WO2013099151A1 - 固体撮像素子、撮像装置、および信号処理方法 - Google Patents
固体撮像素子、撮像装置、および信号処理方法 Download PDFInfo
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- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
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- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
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Definitions
- This application relates to a technology for increasing the sensitivity and color of a solid-state imaging device.
- image sensors In recent years, there has been a remarkable increase in functionality and performance of digital cameras and digital movies using solid-state image sensors such as CCDs and CMOSs (hereinafter sometimes referred to as “image sensors”). In particular, due to rapid progress in semiconductor manufacturing technology, the pixel structure in an image sensor has been miniaturized. As a result, the pixels of the image sensor and the drive circuit are highly integrated, and the performance of the image sensor is increasing. In particular, in recent years, a camera using a backside illumination type image sensor that receives light on the back surface side rather than the surface (front surface) side on which the wiring layer of the solid-state image sensor is formed has been developed, and its characteristics are attracting attention. ing. On the other hand, with the increase in the number of pixels of the image sensor, the amount of light received by one pixel is reduced, which causes a problem that the camera sensitivity is reduced.
- ⁇ The sensitivity of the camera is reduced due to the use of color filters for color separation in addition to the increase in the number of pixels.
- a subtractive color filter using an organic pigment as a coloring matter is arranged facing each photosensitive cell of the image sensor. Since the color filter absorbs light other than the color component to be used, when such a color filter is used, the light utilization rate of the camera is lowered.
- each color filter of R, G, B is Only the R, G, B light is transmitted and the remaining light is absorbed. Therefore, the light used in the color camera with the Bayer array is about 1/3 of the entire incident light.
- Japanese Patent Application Laid-Open No. H10-228561 discloses a technique for increasing the amount of received light by attaching a microlens array to the light receiving portion of the image sensor in order to capture much incident light.
- the light aperture ratio in the image sensor can be substantially improved by condensing the light sensing cell using the microlens.
- This technique is currently used in most solid-state image sensors. If this technique is used, the substantial aperture ratio is certainly improved, but it does not solve the problem of a decrease in the light utilization rate due to the color filter.
- Patent Document 2 discloses a technique for making maximum use of light by combining a multilayer color filter (dichroic mirror) and a microlens.
- a multilayer color filter dichroic mirror
- a microlens a plurality of dichroic mirrors that selectively transmit light in a specific wavelength region and reflect light in other wavelength regions without absorbing light are used.
- FIG. 10 is a diagram schematically showing a cross section in a direction perpendicular to the imaging surface of the imaging device disclosed in Patent Document 2.
- the imaging device includes condensing microlenses 4a and 4b, a light shielding unit 20, photosensitive cells 2a, 2b, and 2c, and dichroic mirrors 17, 18, and 19 disposed on and inside the imaging device, respectively. It has.
- the dichroic mirrors 17, 18, and 19 are disposed so as to face the photosensitive cells 2a, 2b, and 2c, respectively.
- the dichroic mirror 17 has characteristics of transmitting R light and reflecting G light and B light.
- the dichroic mirror 18 has a characteristic of reflecting G light and transmitting R light and B light.
- the dichroic mirror 19 has characteristics of reflecting B light and transmitting R light and G light.
- the light incident on the microlens 4 a is incident on the first dichroic mirror 17 after the light flux is adjusted by the microlens 4 b.
- the first dichroic mirror 17 transmits R light but reflects G light and B light.
- the light transmitted through the first dichroic mirror 17 is incident on the photosensitive cell 2a.
- the G light and B light reflected by the first dichroic mirror 17 are incident on the adjacent second dichroic mirror 18.
- the second dichroic mirror 18 reflects G light out of incident light and transmits B light.
- the G light reflected by the second dichroic mirror 18 enters the photosensitive cell 2b.
- the B light transmitted through the second dichroic mirror 18 is reflected by the third dichroic mirror 19 and is incident on the photosensitive cell 2c immediately below it.
- Patent Document 3 discloses an image sensor that can prevent light loss by using a microprism.
- This imaging device has a structure in which different photosensitive cells receive light separated into red, green, and blue by a microprism. Such an image sensor can also prevent light loss.
- Patent Document 2 and Patent Document 3 it is necessary to provide as many photosensitive cells as the number of dichroic mirrors to be used or the number of spectrums. For example, in order to detect light of three colors of RGB, there is a problem that the number of photosensitive cells must be increased by a factor of three compared to the number of photosensitive cells when a conventional color filter is used.
- Patent Document 4 discloses a technique for increasing the utilization factor of light using a dichroic mirror and reflection.
- FIG. 11 shows a part of a cross-sectional view of an image sensor using the technique.
- dichroic mirrors 22 and 23 are disposed in a translucent resin 21.
- the dichroic mirror 22 has characteristics of transmitting G light and reflecting R light and B light.
- the dichroic mirror 23 has characteristics of transmitting R light and reflecting G light and B light.
- R light and G light can all be detected by the following principle.
- the R light is reflected by the dichroic mirror 22 and transmitted by the dichroic mirror 23.
- the R light reflected by the dichroic mirror 22 is further reflected at the interface between the translucent resin 21 and air and enters the dichroic mirror 23.
- the R light passes through the dichroic mirror 23, and further passes through the organic dye filter 25 and the microlens 26 having R light transmittance. In this way, although part of the light is reflected by the metal layer 27, most of the R light incident on the dichroic mirrors 22 and 23 is incident on the light sensing unit.
- the G light when the G light is incident on the dichroic mirrors 22 and 23, the G light is transmitted through the dichroic mirror 22 and reflected by the dichroic mirror 23.
- the G light reflected by the dichroic mirror 23 is further totally reflected at the interface between the translucent resin 21 and air, and enters the dichroic mirror 22.
- the G light passes through the dichroic mirror 22, and further passes through the organic dye filter 24 and the micro lens 26 having G light transmittance. In this way, although part of the light is reflected by the metal layer 27, most of the G light incident on the dichroic mirrors 22 and 23 is incident on the light sensing unit without any loss.
- the technique disclosed in Patent Document 4 can receive two colors with almost no loss, although one color of RGB light is lost. For this reason, it is not necessary to arrange the light sensing units for the three colors RGB.
- the light utilization rate with only the organic dye filter is about 3
- the light utilization factor when using this technique is about 2/3 of the total incident light. That is, according to this technique, the imaging sensitivity is improved about twice. However, even with this technique, one of the three colors is lost.
- Patent Document 5 discloses a colorization technique that increases the light utilization rate without significantly increasing the number of photosensitive cells using a spectral element. According to this technique, light is incident on different photosensitive cells depending on the wavelength range by the spectral elements arranged corresponding to the photosensitive cells. Each photosensitive cell receives light on which components in different wavelength ranges are superimposed from a plurality of spectral elements. As a result, a color signal can be generated by signal calculation using a photoelectric conversion signal output from each photosensitive cell.
- this colorization technique is suitable for an image sensor with a cell pitch of about 1 micron, the colorization performance tends to deteriorate as the cell pitch increases.
- Embodiments of the present invention can increase the light utilization rate without significantly increasing the number of photosensitive cells, and can perform color reproduction even when using a high-sensitivity imaging device with a cell pitch greatly exceeding 1 micron. Provide color imaging technology with good characteristics.
