Abstract:
An input device includes: a position detection unit that defines a detection region in a space in front of a prescribed reference surface and detects a position coordinate in the detection region of a detection object that has entered the detection region for an input operation on a coordinate axis perpendicular to the reference surface; and a processor that defines a virtual plane in parallel to the reference surface so as to partition the detection region in a direction of the coordinate axis, and that compares the position coordinate on the coordinate axis of the detection object as detected by the position detection unit with a position coordinate on the coordinate axis of the virtual plane, the processor further determining the input operation of the detection object in accordance with a result of the comparison.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an input device. 
       BACKGROUND ART 
       [0002]    As shown in Patent Document 1, a non-contact input device is known for which an input operation such as switching display images by a user moving his/her hand in a space in front of a display panel is performed. In this device, movements of the user&#39;s hand (that is, gestures) are captured by camera, and this image data is used to recognize gestures. 
       RELATED ART DOCUMENT 
     Patent Document 
       [0003]    Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2010-184600 
       Problems to be Solved by the Invention 
       [0004]    In gesture recognition using a camera, hand movement parallel to the surface of the display panel is easy to recognize, but hand movement perpendicular to the display surface (that is hand movement back and forth with respect to the display surface) is difficult to recognize due to reasons such as the difficulty in measuring distance of movement. 
       SUMMARY OF THE INVENTION 
       [0005]    An object of the present invention is to provide a non-contact input device having excellent input operability. 
       Means for Solving the Problems 
       [0006]    An input device of the present invention includes: a reference surface; a position detection unit that forms a detection region in a space in front of the reference surface and detects position coordinates in the detection region of a detection object such as a finger that has entered the detection region; a comparison unit that compares a position coordinate in a front-to-rear direction of a virtual plane set so as to partition the detection region front and rear, with a position coordinate in the front-to-rear direction of the detection object, the position coordinate having been detected by the position detection unit; and a determination unit that determines an input operation of the detection object on the basis of comparison results of the comparison unit. 
         [0007]    By comparing a position coordinate in a front-to-rear direction of a virtual plane set so as to partition the detection region front and rear, with a position coordinate in the front-to-rear direction of the detection object, the position coordinate having been detected by the position detection unit, the input device can determine the input operation of the detection object. In other words, the input device can determine the input operation in the front-to-rear direction of the detection object, and has excellent input operability. 
         [0008]    In the input device, when the comparison results by the comparison unit indicate that the position coordinate of the detection object is less than or equal to the position coordinate in the virtual plane, the determination unit may determine that the input operation is a click operation that passes through the virtual plane in a direction towards the reference surface. 
         [0009]    Furthermore, an input device of the present invention includes: a reference surface; a position detection unit that forms a detection region in a space in front of the reference surface and detects position coordinates in the detection region of a detection object such as a finger that has entered the detection region; a virtual plane that partitions the detection region in a front-to-rear direction such that the detection region is divided into a first detection region and a second detection region; a standby detection unit that detects that the detection object has stayed in the second detection region for a prescribed time in accordance with detection results of the position detection unit; a change amount detection unit that detects, in accordance with the detection results of the position detection unit, an amount of change in position of the detection object from the second detection region towards the first detection region after staying in the second detection region for the prescribed time; and a determination unit that determines an input operation of the detection object in accordance with the detection results of the change amount detection unit. 
         [0010]    In the input device, the detection region is divided front and rear into the first detection region and the second detection region by the virtual plane, and thus, the input device can determine the input operation in the front-to-rear direction of the detection object, and has excellent input operability. 
         [0011]    Furthermore, an input device of the present invention includes: a reference surface; a position detection unit that forms a detection region in a space in front of the reference surface and detects position coordinates in the detection region of a detection object such as a finger that has entered the detection region; a virtual plane that partitions the detection region in a front-to-rear direction such that the detection region is divided into a first detection region and a second detection region; a standby detection unit that detects that the detection object has stayed in the first detection region for a prescribed time in accordance with detection results of the position detection unit; a change amount detection unit that detects, in accordance with the detection results of the position detection unit, an amount of change in position of the detection object from the first detection region towards the second detection region after staying in the first detection region for the prescribed time; and a determination unit that determines an input operation of the detection object on the basis of detection results of the change amount detection unit. 
