User interface with optical detection device

Abstract

A user interface is disclosed, comprising a device enabling optical detection of the presence and position of an object (2) in a detection zone (3). The device comprises a means (7) for illuminating the detection zone (3) and a linear detection strip (5) including an array of light sensors (6) directed towards the detection zone (3) and configured to measure the light intensity of the light emitted by the illuminating means (7). The sensitivity to light of each light sensor (6) is weighted according to the position of the light sensor (6) along the array of light sensors (6).

Description

[Technical Field]

[0001] The present invention relates particularly to the field of interfaces that allow users to interact with devices (machines), and more particularly to devices that are capable of detecting commands or instructions physically expressed by a user. [Background technology]

[0002] Many interfaces allow users to interact with devices such as computers. Among the most common, keyboards allow users to input text by pressing physical keys. Similarly, mice allow users to control the movement of a pointer on a screen through the physical movement of the mouse.

[0003] User interfaces, in particular, have undergone substantial development to keep pace with the evolution of computer hardware and software, and one of the axes of this development is the detection of user instructions by directly interpreting the user's movements, without the manipulation of physical elements. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to improve upon the user interfaces of the prior art. [Means for solving the problem]

[0005] To this end, the invention relates to a user interface comprising a device allowing optical detection of the presence and position of an object in a detection zone, said interface comprising: means for illuminating the detection zone; a linear detection strip including an array of light sensors directed towards the detection zone and configured to measure the light intensity of the light emitted by the illuminating means; Equipped with The sensitivity of each photosensor to light is weighted according to the photosensor's position along the row of photosensors.

[0006] The user interface according to the present invention allows the presence and position of an object such as a user's finger, hand, or other body part to be detected without the need for a camera, touch-activated device, or physical device. The position is detected in an absolute manner and with great accuracy.

[0007] The device of the present invention may be used in any environment in a manner that is more intuitive for the user while minimizing the physical equipment required.

[0008] The position is detected contactlessly in a manner that is immune to and does not generate electromagnetic interference. Optical detection has the expected advantages of optical position detection technology, namely reliability, simplicity, and electromagnetic compatibility.

[0009] The device enabling optical detection according to the present invention may have the following additional features, either alone or in combination: The sensitivity of each light sensor to light is weighted such that the sensitivity of the light sensor to light increases with the ordinal position of the light sensor along the row of light sensors; · The sensitivity of each light sensor to light is weighted by applying a weighting factor to the output signal of each light sensor; Each light sensor has a sensitivity cone that defines the angle at which the light sensor can sense light radiation, and the light sensors have overlapping sensitivity cones; · The degree of overlap of the sensitivity cones of the optical sensors is at least 15%; · the user interface is configured to determine the position of the object based on a weighted sum of the output signals of each of the optical sensors; The sensitivity of the light sensors to light is weighted in parallel according to at least two weightings, a first weighting considering all the light sensors and a second weighting considering only some of the light sensors; the sensitivity to light of each light sensor considered according to the second weighting is weighted according to the second weighting such that the sensitivity to light of said light sensor increases with the ordinal position of the light sensor along the row of light sensors; · The sensitivity to light of each light sensor is weighted according to the second weighting by applying a weighting coefficient to the output signal of each light sensor; The user interface is configured to determine the position of the object based on a sum of weighted values ​​of the output signals of each optical sensor according to a first weighting or a second weighting depending on the distance between the object and the linear detection strip, i.e., the user interface is configured to determine the position of the object based on a sum of weighted values ​​of the output signals of each optical sensor according to the first weighting when the distance between the object and the linear detection strip is less than a predetermined value, and according to the second weighting when the distance between the object and the linear detection strip is greater than the predetermined value; The sum of the weighted values ​​is divided by the average of the sum of the weighted values ​​according to the first weighting and the sum of the weighted values ​​according to the second weighting; · the user interface comprises an additional distance sensor configured to determine a distance between the object and the linear detection strip; the light sensors are regularly distributed along the row of light sensors with a pitch p, and the second weighting only considers light sensors with a pitch 2p; The user interface includes a control module including a first computing element configured to compute a sum of light intensity values ​​detected by the light sensors while applying a weighting coefficient to each light sensor; · the control module includes a second computing element configured to apply a weighting coefficient to each light sensor while computing a sum of the light intensity values ​​detected by the light sensors taken into account according to the second weighting; · the illuminating means includes a plurality of light emitters interposed between the optical sensors and directed towards the detection zone; Each light emitter has an emission cone that defines the angle at which the light emitter emits light radiation, the light emitters having overlapping emission cones; and The illuminating means is configured to flash at a predetermined frequency, and the output signal of each light sensor is demodulated at the same frequency. [Brief explanation of the drawings]

