Proximity detection device

Abstract

A proximity detection device is provided that can well detect the approach of a user's hand over the entire area of ​​a display surface of a display. Four infrared LEDs and two PDs are arranged in sequence on the left and right. The smaller the max(Ei) / max(Aj) obtained from the detection signal (A1) of PD (PD1) when LED (LED1) emits light, the detection signal (A2) of PD (PD1) when LED (LED2) emits light, the detection signal (A3) of PD (PD2) when LED (LED3) emits light, the detection signal (A4) of PD (PD2) when LED (LED4) emits light, the detection signal (E1) of PD (PD2) when LED (LED1) emits light, and the detection signal (E2) of PD (PD1) when LED (LED4) emits light, the smaller the threshold is set, and if max(Aj) exceeds the threshold, the approach of the user's hand is detected.

Description

Technical Field

[0001] The present invention relates to a technology for detecting the approach of a user's hand to a display surface of a display. Background Art

[0002] As a technology for detecting the approach of a user's hand to the display surface of a display, the following technology is known: infrared light is irradiated toward the front of the display surface of the display from several infrared LEDs arranged along the lower side of the display surface of the display, and reflected light of the infrared light reflected by the user's hand is detected by a photodiode, thereby detecting the approach of the user's hand to the display surface of the display (for example, patent document 1).

[0003] Prior Art Literature

[0004] Patent Literature

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-74465 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In general, an infrared LED has directivity, and therefore the intensity of infrared light becomes weaker in a direction where the angle of view from the infrared LED is large relative to the central axis of the directivity angle.

[0008] Therefore, in the above-mentioned technology of setting several infrared LEDs below the lower edge of the display and detecting the approach of the user's hand to the display surface of the display, the area below the display which is located close to the infrared LED in the direction of the central axis of the directional angle of the infrared LED and has a weaker irradiation intensity of infrared light than other areas, sometimes cannot detect the approach of the user's hand to this area well.

[0009] Such a problem can be solved by arranging a plurality of infrared LEDs at narrow intervals so as to avoid generating areas with weak infrared light irradiation intensity. However, this will increase the required number of infrared LEDs and lead to increased costs.

[0010] Therefore, an object of the present invention is to detect the approach of a user's hand well over the entire display surface of a display using a relatively small number of infrared LEDs.

[0011] Means for solving problems

[0012] In order to solve the above-mentioned problem, the present invention relates to a proximity detection device for detecting the approach of a user to a display surface of a display, and is provided with: a plurality of infrared light sources arranged along a first side which is one side of the display surface on the outer side of the display surface of the display, emitting infrared light passing in front of the display surface; a plurality of light detectors arranged along the first side on the outer side of the display surface; a proximity detection unit for detecting the approach of a user to the display surface with a set sensitivity using a first detection reflection intensity, wherein the first detection reflection intensity is the intensity of reflected light of infrared light emitted by each of the infrared light sources detected by the light detector located at a position relatively close to the infrared light source emitting the infrared light; and a sensitivity setting unit for setting the sensitivity of the proximity detection unit in a manner that makes the sensitivity higher than a case where the intensity of the reflected light detected by the light detector located at a position relatively far from the infrared light source and the first detection reflection intensity show a high probability of reflection occurring in a region near the first side in front of the display surface when only one of the infrared light sources emits infrared light.

[0013] In addition, in order to solve the above-mentioned problem, the present invention relates to a proximity detection device for detecting the approach of a user to a display surface of a display, and comprising: a plurality of infrared light sources arranged along a first side which is one side of the display surface on the outer side of the display surface of the display, and emitting infrared light passing in front of the display surface; a plurality of light detectors arranged along the first side on the outer side of the display surface; a proximity detection unit for detecting, for each of the plurality of infrared light sources, an intensity of reflected light of the infrared light emitted by the infrared light source detected by the light detector corresponding to the infrared light source in accordance with a predetermined correspondence, as a first detected reflection intensity of the emitted light of the infrared light source, and the infrared light represented by the first detected reflection intensity of the emitted light of each infrared light source When the intensity of reflected light of external light exceeds a set threshold, the approach of the user to the display surface is detected; and a threshold setting unit takes one or more infrared light sources among the multiple infrared light sources as target infrared light sources, and for each target infrared light source, takes the intensity of reflected light of infrared light emitted by the target infrared light source detected by a light detector that is farther away from the target infrared light source than the light detector that establishes a correspondence with the infrared light source as the target infrared light source according to the correspondence as the second detected reflection intensity of the emitted light of the target infrared light source, and sets the threshold for the proximity detection unit in a manner that changes the threshold according to each second detected reflection intensity and each first detected reflection intensity and an evaluation value calculated according to a prescribed evaluation function.