         [0012]    In the input device, the detection region is divided front and rear into the first detection region and the second detection region by the virtual plane, and thus, the input device can determine the input operation in the front-to-rear direction of the detection object, and has excellent input operability. 
         [0013]    In the input device, the reference surface may be a display surface of a display unit that displays images. 
         [0014]    The input device may include a display switching unit that switches an image displayed on the display surface of the display unit to another image corresponding to the input operation, on the basis of determination results of the determination unit. 
         [0015]    Furthermore, an input device of the present invention includes: a display unit that displays a three-dimensional image so as to float in front of a display surface; a position detection unit that forms a detection region in a space in front of the display surface and detects position coordinates in the detection region of a detection object such as a finger that has entered the detection region; a comparison unit that compares a position coordinate in a front-to-rear direction of a virtual plane partitioning the detection region in the front-to-rear direction and overlapping a position of the three-dimensional image that floats in front of the display surface with a position coordinate in the front-to-rear direction of the detection object as acquired by the position detection unit; and a determination unit that determines an input operation of the detection object in accordance with comparison results of the comparison unit. 
         [0016]    In the input device, the position of the virtual plane that partitions the detection region front and rear is set so as to overlap in position the three-dimensional image, which appears to float in front of the display surface of the display unit, and by the user performing an input operation in the front and rear direction using a finger or the like, the user can perform an input operation with the sense of directly touching the three-dimensional image. 
         [0017]    In the input device, when the comparison results by the comparison unit indicate that the position coordinate of the detection object is less than or equal to the position coordinate in the virtual plane, the determination unit may determine that the input operation is a click operation that passes through the virtual plane in a direction towards the reference surface. 
         [0018]    The input device may include a display switching unit that switches a three-dimensional image displayed so as to float in front of the display surface of the display unit to another three-dimensional image corresponding to the input operation, on the basis of determination results of the determination unit. If the three-dimensional image is switched to another three-dimensional image in this manner, the user can experience the sense of having switched the original three-dimensional image to the other three-dimensional image by directly touching the original three-dimensional image. 
         [0019]    In the input device, it is preferable that the position detection unit have a sensor including a pair of electrodes for forming the detection region by an electric field, the position coordinates of the detection object being acquired on the basis of static capacitance between the electrodes. In other words, the position detection unit constituted by capacitance sensors or the like has excellent detection accuracy in the front and rear direction of the reference surface (or display surface) compared to other general modes of position detection units. Thus, it is preferable that a position detection unit including such capacitive sensors be used. 
       Effects of the Invention 
       [0020]    According to the present invention it is possible to provide a non-contact input device having excellent input operability. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a descriptive drawing that schematically shows the outer appearance of a display operation device of Embodiment 1. 
           [0022]      FIG. 2  is a function block diagram showing main components of the display operation device of Embodiment 1. 
           [0023]      FIG. 3  is a descriptive drawing that schematically shows an electric field distribution formed to the front of the display surface. 
           [0024]      FIG. 4  is a descriptive drawing that schematically shows a signal strength of a capacitive sensor in the Z axis direction. 
           [0025]      FIG. 5  is a flowchart showing steps of an input process of the display operation device based on a click operation by a fingertip. 
           [0026]      FIG. 6  is a descriptive drawing that schematically shows a single click operation. 
           [0027]      FIG. 7  is a descriptive drawing that schematically shows a double click operation. 
           [0028]      FIG. 8  is a flowchart showing steps of an input process of the display operation device based on a forward movement operation by a fingertip. 
           [0029]      FIG. 9  is a descriptive drawing that schematically shows a state in which a fingertip is held still in a second detection region prior to forward movement. 
           [0030]      FIG. 10  is a descriptive drawing that schematically shows a state in which the fingertip moves forward to a first detection region. 
           [0031]      FIG. 11  is a flowchart showing steps of an input process based on a backward movement operation by a fingertip. 
           [0032]      FIG. 12  is a descriptive drawing that schematically shows a state in which a fingertip is held still in the first detection region prior to backward movement. 