[0010] Other characteristics and advantages of the present invention will become apparent from the following non-limiting description, which refers to the accompanying drawings, in which: [Figure 1] 1 is a schematic diagram of an apparatus enabling optical detection according to the present invention; [Figure 2] 1 is a graph illustrating signal processing that enables light detection. [Figure 3] 1 is a graph illustrating signal processing that enables light detection. [Figure 4] 1 is a graph illustrating signal processing that enables light detection. [Figure 5] 1 is a graph illustrating signal processing that enables light detection. [Figure 6] 1 is a graph illustrating signal processing that enables light detection. [Figure 7] FIG. 10 is an explanatory diagram of parameters relating to light detection.

[0011] Similar elements common to the various embodiments are designated by the same reference numerals in all figures. DETAILED DESCRIPTION OF THE INVENTION

[0012] 1 shows diagrammatically a device 1 enabling optical detection according to the invention. In this example, this device forms part of an interface that allows a user to send commands to a computing device by presenting a finger 2 at one or more predetermined positions within a detection zone 3. For example, the detection zone 3 may be a virtual keyboard or a virtual console, optionally embodied by a two-dimensional or three-dimensional visual element.

[0013] In Figure 1, a user's finger 2 is shown schematically from the front, and the device 1 is able to determine the position of this finger along a detection axis 4 that extends as indicated by the double-headed arrow shown in Figure 1. Detection of the finger 2 at a given abscissa along the detection axis 4 corresponds to a command given to the device by the user.

[0014] The device 1 comprises a linear detection strip 5 including light sensors 6 aligned along a detection axis 4, thus forming a row of light sensors 6. The distance between the linear detection strip 5 and the finger 2 is denoted D.

[0015] Generally, the light sensors are designated by the reference numeral 6 in the figures and are individually numbered Ph1, Ph2, Ph3, ..., Ph5 in Figure 1. The light sensors may be of any known type, such as photodiodes, photoresistors, etc., and have a Gaussian angular sensitivity to light. In Figure 1, a Gaussian sensitivity curve is shown above each light sensor 6.

[0016] The linear detection strip 5 is directed towards the detection zone 3, i.e. the optical sensor 6 is directed towards the detection zone 3.

[0017] Furthermore, the device 1 comprises means 7 for illuminating the detection zone 3. An advantageous example is to form the illuminating means 7 with light emitters (e.g. light emitting diodes) inserted regularly between the light sensors 6 and directed towards the detection zone 3. Each of these light emitters has an emission cone that defines the angle at which it emits light radiation. Preferably, these emission cones overlap. In this example, a light emitter is inserted every two light sensors 6 in the row of light sensors 6.

[0018] In the linear detection strip 5, the light sensors 6 are regularly arranged at regular intervals corresponding to a pitch indicated as p in FIG.

[0019] Along a row of light sensors 6, the light sensitivity value of each light sensor 6 is weighted according to the position of the light sensor along the row. Here, this weighting is achieved by forming the row of light sensors 6 from light sensors that have increasing light sensitivity along the row of light sensors 6. Thus, the light sensitivity of each light sensor 6 is weighted such that the light sensitivity of the light sensor 6 increases according to the ordinal position of the light sensor 6 along the row of light sensors 6. In other words, the second light sensor 6 (along the row of light sensors 6) is more sensitive to light than the first light sensor 6. The third light sensor 6 is more sensitive to light than the second light sensor 6. The fourth light sensor 6 is more sensitive to light than the third light sensor 6, and so on.

[0020] In this example, each light sensor 6 is assigned a weighting coefficient by which the value of its sensitivity to the measured light is multiplied, this coefficient corresponding to the ordinal position of the light sensor along the line.

[0021] The device 1 comprises a control module 8 formed by any suitable analog or digital electronic means, such as a microcontroller.

[0022] The control module 8 comprises a first calculation element 9 configured to calculate the sum of the light intensity values ​​detected by the light sensors while applying a weighting coefficient to each light sensor equal to the ordinal position of the light sensor in the string of light sensors.

[0023] In FIG. 1, the first computing element 9 is receiving the light intensity of the first light sensor Ph1 and applying a weighting factor of 1 thereto; receiving the light intensity of the second light sensor Ph2 and applying a weighting factor of 2 thereto; Receive the light intensity of the third light sensor Ph3 and apply a weighting factor of 3 to it.

[0024] In the schematic diagram of Figure 1, only three light sensors 6 are supplied to the first computing element 9, but it will be appreciated that the linear detection strip can include as many light sensors 6 as necessary to cover the desired length of the detection axis 4.

