JP6093061B2 - Optical sensor and output circuit thereof - Google Patents

Description

  The present invention relates to an optical sensor and an output circuit thereof.

  Conventionally, a technique for extracting light in a specific area from sunlight is known. For example, Patent Document 1 discloses an ultraviolet sensor that receives ultraviolet light and outputs a photocurrent. Patent Document 2 discloses a semiconductor light receiving element that can detect the illuminance of only visible light among received light.

JP 2007-067331 A JP 2005-317994 A

  However, according to the prior art, desired light cannot be extracted with high accuracy due to the influence of the sensitivity shift caused by the ringing of the spectral sensitivity of the transmittance of the filter.

  For example, a case will be described in which light in the UV region R1 as shown in FIG. 21B is extracted from sunlight as shown in FIG. 21A using a UV cut filter and two photodiodes. In such a case, in order to extract the light in the UV region R1, from the “output of the photodiode A1 without filter” as shown in FIG. 22A, the “photo with filter” as shown in FIG. It is necessary to pull the output of the diode A2. However, when a UV cut filter is attached to the photodiode, for example, as shown in FIG. 23A, light other than UV light is transmitted, but ringing of the spectral sensitivity of the transmittance of the filter occurs. The ringing occurs because the reflected wave interferes between the filter surface and the lower part of the filter as shown in FIG. If the output of the photodiode A2 has ringing as shown in FIG. 22B, as shown in FIG. 22C, (output of the photodiode A1−output of the photodiode A2) is also other than the UV region R1. Light remains in the region, causing a sensitivity shift. As described above, conventionally, the manufacturing variation of the filter directly affects (the output of the photodiode A1−the output of the photodiode A2).

  An object of the present invention is to provide an optical sensor and an output circuit thereof that can reduce the sensitivity deviation due to ringing and achieve high accuracy.

According to one aspect of the present invention, a first photodiode, a second photodiode having different characteristics from the first photodiode, a first cut filter that cuts light in a specific wavelength region, and a second photodiode A cut filter, and the same configuration as the first photodiode, the third photodiode having the first cut filter on the light receiving surface, and the same configuration as the second photodiode, A fourth photodiode having the second cut filter on the light receiving surface; (output of the first photodiode−output of the third photodiode) − (output of the second photodiode−the output of the second photodiode; and an output circuit for calculating an output) of the fourth photodiode, (output of the first photodiode - output of the third photodiode) - ( (The output of the second photodiode−the output of the fourth photodiode)), the current values of the first to fourth photodiodes are set so that the current value in the region other than the specific wavelength region becomes zero. An optical sensor having a pre-adjusted area is provided.
According to another aspect of the present invention, a first photodiode, a second photodiode having different characteristics from the first photodiode, and a first cut filter for cutting light in a specific wavelength region And the second cut filter, the third photodiode having the same configuration as the first photodiode, and having the first cut filter on the light receiving surface, and the same configuration as the second photodiode. A fourth photodiode having the second cut filter on the light receiving surface, and (output of the first photodiode−output of the third photodiode) − (of the second photodiode) An output circuit for calculating an output—an output of the fourth photodiode), and an output of the first photodiode—an output of the third photodiode. )-(Output of the second photodiode-output of the fourth photodiode), the calculation method in the output circuit is such that the current value in the region other than the specific wavelength region becomes zero. A preconditioned optical sensor is provided.
According to another aspect of the present invention, a first photodiode, a second photodiode having different characteristics from the first photodiode, and a first cut filter for cutting light in a specific wavelength region And the second cut filter, the third photodiode having the same configuration as the first photodiode, and having the first cut filter on the light receiving surface, and the same configuration as the second photodiode. Connected to a fourth photodiode having the second cut filter on the light receiving surface, (output of the first photodiode-output of the third photodiode)-(second And a conversion circuit for converting an analog signal from the calculation circuit into a digital signal. A logic circuit that performs a predetermined arithmetic process on the digital signal from the conversion circuit and outputs the digital signal, (output of the first photodiode−output of the third photodiode) − (the second photo diode) The area of the first to fourth photodiodes is adjusted in advance so that the current value in the region other than the specific wavelength region becomes 0 when the output of the diode-the output of the fourth photodiode is calculated. An output circuit is provided.
According to another aspect of the present invention, a first photodiode, a second photodiode having different characteristics from the first photodiode, and a first cut filter for cutting light in a specific wavelength region And the second cut filter, the third photodiode having the same configuration as the first photodiode, and having the first cut filter on the light receiving surface, and the same configuration as the second photodiode. Connected to a fourth photodiode having the second cut filter on the light receiving surface, (output of the first photodiode-output of the third photodiode)-(second And a conversion circuit for converting an analog signal from the calculation circuit into a digital signal. A logic circuit that performs a predetermined arithmetic process on the digital signal from the conversion circuit and outputs the digital signal, (output of the first photodiode−output of the third photodiode) − (the second photo diode) An output circuit is provided in which the calculation method is adjusted in advance so that the current value in the region other than the specific wavelength region becomes 0 when the output of the diode—the output of the fourth photodiode is calculated.

