JP7675414B2 - Optical keyboard - Google Patents

Description

The present invention relates to a keyboard.

Patent Document 1 describes an optical keyboard. This keyboard has buttons at the intersections of rows and columns of optical paths arranged in a matrix, and when a button is pressed, one of the optical paths of the rows and columns is blocked. The pressed button is identified by identifying the blocked row and column.
Patent Document 2 describes a release switch that can optically detect the amount of button depression. In this release switch, a line sensor with multiple light receiving elements and a surface light emitter face each other across a stem with a through hole, and when the button is pressed, the stem moves, changing the light receiving element into which light emitted by the surface light emitter (light source) enters through the through hole. This is used to detect the amount of button depression.
Patent Document 3 describes a switch that can optically detect the amount of button depression. In this switch, highly directional light from a light-emitting element, which is the light source, is reflected by a reflector and made to enter one of the light-receiving elements in a light-receiving element group. By rotating or moving the reflector as the button is pressed, the light-receiving element to which the light enters changes depending on the amount of button depression. This is used to detect the amount of button depression.

Japanese Patent Application Publication No. 07-306738 JP 2010-192410 A JP 2005-158586 A

However, when trying to detect the amount of depression of each push button on a keyboard with multiple push buttons, the switches in Patent Documents 2 and 3 require a light source and a light receiving element to be individually provided for each push button, which is costly.

In theory, it is possible to apply mechanisms equivalent to those in Patent Documents 2 and 3 to the keyboard of Patent Document 1, consolidating the light source and light receiving element group into multiple push buttons to reduce costs and also make it possible to detect the amount of depression of each push button. In other words, in the keyboard of Patent Document 1, it is possible to place the stem, i.e., the light blocking means of Patent Document 2, or the reflector, i.e., the light reflecting means of Patent Document 3, at each intersection of the light paths of the rows and columns, and to configure it so that the light path is changed by displacing it according to the amount of depression of the push button, and that the change can be detected by the consolidated light receiving element group. However, there are at least the following two problems with configuring such a keyboard in reality.

The first problem is that the light reflecting means (mirrors) need to be aligned (positional relationship and orientation) with high precision to form a matrix of light paths. In the keyboard of Patent Document 1, light from one light source is sent in a time-division manner to multiple light paths in a matrix of rows and columns, but light reflecting means are used to form these light paths, and these need to be aligned with high precision so that the light from the light source reaches the light receiving elements.

The second problem is that alignment errors in the optical elements that make up the optical path make it difficult to detect the amount of depression of the push button.
Because keyboards are subject to external forces such as pressing down on buttons, and because keyboards are not necessarily used in a constant temperature environment, it is highly likely that the structure that supports the buttons, light source, and light receiving elements, i.e., the keyboard housing, etc., will become distorted by external forces or thermal expansion. This distortion will result in alignment errors and changes in the optical path, causing errors in the detection of the amount of pressing or making it impossible to detect.

The first object of the present invention is to provide an optical keyboard that can optically detect the amount of depression of multiple push buttons using a centralized light source and a centralized group of light receiving elements, without using a matrix-shaped optical path that requires highly accurate alignment of optical elements such as light reflecting means.

The second object of the present invention is to provide an optical keyboard that aggregates light sources and light receiving elements into multiple push buttons and can detect the amount of depression of each push button even if distortion occurs in the structure of the keyboard housing, etc.

In a first aspect of the present invention, there is provided an optical keyboard including a button module having a push button with a protrusion and a package that stores the push button in a manner that allows the protrusion to protrude from a hole, the push button is multiple, and the light scattering characteristics or fluorescence characteristics of at least a part of the protrusion and at least a part of the exterior of the package are different, and the more the push button is pressed, the more the protrusion protrudes from the package.

According to the first aspect, it becomes possible to optically observe the protrusion protruding from the package based on the difference in light scattering characteristics or fluorescence characteristics between the package and the protrusion.
Also, the amount of depression of each push button can be detected by observing the amount of projection of the protruding portion from the package.
Furthermore, since the protrusions protrude from the package, it is possible to illuminate the protrusions of multiple push buttons using a single light source without using a matrix-shaped light path, and to observe the scattered light or fluorescence from the protrusions of multiple push buttons using a single imaging element.
In other words, the amount of depression of each push button can be optically detected by scattered light or fluorescent light using a concentrated light source and a concentrated group of light receiving elements, without using a matrix-like optical path.

As a second aspect of the present invention, there is provided an optical keyboard according to the first aspect, in which a part of the protrusion protrudes from the package even when the push button is not depressed.

With this second aspect, the protrusion always protrudes from the package, so the protrusion can always be optically observed. Therefore, even if structural distortion such as deformation of the housing occurs and the relative position of the protrusion changes, the change in position can be continuously tracked. In other words, even if structural distortion such as deformation of the housing occurs, the protrusion will not be lost and it will not be confused with the protrusion of another push button, and the amount of depression of the push button can be optically detected by scattered light or fluorescence.