[0025] The weighted sum S1 of the output values ​​of the optical sensor 6 is defined as follows:

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[0026] In this example, the control module 8 also performs a second weighting in parallel with the first weighting, which can optionally improve the measurement. In addition to the weighting described above, the control module 8 is configured to weight the outputs of the light sensors 6 that are separated by a distance 2p. The control module 8 therefore comprises a second calculation element 10 configured to calculate the sum of the light intensity values ​​detected by the light sensors 6 involved, i.e., every other light sensor 6 for the first weighting, using this second weighting, while applying a weighting to each light sensor 6 that depends on its ordinal position. Thus, according to this second weighting, only the light sensors 6 separated by the pitch 2p are considered to form a row of light sensors 6, and the light intensity measured by each is multiplied by a coefficient corresponding to the ordinal position of each light sensor 6 in this row of light sensors 6.

[0027] In FIG. 1, the second computing element 10 is receiving the light intensity of the first light sensor Ph1 and applying a weighting factor of 1 thereto; receiving the light intensity of the third light sensor Ph3 and applying a weighting factor of 2 thereto; Receive the light intensity of the fifth light sensor Ph5 and apply a weighting factor of 3 to it.

[0028] The weighted sum S2 of the output values ​​of only the light sensors 6 taken into account by the second weighting is defined as follows:

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[0029] When the user places the finger 2 at the correct position within the detection zone 3, the finger 2 is illuminated by the illumination means 7, and the finger 2 has a luminous intensity that is greater than the ambient luminous intensity. The presence of this illuminated object provides each light sensor 6 with a light intensity that decreases with the distance between the light sensor 6 and the finger 2.

[0030] The light sensors 6 have sensitivity cones that define the angles over which the light sensors 6 can sense optical radiation. The light sensors 6 are selected and positioned so that the sensitivity cones overlap. Preferably, the light sensors 6 have an overlap of 15% or greater between their sensitivity cones.

[0031] Figure 2 shows the weighted sum Si as a function of the linear position of the finger 2 along the detection axis 4, in centimeters around position 0. Figure 2 shows four curves corresponding to four different distances: Curve 11 represents the weighted sum S1 when the distance D between the finger 2 and the linear detection strip 5 is 5 cm; · Curve 12 represents the weighted sum S1 when the distance D is 10 cm, · Curve 13 represents the weighted sum S1 when the distance D is 15 cm, · Curve 14 represents the weighted sum S1 when the distance D is 20 cm.

[0032] In this example, the pitch p is 2 cm, the angular width (full width maximum at half maximum) of each Gauss (characteristic of the sensitivity cone of the light sensor 6) is 20°, and the width of the finger 2 is 2 cm.

[0033] FIG. 2 shows that finger 2 can be positioned linearly with great accuracy over a range extending from approximately −5 cm to approximately +5 cm. Specifically, over this range, the curve of finger 2 position as a function of weighted sum S1 output by first computing element 9 is very close to a straight line. In other words, control module 8 can directly determine the position of finger 2 on detection axis 4 from a simple digital value converted by a linear function (the slope of the corresponding straight line). This conversion is fast and requires very little computational resources, particularly much less than the processing of images collected by a camera. Nevertheless, this simple operation allows finger 2 to be positioned very accurately.

[0034] Figure 3 is a graph similar to Figure 2, but for the weighted sum S2. Thus, Figure 3 shows the weighted sum S2 as a function of the linear position of the finger 2 along the detection axis 4, in centimeters around position 0. Figure 3 shows four curves corresponding to the same four distances as Figure 2: · Curve 15 represents the weighted sum S2 when the distance D is 5 cm, · Curve 16 represents the weighted sum S2 when the distance D is 10 cm, · Curve 17 represents the weighted sum S2 when the distance D is 15 cm, · Curve 18 represents the weighted sum S2 when the distance D is 20 cm.

[0035] 3 shows that the finger 2 may be positioned linearly with great accuracy over a wider range than is possible with the weighted sum S1, but only for distances corresponding to curves 17 and 18. Furthermore, for these curves 17, 18 the gain is approximately constant as a function of distance D, which makes it possible to obtain a correspondence between the weighted sum S2 output by the second computing element 10 and the linear position of the finger on the detection axis 4 given by a single straight line, regardless of the distance between the finger 2 and the linear detection strip 5.

[0036] In contrast, for distances less than 15 cm (curves 15 and 16), the measurements become less and less linear and the appearance of undulations prevents an objective correspondence between the weighted sum and the finger position.