  According to the present invention, it is possible to provide an optical sensor and an output circuit thereof capable of reducing the sensitivity deviation due to ringing and achieving high accuracy.

FIG. 3 is a graph conceptually showing the processing content of the photosensor according to the first embodiment, and is a graph showing (a) (output of the first photodiode A1−output of the third photodiode A2); b) a graph showing the output of the second photodiode B1, (c) a graph showing the output of the fourth photodiode B2, and (d) (output of the second photodiode B1−output of the fourth photodiode B2). (E) (output of the first photodiode A1−output of the third photodiode A2) − (output of the second photodiode B1−output of the fourth photodiode B2). . FIG. 3 is a schematic plan view showing a layout example of the photosensor according to the first embodiment. FIG. 2 is a schematic block configuration diagram showing a configuration example of an output circuit according to the first embodiment. FIG. 2 is a schematic circuit configuration diagram showing an example of an internal configuration of an arithmetic circuit according to the first embodiment. It is a figure for demonstrating the specific example of the UV light output which concerns on 1st Embodiment, Comprising: (a) The graph which shows the characteristic of the 1st and 2nd UV cut filter, (b) Shows sunlight spectrum Graph. It is a figure for demonstrating the specific example of the UV light output which concerns on 1st Embodiment, (a) The graph which shows the output of 1st photodiode A1, and the output of 3rd photodiode A2, (b) ) (A graph showing the output of the first photodiode A1−the output of the third photodiode A2), (c) a graph showing the output of the second photodiode B1 and the output of the fourth photodiode B2. ) (Second photodiode B1 output-fourth photodiode B2 output), graph (e) (first photodiode A1 output-third photodiode A2 output)-(second The output of the photodiode B1 of FIG.-the output of the fourth photodiode B2. FIG. 3 is a diagram for explaining the area of the photodiode according to the first embodiment. FIG. 2 is a schematic cross-sectional structure diagram of a photodiode according to the first embodiment. FIG. 2 is a schematic circuit configuration diagram of a photodiode according to the first embodiment. 3 is a graph showing characteristics of the photodiode according to the first embodiment. The typical cross-section figure of the filter layer concerning a 1st embodiment. FIG. 6 is a schematic cross-sectional structure diagram of another filter layer according to the first embodiment. The typical top view which shows the example of a layout of the optical sensor which concerns on 2nd Embodiment. The graph which shows the characteristic of the 1st and 2nd UV transmissive filter which concerns on 2nd Embodiment. The typical block block diagram which shows the structural example of the output circuit which concerns on 2nd Embodiment. The typical circuit block diagram which shows the internal structural example of the arithmetic circuit which concerns on 2nd Embodiment. It is a figure for demonstrating the specific example of the UV light output which concerns on 2nd Embodiment, Comprising: (a) The graph which shows the output of 5th photodiode A3, (b) The output of 6th photodiode B3 The graph which shows (c) (the output of 5th photodiode A3-the output of 6th photodiode B3). The typical block block diagram which shows the structural example of the output circuit which concerns on 3rd Embodiment. FIG. 10 is a schematic circuit configuration diagram of a photodiode according to a third embodiment, and illustrates a case where a current I _A1 + I _B1 is extracted. FIG. 4 is a schematic circuit configuration diagram of a photodiode according to a third embodiment, where (a) a diagram illustrating a case where a current I _B2 is extracted, (b) a diagram illustrating a case where a current I _A2 is extracted, and (c) a current. The figure which shows the case where I _A1 + I _B1 is taken out, (d) The figure which shows the case where current I _B1 is taken out. It is a figure for demonstrating the conventional subject, Comprising: (a) The graph which shows a sunlight spectrum, (b) The graph which shows the case where the light of UV region is taken out. It is a figure for demonstrating the conventional subject, Comprising: (a) The graph which shows the output of the photodiode without a filter, (b) The graph which shows the output of the photodiode with a filter. It is a figure for demonstrating the conventional subject, Comprising: (a) The graph which shows the characteristic of a UV cut filter, (b) The figure for demonstrating ringing.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness of each component and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the embodiments of the present invention include the material, shape, and structure of each component. The arrangement is not specified below. Various modifications can be made to the embodiment of the present invention within the scope of the claims.

