodiment of the invention is illustrated in  FIG. 4   h  wherein like parts have like reference numerals with an additional suffix. In this embodiment a plurality of photoemitters  68 . h  are arranged in an alternating pattern with a plurality of pixel elements  70 . h.  A photoemitter density can be different than a pixel element density.  
         [0054]     Another embodiment of the invention is illustrated in  FIG. 5 , wherein like parts have like reference numerals with an additional suffix. A photoemitter indicated generally by reference numeral  68 . 5  is separated from a pixel element indicated generally by reference numeral  70 . 5 . The photoemitter  68 . 5  and the pixel element  70 . 5  are formed on and in a first layer of silicon  74 . The first layer of silicon is formed on top of a silicon oxide (SiO 2 ) layer  76 , which is formed on top of a silicon substrate  78 .  
         [0055]     In this embodiment the photoemitter  68 . 5  is similar to a semiconductor device for electro-optic applications described in European Patent EP1210752 by Coffa et al., which is incorporated by reference herein. An N −  region  80 , an N region  82  and a P +  region  84  are formed in the silicon layer  74 , and together make a PN junction that under reverse bias emits light  92 . One skilled in the art will recognize that the PN junction is similar to a base-collector junction of a bipolar transistor having a base electrode  83 , a collector electrode  85  and an emitter electrode  87 . A rare earth ions doped region  86 , in this case Erbium, enables the PN junction to emit light  92  having a wavelength around 1.54 um. Using other rare earth ions allows light to be emitted having different wavelengths. For instance, as a non-limiting example, Terbium and Ytterbium provide light having a wavelength around 540 nm and 980 nm respectively.  
         [0056]     A trench, indicated generally by reference numeral  88 , serves to reduce lateral light transmission from the rare earth ions doped region  86  towards the pixel element  70 . 5 . The trench  88  has a wall  90  upon which there is a film of silicon oxide (SiO 2 )  91 . Light  92  travelling from the rare earth ions doped region  86  towards the pixel element  70 . 5  through the semiconductor layer  74  must cross the wall  90  and travel through the film of silicon oxide (SiO 2 )  91 . The refractive index of silicon oxide (SiO 2 ) is less than the refractive index of silicon. This causes light incident on the wall  90  having an angle of incidence, from a normal to the wall, greater than a critical angle to undergo total internal reflection. In other embodiments multiple trenches having films of silicon oxide (SiO 2 ) can be used to further reduce lateral light transmission. The trench  88  has the advantage of reducing phantom images in and preventing blurring of pixel element  70 . 5  as caused by the above mentioned lateral light transmission.  
         [0057]     The light  92  emitted from the rare earth ions doped region  86  has random directions. The light  92  strikes a surface  104 , defined by a boundary between the silicon layer  74  and a silicon oxide layer  106 , at various angles of incidence to a normal to the surface. Light  92  having the angle of incidence greater then the critical angle will be internally reflected. It is advantageous, then, that the light  92  be substantially normal to the surface  104  in order for maximum light emission from the surface. The goal is to maximize an external quantum efficiency, a problem well known in the art. In another embodiment, a photoemitter can be provided similar to a device presented in “Si-based Resonant Cavity Light Emitting Devices” by Castagna et al in SPIE Vol 5366, which is incorporated by reference herein. This has the advantage that light generated is substantially normal to surface  104 . This has a further advantage of reducing lateral light transmission through the semiconductor layer  74  towards the pixel element  70 . 5 .  
         [0058]     The pixel element  70 . 5  of the present embodiment is commonly known in the prior art, as disclosed by U.S. Pat. No. 5,965,875 by Merril, which is incorporated by reference herein, and as such will not be described in great detail here. The pixel element  70 . 5  includes a photosensor structure  72 . The photosensor structure  72  is based on a triple well structure forming a first PN junction  94 , a second PN junction  96  and a third PN junction  98 . Incident light  100  having different wavelengths penetrates the photosensor structure  72  at varying depths depending on the wavelength. Red light penetrates to around the depth of the first PN junction  94  where it produces a red photo current. Green light penetrates to around the depth of the second PN junction  96  where it produces a green photo current. Blue light penetrates to around the depth of the third PN junction  96  where it produces a blue photo current. A photocurrent sensor indicated generally by reference numeral  102  measures the red, green and blue photocurrents.  
         [0059]     When the incident light  100  is in the near ultraviolet and near infrared bands of the electromagnetic spectrum, the photosensor structure  72  is still capable of functioning well. A study performed by Alternate Vision Corporation indicates that the photosensor structure  72  performs well under such conditions. The results of the study were published in a paper titled “Infrared and ultraviolet imaging with a CMOS sensor having layered photodiodes” by Gilblom et al.  