- a solid-state imaging device includes a first photosensitive cell, a second photosensitive cell, a third photosensitive cell, and a fourth photosensitive cell.
- the light received by each photosensitive cell is the cell incident light of each photosensitive cell, and the visible light included in the cell incident light includes the first color component
- the second When the visible light of the color component excluding each color component is used as the complementary color light of the color component, the spectral element array includes the color component and the third color component. A part of the light of the first color component included in the cell incident light of each of the first and second photosensitive cells is incident on the first photosensitive cell, and the second type of spectral element is used. A part of the light of the second color component included in the cell incident light of each of the third and fourth photosensitive cells is incident on the fourth photosensitive cell.
- the light utilization rate is high and the cell pitch is 1 without significantly increasing the number of photosensitive cells.
- Color imaging with high color reproducibility is possible even for highly sensitive imaging devices that greatly exceed micron.
- FIG. 2B is a diagram showing the amount of light received by each photosensitive cell in the configuration shown in FIGS. 2A to 2E.
- FIG. 3B is a sectional view taken along line BB ′ in FIG. 3A. It is CC 'sectional view taken on the line in FIG. 3A. It is DD 'sectional view taken on the line in FIG. 3A.
- FIG. 4 is a diagram showing the amount of light received by each photosensitive cell in the configuration shown in FIGS. 3A to 3E. It is a block diagram which shows schematic structure of the imaging device of Embodiment 1 of this invention. It is a figure which shows the lens and imaging device in Embodiment 1 of this invention.
- FIG. 8 is a diagram showing the amount of light received by each photosensitive cell in the configuration shown in FIGS.
- FIG. 6 is a plan view showing a basic structure of an image sensor in a modification of the first embodiment. It is AA 'line sectional drawing in FIG. 9A.
- FIG. 9B is a sectional view taken along line BB ′ in FIG. 9A. It is sectional drawing of the conventional image pick-up element using a micro lens and a multilayer film filter (dichroic mirror). It is sectional drawing of the conventional image pick-up element using a multilayer filter (dichroic mirror) and reflection.
- a solid-state imaging device includes a first photosensitive cell, a second photosensitive cell, a third photosensitive cell, and a fourth photosensitive cell.
- the light received by each photosensitive cell is the cell incident light of each photosensitive cell, and the visible light included in the cell incident light includes the first color component
- the second When the visible light of the color component excluding each color component is used as the complementary color light of the color component, the spectral element array includes the color component and the third color component. A part of the light of the first color component included in the cell incident light of each of the first and second photosensitive cells is incident on the first photosensitive cell, and the second type of spectral element is used. A part of the light of the second color component included in the cell incident light of each of the third and fourth photosensitive cells is incident on the fourth photosensitive cell.
- each of the first to fourth photosensitive cells has a quadrangular shape, and the first to fourth photosensitive cells are arranged in two rows and two columns, and The type of spectral element is disposed at a position facing the boundary between the first and second photosensitive cells, and the second type of spectral element is opposed to the boundary between the third and fourth photosensitive cells. It is arranged at the position to do.
- the first type of spectral element is further disposed at a position facing a boundary between the first and third photosensitive cells, and the second type of spectral element is further It arrange
- the first type of spectroscopic element further converts a part of the light of the first color component included in cell incident light of each of the first and third photosensitive cells to the first.
- the second type spectral element is further incident on one of the light-sensitive cells of the second color component included in the light incident on each of the second and fourth light-sensitive cells. Part is incident on the fourth photosensitive cell.
- the first type of spectroscopic element includes a part of light of the first color component out of cell incident light of each of the first and second photosensitive cells. The remaining light of the first color component and the complementary color light of the first color component are incident on the second photosensitive cell.
- the second type of spectroscopic element is configured to transfer, to the fourth photosensitive cell, a part of the light of the second color component out of the cell incident light of each of the third and fourth photosensitive cells. The remaining light of the second color component and the complementary color light of the second color component are incident on the third photosensitive cell.
- the first type of spectral element further includes a part of the light of the first color component out of the cell incident light of each of the first and third photosensitive cells.
- the light is incident on the first photosensitive cell, and the remaining light of the first color component and the complementary color light of the first color component are incident on the third photosensitive cell.
- the second type of spectral element further includes a part of the light of the second color component out of the cell incident light of each of the second and fourth light sensing cells, and the fourth light sensing. The light is incident on the cell, and the remaining light of the second color component and the complementary color light of the second color component are incident on the second photosensitive cell.
- the first type of spectroscopic element includes four spectroscopic elements disposed at positions opposite to a peripheral boundary of the first photosensitive cell
- the second type of spectroscopic element includes: , Including four spectral elements disposed at positions facing the peripheral boundary of the fourth photosensitive cell.
- the first color component is one of red and blue
- the second color component is the other of red and blue
- each of the first-type spectral element and the second-type spectral element includes a light-transmitting member, the shape of the light-transmitting member, and the light-transmitting member and the light-transmitting member Spectroscopy is performed using a difference in refractive index with another light-transmitting member having a refractive index lower than that of the light-transmitting member.
- An imaging apparatus includes any one of the solid-state imaging devices described above, an optical system that forms an image on the solid-state imaging device, and a signal processing unit that processes a signal output from the solid-state imaging device.
- a signal processing unit that generates color information by calculation using a third photoelectric conversion signal and a fourth photoelectric conversion signal output from the fourth photosensitive cell.
- the signal processing unit calculates a difference between the first photoelectric conversion signal and an average value of the first to fourth photoelectric conversion signals, and the fourth photoelectric conversion signal and the first to fourth photoelectric conversion signals.
- a first color difference signal and a second color difference signal are generated by a difference calculation with the fourth photoelectric conversion signal.
- a signal processing method is a method for processing a signal output from any one of the solid-state imaging devices described above, and includes a first photoelectric conversion signal output from the first photosensitive cell, The second photoelectric conversion signal output from the second photosensitive cell, the third photoelectric conversion signal output from the third photosensitive cell, and the fourth photoelectric signal output from the fourth photosensitive cell.
- Step A for acquiring the photoelectric conversion signal of the first and fourth steps for generating color information using the first to fourth photoelectric conversion signals.
- the step B includes a step of generating a first difference signal generated by calculating a difference between the first photoelectric conversion signal and the second photoelectric conversion signal, and the third photoelectric conversion. Generating a second difference signal generated by calculating a difference between the signal and the fourth photoelectric conversion signal.
- the step B includes the addition of the first and second photoelectric conversion signals, the addition of the third and fourth photoelectric conversion signals, and the addition of the first to fourth photoelectric conversion signals.
- a solid-state imaging device includes a photosensitive cell array including a plurality of photosensitive cells (pixels) arranged two-dimensionally on an imaging surface, and a spectral element array including a plurality of spectral elements.
- FIG. 1 is a perspective view schematically showing a part of the photosensitive cell array 200 and the spectral element array 100 formed on the imaging surface of the solid-state imaging device 10.
- the spectral element array 100 is disposed on the light incident side facing the photosensitive cell array 200.
- the arrangement, shape, size, and the like of the photosensitive cells 2 are not limited to the example shown in this figure, and may be any known arrangement, shape, and size.