[0014] Here, such a proximity detection device can also be constructed as follows: in the threshold setting unit, the ratio of the maximum value of each second detection reflection intensity to the maximum value of each first detection reflection intensity is estimated as the evaluation value, and when the estimated evaluation value is less than a specified level, the threshold value of the proximity detection unit is set in a manner that makes the threshold value smaller than when the evaluation value is not less than the specified level.

[0015] Alternatively, such a proximity detection device may also be configured as follows: in the threshold setting unit, the ratio of the maximum value of each second detection reflection intensity to the maximum value of each first detection reflection intensity is estimated as the evaluation value, and the threshold value of the proximity detection unit is set in such a manner that the smaller the estimated evaluation value, the smaller the threshold value.

[0016] Furthermore, the proximity detection device may be configured such that, in the proximity detection unit, when a maximum value of each first detected reflection intensity exceeds a set threshold value, approach of the user to the display surface is detected.

[0017] According to the proximity detection device as described above, it is detected whether reflection occurs in an area near the edge of a display equipped with an infrared light source where the irradiation intensity of infrared light becomes weak. When reflection occurs in this area, the detection sensitivity to the user's hand is improved. Therefore, it is possible to detect the approach of the user's hand to the display surface of the display in a manner in which the detection sensitivity to the approach of the user is improved only in this area.

[0018] Therefore, the approach of the user's hand can be well detected with respect to the entire area of ​​the display surface of the display.

[0019] Here, the present invention also provides a display unit including the above-mentioned proximity detection device and the display integrated with the proximity detection device.

[0020] In addition, the present invention also provides an information processing system, comprising the above-mentioned proximity detection device, the display and a data processing device that uses the display for display output. When the proximity detection device detects the user approaching the display surface, it notifies the data processing device of the intention of the approach.

[0021] Effects of the Invention

[0022] As described above, according to the present invention, it is possible to detect the approach of the user's hand well with respect to the entire area of ​​the display surface of the display using a relatively small number of infrared LEDs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a block diagram showing the configuration of an information processing system according to an embodiment of the present invention.

[0024] Figure 2 It is a diagram showing the arrangement of a display according to an embodiment of the present invention.

[0025] Figure 3 It is a diagram showing the arrangement of proximity detection sensors according to the embodiment of the present invention.

[0026] Figure 4 It is a diagram showing an operation sequence of the proximity detection sensor according to the embodiment of the present invention.

[0027] Figure 5 It is a diagram showing another operation sequence of the proximity detection sensor according to the embodiment of the present invention.

[0028] Figure 6 It is a diagram showing the principle of area detection by the proximity detection sensor according to the embodiment of the present invention.

[0029] Figure 7 Detailed Description of the Invention It is a flowchart showing a proximity detection process according to an embodiment of the present invention.

[0030] Figure 8 It is a diagram showing another arrangement example of the proximity detection sensor according to the embodiment of the present invention.

[0031] Description of reference numerals:

[0032] 1...data processing device, 2...display, 3...proximity detection device, 4...peripheral device, 10...display unit, 31...proximity detection sensor, 32...proximity detection controller, 321...driving unit, 322...detection unit, 323...detection control unit, 3221...signal processing unit, 3222...analog-to-digital converter, 3223...multiplexer. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present invention will be described.

[0034] exist Figure 1 The configuration of the information processing system involved in this embodiment is shown in FIG.

[0035] The information processing system is a system installed in a car and comprises: a data processing device 1 for executing car navigation applications, media player applications, etc., a display 2 for displaying images by the data processing device 1, a proximity detection device 3, and other peripheral devices 4 used by the data processing device 1.

[0036] Here, if Figure 2 As shown, a display unit 10 in which the display 2 and the proximity detection device 3 are integrated is arranged between the driver's seat and the passenger seat of the instrument panel of the automobile with the display surface facing rearward.

[0037] return Figure 1 The proximity detection device 3 includes a proximity detection sensor 31 and a proximity detection controller 32 .

[0038] The proximity detection sensor 31 includes four infrared LEDs, LED1 , LED2 , LED3 , and LED4 , and two photodiodes, PD1 and PD2 , for detecting infrared light.