[First Embodiment]
Hereinafter, the optical sensor according to the first embodiment will be described with reference to FIGS.

  The optical sensor according to the present embodiment includes a first photodiode A1, a second photodiode B1 having different characteristics from the first photodiode A1, and first and second light that cut light in the UV region R1. Sensitivity shift that occurs when the first UV cut filter f1a is used for the first photodiode A1 and the UV cut filters f1a and f1b when the second UV cut filter f1b is used for the second photodiode B1. And an output circuit 1 that outputs only light in the UV region R1 by correcting based on the generated sensitivity shift.

  Specifically, the first photodiode A1, the second photodiode B1 having different characteristics from the first photodiode A1, the first UV cut filter f1a for cutting light in the UV region R1, and the second photodiode The third photodiode A2 having the same configuration as the UV cut filter f1b and the first photodiode A1, and having the first UV cut filter f1a on the light receiving surface, and the same configuration as the second photodiode B1 And a fourth photodiode B2 having a second UV cut filter f1b on the light receiving surface, and (output of the first photodiode A1−output of the third photodiode A2) − (second photodiode) And an output circuit 1 for calculating (output of B1−output of the fourth photodiode B2).

  Further, when (output of the first photodiode A1−output of the third photodiode A2) − (output of the second photodiode B1−output of the fourth photodiode B2) is calculated, the region other than the UV region R1 The areas of the first to fourth photodiodes A1, A2, B1, and B2 may be adjusted in advance so that the current value in the region becomes zero.

  Further, when (output of the first photodiode A1−output of the third photodiode A2) − (output of the second photodiode B1−output of the fourth photodiode B2) is calculated, the region other than the UV region R1 The calculation method in the output circuit 1 may be adjusted in advance so that the current value in the above region becomes zero.

  Further, the first photodiode A1 may be a photodiode having high sensitivity in the UV region R1, and the second photodiode B1 may be a photodiode having low sensitivity in the UV region R1.

(Processing content of optical sensor)
FIG. 1 is a graph conceptually showing processing contents of the optical sensor according to the first embodiment. FIG. 1A shows (output of the first photodiode A1−output of the third photodiode A2). The first photodiode A1 is a photodiode having a high sensitivity in the UV region R1. The third photodiode A2 has the same configuration as the first photodiode A1, and has the first UV cut filter f1a on the light receiving surface. As indicated by a dotted line in the figure, a sensitivity shift caused by the filter occurs in a region other than the UV region R1 to be extracted. FIG. 1B shows the output of the second photodiode B1. The second photodiode B1 is a photodiode having a low sensitivity in the UV region R1. FIG. 1C shows the output of the fourth photodiode B2. The fourth photodiode B2 has the same configuration as the second photodiode B1, and has the second UV cut filter f1b on the light receiving surface. FIG. 1 (d) shows (output of second photodiode B1−output of fourth photodiode B2). FIG. 1 (e) is obtained by subtracting the calculation result of FIG. 1 (d) from the calculation result of FIG. 1 (a). That is, (output of the first photodiode A1−output of the third photodiode A2) − (output of the second photodiode B1−output of the fourth photodiode B2) is shown. As shown in FIG. 1 (e), by adding the outputs of the four photodiodes A1, A2, B1, and B2, the sensitivity deviation due to the ringing of the spectral sensitivity of the filter transmittance is reduced and the accuracy is improved. Can be achieved.