As a third aspect of the present invention, there is provided an optical keyboard according to the first or second aspect, in which at least a portion of the protrusion and at least a portion of the exterior of the package have a surface that suppresses light reflection.

This third aspect makes it possible to optically detect the amount of depression of the push button using scattered light or fluorescence without being affected by reflected light from the protrusion or package.

In a fourth aspect of the present invention, an optical keyboard according to any one of the first to third aspects is provided, which includes a light source having directionality for irradiating the plurality of protrusions and their surroundings, an imaging element having a light receiving surface, and an imaging element for forming an image on the light receiving surface of scattered light or fluorescent light emitted by at least a portion of each of the plurality of protrusions.

This fourth aspect allows the scattered light or fluorescence emitted by the protrusion to be imaged on the light receiving surface of the image sensor by the imaging element, making it possible to observe the protrusion based on the difference in light scattering characteristics or fluorescence characteristics between the protrusion and other parts using image data output by the image sensor.

As a fifth aspect of the present invention, there is provided an optical keyboard according to any one of the first to fourth aspects, which comprises a processor and a memory, and the processor calculates the amount of depression based on a metric value of a pixel set whose elements are pixels of image data stored in the memory, pixels whose pixel values have a predefined relationship with a reference pixel value stored in the memory, and pixels that are adjacent to the reference coordinates stored in the memory.

This fifth aspect allows the processor to analyze the image data and calculate the amount of depression based on the metric value of the set of pixels corresponding to the protrusion.
Here, the reference coordinates are the coordinates on the image data of a pixel that is known to be a pixel corresponding to a protrusion of a particular push button, the reference pixel value is a pixel value that is characteristic of a pixel corresponding to a protrusion on the image data, and a pixel whose pixel value has a predefined relationship to the reference pixel value can be considered to be a pixel corresponding to a protrusion.
Therefore, a pixel set whose elements are pixels whose pixel values have a predetermined relationship with a reference pixel value and whose pixels are neighbors of the reference coordinates is a set of pixels that correspond to a specific push button protrusion determined by the reference coordinates. The metric value of the set increases as the push button is pressed down and the protrusion protrudes more, and the amount of press can be calculated based on this.

As a sixth aspect of the present invention, there is provided an optical keyboard in which, in the optical keyboard of the fifth aspect, if the pixel value of the pixel at the reference coordinate is not in a predetermined relationship with the reference pixel value, the processor searches for a pixel in the vicinity of the reference coordinate of the image data whose pixel value has a predetermined relationship with the reference pixel value, and writes the coordinates into the memory as new reference coordinates.

With this sixth aspect, even if structural distortion such as deformation of the housing occurs, causing a change in the relative position of the protrusion, causing the pixel corresponding to the protrusion in the image data to move from the reference coordinates, the pixel corresponding to the protrusion can be found near the reference coordinates and its coordinates can be reset as new reference coordinates, making it possible to continue detecting the amount of pressure being applied.

The present invention provides an optical keyboard that can optically detect the amount of depression of multiple push buttons using a centralized light source and a centralized group of light receiving elements, without using a matrix-shaped optical path that requires highly accurate alignment of optical elements.

The present invention also makes it possible to provide an optical keyboard in which light sources and light receiving elements are aggregated in multiple push buttons, and the amount of depression of each push button can be detected even if distortion occurs in the structure of the keyboard housing, etc.

1 is an isometric projection view illustrating the appearance of an optical keyboard 1 according to the present invention. FIG. 2 is a plan view illustrating the upper surface of the optical keyboard 1 according to the present invention. 3 is a cross-sectional view taken along line A-A in FIG. 2. FIG. 3 is a cross-sectional view taken along line B-B in FIG. 2 is a block diagram illustrating the configuration of an information processing unit 30. FIG. FIG. 3 is a diagram showing an example of data in table 34. FIG. 4 is a diagram showing a specific example of image data. 10 is a flowchart illustrating the operation of the processor 31 when image data is received from the imaging element 22. FIG. 4 is a diagram showing a specific example of image data.

Below, an embodiment of the present invention will be described with reference to the attached drawings. However, in the second embodiment, components that are the same as or similar to those in the first embodiment are indicated with the same or similar reference numerals as in the first embodiment, and detailed descriptions will be omitted as appropriate. In addition, with regard to the effects obtained in the second embodiment that are similar to those in the first embodiment, descriptions will be omitted as appropriate. The drawings of each embodiment are illustrative, and the dimensions and shapes of each part are schematic, and the technical scope of the present invention should not be interpreted as being limited to the embodiments.