         [0060]     The pixel element  70 . 5  of this embodiment is advantageous since it takes less area of surface  104  to sense red, green and blue components of light  100 . This allows increased resolution for a given surface area. Nevertheless, other image sensor structures formed in silicon can be used for the present invention. This includes CMOS image sensor structures, such as in  FIG. 1 , and CCD image sensor structures.  
         [0061]     Referring now to  FIG. 6 , another embodiment of the invention is illustrated wherein like parts have like reference numerals with an additional suffix. The photoemitter  68 . 6  is in this case formed using a PN junction diode, indicated generally by reference numeral  108 , with un-annealed implant dislocations used to enhance light emission. The structure of the PN junction diode  108  is described in great detail in U.S. Pat. No. 6,710,376 by Worley, which is incorporated by reference herein. The pixel element  70 . 6  is similar to the pixel element  70 . 5  in  FIG. 5 .  
         [0062]     The PN junction  108  is comprised of an N+implant region  110 , in a doped P type region  112 , and a P+implant  114  that is used to make a good electrical connection between the P-type region and metal terminals  116 . A connection is made to the N+ implant region  110  using the metal terminal  118 .  
         [0063]     Several light emitting devices are known in the prior art that use Ill-V or II-VI semiconductors and compound semiconductors, for example LEDs, resonant cavity light emitting diodes (RCLED) and vertical cavity surface emitting lasers (VCSEL). It would be advantageous to include these types of devices with a silicon based image sensor.  
         [0064]     Another embodiment of the invention is illustrated in  FIG. 7  wherein like parts have like reference numerals with an additional suffix. A first semiconductor substrate  120  is illustrated above a second semiconductor substrate  122 . The first semiconductor substrate  120  is formed from Ill-V or II-VI compound semiconductor materials, whereas the second semiconductor substrate  122  is formed from silicon. A photoemitter  68 . 7  is formed in the first semiconductor substrate  120 , and a pixel element  70 . 7  is formed in the second semiconductor substrate  122 . The pixel element  70 . 7  is similar to the pixel element  70 . 5  in  FIG. 5 .  
         [0065]     In the present embodiment, the photoemitter  68 . 7  is similar to a light emitting device disclosed in U.S. Pat. 5,493,577 by Choquette et al, which is incorporated by reference herein, wherein the light emitting device has a structure compatible for both RCLEDs and VCSELs. The photoemitter  68 . 7  comprises a first distributed Bragg reflector (DBR)  124 , a second DBR  126 , an active region  128  and a control layer  130 . The first and second DBRs  124  and  126  and the active region  128  form a resonator, or what is commonly called a Fabry-Perot resonator. A substrate  132  attaches the first DBR  124  to a first electrode  134 . A second electrode  136  is deposited on the second DBR  126 . Choquette describes the operation of the photoemitter  68 . 7  for RCLED and VCSEL embodiments in great detail.  
         [0066]     Light  92 . 7  is emitted substantially along an axis and normal to a surface  140 . Since the index of refraction of the second DBR  126  is greater than that of air, the surrounding environment, this has the advantage of minimizing the effects of internal reflection at the surface  140 . This increases an external quantum efficiency of the photoemitter  68 . 7 . Another advantage of the orientation of light  92 . 7  to surface  140  is that light is substantially not emitted towards the photosensor structure  72 . 7 . This prevents the formation of phantom images in and/or blurring of the pixel element  70 . 7 . In this embodiment the light  92 . 7  has a wavelength of 980 nm which is in the near infrared region.  
         [0067]     The first semiconductor substrate  120  is attached to the second semiconductor substrate  122 . The first electrode  134  is operatively connected to photoemitter control circuitry  138 , which can enable, disable and control the intensity of light emission of the photoemitter  68 . 7 . Attaching different types of semiconductor substrates together, for instance GaAs and Si, and providing many electrical connections between them is well known in the art. The company Xanoptix Inc. provides such hybrid integrated circuit technology.  
         [0068]     In another embodiment, a light emitting and image sensing device using a III-V compound semiconductor substrate and a silicon substrate is illustrated in  FIG. 8 , wherein like parts have like reference numerals with an additional suffix. In this embodiment, the photoemitter  68 . 8 , again, is formed in the first semiconductor substrate  120 . 8 , and the pixel element  70 . 8  is formed in a second semiconductor substrate  122 . 8 . The photoemitter  68 . 8  is similar in structure to a VCSEL disclosed in U.S. Pat. No. 6,590,917 by Nakayama et al., which is incorporated by reference herein. The photoemitter  68 . 8  includes an n-type GaAs substrate  150 , an epitaxial n-type GaAs layer  152 , an n-type DBR  154 , an active layer region  156 , a p-type DBR  158 , a first mode control layer  160 , a second mode control layer  162  and an electrode  164 .  