- the spectral element array 100 is represented by a quadrangular prism for convenience, the spectral element array 100 does not actually have such a shape and can have various structures.
- the spectral element array 100 includes a plurality of spectral elements. Each spectral element is, for example, a microlens or a transparent member having a high refractive index, and is designed to separate incident light in different directions depending on the wavelength.
- each light sensing cell 2 When each light sensing cell 2 receives light, it outputs an electrical signal (hereinafter referred to as a “photoelectric conversion signal” or a “pixel signal”) corresponding to the intensity of the light received by photoelectric conversion (incident light amount). To do.
- each photosensitive cell 2 receives light in a plurality of wavelength regions (color components) whose traveling directions are changed by the spectral element array 100.
- the light received by each photosensitive cell 2 has a spectral distribution (intensity distribution for each wavelength range) different from the light received when it is assumed that there is no spectral element.
- the spectral element array 100 does not necessarily split all incident light, but splits by a certain ratio k (k is a real number that is greater than 0 and equal to or less than 1).
- FIG. 2A is a plan view showing an example of a basic pixel configuration (unit block) 40 of the photosensitive cell array 200.
- FIG. The photosensitive cell array 200 has a structure in which a plurality of unit blocks 40 each including four photosensitive cells 2a, 2b, 2c, and 2d are two-dimensionally arranged on the imaging surface. In the example shown in the figure, four photosensitive cells are arranged in two rows and two columns in one unit block. Each photosensitive cell has a quadrangular shape. This configuration is merely an example, and the arrangement and shape of the photosensitive cells are not limited to this example.
- the spectral element array 100 has a plurality of spectral elements as described above. Of the light incident on the spectral element array 100, light corresponding to the ratio k is split by these spectral elements, and the light corresponding to the ratio (k-1) is transmitted without being split.
- the spectral element array includes a first type of spectral element and a second type of spectral element having different spectral characteristics. Each spectral element separates incident light in different directions according to color components using refraction and diffraction.
- 2B and 2C show the state of spectroscopy in the horizontal direction (x direction shown in FIG. 2A), and the cross sectional views shown in FIGS. 2D and 2E show in the vertical direction (y direction shown in FIG. 2A). The state of spectroscopy is shown.
- the light received by each photosensitive cell is referred to as “cell incident light” of the photosensitive cell.
- the photosensitive cells 2a to 2d included in one unit block 40 are close to each other, it can be considered that the light intensity and the spectral distribution included in the cell incident light of the photosensitive cells are substantially the same.
- the intensity of the visible light component of the cell incident light of these photosensitive cells is represented by the symbol “W”.
- the light intensity of the cell incident light ratio k is expressed by adding k to the light intensity. Then, of the cell incident light of each photosensitive cell, the intensity of the light split by the spectral element is expressed by kW, and the intensity of the light not split is expressed by (1-k) W.
- the visible light color component excluding each color component is referred to as “complementary color” of the color component
- the complementary color light is referred to as “complementary color light”.
- the complementary color of the first color component C1 is represented by C2 + C3
- the complementary color of the second color component C2 is represented by C1 + C3
- the complementary color of the third color component C3 is represented by C1 + C2.
- the complementary color of the color component Cn (Cn is any one of C1, C2, and C3) and its intensity may be represented by Cn ⁇ .
- the combination of the first to third color components is typically a combination of three primary colors of red (R), green (G), and blue (B), but divides visible light into three wavelength ranges. Any other combination of color components may be used.
- the operation of the spectral element array 100 in the example shown in FIGS. 2A to 2E will be described.
- the spectroscopy is performed by the first type of spectral elements and the second type of spectral elements included in the spectral element array 100.
- the first type of spectral element is designed to separate incident light into light of the first color component and complementary color light of the first color component.
- the second type of spectral element is designed to separate incident light into light of the second color component and complementary color light of the second color component.
- the spectral element array 100 divides the light (intensity kW) of k times among the incident light (intensity W) of each cell of the first photosensitive cell 2a and the second photosensitive cell 2b.
- the light of the first color component (intensity kC1) in the spectrum is supplied to the first photosensitive cell 2a, and the complementary color light (intensity kC1 ⁇ ) of the first color component in the spectrum is detected as the second light.
- W ′ (1 ⁇ k) W
- FIG. 2B light represented by arrows is incident on the first photosensitive cell 2a and the second photosensitive cell 2b from both sides, and the total of these lights.
- kC1 and kC1 ⁇ respectively.
- the spectroscopy is performed by the first type of spectral element.
- the spectral element array 100 divides the light (intensity kW) that is k times of the incident light (intensity W) of each of the third photosensitive cell 2c and the fourth photosensitive cell 2d. Then, the light (intensity kC2) of the second color component in the spectrum is supplied to the fourth photosensitive cell 2d, and the complementary color light (intensity kC2 ⁇ ) of the second color component in the spectrum is supplied to the third cell.
- the spectral element array 100 splits light (intensity kW) that is k times of the incident light (intensity W) of each cell of the first photosensitive cell 2a and the third photosensitive cell 2c.
- the light of the first color component (intensity kC1) in the spectrum is supplied to the first photosensitive cell 2a, and the complementary color light (intensity kC1 ⁇ ) of the first color component in the spectrum is supplied to the third light.
- the spectral element array 100 divides k times (intensity kW) of each cell incident light (intensity W) of the second photosensitive cell 2b and the fourth photosensitive cell 2d. Then, the light of the second color component (intensity kC2) in the spectrum is supplied to the fourth photosensitive cell 2d, and the complementary color light (intensity kC2 ⁇ ) of the second color component in the spectrum is supplied to the second light detection cell 2d.
- FIG. 2F is a diagram showing the intensity of light received by each photosensitive cell.
- the photosensitive cells 2a, 2b, 2c, and 2d receive light having the intensities represented by kC1, kC1 ⁇ , kC2 ⁇ , and kC2, respectively, in the vertical direction.
- the light of the intensity represented by kC1, kC2 ⁇ , kC1 ⁇ , and kC2 is received by the direction spectroscopy.
- Each light sensitive cell receives in addition to it the unsplit light of intensity W '.
- the photosensitive cells 2a, 2b, 2c and 2d have the intensities represented by W ′ + 2kC1, W ′ + kC1 ⁇ + kC2 ⁇ , W ′ + kC1 ⁇ + kC2 ⁇ and W ′ + 2kC2, respectively, as shown in FIG. 2F.
- Each photosensitive cell outputs a photoelectric conversion signal (pixel signal) corresponding to these intensities.
- S2a to S2d can be expressed by the following formulas 1 to 4, respectively.
- S2a W's + 2kC1s
- the ratio k of the splitting light to the incident light is a design value and is known
- (1-k) Sav is subtracted from the signal S2a. Dividing by 2k gives C1s.
- (1-k) Sav is subtracted from signal S2d and divided by 2k
- C2s is obtained.
- C3s is obtained by subtracting 2Sav from the signal (S2b + S2c) and dividing by 2k.
- the color signals of C1s, C2s, and C3s are obtained by the calculations of Expressions 5 to 7.
- the color signal can be calculated by signal calculation based on the four photoelectric conversion signals S2a to S2d output from the photosensitive cells 2a to 2d.