First Embodiment
An optical keyboard 1 according to a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an isometric projection view illustrating the appearance of an optical keyboard 1, FIG. 2 is a plan view illustrating the upper surface of the same, and FIG. 3 is a cross-sectional view taken along line AA.
The optical keyboard 1 includes a housing 2 having a top panel 4, one or more button modules 10, a depression amount detection module 20, and a light source 3.

The light source 3 is a light source that irradiates light into the inside of the housing 2. Since the depression amount detection module 20 captures scattered light from the protrusion 115 of the push button 11 obtained by irradiating the protrusion 115 of the push button 11 with light from the light source 3, the light source 3 needs to have a directivity such that it can simultaneously irradiate a plurality of, preferably all, protrusions 115 of the push button 11, preferably including the periphery of the protrusion 115, and emit light that includes a wavelength band used by the depression amount detection module 20 to detect the amount of depression.
With regard to the position and directivity of the light source 3, in a method of controlling the light path by reflection or shading as in the background art, the position and directivity of the light source must be determined with high precision. However, in this embodiment, it is sufficient that the scattered light from the protrusion 115 reaches the depression amount detection module 20, so the position and irradiation direction of the light source 3 can be determined relatively freely as long as it is possible to illuminate the protrusions 115 of all push buttons 11 with a sufficiently wide-angle directivity.
The light source 3 may emit light continuously in time, but may be controlled so as to emit light only during the period during which the image sensor 22 receives light necessary to generate image data.

The housing 2 has one or more openings 5 in its top panel 4 into which the button modules 10 are inserted.
It is preferable that the housing 2 has a high light blocking property in order to prevent light (ambient light) from the outside of the housing 2 from entering the press amount detection module 20 and affecting the press amount detection process.
It is preferable that at least a part of the inner surface of the housing 2 has a surface that suppresses reflection of light. Alternatively, it is preferable that the housing 2 has a surface that suppresses reflection of the light emitted from the light source 3. This is to prevent the reflected light, in addition to the scattered light of the light emitted from the light source 3 by the inner surface of the housing 2, from entering the press-down amount detection module 20 and affecting the press-down amount detection process. For example, it is preferable to apply an anti-reflection coating or a rough surface finish to the surface.

The button module 10 comprises a push button 11, a package 12, and an elastic body 13, and is inserted into the opening 5 of the housing 2 for use.

The push button 11 has a pressing portion 111 , an upper limit stopper portion 112 , a reaction force application portion 113 , a lower limit stopper portion 114 , and a protruding portion 115 .
The depressing portion 111 is a portion that can protrude from a hole in the top surface portion 121 of the package 12. The depressing portion 111 may directly receive a depressing force from a keyboard operator. Alternatively, a key cap (not shown) may be placed on the depressing portion 111, and the depressing force may be indirectly received through the key cap.
The upper limit stopper portion 112 is a portion that interferes with the package 12 to determine the uppermost state of the push button 11 .
The reaction force application portion 113 is a portion that comes into contact with the elastic body 13 and transmits the elastic force from the elastic body 13 to the push button 11 .
The lower limit stopper portion 114 is a portion that interferes with the package 12 to determine the lowest position of the push button 11 .

The protruding portion 115 is a portion that can protrude from a hole in the underside portion 123 of the package 12 to the outside of the package 12 when the push button 11 is pressed. It is preferable that the protruding portion 115 protrudes more to the outside of the package 12 the greater the amount by which the push button 11 is pressed down (the amount of depression) when a pressing force is applied to the pressing portion 111.

It is preferable that at least a portion of the protrusion 115 protrudes outside the package 12 even when the push button 11 is not depressed, i.e., when the push button 11 is not pressed and is in its highest position.

It is preferable that at least a portion of the protrusion 115 has a surface that suppresses reflection of light. Alternatively, it is preferable that the protrusion 115 has a surface that suppresses reflection of the light emitted from the light source 3. This is to prevent the reflected light, in addition to the scattered light of the light emitted from the light source 3 by the protrusion 115, from entering the press amount detection module 20 and affecting the press amount detection process. For example, it is preferable to apply an anti-reflective coating or a roughened surface finish.

At least a part of the protrusion 115 needs to have different light scattering characteristics in the wavelength band of light emitted by the light source 3 from both the inside of the housing 2 and the outer part of the package 12 exposed inside the housing 2. This is to enable the scattered light from the protrusion 115 and the scattered light from other places to be clearly distinguished as different pixel values in the image data output by the image sensor 22. The degree to which the light scattering characteristics differ is preferably such that they can be clearly distinguished on the image data output by the image sensor 22.
As an example of a case where the wavelength band of the light source 3 is visible light, the protrusion 115 may be white and the inside of the housing 2 and the outside of the package 12 may be black. Conversely, the protrusion 115 may be black and the inside of the housing 2 and the outside of the package 12 may be white.
In addition, the color of the protrusion 115 may be arbitrarily determined, and one or more colors that are significantly different from the color of the protrusion 115 in one or more of lightness, saturation, and hue (i.e., that are clearly distinguishable in image data) may be selected and used for the inside of the housing 2 and the outside of the package 12. When the light source 3 is in a wavelength band other than visible light, the scattering characteristics of the protrusion 115, the inside of the housing 2, and the outside of the package 12 in that wavelength band may be made different.