         [0069]     The photoemitter  68 . 8  is similar in structure to a VCSEL disclosed in U.S. Pat. No. 6,590,917 by Nakayama et al. The photoemitter  68 . 8  includes an n-type GaAs substrate  150 , an epitaxial n-type GaAs layer  152 , an n-type DBR  154 , an active layer region  156 , a p-type DBR  158 , a first mode control layer  160 , a second mode control layer  162  and an electrode  164 .  
         [0070]     Light  92 . 8 , again, is emitted substantially normal to a surface  140 . 8  having the advantage of increasing an external quantum efficiency and minimizing light emitted towards the photosensor structure  72 . 8 .  
         [0071]     Referring back to  FIGS. 4   a - h,  the light emitting and image sensing devices  60  and  60   b - h  include the plurality of pixel elements  70  and  70   b - h  respectively. Each one of the pixel elements  70  and  70   b - h  can be the pixel element  70 . 5  illustrated  FIG. 5 . In another embodiment, the pixel element  70 . 5  illustrated in  FIGS. 5 , and similarly the pixel elements  70 . 6 ,  70 . 7  and  70 . 8  illustrated in  FIGS. 6, 7 , and  8  respectively, can be arranged in a matrix configuration as illustrated in  FIG. 9 , wherein like parts have like reference numerals with an additional suffix. Four such pixel elements  70 . 9  are illustrated in  FIG. 9  in a matrix having two rows and two columns (2×2), however, there may be any number of rows and columns. Each pixel element  70 . 9  comprises a photosensor structure and an active pixel circuit indicated generally by reference numeral  72 . 9  and  170  respectively. The pixel element  70 . 9  is further illustrated in  FIG. 10 , wherein the active pixel circuit  170  is presented in greater detail. The operation of the pixel elements  70 . 9  is described in great detail in Merril.  
         [0072]     Again, referring back to  FIGS. 4   b - d  and  4   f - h,  the light emitting and image sensing devices  60   b - d  and  60   f - h  include a plurality of photoemitters  68   b - d  and  68   f - h  respectively. In another embodiment, a plurality of photoemitters  68 . 11  in a light emitting and image sensing device is controlled by a photoemitter controller  138 . 11  as illustrated in  FIGS. 11   a - b,  wherein like parts have like reference numerals with an additional suffix. The photoemitter controller  138 . 11  enables the photoemitters  68 . 11  to emit light, disables the emission of light and controls the intensity of emitted light. The photoemitter controller  138 . 11  can be an adjustable current source, for example, which is well known in the art. The light emitting and image sensing device includes the photoemitter controller  138 . 11 . In other embodiments, the photoemitter control means  138 . 11  can be external of a light emitting and image sensing device. In this case, the photoemitters  68 . 11  are connected to the photoemitter controller  138 . 11  by an electrical connector for example a connecting pin, or pad.  
         [0073]     Referring back to  FIGS. 5 , and similarly with  FIGS. 6, 7  and  8 , the trench  88  operates to reduce light transmission from the photoemitter  68 . 5  towards the pixel element  70 . 5 . In another embodiment of the invention illustrated in  FIG. 12 , wherein like parts have like reference numerals with an additional suffix, a trench  88 . 12  separates two regions in a semiconductor layer  74 . 12 , for instance a silicon layer. The trench  88 . 12  extends from a surface  172  to a boundary surface  174  between the semiconductor layer  74 . 12  and a layer  78 . 12 , for instance a silicon oxide (SiO 2 ) layer. A light emitting region  62 . 12  and an image sensing region  64 . 12  correspond to the corresponding regions in the light emitting and image sensing devices  60 ,  60 . b  and  60 . c  of  FIGS. 4   a - c  respectively. The trench  88 . 12  serves to substantially reduce light transmission from the light emitting region  62 . 12  through the semiconductor layer  74 . 12  towards the image sensing region  64 . 12 . When the semiconductor layer  74 . 12  is silicon (or doped silicon) the trench  88 . 12  can have a wall, next to the light emitting region  62 . 12 , which has a film of silicon oxide (SiO 2 ) thereon.  