(Example of optical sensor layout)
FIG. 2 is a schematic plan view showing a layout example of the photosensor according to the first embodiment. This optical sensor extracts only UV light using two UV cut filters f1a and f1b and four photodiodes A1, A2, B1 and B2.

  The first and second UV cut filters f1a and f1b cut light in the UV region R1. The first UV cut filter f1a and the second UV cut filter f1b have the same cross-sectional structure but may have different areas.

  As already described, the first photodiode A1 is a photodiode having a high sensitivity in the UV region R1. The third photodiode A2 has the same configuration as the first photodiode A1, and has the first UV cut filter f1a on the light receiving surface. The second photodiode B1 is a photodiode having a low sensitivity in the UV region R1. The fourth photodiode B2 has the same configuration as the second photodiode B1, and has the second UV cut filter f1b on the light receiving surface.

  Here, the first photodiode A1 and the third photodiode A2 have the same configuration when the first photodiode A1 and the third photodiode A2 have the same cross-sectional structure in the junction depth direction. It means having. The first photodiode A1 and the third photodiode A2 may have different areas.

  Here, the second photodiode B1 and the fourth photodiode B2 have the same configuration. The second photodiode B1 and the fourth photodiode B2 have the same cross-sectional structure in the junction depth direction. It means having. The area of the second photodiode B1 and the fourth photodiode B2 may be different.

(Example of output circuit configuration)
FIG. 3 is a schematic block diagram illustrating a configuration example of the output circuit 1 according to the first embodiment. The output circuit 1 is a circuit that performs a predetermined process on the outputs of the four photodiodes A1, A2, B1, and B2 and outputs them by a communication method such as I2C (Inter-Integrated Circuit). Specifically, as shown in FIG. 3, an arithmetic circuit 10, an ADC 20, and a logic circuit 30 are provided. The arithmetic circuit 10 detects the sensitivity shift that occurs when the first UV cut filter f1a is used for the first photodiode A1, and the sensitivity shift that occurs when the second UV cut filter f1b is used for the second photodiode B1. An operation for correction is performed based on Specifically, (output of the first photodiode A1−output of the third photodiode A2) − (output of the second photodiode B1−output of the fourth photodiode B2) is calculated. An example of the internal configuration of the arithmetic circuit 10 is shown in FIG. Of course, the internal configuration of the arithmetic circuit 10 is not limited to this. The ADC 20 converts the analog signal from the arithmetic circuit 10 into a digital signal. The logic circuit 30 performs a predetermined arithmetic process on the digital signal from the ADC 20 and outputs the result.

(Specific example of UV light output)
FIG. 5A is a graph showing the characteristics of the first and second UV cut filters f1a and f1b. The first and second UV cut filters f1a and f1b are multilayer filters that cut light in the UV region R1. As indicated by a dotted line in the figure, the multilayer filter has ringing, which includes an error that cannot be cut in the visible light region. FIG. 5B shows a sunlight spectrum. The relative output of visible light 380-780 [nm] is much larger than that of UV light 100-380 [nm], and the influence of visible light is greater. As can be seen from the dotted line in the figure, the peak of visible light is higher than that of UV light.

  FIG. 6A shows the output of the first photodiode A1 and the output of the third photodiode A2. As the first photodiode A1, “NSD / PW without multilayer filter” is illustrated, and as the third photodiode A2, “NSD / PW with multilayer filter” is illustrated. FIG. 6B shows (output of the first photodiode A1−output of the third photodiode A2). FIG. 6C shows the output of the second photodiode B1 and the output of the fourth photodiode B2. The second photodiode B1 is exemplified by “LI / BL without multilayer filter”, and the fourth photodiode B2 is exemplified by “LI / BL with multilayer filter”. FIG. 6D shows (output of the second photodiode B1−output of the fourth photodiode B2). FIG. 6E shows (output of the first photodiode A1−output of the third photodiode A2) − (output of the second photodiode B1−output of the fourth photodiode B2). . Comparing the regions surrounded by the dotted lines in FIGS. 6B and 6E, it can be seen that the ringing in the visible light region R2 to be cut is reduced. Thus, according to the present embodiment, it is possible to obtain an output of a photodiode having sensitivity only to UV light.