[0039] In addition, the proximity detection controller 32 includes: a driving unit 321, which drives LED1, LED2, LED3, and LED4 to make them emit light; a detection unit 322, which converts the current signal output by PD1 and PD2 into an intensity signal representing the intensity of the infrared light incident on PD1 and PD2 and outputs it; and a detection control unit 323, which controls the operation of the driving unit 321 and the detection unit 322, and detects the approach of the user's hand to the display surface of the display 2 based on the intensity of the infrared light represented by the signal converted by the detection unit 322, and notifies the data processing device 1.

[0040] Next, if Figure 3 As shown in a and b of FIG. 1 , it is assumed that the left-right direction, the up-down direction, and the front-back direction are determined relative to the display 2, and LED1, LED2, LED3, and LED4 are arranged in the order of LED1, LED2, LED3, and LED4 from left to right at approximately equal intervals and slightly below the bottom of the display 2. Among them, the front direction is the display direction of the display 2.

[0041] In addition, PD1 is arranged at a position between LED1 and LED2, and PD2 is arranged at a position between LED3 and LED4, and each converts reflected light of incident infrared light into a current signal.

[0042] Figure 3 The arrows in a and b represent the central axes of the directional angles of LED1 , LED2 , LED3 , and LED4 . LED1 , LED2 , LED3 , and LED4 irradiate infrared light obliquely toward the upper front of the display 2 .

[0043] Figure 3 Ref. c represents the distribution of the infrared light irradiation intensity of LED1, LED2, LED3, and LED4 observed in the front-to-back direction. In the portion below the display 2, since the angle relative to the central axis is large regardless of which LED is observed from, there is an area where the infrared light irradiation intensity becomes weak.

[0044] Next, the detection control unit 323 of the proximity detection controller 32 controls the actions of the driving unit 321 and the detection unit 322 so that the driving unit 321 and the detection unit 322 are repeatedly controlled. Figure 4 The cycle shown in a.

[0045] Here, each cycle includes the following time periods: a time period in which the driving unit 321 only makes LED1 emit light, and the detection unit 322 outputs an intensity signal A1 representing the intensity of the infrared light incident to PD1 and an intensity signal E1 representing the intensity of the infrared light incident to PD2; a time period in which the driving unit 321 only makes LED2 emit light, and the detection unit 322 outputs an intensity signal A2 representing the intensity of the infrared light incident to PD1; a time period in which the driving unit 321 only makes LED3 emit light, and the detection unit 322 outputs an intensity signal A3 representing the intensity of the infrared light incident to PD2; and a time period in which the driving unit 321 only makes LED4 emit light, and the detection unit 322 outputs an intensity signal A4 representing the intensity of the infrared light incident to PD2 and an intensity signal E2 representing the intensity of the infrared light incident to PD1.

[0046] Next, in Figure 4 The structure of the detection unit 322 is shown in b.

[0047] As shown in the figure, the detection unit 322 includes a set of a signal processing unit 3221 and an analog-to-digital converter 3222 (A / D3222 ) provided corresponding to the two photodiodes PD1 and PD2 , respectively.

[0048] The signal processing unit 3221 of each group performs signal processing such as converting the current signal output by the corresponding photodiode into a voltage signal, and the analog-to-digital converter 3222 of each group performs digital conversion on the voltage signal output by the signal processing unit 3221 of the same group and outputs it to the detection control unit 323 .

[0049] Here, the detection control unit 323 of the proximity detection controller 32 may also control the actions of the driving unit 321 and the detection unit 322 to replace Figure 4 The cycle shown in a is repeated Figure 5 The cycle shown in a.

[0050] Figure 5The cycle shown in a includes the following time periods: a time period in which the driving unit 321 only makes LED1 emit light, and the detection unit 322 outputs an intensity signal A1 representing the intensity of the infrared light incident to PD1; a time period in which the driving unit 321 only makes LED2 emit light, and the detection unit 322 outputs an intensity signal A2 representing the intensity of the infrared light incident to PD1; a time period in which the driving unit 321 only makes LED3 emit light, and the detection unit 322 outputs an intensity signal A3 representing the intensity of the infrared light incident to PD2; a time period in which the driving unit 321 only makes LED4 emit light, and the detection unit 322 outputs an intensity signal A4 representing the intensity of the infrared light incident to PD2; a time period in which the driving unit 321 only makes LED1 emit light, and the detection unit 322 outputs an intensity signal E1 representing the intensity of the infrared light incident to PD2; and a time period in which the driving unit 321 only makes LED4 emit light, and the detection unit 322 outputs an intensity signal E2 representing the intensity of the infrared light incident to PD1.