Another way to change the scattering characteristics is to make the polarization different. For example, the scattered light from the protrusion 115 may be vertically polarized, and the scattered light from the inside of the housing 2 and the outside of the package 12 may be horizontally polarized. As a method for polarizing the scattered light, for example, the surface of the protrusion 115 may be covered with a film-like polarizing filter.

The package 12 has an upper surface portion 121, a side surface portion 122 and a lower surface portion 123, and houses the push button 11 so that a part of it protrudes outward and is movable up and down, and also houses the elastic body 13.
A hole is formed in the top surface portion 121, and the depressing portion 111 of the push button 11 protrudes from the hole. The top surface portion 121 also abuts against the top panel 4 of the housing 2, thereby functioning as a stopper when the button module 10 is inserted into the opening 5, and is also a portion that transmits the depressing force on the push button 11 to the housing 2.
The side surface portion 122 has a locking piece 124 that locks the button module 10 inserted into the opening 5 so that it does not come off.
A hole is formed in the lower surface portion 123, and the protruding portion 115 of the push button 11 protrudes through the hole. The lower surface portion 123 also abuts against and supports the elastic body 13, thereby applying a reaction force to the push button 11 via the elastic body 13 when the push button 11 is pressed.

It is preferable that the package 12 has a high light-blocking property in order to prevent external ambient light from entering the housing 2 via the button module 10 and affecting the pressing amount detection process by the pressing amount detection module 20. For this reason, it is preferable that the package 12 has a shape that completely covers the entire surface with minimal gaps except for the upper and lower holes through which the push buttons 11 protrude. It is also preferable that the package 12 is made of a material with a high light-blocking property.
For the same reason as for the protrusion 115, it is preferable that at least a part of the outer portion of the package 12 exposed to the inside of the housing 2 has a surface that suppresses reflection of light. Alternatively, it is preferable that the package 12 has a surface that suppresses reflection of the light emitted from the light source 3.

The elastic body 13 contacts the push button 11 and the package 12, and applies an elastic restoring force to the push button 11 according to the amount of depression of the push button 11 as a reaction force against the pressing force. A coil spring or rubber may be used as the elastic body 13. It is also possible to use a magnet or other magnetic force to perform the same function.

Note that while the drawings show one button module 10 containing one push button 11 and one elastic body 13 in one package 12, it may be configured to contain multiple push buttons 11 and multiple elastic bodies 13 in one package 12.

Next, the depression amount detection module 20 will be described with reference to FIG. 4. FIG. 4 is a cross-sectional view of the optical keyboard 1 taken along line B-B. The depression amount detection module 20 includes an imaging element 21, an imaging element 22, and an information processing unit 30.

The imaging element 21 is an optical element that focuses scattered light emitted by at least a part of what is present inside the housing 2, i.e., the inner surface of the housing 2, the button module 10, etc., on the light receiving surface 23. The imaging element 21 is required to focus light from at least a part of each of the multiple protrusions 115 on the light receiving surface 23. It is preferable that the imaging element 21 is such that light from one point inside the housing 2 reaches approximately the same place on the light receiving surface 23, and light from two sufficiently separated points inside the housing 2 reaches places on the light receiving surface 23 that are separated from each other. The imaging element 21 may be a lens, a pinhole, or a concave mirror.

The image sensor 22 has a light receiving surface 23 that receives incident light, and is an element that outputs image data corresponding to the intensity distribution of the incident light on the light receiving surface 23. The image sensor 22 repeats the operation of receiving the incident light and outputting image data corresponding to the intensity distribution. The time period of this repetition may be constant, but the period may also be changed depending on, for example, the degree of change in the image data. The image sensor 22 may be a charge-coupled device (CCD) image sensor or a CMOS image sensor.
The image data is configured to include a set of values for each pixel corresponding to a small area on the light-receiving surface 23, and the pixel value corresponds to the received light intensity of the corresponding pixel in the small area on the light-receiving surface 23. The pixel value may be a scalar value representing the received light intensity of a single wavelength band, or a vector value that bundles together the received light intensities of multiple wavelength bands.
A filter 24 may be provided in front of the light receiving surface 23 to attenuate a portion of the light incident on the light receiving surface 23. The filter 24 may, for example, attenuate a portion of the wavelength band of the light incident on the light receiving surface 23. Also, the filter 24 may attenuate a portion of the polarization of the light incident on the light receiving surface 23.