[0037] Thus, weighted sum S2 may alternatively be used to complete the correspondence given by weighted sum S1 for distances D for which weighted sum S2 is available, improving the measurement range and providing a constant gain measurement. Figure 4 shows this combination, where control module 8 selects weighted sum S1 or weighted sum S2 depending on the distance D between finger 2 and linear detection strip 5. Weighted sum S2 is used for distances D from 10 cm to 20 cm, and weighted sum S1 continues to be used for distances D up to 10 cm.

[0038] The interface is therefore configured to determine the position of the object 2 based on the weighted sum of the output signals of each light sensor 6: If the distance between the object 2 and the linear detection strip 5 is less than a predetermined value, then, depending on the first weighting, According to a second weighting, if the distance between the object 2 and the linear detection strip 5 is greater than a predetermined value.

[0039] Optionally, a correction gain may be applied to obtain substantially the same slope for each range.

[0040] To implement this solution of combining the weighted sums S1 and S2, an additional distance sensor, for example of the Time of Flight (ToF) or rangefinder type, may be used to obtain the distance D.

[0041] Thus, the sensitivity to light of the light sensors 6 of the row of light sensors 6 is weighted in parallel according to at least two weightings, namely a first weighting that takes into account all light sensors (at pitch p) and a second weighting that takes into account only a portion of the light sensors 6 (here, the light sensors 6 at pitch 2p).

[0042] In this example, the weighted sum S2 is relative to the pitch 2p, i.e., only one out of two light sensors 6 is considered. However, as a variant, the weighted sum S2 may be calculated for different pitch choices. For example, depending on the distance allowed for the finger 2, one out of three light sensors 6 (corresponding to a pitch 3p) or one out of four light sensors 6 (corresponding to a pitch 4p) may be considered.

[0043] Also, Figure 5 relates to a combination of Figure 4. Figure 5 shows a projected Gaussian curve as a function of distance D and finger position (in this example a Gaussian curve with a full width at half maximum of 20°).

[0044] For the weighted sum S1, the three curves 19, 20, 21 show Gaussian curves for three light sensors 6 located at 0, 2 and 4 cm, respectively, for a distance D of 5 cm.

[0045] For the weighted sum S2, three curves 22, 23, 24 show Gaussian curves for three light sensors 6 located at 0, 4 and 8 cm, respectively, for a distance D of 20 cm.

[0046] Figure 5 shows the advantage of choosing the distribution of either curves 19, 20, 21 or curves 22, 23, 24 depending on the distance D, since it allows maintaining a sufficient Gaussian overlap to ensure that the fingers are positioned with good linearity.

[0047] Furthermore, in order to eliminate the influence of environmental disturbances, the light sensors 6 can be matched to the light emitted by the illuminating means 7. For example, the illuminating means 7 can be made to blink at a certain frequency, and this modulated signal can be used to demodulate the output signal of each light sensor 6 via synchronous detection. Thus, the influence of fluctuations in ambient lighting, for example due to the sun or artificial lighting, can be eliminated. Also, a selective filter (rejector) can be added to eliminate lighting disturbances due to ambient lighting flicker (for example, 100 Hz fluorescent tubes or some LED lights).

[0048] Alternatively, in addition to weighted sum S2, other additional weighted sums may be used to complete weighted sum S1, taking into account the selection of photosensors with pitches other than p and 2p.

[0049] As a modification, in addition to the weighted sums S1 and S2, the average sum S moy Calculate S1 and S moy Divide S2 by S moy You can also divide by , which normalizes the sum.

[0050] In this case, the weighted sums S1 and S2 normalized in this way can be expressed as:

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[0051] Figure 6 shows the form of the normalized sums S1 and S2 in this way: Curve 25 represents the weighted sum S1 normalized in this way when the distance D is 5 cm, Curve 26 represents the weighted sum S1 normalized in this way when the distance D is 10 cm, Curve 27 represents the weighted sum S2 normalized in this way when the distance D is 15 cm, Curve 28 represents the weighted sum S2 normalized in this way when the distance D is 20 cm.

[0052] The change in slope is limited to obtain an odd curve that is advantageous for position purposes, where the normalized sum S2 is selected for distances of 15 cm and 20 cm, and the normalized sum S1 is selected for distances of 5 cm and 10 cm.

[0053] With reference to FIG. 7, an example of a model used to define the position of the finger 2 is presented.

[0054] Finger 2 is considered as a contrasting strip of intensity I1 situated on a background of intensity I2. The width of the strip is Δ fThe finger 2 is at a distance D from the linear detection strip 5 and its abscissa on the detection axis 4 is b The abscissas of the optical sensors 6 (their positions along the detection axis 4) are denoted Xpi. L1 and L2 are the detection angles of the finger 2 edges.