(Adjustment process)
In the present embodiment, when (output of first photodiode A1−output of third photodiode A2) − (output of second photodiode B1−output of fourth photodiode B2) is calculated, Adjustment is made in advance so that the current value in the region other than the UV region R1 becomes zero. Thereby, since sunlight is integrated, visible light is cut.

  For example, the areas of the photodiodes A1, A2, B1, and B2 are adjusted in advance. Specifically, as shown in FIG. 6E, the junction areas of the photodiodes A1, A2, B1, and B2 are trimmed by a method such as trimming so that the integrated value of the visible light region R2 to be cut becomes zero. adjust. An example of the adjustment result is shown in FIG. Here, the area ratio of “NSD / PW without filter” is 1.000. In this case, the area ratio of “NSD / PW with filter” is 0.957, the area ratio of “LI / BL without filter” is 0.600, and the area ratio of “LI / BL with filter” is 0.569. Is appropriate.

Alternatively, the calculation method in the output circuit 1 may be adjusted in advance. For example, each current value output from the photodiodes A1, A2, B1, and B2 can be adjusted by adjusting the mirror ratio of the current mirror. Specifically, the current values here are current values I _A1 , I _A2 , I _B1 , and I _B2 shown in FIG. 4. In this way, by adjusting the current values I _A1 , I _A2 , I _B1 , and I _B2 , the current values in the regions other than the UV region R1 become 0 even if the photodiodes A1, A2, B1, and B2 have the same area. Can be adjusted as follows.

(Photodiode, filter)
FIG. 8 is a schematic sectional view of the photodiode according to the first embodiment, and FIG. 9 is an equivalent circuit diagram thereof. As shown in this figure, there are three PN junctions of BL / sub, BL / LI (PW), and NSD / PW, each having different characteristics. That is, as shown in FIG. 10, the shorter the surface, the easier it is to absorb light having a shorter wavelength. In FIGS. 8 and 9, BL / sub is described as a photodiode D1, NSD / PW as a photodiode D2, and BL / LI as a photodiode D3. In the present embodiment, the first photodiode A1 having a high sensitivity in the UV region R1 and the second photodiode B1 having a low sensitivity in the UV region R1 are used. The first photodiode A1 corresponds to the photodiode D2, and the second photodiode B1 corresponds to the photodiode D3.

As shown in FIG. 8, a passivation layer 42 is formed on the photodiode structure 43, and a filter layer 41 is further formed thereon. For example, the filter layer 41 is a multilayer film in which SiO ₂ and TiO ₂ are repeatedly laminated in order as shown in FIG. The filter characteristics can be changed depending on the film thickness and the number of layers. Or as shown in FIG. 12, you may make it form the filter layer 41 by acrylic resin (PMMA). The filter layer 41 has various configurations and is not particularly limited.

  As described above, in the present embodiment, (output of the first photodiode A1−output of the third photodiode A2) − (output of the second photodiode B1−output of the fourth photodiode B2). Is calculated. In other words, the sensitivity shift that occurs when the first UV cut filter f1a is used for the first photodiode A1 is based on the sensitivity shift that occurs when the second UV cut filter f1b is used for the second photodiode B1. Have been corrected. As a result, sensitivity deviation due to ringing can be reduced and higher accuracy can be achieved, so that wavelength selectivity can be improved and output of a photodiode having sensitivity only to light of a specific wavelength can be obtained. Become.

[Second Embodiment]
Hereinafter, the optical sensor according to the second embodiment will be described mainly with respect to differences from the first embodiment with reference to FIGS. 13 to 17.

  The optical sensor according to the present embodiment includes a first photodiode A1, a second photodiode B1 having different characteristics from the first photodiode A1, and first and second light that transmit light in the UV region R1. The sensitivity shift that occurs when the first UV transmission filter f2a is used for the UV transmission filters f2a and f2b and the first photodiode A1 is obtained when the second UV transmission filter f2b is used for the second photodiode B1. And an output circuit 1 that outputs only light in the UV region R1 by correcting based on the generated sensitivity shift.