[0051] Here, the detection control unit 323 of the proximity detection controller 32 controls the operation of the driving unit 321 and the detection unit 322 so that the operation is repeated. Figure 5 In the case of the cycle shown in a, the detection unit 322 is configured as follows Figure 5 As shown in b, replace Figure 4 The composition shown in b.

[0052] exist Figure 5 In the configuration shown in b, the control unit includes a multiplexer 3223 (MPX3223), a signal processing unit 3221, and an analog-to-digital converter 3222.

[0053] Multiplexer 3223 in Figure 5 In the cycle shown in a, during the period when the detection unit 322 outputs the intensity signals A1, A2, and E2 representing the intensity of the infrared light incident on PD1, the current signal output by PD1 is selected and output to the signal processing unit 3221, and during the period when the detection unit 322 outputs the intensity signals A3, A4, and E1 representing the intensity of the infrared light incident on PD2, the current signal output by PD2 is selected and output to the signal processing unit 3221. The signal processing unit 3221 performs signal processing such as converting the current signal input from the multiplexer 3223 into a voltage signal, and the analog-to-digital converter 3222 performs digital conversion on the voltage signal output by the signal processing unit 3221 and outputs it to the detection control unit 323.

[0054] Here, Figure 5 The cycle shown in a does not include a period of time in which an intensity signal representing the intensity of the infrared light incident on PD1 and an intensity signal representing the intensity of the infrared light incident on PD2 are simultaneously obtained, and thus has the following advantages: Figure 4 In the loop shown in a Figure 4 As shown in b, two sets of signal processing units 3221 and analog-to-digital converters 3222 are required in the detection unit 322. Figure 5 The reduction shown in b is 1 group.

[0055] exist Figure 4 a, Figure 5 In the cycle of a, the intensity signal E1 representing the intensity of the infrared light incident on PD2 when only LED1 is illuminated is as follows Figure 6 When reflection occurs in the area A_E1 on the upper left of the display 2 indicated by a1 , due to the hand of the user, a larger value is shown compared to when reflection occurs in other areas.

[0056] This is because: the area A_E1 on the upper left of the display 2 is irradiated with relatively strong infrared light emitted by LED1, and the positional relationship between LED1, PD2 and the area A_E1 is as follows: Figure 6 As shown in a1, the reflected light of the infrared light emitted by LED1 due to the reflection occurring in area A_E1 reaches PD2 with a relatively strong intensity. In contrast, other areas become areas where the intensity of the infrared light emitted by LED1 is relatively weak, or the positional relationship between LED1 and PD2 is as shown in FIG. Figure 6 A2 indicates an area of ​​positional relationship in which the reflected light of the infrared light emitted by LED1 does not reach PD2 or reaches PD2 only with relatively weak intensity due to reflection occurring in this area.

[0057] In addition, similarly Figure 4 a, Figure 5 In the cycle of a, the intensity signal E2 representing the intensity of the infrared light incident on PD1 when only LED4 is illuminated is as follows Figure 6 When reflection occurs in the area A_E2 at the upper right of the display 2 shown in b due to the user's hand, a larger value is shown compared to the case where reflection occurs in other areas.

[0058] Therefore, the magnitudes of the intensity signals E1 and E2 serve as a reference for determining whether the user's hand is located in the area (area A_E1 or area A_E2) above the display 2 .

[0059] Next, the proximity detection process performed by the detection control unit 323 of the proximity detection controller 32 will be described.

[0060] exist Figure 7 The order of the proximity detection processing is shown in FIG.

[0061] As shown in the figure, the detection control unit 323 Figure 4 a or Figure 5In each cycle shown in a of , if the intensity signals A1, A2, A3, A4, E1, E2 are obtained from the detection unit 322 (step 702), the evaluation index V of the intensity signals A1, A2, A3, A4 is calculated by V=f(A1, A2, A3, A4) using the prescribed evaluation function f() (step 704). The evaluation function f() is set as a function that calculates the size of the reflection caused by the object near the display surface in front of the display surface based on the intensity signals A1, A2, A3, A4. As an example, the evaluation function f() can use a function that calculates the maximum value of the intensity signals A1, A2, A3, A4, or a first combination function of A1, A2, A3, A4 (a×A1+b×A2+c×A3+d×A4), etc.