The information processing unit 30 will be described with reference to FIG. 5. FIG. 5 is a block diagram illustrating the configuration of the information processing unit 30. The information processing unit 30 includes a processor 31 that processes data according to a program 33, and a memory 32 that stores the program 33 in a readable manner and stores data such as a table 34 in a readable and writable manner. The program 33 controls the operation of the processor 31, and causes the processor 31 to perform a depression amount detection process that receives image data generated by the imaging element 22 and detects the amount of depression of the push button 11.

Before describing the pressing amount detection process by processor 31, we will explain its partial process, the evaluation value calculation process. The evaluation value calculation process is a process that outputs an evaluation value from input of image data, reference coordinates, and reference pixel value. More specifically, it is a process that calculates a metric value of a pixel set whose elements are pixels in the input image data whose pixel values have a predefined relationship with the input reference pixel value and which are adjacent to the input reference coordinates, and outputs the metric value as an evaluation value.
It is assumed that this evaluation value will be larger the more the input image data is that of the image data when push button 11 is pressed down. In other words, when push button 11 is pressed down further, protrusion 115 protrudes more from package 12, and the area of light receiving surface 23 that receives scattered light from protrusion 115 through imaging element 21 also becomes larger, and the image data output by imaging element 22 at that time will also show pixel values specific to the scattered light from protrusion 115 in more pixels. The evaluation value calculation process need only capture this and output a larger evaluation value.

The reference coordinates and reference pixel values, which are inputs to the evaluation value calculation process, are values specific to each of the multiple push buttons 11 of the optical keyboard 1. The reference coordinates are coordinates in the image data at which a pixel value specific to the scattered light from the protrusion 115 of a particular push button 11 appears, and the reference pixel value is that specific pixel value.

In the evaluation value calculation process, a pixel value being in a predefined relationship with a reference pixel value means that the pixel value satisfies a predefined relationship when compared with the reference pixel value. When the pixel value is a scalar value, it may be that the pixel value matches the reference pixel value within a certain error range. It may also be that the pixel value is greater than the reference pixel value. It may also be that the pixel value is smaller than the reference pixel value. When the pixel value is a vector value, it may be scalarized using a norm to determine whether the pixel value matches or is larger than the reference pixel value within the error range, or it may be scalarized using a scalar product with a predefined vector to determine whether the pixel value matches or is larger than the reference pixel value within the error range.

In the evaluation value calculation process, a pixel that is a neighborhood of the reference coordinates may be, for example, a pixel whose coordinates are within a predetermined distance from the reference coordinates. As another example, starting from the pixel of the reference coordinates, pixels that can be reached only via pixels whose pixel values have a predetermined relationship with the reference pixel value may be considered to be a neighborhood of the reference coordinates. The pixel of the reference coordinates itself may also be included.

In the evaluation value calculation process, the metric value of a pixel set may be, for example, the number of pixels contained in the set. As another example, it may be the maximum inter-pixel distance between any two pixels contained in the set.

Next, table 34 stored in memory 32 will be described with reference to FIG. 6. Table 34 is data that has one or more push button data including a reference coordinate, a reference pixel value, a minimum value, a maximum value, and a code. An example of the data structure and data of table 34 is shown in FIG. 6. In the example of FIG. 6, the data structure is in tabular form, with the reference coordinate, reference pixel value, minimum value, maximum value, and code of the push button data being represented as columns of the table, and the four push button data being represented as rows of the table.

The push button data is data that can be obtained as follows for a specific push button 11 using image data when the push button 11 is not pressed and image data when the push button 11 is pressed to the fullest extent.
The reference coordinates are the coordinates of a pixel that captures scattered light from the protrusion 115 in the image data when the push button 11 is not pressed. If there are multiple pixels, the coordinates of one of them shall be used.
The reference pixel value is the pixel value of the pixel at the reference coordinates in the image data when the push button 11 is not pressed.
The minimum value is an evaluation value calculated by inputting the image data when the push button 11 is not pressed, the reference coordinates, and the reference pixel value into the evaluation value calculation process described above.
The maximum value is an evaluation value calculated by inputting the image data when the push button 11 is fully pressed, the reference coordinates, and the reference pixel value into the evaluation value calculation process described above.
The code is a number or a character string that is uniquely assigned to the push button 11 in question.

The relationship between the reference coordinate, the reference pixel value, and the minimum and maximum values will be explained using concrete examples. Figure 7 shows an example of image data. Figure 7(a) is an example of image data when the push button 11 is not pressed, and Figure 7(b) is an example of image data when the push button 11 is fully pressed. Each square of the grid, which has 10 squares along the horizontal axis (X axis) and 10 squares along the vertical axis (Y axis), represents a pixel, and the value in the square represents the pixel value. In this example, scalar values are used for the pixel values, but vector values such as RGB values can also be used. The consecutive numbers on the X and Y axes represent the coordinates of each axis. If the position 5 on the X axis and 2 on the Y axis are expressed as (5,2), then the pixel value of the pixel at coordinates (5,2) in the image data of Figure 7(a) is 1.