- FIG. 3A is a plan view showing the unit block 40 of the photosensitive cell array 200 in this example.
- the unit block 40 of the photosensitive cell 200 has a configuration similar to that shown in FIG. 2A.
- the spectral element array 100 includes a first type of spectral element and a second type of spectral element.
- the first type of spectral element converts incident light into a part of the first color component light, a remaining part of the first color component light, and a complementary color light of the first color component light. To separate.
- the second type of spectral element converts incident light into a part of the second color component light, a remaining part of the second color component light, and a complementary color light of the second color component light. To separate.
- the incident light to each photosensitive cell will be described separately in the horizontal direction and the vertical direction.
- the spectral element array 100 divides the light (intensity kW) of k times out of the cell incident light (intensity W) of the first photosensitive cell 2a and the second photosensitive cell 2b. Half of the light of the first color component in the spectrum (intensity kC1 / 2) is sent to the first photosensitive cell 2a, and the other half of the light of the first color component in the spectrum (intensity kC1 /).
- the spectral element array 100 splits light (intensity kW) that is k times of the incident light (intensity W) of each of the third photosensitive cell 2c and the fourth photosensitive cell 2d.
- W ′ (1 ⁇ k) W
- the light represented by arrows from both sides is incident on the third photosensitive cell 2c and the fourth photosensitive cell 2d, and the total of these lights.
- the spectroscopy is performed by the second type of spectral element.
- the spectral element array 100 splits light (intensity kW) that is k times out of the incident light (intensity W) of each of the first photosensitive cell 2a and the third photosensitive cell 2c.
- Half of the light of the first color component in the spectrum (intensity kC1 / 2) is sent to the first photosensitive cell 2a, and the other half of the light of the first color component in the spectrum (intensity kC1 /).
- the spectral element array 100 divides the light (intensity kW) of k times out of the cell incident light (intensity W) of the second photosensitive cell 2b and the fourth photosensitive cell 2d.
- the light-sensitive cell 2b and the fourth light-sensitive cell 2d are made incident. As shown in FIG.
- the light represented by arrows from both sides is incident on the second photosensitive cell 2b and the fourth photosensitive cell 2d, and the total of these lights.
- the total of these lights are represented by kC2 ⁇ + kC2 / 2 and kC2 / 2, respectively.
- the spectroscopy is performed by the second type of spectral element.
- FIG. 3F is a diagram showing the intensity of light received by each photosensitive cell.
- the photosensitive cells 2a, 2b, 2c, and 2d have W ′ + kC1, W ′ + kC1 ⁇ + kC1 / 2 + kC2 ⁇ + kC2 / 2, W ′ + kC1 ⁇ + kC1 / 2 + kC2 ⁇ + kC2 / 2, W ′ + kC2, respectively. It receives light of the intensity represented by Each photosensitive cell outputs a photoelectric conversion signal (pixel signal) corresponding to these intensities.
- pixel signal photoelectric conversion signal
- the photoelectric conversion signals S2a to S2d output from the photosensitive cells 2a to 2d can be expressed by the following equations 8 to 11, respectively.
- S2a W's + kC1s
- S2b W's + kC1 ⁇ s + kC1s / 2 + kC2 ⁇ s + kC2s / 2
- S2c W's + kC1 ⁇ s + kC1s / 2 + kC2 ⁇ s + kC2s / 2
- S2d W's + kC2s
- a color signal can be calculated by signal calculation based on the four photoelectric conversion signals S2a to S2d output from the photosensitive cells 2a to 2d.
- color information can be obtained by signal calculation using a spectral element without using a color filter that absorbs part of light. Therefore, loss of light can be prevented and imaging sensitivity can be increased.
- the spectral element array 100 is depicted as a continuous element covering a plurality of photosensitive cells, but the spectral element array 4 is spatially separated. It may be an aggregate of a plurality of spectral elements.
- a spectral element for example, a high refractive index transparent member, a dichroic mirror, a microprism, etc., which will be described later, can be used.
- the spectral element array 100 in the present embodiment may be configured in any way as long as the photoelectric conversion signal shown in the above example is obtained.
- the spectral element array 100 may perform spectroscopy using a hologram element or the like.
- FIG. 4 is a block diagram illustrating the overall configuration of the imaging apparatus according to the first embodiment.
- the imaging apparatus according to the present embodiment is a digital electronic camera, and includes an imaging unit 300 and a signal processing unit 400 that generates a signal (image signal) indicating an image based on a signal transmitted from the imaging unit 300. ing. Note that the imaging device may generate only a still image or may have a function of generating a moving image.
- the imaging unit 300 is an optical lens 12 for imaging a subject, an optical filter 11, and a solid-state imaging device 10 (converting optical information imaged through the optical lens 12 and the optical filter 11 into an electrical signal by photoelectric conversion ( Image sensor).
- the imaging unit 300 further generates a basic signal for driving the imaging device 10, receives an output signal from the imaging device 10, and sends it to the signal processing unit 400, and signal generation / reception.
- an element driving unit 14 that drives the image sensor 10 based on the basic signal generated by the unit 13.
- the optical lens 12 is a known lens and may be a lens unit having a plurality of lenses.
- the optical filter 11 is a combination of a quartz low-pass filter for reducing moire patterns generated due to pixel arrangement and an infrared cut filter for removing infrared rays.
- the image sensor 10 is typically a CMOS or a CCD, and is manufactured by a known semiconductor manufacturing technique.
- the signal generation / reception unit 13 and the element driving unit 14 are configured by an LSI such as a CCD driver, for example.
- the signal processing unit 400 generates an image signal by processing a signal transmitted from the imaging unit 300, a memory 30 for storing various data generated in the process of generating the image signal, and the generated signal And an image signal output unit 16 for sending the image signal to the outside.
- the image signal generation unit 15 can be suitably realized by a combination of hardware such as a known digital signal processor (DSP) and software that executes image processing including image signal generation processing.
- the memory 30 is configured by a DRAM or the like. The memory 30 records the signal transmitted from the imaging unit 300 and temporarily records the image data generated by the image signal generation unit 15 and the compressed image data. These image data are sent to a recording medium (not shown) or a display unit via the image signal output unit 16.
- the imaging apparatus of the present embodiment may include known components such as an electronic shutter, a viewfinder, a power source (battery), and a flashlight, but a description thereof is omitted because it is not particularly necessary for understanding the present invention.
- the above configuration is merely an example, and publicly known elements can be used in appropriate combinations for the constituent elements other than the image sensor 10 and the image signal generation unit 15.
- FIG. 5 is a diagram schematically illustrating a state in which light transmitted through the lens 12 is incident on the image sensor 10 during exposure.
- the lens 12 can be generally composed of a plurality of lenses arranged in the optical axis direction, but is drawn as a single lens for simplicity.
- a photosensitive cell array including a plurality of photosensitive cells (pixels) arranged two-dimensionally is disposed on the imaging surface 10a of the imaging element 10. Each photosensitive cell is typically a photodiode, and outputs a photoelectric conversion signal (pixel signal) corresponding to the amount of incident light by photoelectric conversion.
- Light (visible light) transmitted through the lens 12 and the optical filter 11 is incident on the imaging surface 10a.