[0055] The formula for the Gaussian angular sensitivity s(Ψ) is given as:

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[0056] Next, we need to integrate over the entire angular width of the Gaussian distribution (from minus infinity to plus infinity) to calculate the total strength of the signal received by the light sensor placed under the finger:

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[0057] This gives us:

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[0058] Variants of the embodiment of the device may be implemented: for example, the illuminating means 7 and the associated light sensor 6 may operate at any suitable wavelength (visible or invisible), in particular infrared.

[0059] The example given here relates to detecting the position of a finger 2, but it may also detect the hand, foot or other part of the body, or an object held by the user.

[0060] Furthermore, although the linear detection strip 5 presented as an example is straight, it will be understood that this strip, and therefore the row of light sensors 6 and the detection axis 4, may be curved, in particular semicircular.

[0061] Furthermore, multiple linear detection strips 5 may be combined to detect the position of an object along various detection axes. For example, multiple linear detection strips 5 arranged along different axes may allow detection of a finger 2 in multiple spatial dimensions.

Claims

1. A user interface comprising a device enabling optical detection of the presence and position of an object (2) in a detection zone (3), a means (7) for illuminating said detection zone (3); a linear detection strip (5) directed towards said detection zone (3) and including an array of light sensors (6) configured to measure the light intensity of the light emitted by said illuminating means (7); Equipped with the sensitivity of each light sensor (6) to light is weighted according to the position of the light sensor (6) along the row of light sensors (6); User interface.

2. the sensitivity of each light sensor (6) to light is weighted such that the sensitivity of the light sensor (6) to light increases with the ordinal position of the light sensor (6) along the row of the light sensors (6); The user interface of claim 1 .

3. the sensitivity of each of said light sensors (6) to light is weighted by applying a weighting factor to the output signal of each of said light sensors (6); A user interface according to claim 1 or 2.

4. each said light sensor (6) having a sensitivity cone defining an angle over which said light sensor (6) can sense optical radiation, said light sensors (6) having overlapping sensitivity cones; A user interface according to any one of claims 1 to 3.

5. the overlap of the sensitivity cones of the optical sensors (6) is at least 15%; The user interface of claim 4.

6. configured to determine the position of the object (2) based on a weighted sum of the output signals of each of the optical sensors (6). A user interface according to any one of the preceding claims.

7. the sensitivity of the light sensors (6) to light is weighted in parallel according to at least two weightings, a first weighting taking into account all the light sensors (6) and a second weighting taking into account only a portion of the light sensors (6); A user interface according to any one of the preceding claims.

8. the sensitivity to light of each of the photosensors (6) considered according to the second weighting is weighted according to the second weighting such that the sensitivity to light of the photosensor (6) increases with the ordinal position of the photosensor (6) along the row of the photosensors (6); The user interface of claim 7.

9. the sensitivity to light of each of said light sensors (6) is weighted according to said second weighting by applying a weighting factor to the output signal of each of said light sensors (6); A user interface according to claim 7 or 8.

10. Depending on the distance between the object (2) and the linear detection strip (5), a weighted value (S １ , S ２ ) configured to determine the position of the object (2), A user interface according to any one of claims 7 to 9.

11. the sum of the weighted values ​​is divided by an average of the sum of the weighted values ​​according to the first weighting and the sum of the weighted values ​​according to the second weighting; The user interface of claim 10.

12. an additional distance sensor configured to determine the distance between the object and the linear detection strip (5); A user interface according to claim 10 or 11.

13. the light sensors (6) are regularly distributed along the row of the light sensors (6) with a pitch p, and the second weighting only takes into account the light sensors (6) with a pitch 2p; A user interface according to any one of claims 7 to 12.

14. The sum of the light intensity values ​​detected by the light sensors (6) while applying a weighting coefficient to each of the light sensors (S １ a control module (8) including a first computing element (9) configured to compute A user interface according to any preceding claim.

15. The control module (8) applies a weighting factor to each of the light sensors while calculating a sum (S ２ a second computing element (10) configured to compute A user interface according to claim 14 when dependent on claim 7.

16. The illuminating means (7) includes a plurality of light emitters interposed between the light sensors (6) and directed towards the detection zone. A user interface according to any one of the preceding claims.

17. each said light emitter having an emission cone defining an angle at which the light emitter emits light radiation, said light emitters having overlapping emission cones; 17. The user interface of claim 16.

18. the illuminating means (7) is configured to flash at a predetermined frequency, and the output signal of each of the light sensors (6) is demodulated at the same frequency; A user interface according to any preceding claim.

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