Note that the image data needs to include pixels corresponding to each of the protrusions 115 of the multiple button modules 10 of the optical keyboard 1, and so more than 10 pixels are required in both the vertical and horizontal directions. It should be noted that, in order to explain the invention in an easy-to-understand manner, FIG. 7 only shows a portion of the image data, the pixels corresponding to one protrusion 115 and its surrounding pixels. This is the same for all subsequent drawings which show image data.

7, the reference coordinates are the coordinates of the pixel that captures the scattered light from the protrusion 115 in the image data when the push button 11 is not pressed, i.e., the image data in Fig. 7(a), and here, as an example, the coordinates are (4,3). In Fig. 7(a), the box with the coordinates (4,3) is shown inverted black and white, but this is a notation that conveniently indicates that the coordinates are the reference coordinates, and this will be the same in the subsequent drawings.
The reference pixel value is the pixel value of the pixel at the reference coordinates in the image data when the push button 11 is not pressed, and is therefore the pixel value of the pixel at coordinates (4,3) in the image data in FIG.

The minimum value is an evaluation value calculated by inputting the image data when the push button 11 is not pressed, the reference coordinates, and the reference pixel value into the evaluation value calculation process described above. The evaluation value calculation process is a process for calculating a metric value of a pixel set whose elements are pixels whose pixel values have a predefined relationship with the reference pixel value and pixels that are neighbors of the reference coordinates, and outputting the metric value as an evaluation value. Here, as an example, a pixel value having a predefined relationship with the reference pixel value is defined as a pixel value that matches the reference pixel value within an error range of plus or minus 1, a pixel that is neighbors of the reference coordinates is defined as a pixel that can be reached starting from the pixel of the reference coordinates and passing only through pixels whose pixel values have a predefined relationship with the reference pixel value, and the metric value of a pixel set is defined as the number of pixels included in the set.
Then, "a pixel set whose elements are pixels whose pixel values have a predefined relationship with the reference pixel value and are adjacent to the reference coordinate" is the set consisting of the pixels with coordinates (3,3), (5,3), (4,4), and (5,4). The minimum value is the metric value of this pixel set, i.e., the number of pixels, i.e., 4.

The maximum value is the evaluation value calculated by inputting the image data when the push button 11 is fully pressed, the reference coordinates, and the reference pixel value into the evaluation value calculation process described above. If the evaluation value calculation process is the same as that for the minimum value, then the "pixel set whose elements are pixels whose pixel values have a predefined relationship with the reference pixel value and which are neighbors of the reference coordinates" is the set consisting of the pixels with coordinates (3,3), (5,3), (4,4), (5,4), (6,4), (5,5), (6,5), and (6,6). The maximum value is the metric value of this pixel set, i.e., 8.

Next, the operation of the pressing amount detection process by the processor 31 controlled by the program 33 will be described with reference to Fig. 8. Fig. 8 is a flowchart illustrating the operation of the processor 31 when image data is input from the imaging element 22.
When image data is input to the processor 31, the processor 31 stores the image data in the memory 32 (S1).
Next, the processor 31 sets the first row of the table 34 stored in the memory 32 as the row to be processed (S2).
Next, the processor 31 reads the row to be processed in the table 34, and obtains the reference coordinates, the reference pixel value, the minimum value, the maximum value, and the code (S3).
Next, the processor 31 reads the pixel value of the pixel at the reference coordinate of the image data stored in the memory 32 and checks whether it has a predetermined relationship with the reference pixel value (S4). If it does, the process proceeds to step S6; if not, the process proceeds to step S5.
Note that the term "having a default relationship with the reference pixel value" means a relationship equivalent to that in the evaluation value calculation process, and this also has the same meaning in the next step S5.

If the process proceeds to step S5, the processor 31 searches for a pixel in the vicinity of the reference coordinate of the image data stored in the memory 32 whose pixel value has a predetermined relationship with the reference pixel value, writes the coordinate of the found pixel as a new reference coordinate in the reference coordinate column of the row to be processed in the table 34 (S5), and proceeds to step S3.
When the process proceeds to step S6, the processor 31 inputs the image data stored in the memory 32, the reference coordinates, and the reference pixel value into the evaluation value calculation process, and calculates an evaluation value (S6).
Next, the processor 31 outputs the depression amount indicator calculated by the following formula together with the code (S7).
Press amount index = (evaluation value - minimum value) / (maximum value - minimum value)
This depression amount index is an index that represents the amount of depression of the push button 11 and is normalized so that it is 0 when the push button 11 is not pressed and 1 when the push button is pressed to the maximum.

Next, processor 31 checks whether the row to be processed is the last row of table 34 (S8), and if so, ends the process, otherwise proceeds to step S9.
If the process proceeds to step S9, the processor 31 sets the row next to the current row in the table 34 as the new row to be processed (S9), and the process proceeds to step S3.