         [0074]     In another embodiment of the invention illustrated in  FIG. 13 , wherein like parts have like reference numerals with an additional suffix, a trench  88 . 13  in a semiconductor substrate  74 . 13  separates a light emitting region  62 . 13  and an image sensing region  64 . 13 . The light emitting region  62 . 13  and the image sensing region  64 . 13  correspond to the corresponding regions in the light emitting and image sensing devices  60   e - g  of  FIGS. 4   e - g  respectively. Again, the trench  88 . 13  serves to substantially reduce light transmission from the light emitting region  62 . 13  through the semiconductor layer  74 . 13  towards the image sensing region  64 . 13 .  
         [0075]      FIG. 14  illustrates another embodiment of the invention, wherein like parts have like reference numerals with an additional suffix. A plurality of trenches  88 . 14  in a semiconductor substrate  74 . 14  separate a plurality of light emitting regions  62 . 14  from an image sensing region  64 . 14 . The plurality of light emitting regions  62 . 14  contain photoemitters corresponding to the photoemitters  68 . h  of the light emitting and image sensing device  60 . h  of  FIG. 4   h.  The image sensing region  64 . 14  contains a plurality of pixel elements corresponding to the pixel elements  70 . h  of the light emitting and image sensing device  60   h  of  FIG. 4   h.    
         [0076]     Another embodiment of the invention is illustrated in  FIGS. 15 and 16 , wherein like parts have like reference numerals with an additional suffix. Referring to  FIG. 16  first, a light emitting and image sensing device  60 . 16  is mounted on a substrate  182 , for instance a printed circuit board (PCB), and a single light channel housing  180  is mounted to the substrate overtop the light emitting and image sensing device. The light emitting and image sensing device  60 . 16  in this embodiment can be the device  60 . h  illustrated in  FIG. 4   h.    
         [0077]     Referring to  FIGS. 15 and 16 , the single channel housing  180  has a first end  184  and a second end  186  and a light channel  185 . A lens  188  is attached at the first end  184 . The first and second ends  184  and  186  can have different shapes, for instance circular, square or rectangular. The light channel  185  has an inner surface  187 . The inner surface  187  can be shaped such that at the first end  184  it is one shape, for instance annular, and at the second end  186  it is a second shape, for instance square, with a smooth transformation of the inner surface between the ends  184  and  186 .  
         [0078]     Another embodiment of the invention is illustrated in  FIGS. 17 and 18 , wherein like parts have like reference numerals with an additional suffix. Referring to  FIG. 18  first, a light emitting and image sensing device  60 . 18  is mounted on a substrate  182 . 18 , and an adjacent light channel housing  180 . 18  is mounted to the substrate overtop the light emitting and image sensing device. The light emitting and image sensing device  60 . 18  in this embodiment can be either one of the devices  60 . e,    60 . f  and  60 . g  illustrated in  FIGS. 4   e,    4   f  and  4   g  respectively.  
         [0079]     Referring to  FIGS. 17 and 18 , the adjacent light channel housing  180 . 18  has a first light channel  190  adjacent a second light channel  192 . The first light channel  190  has opposite ends  194  and has a lens  198  attached at one end thereof. The lens  198  can be biconcave as well as other types of diverging lenses. Light from a light emitting region  62 . 18  of the light emitting and image sensing device  60 . 18  travels through lens  198  towards a scene, or an object. The lens  200  can be biconvex as well as other types of converging lenses. The opposite ends  194  can have different shapes, for instance circular, rectangular or square. The second light channel has opposite ends  196  and has a lens  200  attached at one end thereof. Light from the scene or the object travels through lens  200  towards an image sensing region  64 . 18  of the light emitting and image sensing device  60 . 18 . The opposite ends  196  can have different shapes, for instance circular, rectangular or square.  
         [0080]     Another embodiment of the invention is illustrated in  FIGS. 19 and 20 , wherein like parts have like reference numerals with an additional suffix. Referring to  FIG. 20  first, a light emitting and image sensing device  60 . 20  is mounted on a substrate  182 . 20 , and a dual light channel housing  180 . 20  is mounted to the substrate overtop the light emitting and image sensing device. The light emitting and image sensing device  60 . 20  in this embodiment can be either of the devices  60 ,  60 . b  and  60 . c  of  FIGS. 4   a,    4   b  and  4   c  respectively.  