- the intensity of light incident on the imaging surface 10a and the distribution (spectral distribution) of the amount of incident light for each wavelength range differ depending on the incident position.
- the photosensitive cell array 200 includes a plurality of photosensitive cells arranged in a square lattice pattern on the imaging surface 10a as shown in FIG. 6A.
- the photosensitive cell array 200 includes a plurality of unit blocks 40, and each unit block 40 includes four photosensitive cells 2a, 2b, 2c, and 2d.
- the arrangement of the photosensitive cells is not such a square lattice arrangement, but may be, for example, an oblique arrangement shown in FIG. 6B or another arrangement.
- the four photosensitive cells 2a to 2d included in each unit block are preferably close to each other. By configuring, color information can be obtained.
- Each unit block may include five or more photosensitive cells.
- a spectral element array including a plurality of spectral elements is disposed on the light incident side facing the photosensitive cell array 200.
- one spectral element is provided for one boundary so as to surround each of the four photosensitive cells included in each unit block.
- the first type of spectral element 1a is arranged so as to cover at least a part of the boundary around the first photosensitive cell 2a.
- the second type of spectral element 1b is arranged so as to cover at least a part of the boundary around the fourth photosensitive cell 2d.
- the spectroscopic element in the present embodiment is an optical element that directs incident light in different directions according to the wavelength range by using diffraction of light generated at the boundary between two types of translucent members having different refractive indexes.
- This type of spectroscopic element consists of a high refractive index transparent member (core part) formed of a material having a relatively high refractive index and a low contact with each side surface of the core part formed of a material having a relatively low refractive index. And a refractive index transparent member (cladding portion). Due to the difference in refractive index between the core part and the clad part, a phase difference occurs between the light transmitted through the core part and diffraction occurs.
- a high refractive index transparent member may be referred to as a “spectral element” because spectroscopy is possible due to a difference in refractive index between the core portion and the cladding portion. Details of such a diffractive spectral element are disclosed in, for example, Japanese Patent No. 4264465.
- the spectral element array having the spectral elements as described above can be manufactured by performing thin film deposition and patterning by a known semiconductor manufacturing technique.
- the material (refractive index), shape, size, arrangement pattern, and the like of the spectral elements it becomes possible to separate and integrate light in a desired wavelength range into individual photosensitive cells.
- a signal corresponding to a necessary color component can be calculated from a set of photoelectric conversion signals output from each photosensitive cell.
- FIGS. 7A to 7F a back-illuminated image sensor is used.
- the type of the image sensor 10 is the back side illumination type or the front side illumination type, and the image sensor 10 may be the front side illumination type.
- the cell pitch of the image sensor is about 4 microns in both the horizontal direction and the vertical direction, which is a relatively high sensitivity image sensor.
- FIG. 7A is a plan view showing the basic structure of the image sensor 10.
- the spectroscopic elements 1a and 1b are arranged near the boundaries of the four photosensitive cells 2a, 2b, 2c, and 2d. A plurality of patterns having such a basic structure are repeatedly formed on the imaging surface 10a.
- the image pickup device 10 includes a semiconductor substrate 7 made of a material such as silicon, photosensitive cells 2a to 2d disposed in the semiconductor substrate 7, and a back surface side of the semiconductor substrate 7 (a light incident side). ) And a plate-like high refractive index transparent member 1a, 1b disposed inside the transparent layer 6a.
- a wiring layer 5 is formed on the surface side of the semiconductor substrate 7 (the side opposite to the light incident side).
- a fixed base 9 that supports the semiconductor substrate 7, the wiring layer 5, and the like is disposed on the surface side.
- the fixed substrate 9 is bonded to the semiconductor substrate 7 through the transparent layer 6b.
- the high refractive index transparent members 1a and 1b function as spectral elements.
- the image sensor 10 shown in FIGS. 7A to 7E can be manufactured by a known semiconductor manufacturing technique.
- the image sensor 10 shown in FIGS. 7A to 7E has a back-illuminated structure in which light enters each photosensitive cell from the opposite side of the wiring layer 5.
- the imaging element 10 of the present embodiment is not limited to such a structure, and may have a surface irradiation type structure that receives light from the surface side of the wiring layer 5.
- the first type of spectroscopic element 1a and the second type of spectroscopic element 1b have a rectangular cross section that is long in the direction in which light is transmitted. Spectroscopy by the difference in refractive index between them.
- the light-splitting element 1a surrounds the light-sensitive cell 2a and is disposed on the upper part of the boundary with the other light-sensitive cells, and the light-splitting element 1b surrounds the light-sensitive cell 2d and is located above the boundary with the other light-sensitive cell. Is arranged.
- the light-splitting element 1a splits incident light into cyan (Cy) light in the straight traveling direction and R light (with a light intensity of R / 8) in diagonal directions on both sides.
- the light-splitting element 1b splits incident light into yellow (Ye) light in the straight traveling direction and B light (light intensity of B / 4 each) in the diagonal direction on both sides.
- the spectral elements 1a and 1b are originally suitable for an image sensor with a photosensitive cell pitch of about 1 micron. However, the image sensor of this embodiment has a large photosensitive cell pitch of about 4 microns, so it does not split all incident light. , About 50% of the incident light is dispersed.
- the intensity of light incident on each photosensitive cell is represented by W
- W ′ the intensity of light that is not dispersed
- the ratio k of the spectrum is 1/2.
- the red, green, blue, yellow, and cyan light intensities are represented by R, G, B, Ye, and Cy, respectively.
- the spectral element 1a causes red (R) light to enter the photosensitive cell 2a from the upper, lower, left, and right directions by R / 8, and the spectral element 1b Blue (B) light is incident on the sensing cell 2d by B / 8.
- R red
- B spectral element 1b Blue
- the R light represented by the intensity R / 2 is incident on the photosensitive cell 2a from the surrounding four spectral elements 1a, and the intensity is input to the photosensitive cell 2d from the four surrounding spectral elements 1b.
- B light represented by B / 2 is incident.
- the light represented by the intensity R / 4 + Cy / 2 + B / 4 + Ye / 2 is incident on each of the light sensing cells 2b and 2c by both spectral elements.
- the light intensity of the light that is not split is not shown in the figure, but light of light intensity W ′ is incident on each photosensitive cell.
- FIG. 7B is a diagram showing a cross section taken along line AA ′ in FIG. 7A, and shows a situation in which the spectral element 1 a splits incident light and makes a part of the split light enter the photosensitive cells 2 a and 2 b.
- the spectral element 1a is not disposed directly above the boundary between the photosensitive cells 2a and 2b, but is slightly shifted to the photosensitive cell 2b side.
- R light is incident on the light sensing cell 2a by R / 8 (R / 4 in total) from the spectral elements 1a on both sides, and R light and Cy light are incident on the sensing cell 2b.
- FIG. 7C is a diagram showing a cross section taken along line BB ′ in FIG. 7A, and shows a situation in which the spectral element 1 b splits the incident light and causes a part of the split light to enter the photosensitive cells 2 c and 2 d.
- the spectral element 1b is not arranged directly above the boundary between the photosensitive cells 2c and 2d, but is slightly shifted to the photosensitive cell 2c side.