Next, a specific example of the operation of the pressing amount detection process will be described. In this example, the data of Fig. 6 is stored in the memory 32 as the data of the table 34, and the image data shown in Fig. 9(a) is input to the processor 31.
In this specific example, a pixel value having a predefined relationship with a reference pixel value means that the pixel value matches the reference pixel value within an error range of plus or minus 1, a pixel near the reference coordinates means a pixel that can be reached starting from the pixel at the reference coordinates and passing only through pixels whose pixel values have a predefined relationship with the reference pixel value, and the metric value of a pixel set means the number of pixels included in the set.

First, in step S 1 , the processor 31 stores input image data in the memory 32 .
Next, in step S2, the processor 31 sets the first row of the table 34 stored in the memory 32 as the row to be processed.
Next, in step S3, the processor 31 reads the processing target row of the table 34 and obtains the reference coordinate, reference pixel value, minimum value, maximum value, and code. In this case, the reference coordinate=(4,3), reference pixel value=5, minimum value=4, maximum value=8, and code=0x41.
Next, in step S4, processor 31 reads the pixel value of the pixel at the reference coordinates of the image data stored in memory 32, and checks whether it has a predefined relationship with the reference pixel value. In this case, the pixel value at the reference coordinates (4,3) is 1, which is not a predefined relationship with the reference pixel value (=5). Therefore, the process proceeds to step S5.
Next, in step S5, processor 31 searches for a pixel whose pixel value has a predefined relationship with the reference pixel value in the vicinity of the reference coordinates of the image data stored in memory 32. As a pixel whose pixel value has a predefined relationship with the reference pixel value (=5) in the vicinity of reference coordinates (4,3) is a pixel with coordinates (4,4) (pixel value = 4), this pixel is adopted in this example, and the coordinates of that pixel are written into the reference coordinate column of the processing target row of table 34, and the process proceeds to step S3.
The reference coordinates are represented by black and white inverted squares in Figure 9. Before the processing of step S5, the reference coordinates were the black and white inverted squares in Figure 9(a), but after the processing of step S5, the reference coordinates change to the black and white inverted squares in Figure 9(b).

Next, in step S3, processor 31 reads the row to be processed in table 34 and obtains the reference coordinates, reference pixel value, minimum value, maximum value, and code. The reference coordinates have changed from before, and are now reference coordinates=(4,4), reference pixel value=5, minimum value=4, maximum value=8, and code=0x41.
Next, in step S4, processor 31 reads the pixel value of the pixel at the reference coordinates of the image data stored in memory 32, and checks whether it has a predefined relationship with the reference pixel value. In this case, the pixel value at the reference coordinates (4,4) is 4, which has a predefined relationship with the reference pixel value (=5). Therefore, the process proceeds to step S6.
Next, in step S6, the processor 31 inputs the image data stored in the memory 32, the reference coordinates, and the reference pixel value into the evaluation value calculation process to calculate the evaluation value. In this case, the evaluation value is 5.
Next, in step S7, the processor 31 calculates the depression amount index. The depression amount index is (5 - 4) / (8 - 4) = 0.25.
Then, the depression amount index (=0.25) is output along with the code (=0x41).

Next, in step S8, processor 31 checks whether the row to be processed is the last row of table 34. However, since the row to be processed is not the last row, the process proceeds to step S9.
Next, in step S9, processor 31 sets the next row of table 34 to the row to be processed, that is, the second row, as the new row to be processed, and proceeds to step S3.
The subsequent operations are not described here, but similar processing is carried out for all remaining rows in table 34.

In this way, in the pressing amount detection process, if the pixel value of the pixel at the reference coordinate does not have a predetermined relationship with the reference pixel value as a result of the processes in steps S4 and S5, the reference coordinate is moved to the coordinate of a nearby appropriate pixel. Such a case may also occur when the housing 2 is distorted due to the pressing force on the push button 11 or thermal expansion.
In other words, in the previous image data from the imaging element 22, the pixel at the reference coordinates captured the scattered light from the protrusion 115 and showed a pixel value that has a predetermined relationship with the reference pixel value, but in the next image data, the positional relationship between the imaging element 22, the imaging element 21, and the protrusion 115 has changed due to distortion of the housing 2, so that the pixel no longer captures the scattered light from the protrusion 115 and no longer shows a pixel value that has a predetermined relationship with the reference pixel value.
Even in this case, it is expected that the change from the previous image data will be small, unless the distortion of the housing 2 is large and occurs in a short period of time based on the time interval at which the image sensor 22 outputs image data. Therefore, the pixel capturing the scattered light from the protrusion 115 is expected to be near the reference coordinates, and the pixel can be found by the processing of steps S4 and S5, and the reference coordinates can be moved to that pixel. In other words, even if the pixel capturing the scattered light from the protrusion 115 moves on the image data, it is tracked and set to the reference coordinate by the processing of steps S4 and S5. Therefore, even if such distortion occurs, the amount of pressing of the push button 11 can be detected.