[0062] In addition, the maximum value max(A1, A2, A3, A4) of the intensity signals A1, A2, A3, A4 is calculated as MA (step 706), and it is checked whether MA exceeds a predetermined threshold value Thmin (step 708). If not, the process directly returns to step 702 to wait for the intensity signals A1, A2, A3, A4, E1, E2 of the next cycle to be obtained from the detection unit 322. The threshold value Thmin is the minimum value that MA can take when reflection occurs near the display surface in front of the display surface of the display 2 due to the user's hand.

[0063] On the other hand, if MA exceeds the predetermined threshold value Thmin (step 708), the maximum value of the intensity signals E1 and E2 is calculated as ME (step 710).

[0064] Then, EY is calculated by EY=ME / MA (step 712 ), and the threshold value Th is adjusted according to the value of EY (step 714 ).

[0065] In step 714, the threshold value Th is adjusted so as to be smaller when EY is small than when EY is large. More specifically, in step 714, for example, when EY is smaller than a predetermined value, the threshold value Th is set to a first value, and when EY is not smaller than the predetermined value, the threshold value Th is set to a second value larger than the first value. Alternatively, the smaller EY is, the smaller the threshold value Th is set.

[0066] Then, V calculated in step 704 is compared with the threshold Th (step 716). If V is not greater than the threshold Th, the process returns directly to step 702 and waits for the intensity signals A1, A2, A3, A4, E1, and E2 of the next cycle to be obtained from the detection unit 322.

[0067] On the other hand, when the evaluation index V is larger than the threshold value Th, the approach of the user's hand to the display surface of the display 2 is detected, and the approach of the user's hand is notified to the data processing device 1 (step 718).

[0068] Then, the process returns to step 702 to wait for obtaining the intensity signals A1 , A2 , A3 , A4 , E1 , and E2 of the next cycle from the detection unit 322 .

[0069] The proximity detection process performed by the detection control unit 323 has been described above.

[0070] Here, as described above, E1 and E2 take on relatively large values ​​when reflection occurs due to the user's hand in the area above the display 2 , and take on relatively small values ​​when reflection occurs due to the user's hand in the area below the display 2 .

[0071] On the other hand, the magnitude of MA represents the magnitude of reflection caused by the user's hand in the vicinity of the display surface in front of the display surface of the display 2 .

[0072] Therefore, when ME is small relative to MA, that is, when EY=ME / MA calculated in step 712 of the above proximity detection process is small, it can be determined that the position is not in the upper area of ​​the display 2 but in the lower area due to reflection of the user's hand.

[0073] In addition, in step 714, the threshold Th is adjusted so as to be smaller when EY is small than when EY is large, thereby enabling the approach of the user's hand to be detected in the portion below the display 2 where the intensity of the infrared light emitted is weakened using a threshold Th that is smaller than the case where the user's hand is located in the area above the display 2.

[0074] That is, the approach of the user's hand to the display surface of the display 2 can be detected in a manner that the detection sensitivity of the user's hand approaching the portion below the display surface of the display 2 where the irradiation intensity of infrared light is weakened is higher than the detection sensitivity of the user's hand approaching other portions of the display surface of the display 2. Therefore, the approach of the user's hand to the portion below the display 2 where the irradiation intensity of infrared light is weakened can also be well detected. In addition, if the detection sensitivity of the user's hand is uniformly increased with respect to portions other than the portion below the display surface of the display 2, it may lead to erroneous detection such as detecting the user's hand approaching the display surface even when the user's hand is away from the display surface of the display 2. However, according to the present embodiment, the occurrence of such erroneous detection is suppressed.

[0075] Therefore, the approach of the user's hand can be well detected with respect to the entire area of ​​the display surface of the display 2 .

[0076] In addition, in the above proximity detection process, the maximum value of the intensity signals A1, A2, A3, and A4 is used as the evaluation index MA, but the evaluation index MA only needs to express the magnitude of the reflected light detected in PD1 and PD2, and can be set to other values. In addition, in the above proximity detection process, the maximum value of the intensity signals E1 and E2 is used as the evaluation index ME, but the evaluation index ME only needs to express the magnitude of the reflected light detected in PD2 when only LED1 is turned on and the magnitude of the reflected light detected in PD1 when only LED4 is turned on, and can be set to other values. In addition, in the above proximity detection process, ME / MA is used as EY, but EY only needs to be an indicator value that has a rough correlation with whether the detection object is in the upper part or the lower part of the display area, and can be set to other values.