- B light is incident on the light-sensitive cell 2d by B / 8 from both sides of the spectral element 1b (B / 4 in total), and the B light and Ye light are incident on the light-sensitive cell 2c.
- 1b to B / 8 + Ye / 4 (B / 2 + Ye / 2 combined) are incident.
- FIG. 7D is a diagram showing a cross section taken along the line CC ′ in FIG. 7A, and shows a situation where the spectral element 1a splits the incident light and makes a part of the split light enter the photosensitive cells 2a and 2c.
- the spectral element 1a is not arranged directly above the boundary between the photosensitive cells 2a and 2c, but is slightly shifted to the photosensitive cell 2c side.
- R light is incident on the light-sensitive cell 2a by R / 8 (R / 4 in total) from the spectral elements 1a on both sides, and R light and Cy light are incident on the light-sensitive cell 2c.
- the light enters from Rb by R / 8 + Cy / 4 (R / 4 + Cy / 2 in total).
- FIG. 7E shows a DD ′ line cross section in FIG. 7A and shows a situation in which the spectral element 1b splits the incident light and causes a part of the split light to enter the photosensitive cells 2b and 2d.
- the spectral element 1b is not arranged directly above the boundary between the photosensitive cells 2b and 2d, slightly deviates toward the photosensitive cell 2b, and further, the lower end of the spectral element 1b slightly deviates in the center direction. .
- B light is incident on the light sensing cell 2d by B / 8 from the spectral elements 1b on both sides (B / 4 in total), and B light and Ye light are incident on the sensing cell 2b from the left and right directions B / 8 + Ye. / 4 each (when combined, B / 4 + Ye / 2).
- FIG. 7F is a diagram showing the intensity of light incident on each photosensitive cell.
- the light-sensitive cells 2a, 2b, 2c, and 2d have light intensities W ′ + R / 2, W ′ + R / 4 + Cy / 2 + B / 4 + Ye / 2, W, respectively.
- Light of “+ R / 4 + Cy / 2 + B / 4 + Ye / 2, W ′ + B / 4” is incident.
- the photosensitive cells 2a to 2d output photoelectric conversion signals S2a to S2d represented by the following equations 12 to 15, respectively.
- signals corresponding to the intensities of red light, green light and blue light are represented by Rs, Gs and Bs, respectively
- a signal Cs corresponding to the intensity of cyan light is Gs + Bs
- a signal Ys corresponding to the intensity of yellow light is Rs + Gs.
- S2a W's + Rs / 2 (Expression 13)
- S2d W's + Bs / 2
- the image signal generation unit 15 (FIG. 4) generates color information by calculation using the photoelectric conversion signals expressed by the equations 16 to 19.
- color information generation processing by the image signal generation unit 15 will be described with reference to FIG.
- FIG. 8 is a flowchart showing the procedure of color information generation processing in the present embodiment.
- the image signal generation unit 15 acquires photoelectric conversion signals S2a to S2d.
- an average value Sav of S2a to S2d is obtained, and Sav2, which is 1/2 of that, is calculated.
- Sav2 is subtracted from the pixel signals S2a and S2d to obtain R and B signals, and Sav2 of 5 times is subtracted from the addition result of the pixel signals S2b and S2c to obtain a G signal.
- step S16 the calculated R, G, and B signals are doubled to obtain RGB color signals as a set of pixel signals.
- the image signal generation unit 15 executes the above signal calculation for each unit block 40 of the photosensitive cell array 2 to thereby generate a signal (referred to as a “color image signal”) indicating an image of each color component of R, G, and B. Generate.
- the generated color image signal is output to a recording medium (not shown) or a display unit by the image signal output unit 16.
- a color image signal can be obtained by the addition / subtraction process using the photoelectric conversion signals S2a to S2d.
- the imaging device 10 in the present embodiment since an optical element that absorbs light is not used, light loss can be significantly reduced as compared with the conventional technology using a color filter or the like.
- the imaging device 10 of the present embodiment the upper part of the four boundary lines between the photosensitive cell in the first row and the first column and the other photosensitive cells facing the photosensitive cell array in the second row and the second column.
- a first type of spectral element 1a that divides light into red light and non-red light is disposed.
- a second type of spectral element 1b that divides light into blue light and non-blue light is disposed above four boundary lines between the photosensitive cell in the second row and the second column and the other photosensitive cells.
- the spectral elements 1a and 1b are arranged over the entire upper part of the photosensitive cells arranged in a two-dimensional manner with this configuration as a basic configuration.
- the four photoelectric conversion signals obtained are: It is always a combination of four signals represented by equations 16-19. That is, by performing the above signal calculation while shifting the pixel block to be calculated one row and one column at a time, it is possible to obtain information on each RGB color component by the number of pixels. This means that the resolution of the imaging device can be increased to the number of pixels.
- the imaging apparatus of the present embodiment can generate a color image with high resolution and high sensitivity in addition to higher sensitivity than the conventional imaging apparatus.
- the image signal generation unit 15 may perform signal amplification, synthesis, and correction as necessary.
- each spectral element has the above-described spectral performance strictly, but the spectral performance may be slightly shifted. That is, the photoelectric conversion signal actually output from each photosensitive cell may be slightly deviated from the photoelectric conversion signals shown in equations 16-19. Even when the spectral performance of each spectral element deviates from the ideal performance, good color information can be obtained by correcting the signal according to the degree of deviation.
- the signal calculation performed by the image signal generation unit 15 in the present embodiment can be executed not by the imaging apparatus itself but by another device.
- the color information can also be generated by causing an external device that has received an input of the photoelectric conversion signal output from the image sensor 10 to execute a program that defines the signal calculation processing in the present embodiment.
- the ratio k of the amount of light to be split with respect to the amount of incident light is 1 ⁇ 2, but this is merely an example.
- Expressions 12 to 15 are rewritten as Expressions 20 to 23 below, respectively.
- W ′s (1 ⁇ k)
- Ws (1 ⁇ k) (Rs + Gs + Bs).
- S2a W's + kRs
- S2b W's + kRs / 2 + kBs / 2 + k (Gs + Bs) + k (Rs + Gs)
- S2c W's + kRs / 2 + kBs / 2 + k (Gs + Bs) + k (Rs + Gs)
- S2d W's + kBs
- Rs is obtained by subtracting W's from S2a and multiplying by 1 / k
- Bs is obtained by subtracting W's from S2d and multiplying by 1 / k
- Gs is obtained by subtracting 5W's from the sum of S2b and S2c and multiplying by 1 / k
- W ′s is a value obtained by multiplying the average value Sav of S2a to S2d by k
- Sav is expressed by the following Expression 24. That is, Rs, Gs, and Bs color signals are obtained by the calculations shown in the following equations 24 to 27.
- a color signal may be obtained by the following processing.
- the image signal generator 15 can also obtain a color signal by generating these luminance signals and color difference signals from the photoelectric conversion signals S2a to S2d and performing RGB conversion on them.
- the basic structure of the image sensor 10 is not limited to the configuration shown in FIGS. 7A to 7F.
- the effect of this embodiment is not changed.
- a slight shift or inclination is given to the arrangement and structure of the spectral elements 1a and 1b, this is only for collecting specific colors in specific pixels, and is not limited to such a configuration.