In order to track pixels capturing scattered light from the protrusion 115, the image data must always contain pixels capturing scattered light from the protrusion 115. In other words, it is necessary to have pixels capturing scattered light from the protrusion 115 not only when the push button 11 is pressed, but also when it is not pressed. For this reason, as described above, it is preferable that at least a portion of the protrusion 115 protrudes outside the package 12 even when the push button 11 is not pressed.

<Second embodiment>
An optical keyboard 1 according to a second embodiment of the present invention will be described focusing on the differences from the first embodiment. In the first embodiment, the image data generated by the image sensor 22 is used to identify the difference between the characteristics of the scattered light caused by the protrusion 115 of the light irradiated by the light source 3 and the characteristics of the scattered light from other parts as a difference in pixel value, whereas in the second embodiment, the image data generated by the image sensor 22 is used to identify the difference between the characteristics of the fluorescence caused by the protrusion 115 excited by the light irradiated by the light source 3 and the characteristics of the fluorescence from other parts as a difference in pixel value.

For this reason, it is necessary that at least a portion of the protrusion 115 has fluorescence characteristics that differ from those of both the inside of the housing 2 and the outer portion of the package 12 that is exposed to the inside of the housing 2 when it receives light emitted by the light source 3.
As one example, protrusion 115 may be configured using a fluorescent material that absorbs light in an excitation wavelength band and emits light in a fluorescence wavelength band different from the excitation wavelength band, while the inside of housing 2 and the outside of package 12 may be configured using a relatively small amount of fluorescent material or no fluorescent material at all. As another example, fluorescent materials having different fluorescence wavelength bands may be used for protrusion 115 and the inside of housing 2 and the outside of package 12. As yet another example, the polarization of fluorescence may be different between protrusion 115 and the inside of housing 2 and the outside of package 12.

The light source 3 must emit light that includes the excitation wavelength band. It is also preferable that the light source 3 does not emit light in the fluorescence wavelength band of the protrusion 115. It is preferable to provide a filter 24 in front of the light receiving surface 23 of the image sensor 22, which weakens the portion of the light that is incident on the light receiving surface 23 other than the fluorescence wavelength band of the protrusion 115.

In the first embodiment, it was required that at least a portion of the protrusion 115 have different light scattering characteristics in the wavelength band of light emitted by the light source 3 from both the inside of the housing 2 and the outer portion of the package 12 exposed inside the housing 2, but this is not necessary in the second embodiment.
Also, in the first embodiment, it is necessary for the light source 3 to emit light including a wavelength band used by the depression amount detection module 20 to detect the depression amount, but this is not necessary in the second embodiment.
In addition, the term "scattered light" in the first embodiment may be read as "fluorescence."

1 Optical Keyboard
2. Chassis
3 light source
4 Top Panel
5 Opening
10 Button Module
11 Push Button
111 Pressing section
115 Protrusion
12 Packages
13 Elastic Body
20. Pressing amount detection module
21 Imaging element
22 Image sensor
23 Photosensitive surface
24 Filters
30 Information Processing Section
31 Processor
32 Memory
33 Programs
34 Table

Claims (2)

An optical keyboard comprising: a button module including a push button having a protruding portion and a package that houses the push button in a manner that allows the protruding portion to protrude from a hole; a light source ; an imaging element having a light receiving surface; an imaging element; a processor; and a memory ;
The push button is a plurality of buttons;
the light scattering or fluorescence characteristics of at least a portion of the protrusion and at least a portion of the exterior of the package are different;
the greater the amount of depression of the push button, the greater the amount of protrusion from the package;
The light source has a directivity such that the light source simultaneously illuminates the protrusions of all the push buttons,
the imaging element forms an image on the light receiving surface of scattered light or fluorescent light emitted from at least a part of the protruding portion of the push button when the button is not pressed;
the imaging element outputs image data corresponding to an intensity distribution of the incident light on the light receiving surface;
When the image data is input from the image sensor, the processor stores the image data in the memory;
The processor calculates the pressing amount based on a metric value of a pixel set whose elements are pixels of the image data stored in the memory, pixels whose pixel values have a predetermined relationship with a reference pixel value stored in the memory, and pixels that are neighbors of the reference coordinates stored in the memory.
Optical keyboard. 2. The optical keyboard of claim 1, wherein, if the pixel value of the pixel at the reference coordinate is not in a predetermined relationship with the reference pixel value, the processor searches for a pixel in the vicinity of the reference coordinate of the image data whose pixel value has a predetermined relationship with the reference pixel value , and writes the coordinates of the pixel into the memory as new reference coordinates.

Images