  Specifically, the first photodiode A1, the second photodiode B1 having different characteristics from the first photodiode A1, the first UV transmission filter f2a that transmits the light in the UV region R1, and the second photodiode The fifth photodiode A3 having the same configuration as the UV transmission filter f2b and the first photodiode A1, and having the first UV transmission filter f2a on the light receiving surface, and the same configuration as the second photodiode B1 A sixth photodiode B3 having a second UV transmission filter f2b on the light receiving surface, and an output circuit 1 for calculating (output of the fifth photodiode A3−output of the sixth photodiode B3) Is provided.

  Further, when (output of the fifth photodiode A3−output of the sixth photodiode B3) is calculated, the fifth and sixth photodiodes A3 are set so that the current value in the region other than the UV region R1 becomes zero. , B3 may be adjusted in advance.

  Further, the calculation method in the output circuit 1 is adjusted in advance so that the current value in the region other than the UV region R1 becomes 0 when (output of the fifth photodiode A3−output of the sixth photodiode B3) is calculated. May be.

(Example of optical sensor layout)
FIG. 13 is a schematic plan view showing a layout example of the photosensor according to the second embodiment. This optical sensor extracts only UV light using two UV transmission filters f2a and f2b and two photodiodes A3 and B3. As shown in FIG. 14, the first and second UV transmission filters f2a and f2b transmit light in the UV region R1. The configurations of the first and second UV transmission filters f2a and f2b are not particularly limited. The first UV transmission filter f2a and the second UV transmission filter f2b have the same cross-sectional structure but may have different areas. The fifth photodiode A3 has the same configuration as the first photodiode A1 and has a first UV transmission filter f2a on the light receiving surface. The sixth photodiode B3 has the same configuration as the second photodiode B1, and has a second UV transmission filter f2b on the light receiving surface.

  Here, the first photodiode A1 and the fifth photodiode A3 have the same configuration when the first photodiode A1 and the fifth photodiode A3 have the same sectional structure in the junction depth direction. It means having. The first photodiode A1 and the fifth photodiode A3 may have different areas.

  Here, the second photodiode B1 and the sixth photodiode B3 have the same configuration. The second photodiode B1 and the sixth photodiode B3 have the same sectional structure in the junction depth direction. It means having. The area of the second photodiode B1 and the sixth photodiode B3 may be different.

(Example of output circuit configuration)
FIG. 15 is a schematic block diagram illustrating a configuration example of the output circuit 1 according to the second embodiment. This is basically the same as in the first embodiment except that the processing target is changed from the outputs of the four photodiodes A1, A2, B1, and B2 to the outputs of the two photodiodes A3 and B3. That is, the output circuit 1 is a circuit that performs a predetermined process on the outputs of the two photodiodes A3 and B3 and outputs the result by a communication method such as I2C. Specifically, as shown in FIG. 15, an arithmetic circuit 11, an ADC 20, and a logic circuit 30 are provided. The arithmetic circuit 11 calculates (output of the fifth photodiode A3−output of the sixth photodiode B3) and passes the calculation result to the ADC 20. An example of the internal configuration of the arithmetic circuit 11 is shown in FIG. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted here.

(Specific example of UV light output)
FIG. 17A shows the output of the fifth photodiode A3. FIG. 17B shows the output of the sixth photodiode B3. FIG. 17C shows (output of fifth photodiode A3−output of sixth photodiode B3). 17A and 17C, it can be seen that the ringing in the visible light region R2 to be cut is reduced when the regions surrounded by dotted lines are compared. Thus, according to the present embodiment, it is possible to obtain an output of a photodiode having sensitivity only to UV light.

  As described above, in the present embodiment, (output of the fifth photodiode A3−output of the sixth photodiode B3) is calculated. In other words, the sensitivity shift that occurs when the first UV transmission filter f2a is used for the first photodiode A1 is based on the sensitivity shift that occurs when the second UV transmission filter f2b is used for the second photodiode B1. Have been corrected. Even with such a configuration, the same effects as those of the first embodiment can be obtained.

[Third Embodiment]
Hereinafter, the optical sensor according to the third embodiment will be described mainly with respect to differences from the first embodiment with reference to FIGS.