         [0081]     Referring to  FIGS. 19 and 20 , the dual light channel housing  180 . 20  has a first light channel  190 . 20 , having an axis  191 , and a second light channel  192 . 20  having the same axis  191 . The first light channel has opposite ends  194 . 20  and has a lens  198 . 20  attached at one end thereof. The lens  198 . 20  can be biconcave as well as other types of diverging lenses. Light from a light emitting region  62 . 20  of the light emitting and image sensing device  60 . 20  travels through the lens  198 . 20  and towards a scene, or an object. The opposite ends  194 . 20  can have different shapes, for instance circular, rectangular or square. The second light channel has opposite ends  196 . 20  and has a lens  200 . 20  attached at one end thereof. The lens  200 . 20  can be biconvex as well as other types of converging lenses. Light from the scene, or the object, travels through the lens  200 . 20  towards an image sensing region  64 . 20  of the light emitting and image sensing device  60 . 20 . The opposite ends  196 . 20  can have different shapes, for instance circular, rectangular or square. Typically, the shapes of the opposite ends  194 . 20  of the first light channel  190 . 20  correspond to the shapes of the opposite ends  196 . 20  of the second light channel  192 . 20 .  
         [0082]     Another embodiment of the invention is illustrated in  FIG. 21  wherein like parts to previous embodiments have like reference numerals with an additional suffix ‘ 21 ’. A first semiconductor substrate  120 . 21  is illustrated above a second semiconductor substrate  122 . 21 . The first semiconductor substrate  120 . 21  can be formed from Ill-V or II-VI compound semiconductor materials, or organic polymers, whereas the second semiconductor substrate  122 . 21  is formed from silicon. A photoemitter  68 . 21  is formed in the first semiconductor substrate  120 . 21 , and a pixel element  70 . 21  is formed in the second semiconductor substrate  122 . 21 . The pixel element  70 . 21  is similar to the pixel element  70 . 5  in  FIG. 5 . The photoemitter  68 . 21  can be in the form of an infrared LED, an organic LED, or an RGB LED.  
         [0083]     Another embodiment of the present invention is illustrated in  FIGS. 22 and 23  wherein like parts to previous embodiments have like reference numerals with an additional suffix ‘ 22 ’. There is a light emitting and image sensing device  60 . 22  connected with a printed circuit board  212 . The light emitting and image sensing device  60 . 22  has a plurality of pixel elements  70 . 22  on one side of the device  60 . 22 . The pixel elements  70 . 22  transform image light into electrical signals. On the opposite side of the device  60 . 22  is a photoemitter  210 . The photoemitter  210  is electrically coupled to the pixel elements  70 . 22 , however other forms of coupling such as optical coupling can be used. The photoemitter  210  sequentially emits light signals representative of respective ones of the electrical signals of the pixel elements  70 . 22 . In other embodiments, the electrical signals of the pixel elements  70 . 22  can be encoded into an encoded signal, which can be emitted in the form of an encoded light signal by the photoemitter  210 . The photoemitter  210  transfers the electrical image captured by the device  60 . 22  off the device into an optical coupler  216  through a channel  214  in the printed circuit board  212 . The optical coupler  216  is connected with a fiber optic cable  218  which carries the light signals generated by the photoemitter  210  to a remote desination.  
         [0084]     Referring to  FIG. 23 , a more detailed description of the light emitting and image sensing device is now given. A first semiconductor substrate  122 . 22  is illustrated above a second semiconductor substrate  120 . 22 . The first semiconductor substrate  122 . 22  is formed from silicon. The second semiconductor substrate  120 . 22  can be formed from Ill-V or II-VI compound semiconductor materials, or organic polymers. A pixel element  70 . 22  is formed in the first semiconductor substrate  122 . 22 . The pixel element  70 . 22  is similar to the pixel element  70 . 5  in  FIG. 5 , however other pixel element structures are possible. A photoemitter  210  is formed in the second semiconductor substrate  120 . 22 . The photoemitter  210  can be in the form of an infrared LED, an RCLED, or a VCSEL, as described previously, but other forms are possible as well. The pixel elements  70 . 22  can be arranged in a matrix configuration as illustrated in  FIG. 9  and described previously. Each of the pixel elements  70 . 22  is similar to the pixel element illustrated in  FIG. 10  and described previously. Note that other pixel element configurations and structures are possible, and this example is not intended to limit the invention. The photoemitter  210  can include a photoemitter controller, similar to that illustrated in  FIGS. 11   a  or  11   b,  and described earlier, however other photoemitter controllers are possible. Note that in other embodiments the photoemitter  210  can be formed in a silicon layer  78 . 22  of the first semiconductor substrate  122 . 22 , e.g. similar to the photoemitter in  FIGS. 5 and 6 .  
         [0085]     As will be apparent to those skilled in the art, modifications can be made to the above-described invention within the scope of the appended claims.