- a spectral element that spatially separates light into RGB it is arranged around the pixel in the first row and first column, collects only the R light, and is arranged around the pixel in the second row and second column, and only the B light is emitted. It is also possible to collect light. If it does so, the effect similar to the colorization shown in the said embodiment can be acquired.
- the spectroscopic element is not limited as long as light of a desired color component can be incident on each photosensitive cell. It may be anything.
- a microprism or a dichroic mirror may be used as the spectral element. It is also possible to use different types of spectral elements in combination.
- the spectroscopy is performed in both the x direction and the y direction, but the present invention is not limited to such a configuration.
- the configuration may be such that spectroscopy is performed only in either the x direction or the y direction. Specifically, only in the horizontal direction shown in FIGS. 2B, 2C, 3B, 3C, 7B, and 7C, or in the vertical direction shown in FIGS. 2D, 2E, 3D, 3E, 7D, and 7E.
- the spectral element array 100 may be configured so that only the spectroscopy is performed. Examples of such a configuration are shown in FIGS. 9A to 9C.
- FIG. 9A is a diagram illustrating a basic configuration example of an imaging element configured to perform only horizontal spectroscopy.
- 9B is a cross-sectional view taken along line AA ′ in FIG. 9A
- FIG. 9C is a cross-sectional view taken along line BB ′ in FIG. 9A.
- the first type of spectral element 1a is arranged at the boundary between the first photosensitive cell 2a and the second photosensitive cell 2b.
- the light-splitting element 1a is configured to convert a part (intensity kC1) of the light of the first color component contained in the cell incident light of each of the first photosensitive cell 2a and the second photosensitive cell 2b to the first photosensitive cell.
- the complementary color light (intensity kC1 ⁇ ) is incident on the second photosensitive cell 2b.
- the second type of spectral element 1b is arranged at the boundary between the third photosensitive cell 2c and the fourth photosensitive cell 2d.
- the light-splitting element 1b converts a part of the light of the second color component (intensity kC2) included in the cell incident light of each of the third photosensitive cell 2c and the fourth photosensitive cell 2d to the fourth photosensitive cell. 2d, and the complementary color light (intensity kC2 ⁇ ) is incident on the third photosensitive cell 2c.
- Color signals C1s, C2s, and C3s can be obtained. Specifically, W ′s is obtained by multiplying the average value Sav of the signals of the four photosensitive cells by (1 ⁇ k), and W ′s is subtracted from the first and second photoelectric conversion signals S2a and S2d. The color signals C1s and C2s can be obtained. If the color signals C1s and C2s are obtained, the color signal C3s can also be obtained by calculating Sav ⁇ C1s ⁇ C2s.
- the solid-state imaging device, imaging apparatus, method, and program of the present disclosure are effective for all cameras that use the solid-state imaging device.
- it can be used for consumer cameras such as digital still cameras and digital video cameras, and industrial solid-state surveillance cameras.
- Photosensitive cell 4a 1a, 1b Spectral element 2, 2a, 2b, 2c, 2d Photosensitive cell 4a, 4b Microlens 5 Image sensor wiring layer 6a, 6b Transparent layer 7 Silicon substrate 9 Fixed substrate 10 Image sensor 11 Optical filter 12 Optical Lens 13 Signal generation / reception unit 14 Element drive unit 15 Image signal generation unit 16 Image signal output unit 17 Multilayer filter (dichroic mirror) reflecting other than red (R) 18 Multi-layer filter that reflects only green (G) (dichroic mirror) 19 Multilayer filter that reflects only blue (B) (dichroic mirror) 20 Light shielding part 21 Translucent resin 22 G light transmissive multilayer filter (dichroic mirror) 23 R light transmission multilayer filter (dichroic mirror) 24 G light transmitting organic dye filter 25 R light transmitting organic dye filter 26 Micro lens 27 Metal layer 30 Memory 40 Photosensitive cell unit block 100 Spectral element array 200 Photosensitive cell array 300 Imaging unit 400 Signal processing unit
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Abstract
Description
(式1) S2a=W’s+2kC1s