  The output circuit 1 according to the present embodiment performs predetermined arithmetic processing on the ADC 21 that converts an analog signal into a digital signal, the ADC 22 that converts an analog signal into a digital signal, and the digital signals from the ADC 21 and the ADC 22. The sensitivity shift that occurs when the first UV cut filter f1a is used for the first photodiode A1 is corrected based on the sensitivity shift that occurs when the second UV cut filter f1b is used for the second photodiode B1. And a logic circuit 31 that performs an operation for the purpose.

  Specifically, the first photodiode A1, the second photodiode B1 having different characteristics from the first photodiode A1, the first UV cut filter f1a and the second UV cut filter f1b, The third photodiode A2 having the same configuration as the photodiode A1 of FIG. 1 and having the first UV cut filter f1a on the light receiving surface and the same configuration as the second photodiode B1 are provided on the light receiving surface. Connected to the fourth photodiode B2 having two UV cut filters f1b, (output of the first photodiode A1−output of the third photodiode A2) + (output of the fourth photodiode B2 + second output). The output of the second photodiode B1) from the analog signal to the digital signal, and the second photodiode B1 The ADC 22 that converts (the output of the second photodiode B1 + the output of the second photodiode B1) from an analog signal to a digital signal, and by applying predetermined arithmetic processing to the digital signals from the ADC 21 and ADC 22, And a logic circuit 31 that calculates (output of the first photodiode A1−output of the third photodiode A2) − (output of the second photodiode B1−output of the fourth photodiode B2).

(Example of output circuit configuration)
FIG. 18 is a schematic block diagram illustrating a configuration example of the output circuit 1 according to the third embodiment. The difference from the first embodiment (FIG. 3) is that the arithmetic circuit 10 is not used. The combination of the photodiodes is divided into two sets, the respective outputs are processed by the ADCs 21 and 22, and the digital signal is subjected to predetermined arithmetic processing by the logic circuit 31, so that the same output as in the first embodiment can be obtained. It has become. Specifically, as shown in FIG. 18, the current value (A) = (I _A1 −I _A2 ) + (I _B2 + I _B1 ) is input to the ADC 21, and the current value (B) = I _B1 is input to the ADC 22. + I _B1 is input. When these current values (A) and (B) are input, the logic circuit 31 calculates (A) − (B) = (I _A1 −I _A2 ) − (I _B1 −I _B2 ). A shows the output of NSD / PW, and B shows the output of LI / BL. Since the current of only A (NSD / PW) cannot be extracted downward, the current I _A1 + I _B1 = NSD / PW + LI / BL is extracted here as shown in FIG.

Hereinafter, a method for extracting each current will be described with reference to FIG. FIG. 20A shows a case where the current _IB2 is taken out, and LI / BL with a filter is taken out. FIG. 20B shows a case where the current I _A2 is extracted, and NSD / PW with a filter is extracted. FIG. 20C shows a case where the current I _A1 + I _B1 is extracted, and NSD / PW without filter + LI / BL without filter is extracted. FIG. 20D shows a case where the current I _B1 is taken out, and the unfiltered LI / BL is taken out. Thus, it is possible to take out each electric current by changing the connection method of the photodiodes D1-D3.

  As described above, since the arithmetic circuit (analog circuit) 10 is not used in the present embodiment, errors due to the analog circuit (leakage current, delay due to parasitic capacitance of the current mirror, current mirror accuracy) are eliminated. Can do. Further, if the ADCs 21 and 22 having the same shape are used, variations in manufacturing can be canceled, so that accuracy is increased. Further, if the integration time of each of the ADCs 21 and 22 is changed, the final output can be trimmed. In addition, adjustment processing is easy because only the integration time needs to be changed. Here, the description is focused on the points different from the first embodiment, but the arithmetic circuit 10 may not be used in the second embodiment as well.

  As described above, according to the present invention, it is possible to provide an optical sensor and its output circuit 1 that can reduce the sensitivity deviation due to ringing and achieve high accuracy.

[Other embodiments]
As described above, the present invention has been described according to the first to third embodiments. However, it should be understood that the descriptions and drawings constituting a part of this disclosure are exemplary and limit the present invention. should not do. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  As described above, the present invention includes various embodiments not described herein. For example, in the first to third embodiments, the optical sensor that extracts only the UV light has been described as an example. However, the present invention includes an optical sensor that extracts light in a wavelength region other than the UV light. is there.