[0077] In the above embodiment, four infrared LEDs LED1, LED2, LED3, and LED4 and two photodiodes PD1 and PD2 are used, but the number of infrared LEDs may be other than four and the number of photodiodes may be other than two.

[0078] In this case, with respect to one or more infrared LEDs that are relatively far apart, an intensity signal detected by a photodiode that is relatively far away from the infrared LED when the infrared LED is turned on will replace the above-mentioned intensity signals E1 and E2 to detect whether the user's hand is located in the area above the display 2.

[0079] That is, for example Figure 8 As shown in b, when six infrared LEDs, namely LED1, PD1, LED2, LED3, PD2, LED4, LED5, PD3, and LED6, and three photodiodes are arranged from left to right in the order described, the position of the user's hand in the area above the display 2 is detected according to the size of the intensity signal detected by PD3 when only LED1 is turned on and the size of the intensity signal detected by PD1 when only LED6 is turned on.

[0080] Alternatively, for example, whether the user's hand is located in the area above the display 2 is detected according to the magnitude of the intensity signal detected by the PD2 when only the LED 1 is turned on and the intensity signal detected by the PD2 when only the LED 6 is turned on.

[0081] Alternatively, for example, whether the user's hand is located in the area above the display 2 is detected according to the magnitude of the intensity signal detected by PD1 when only LED4 or LED5 is turned on, and the magnitude of the intensity signal detected by PD3 when only LED2 or LED3 is turned on.

[0082] In the above embodiment, the plurality of infrared LEDs and the plurality of photodiodes are arranged slightly below the lower side of the display 2, but they may be arranged slightly outside any side of the display 2. Figure 8 As shown in b, the four infrared LEDs LED1, LED2, LED3, and LED4 and the two photodiodes PD1 and PD2 are arranged slightly to the right of the right side of the display 2.

Claims

1. A proximity detection device for detecting a user approaching a display surface of a display, characterized in that: have: A plurality of infrared light sources are arranged outside a display surface of the display along a first side which is one side of the display surface, and emit infrared light passing in front of the display surface; A plurality of light detectors are arranged along the first side outside the display surface; a proximity detection unit that, for each of the plurality of infrared light sources, uses the intensity of reflected light of the infrared light emitted by the infrared light source detected by a light detector corresponding to the infrared light source according to a predetermined correspondence as a first detected reflection intensity of the emitted light of the infrared light source, and detects the approach of the user to the display surface when the intensity of the reflected light of the infrared light represented by the first detected reflection intensity of the emitted light of each infrared light source exceeds a set threshold value; as well as The threshold setting unit takes one or more infrared light sources among the multiple infrared light sources as target infrared light sources, and for each target infrared light source, takes the intensity of reflected light of infrared light emitted by the target infrared light source detected by a light detector that is farther away from the target infrared light source than the light detector that establishes a corresponding relationship with the infrared light source as the target infrared light source as the corresponding relationship, as the second detected reflection intensity of the emitted light of the target infrared light source, and sets the threshold to the proximity detection unit in a manner that changes the threshold based on each second detected reflection intensity and each first detected reflection intensity and in accordance with an evaluation value calculated according to a prescribed evaluation function.

2. The proximity detection device according to claim 1, characterized in that: The threshold setting unit estimates the ratio of the maximum value of each second detected reflection intensity to the maximum value of each first detected reflection intensity as the evaluation value, and when the estimated evaluation value is less than a specified level, sets the threshold for the proximity detection unit in a manner that makes the threshold smaller than when the evaluation value is not less than the specified level.

3. The proximity detection device according to claim 2, characterized in that: The approach detection unit detects the approach of the user to the display surface when the maximum value of the first detected reflection intensities exceeds a set threshold value.

4. The proximity detection device according to claim 1, characterized in that: The threshold setting unit estimates a ratio of a maximum value of each second detected reflection intensity to a maximum value of each first detected reflection intensity as the evaluation value, and sets the threshold for the proximity detection unit so that the threshold is reduced as the estimated evaluation value is reduced.

5. The proximity detection device according to claim 4, characterized in that: The approach detection unit detects the approach of the user to the display surface when the maximum value of the first detected reflection intensities exceeds a set threshold value.

6. The proximity detection device according to claim 1, characterized in that: The approach detection unit detects the approach of the user to the display surface when the maximum value of the first detected reflection intensities exceeds a set threshold value.

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