(式2) S2b=Ws’+kC1^s+kC2^s=Ws’+kWs+kC3s
(式3) S2c=Ws’+kC1^s+kC2^s=Ws’+kWs+kC3s
(式4) S2d=W’s+2kC2s
なお、これらS2a~S2dの信号を合計すると、4Ws’+2kC1s+2kC1^s+2kC2s+2kC2^s=4Ws’+4kWs=4(1-k)Ws+4kWs=4Wsとなることから、光損失が生じていないことがわかる。
(式5) C1s=(S2a-(1-k)Sav)/2k
(式6) C2s=(S2d-(1-k)Sav)/2k
(式7) C3s=(S2b+S2c-2Sav)/2k
すなわち、光感知セル2a~2dから出力される4つの光電変換信号S2a~S2dに基づく信号演算によってカラー信号を算出できる。
(式8) S2a=W’s+kC1s
(式9) S2b=W’s+kC1^s+kC1s/2+kC2^s+kC2s/2
(式10) S2c=W’s+kC1^s+kC1s/2+kC2^s+kC2s/2
(式11) S2d=W’s+kC2s
これらS2a~S2dの信号を合計すると、4W’s+2kC1s+2kC1^s+2kC2s+2kC2^s=4W’s+4kWs=4Wsとなることから、光損失が生じていないことがわかる。この場合も、割合kは設計値であり、既知であるため、式8~11からC1s、C2s、C3sの色信号を得ることができる。
図4は、第1の実施形態による撮像装置の全体構成を示すブロック図である。本実施形態の撮像装置は、デジタル式の電子カメラであり、撮像部300と、撮像部300から送出される信号に基づいて画像を示す信号(画像信号)を生成する信号処理部400とを備えている。なお、撮像装置は静止画のみを生成してもよいし、動画を生成する機能を備えていてもよい。
(式12)S2a=W’s+Rs/2
(式13)S2b=W’s+Rs/4+Bs/4+(Gs+Bs)/2+(Rs+Gs)/2=5W’s/2+Gs/4
(式14)S2c=W’s+Rs/4+Bs/4+(Gs+Bs)/2+(Rs+Gs)/2=5W’s/2+Gs/4
(式15)S2d=W’s+Bs/2
(式16)Sav=(S2a+S2b+S2c+S2d)/4
(式17)Rs=2(S2a-Sav/2)
(式18)Gs=2((S2b+S2c)-5Sav/2)
(式19)Bs=2(S2d-Sav/2)
(式20) S2a=W’s+kRs
(式21) S2b=W’s+kRs/2+kBs/2+k(Gs+Bs)+k(Rs+Gs)
(式22) S2c=W’s+kRs/2+kBs/2+k(Gs+Bs)+k(Rs+Gs)
(式23) S2d=W’s+kBs
(式24) Sav=(S2a+S2b+S2c+S2d)/4
(式25) Rs=(S2a-kSav)/k
(式26) Gs=((S2b+S2c)-5kSav)/k
(式27) Bs=(S2d-kSav)/k
2,2a,2b,2c,2d 撮像素子の光感知セル
4a、4b マイクロレンズ
5 撮像素子の配線層
6a、6b 透明層
7 シリコン基板
9 固定基板
10 撮像素子
11 光学フィルタ
12 光学レンズ
13 信号発生/受信部
14 素子駆動部
15 画像信号生成部
16 画像信号出力部
17 赤(R)以外を反射する多層膜フィルタ(ダイクロイックミラー)
18 緑(G)のみを反射する多層膜フィルタ(ダイクロイックミラー)
19 青(B)のみを反射する多層膜フィルタ(ダイクロイックミラー)
20 遮光部
21 透光性の樹脂
22 G光透過の多層膜フィルタ(ダイクロイックミラー)
23 R光透過の多層膜フィルタ(ダイクロイックミラー)
24 G光透過の有機色素フィルタ
25 R光透過の有機色素フィルタ
26 マイクロレンズ
27 金属層
30 メモリ
40 光感知セルの単位ブロック
100 分光要素アレイ
200 光感知セルアレイ
300 撮像部
400 信号処理部
Claims (14)
- 各々が第1の光感知セル、第2の光感知セル、第3の光感知セル、および第4の光感知セルを含む複数の単位ブロックが2次元状に配列された光感知セルアレイと、
前記光感知セルアレイに対向して配置された、第1の種類の分光要素および第2の種類の分光要素を含む分光要素アレイと、
を備え、
前記分光要素アレイが存在しないと仮定した場合に各光感知セルが受ける光を各光感知セルのセル入射光とし、前記セル入射光に含まれる可視光が、第1の色成分、第2の色成分、および第3の色成分から構成され、各色成分を除く色成分の可視光を、当該色成分の補色光とするとき、
前記分光要素アレイは、前記第1の種類の分光要素によって前記第1および第2の光感知セルの各々のセル入射光に含まれる前記第1の色成分の光の一部を前記第1の光感知セルに入射させ、前記第2の種類の分光要素によって前記第3および第4の光感知セルの各々のセル入射光に含まれる前記第2の色成分の光の一部を前記第4の光感知セルに入射させる、固体撮像素子。 - 前記第1から第4の光感知セルの各々の形状は4角形状であり、
前記第1から第4の光感知セルは、2行2列に配列され、
前記第1の種類の分光要素は、前記第1および第2の光感知セルの境界に対向する位置に配置され、
前記第2の種類の分光要素は、前記第3および第4の光感知セルの境界に対向する位置に配置されている、請求項1に記載の固体撮像素子。 - 前記第1の種類の分光要素は、さらに、前記第1および第3の光感知セルの境界に対向する位置に配置され、
前記第2の種類の分光要素は、さらに、前記第2および第4の光感知セルの境界に対向する位置に配置されている、
請求項2に記載の固体撮像素子。 - 前記第1の種類の分光要素は、さらに、前記第1および第3の光感知セルの各々のセル入射光に含まれる前記第1の色成分の光の一部を前記第1の光感知セルに入射させ、
前記第2の種類の分光要素は、さらに、前記第2および第4の光感知セルの各々のセル入射光に含まれる前記第2の色成分の光の一部を前記第4の光感知セルに入射させる、
請求項1から3のいずれかに記載の固体撮像素子。 - 前記第1の種類の分光要素は、前記第1および第2の光感知セルの各々のセル入射光のうち、前記第1の色成分の光の一部を、前記第1の光感知セルに入射させ、前記第1の色成分の光の残りおよび前記第1の色成分の補色光を、前記第2の光感知セルに入射させ、
前記第2の種類の分光要素は、前記第3および第4の光感知セルの各々のセル入射光のうち、前記第2の色成分の光の一部を、前記第4の光感知セルに入射させ、前記第2の色成分の光の残りおよび前記第2の色成分の補色光を、前記第3の光感知セルに入射させる、請求項1から4のいずれかに記載の固体撮像素子。 - 前記第1の種類の分光要素は、さらに、前記第1および第3の光感知セルの各々のセル入射光のうち、前記第1の色成分の光の一部を、前記第1の光感知セルに入射させ、前記第1の色成分の光の残りおよび前記第1の色成分の補色光を、前記第3の光感知セルに入射させ、
前記第2の種類の分光要素は、さらに、前記第2および第4の光感知セルの各々のセル入射光のうち、前記第2の色成分の光の一部を、前記第4の光感知セルに入射させ、前記第2の色成分の光の残りおよび前記第2の色成分の補色光を、前記第2の光感知セルに入射させる、
請求項5に記載の固体撮像素子。 - 前記第1の種類の分光要素は、前記第1の光感知セルの周囲の境界に対向する位置に配置された4つの分光要素を含み、
前記第2の種類の分光要素は、前記第4の光感知セルの周囲の境界に対向する位置に配置された4つの分光要素を含む、
請求項1から6のいずれかに記載の固体撮像素子。 - 前記第1の色成分は赤および青の一方の色成分であり、前記第2の色成分は赤および青の他方の色成分である、請求項1から7のいずれかに記載の固体撮像素子。
- 前記第1の種類の分光要素および前記第2の種類の分光要素の各々は、透光性部材を有し、前記透光性部材の形状、および前記透光性部材と前記透光性部材よりも屈折率の低い他の透光性部材との屈折率の差を利用して分光する、請求項1から8のいずれかに記載の固体撮像素子。
- 請求項1から9のいずれかに記載の固体撮像素子と、
前記固体撮像素子に像を形成する光学系と、
前記固体撮像素子から出力される信号を処理する信号処理部であって、前記第1の光感知セルから出力される第1の光電変換信号、前記第2の光感知セルから出力される第2の光電変換信号、および前記第3の光感知セルから出力される第3の光電変換信号、前記第4の光感知セルから出力される第4の光電変換信号を用いた演算によって色情報を生成する信号処理部と、
を備える撮像装置。 - 前記信号処理部は、前記第1の光電変換信号と前記第1から第4の光電変換信号の平均値との差分演算、および前記第4の光電変換信号と前記第1から前記第4の光電変換信号との差分演算により、第1の色差信号および第2の色差信号を生成する、請求項10に記載の撮像装置。
- 請求項1から9のいずれかの固体撮像素子から出力される信号を処理する方法であって、
前記第1の光感知セルから出力される第1の光電変換信号、前記第2の光感知セルから出力される第2の光電変換信号、前記第3の光感知セルから出力される第3の光電変換信号、および前記第4の光感知セルから出力される第4の光電変換信号を取得するステップAと、
前記第1から第4の光電変換信号を用いて色情報を生成するステップBと、
を含む信号処理方法。 - 前記ステップBは、
前記第1の光電変換信号と前記第2の光電変換信号との差分演算によって生成される第1の差分信号を生成するステップと、
前記第3の光電変換信号と前記第4の光電変換信号との差分演算によって生成される第2の差分信号を生成するステップと、
を含む、請求項12に記載の信号処理方法。 - 前記ステップBは、
前記第1および第2の光電変換信号の加算、前記第3および第4の光電変換信号の加算、および前記第1から第4の光電変換信号の加算のいずれかを含む演算によって輝度信号を生成するステップと、
前記輝度信号、前記第1の差分信号、および前記第2の差分信号を用いて前記セル入射光に含まれる赤、緑、および青の色信号を生成するステップと、
をさらに含む請求項13に記載の信号処理方法。
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