  The optical sensor and its output circuit according to the present invention can be applied to various electronic devices such as a UV meter, an illuminance meter, a smartphone, and a tablet.

A1 ... 1st photodiode B1 ... 2nd photodiode A2 ... 3rd photodiode B2 ... 4th photodiode A3 ... 5th photodiode B3 ... 6th photodiode f1a ... 1st cut filter ( First UV cut filter)
f1b: second cut filter (second UV cut filter)
f2a: first transmission filter (first UV transmission filter)
f2b ... second transmission filter (second UV transmission filter)
R1 ... UV region 1 ... output circuits 10, 11 ... arithmetic circuit 20 ... conversion circuit (ADC)
21: First conversion circuit (ADC)
22 ... Second conversion circuit (ADC)
30, 31 ... logic circuit 41 ... filter (filter layer)

Claims (4)

A first photodiode;
A second photodiode having different characteristics from the first photodiode;
A first cut filter and a second cut filter for cutting light in a specific wavelength region;
A third photodiode having the same configuration as the first photodiode and having the first cut filter on a light receiving surface;
A fourth photodiode having the same configuration as the second photodiode and having the second cut filter on a light receiving surface;
An output circuit for calculating (output of the first photodiode−output of the third photodiode) − (output of the second photodiode−output of the fourth photodiode);
Equipped with a,
When the (output of the first photodiode−output of the third photodiode) − (output of the second photodiode−output of the fourth photodiode) is calculated, it is other than the specific wavelength region. The optical sensor is characterized in that the areas of the first to fourth photodiodes are adjusted in advance so that the current value of the region becomes zero .   A first photodiode;
  A second photodiode having different characteristics from the first photodiode;
  A first cut filter and a second cut filter for cutting light in a specific wavelength region;
  A third photodiode having the same configuration as the first photodiode and having the first cut filter on a light receiving surface;
  A fourth photodiode having the same configuration as the second photodiode and having the second cut filter on a light receiving surface;
  An output circuit for calculating (output of the first photodiode−output of the third photodiode) − (output of the second photodiode−output of the fourth photodiode);
  With
  When the (output of the first photodiode−output of the third photodiode) − (output of the second photodiode−output of the fourth photodiode) is calculated, it is other than the specific wavelength region. The light sensor is characterized in that the calculation method in the output circuit is adjusted in advance so that the current value in the region is zero.   A first photodiode, a second photodiode having different characteristics from the first photodiode, a first cut filter and a second cut filter for cutting light in a specific wavelength region, and the first photodiode A third photodiode having the same configuration as the photodiode, having the first cut filter on the light receiving surface, and the same configuration as the second photodiode, and having the second cut on the light receiving surface. Connected to a fourth photodiode having a filter, (output of the first photodiode−output of the third photodiode) − (output of the second photodiode−output of the fourth photodiode) Output circuit),
  A conversion circuit for converting an analog signal from the arithmetic circuit into a digital signal;
  A logic circuit that performs a predetermined arithmetic process on the digital signal from the conversion circuit and outputs the digital signal;
  With
  When the (output of the first photodiode−output of the third photodiode) − (output of the second photodiode−output of the fourth photodiode) is calculated, it is other than the specific wavelength region. The output circuit is characterized in that the areas of the first to fourth photodiodes are adjusted in advance so that the current value in the region is zero.   A first photodiode, a second photodiode having different characteristics from the first photodiode, a first cut filter and a second cut filter for cutting light in a specific wavelength region, and the first photodiode A third photodiode having the same configuration as the photodiode, having the first cut filter on the light receiving surface, and the same configuration as the second photodiode, and having the second cut on the light receiving surface. Connected to a fourth photodiode having a filter, (output of the first photodiode−output of the third photodiode) − (output of the second photodiode−output of the fourth photodiode) Output circuit),
  A conversion circuit for converting an analog signal from the arithmetic circuit into a digital signal;
  A logic circuit that performs a predetermined arithmetic process on the digital signal from the conversion circuit and outputs the digital signal;
  With
  When the (output of the first photodiode−output of the third photodiode) − (output of the second photodiode−output of the fourth photodiode) is calculated, it is other than the specific wavelength region. The output circuit is characterized in that the calculation method is adjusted in advance so that the current value in the region is zero.

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