           [0033]      FIG. 13  is a descriptive drawing that schematically shows a state in which the fingertip moves backward to the second detection region. 
           [0034]      FIG. 14  is a descriptive drawing that schematically shows the outer appearance of a display operation device of Embodiment 2. 
           [0035]      FIG. 15  is a function block diagram showing main components of the display operation device of Embodiment 2. 
           [0036]      FIG. 16  is a descriptive drawing that schematically shows the relationship between a three-dimensional image and a detection region formed to the front of the display operation device. 
           [0037]      FIG. 17  is a flowchart showing steps of an input process of the display operation device based on a click operation by a fingertip. 
           [0038]      FIG. 18  is a front view that schematically shows Modification Example 1 of electrodes included in the capacitive sensor. 
           [0039]      FIG. 19  is a cross-sectional view along the line A-A of  FIG. 18 . 
           [0040]      FIG. 20  is a front view that schematically shows Modification Example 2 of electrodes included in the capacitive sensor. 
           [0041]      FIG. 21  is a cross-sectional view along the line B-B of  FIG. 20 . 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
       [0042]    Embodiment 1 of the present invention will be explained below with reference to  FIGS. 1 to 13 . The present embodiment illustrates a display operation device  1  as an example of an input device.  FIG. 1  is a descriptive drawing that schematically shows the outer appearance of a display operation device  1  of Embodiment 1.  FIG. 1  shows the display operation device  1  as viewed from the front. In the display operation device  1 , a user can directly operate an image displayed in the display surface  2   a  of the display unit  2  without touching the display surface  2   a  (reference surface) through hand motions (so-called gestures). The display unit  2  includes the horizontally long rectangular display surface  2   a  as shown in  FIG. 1 . Electrodes  3   a  and  3   b  used for detecting hand motions are provided in the periphery of the display surface  2   a  as will be described later. The display operation device  1  is supported by a stand ST. 
         [0043]      FIG. 2  is a function block diagram showing main components of the display operation device  1  of Embodiment 1. The display operation device  1  includes the display unit  2 , a finger position detection unit  3  (position detection unit), a CPU  4 , ROM  5 , RAM  6 , a timer  7 , a display control unit  8  (display switching unit), a storage unit  9 , and the like. 
         [0044]    The CPU  4  (central processing unit) is connected to each hardware unit through a bus line  10 . The ROM  5  (read-only memory) has stored in advance various control programs, parameters for computation, and the like. The RAM  6  (random access memory) is constituted by SRAM (static RAM), DRAM (dynamic RAM), flash memory, and the like, and temporarily stores various data generated when the CPU  4  executes various programs. The CPU  4  constitutes the determination unit, comparison unit, standby detection unit, change amount detection unit, and the like of the present invention. 
         [0045]    The CPU  4  controls various pieces of hardware by loading control programs stored in advance in the ROM  5  onto the RAM  6  and executing the programs, and operates the device as a whole as the display operation device  1 . Additionally, the CPU  4  receives process command input from a user through the finger position detection unit  3 , as will be described later. The timer  7  measures various times pertaining to processes of the CPU  4 . The storage unit  9  is constituted by a non-volatile storage medium such as flash memory, EEPROM, or HDD. The storage unit  9  has stored in advance various data to be described later (position coordinate data (threshold α, β) for a first virtual plane R 1  and a second virtual plane R 2 , and prescribed time data such as Δt). 
         [0046]    The display unit  2  is a display panel such as a liquid crystal display panel or an organic EL (electroluminescent) panel. Various information (images or the like) is displayed on the display surface  2   a  of the display unit  2  according to commands from the CPU  4 . 
         [0047]    The finger position detection unit  3  is constituted by a capacitive sensor  30 , an integrated circuit such as a programmable system-on-chip, or the like, and detects position coordinates P (X coordinate, Y coordinate, Z coordinate) of a user&#39;s fingertip located in front of the display surface  2   a . In the present embodiment, the origin of the coordinate axes is set to the upper left corner of the display surface  2   a  as seen from the front, with the left-to-right direction being a positive direction along the X axis and the up-to-down direction being a positive direction along the Y axis. The direction perpendicular to and moving away from the display surface  2   a  is a positive direction along the Z axis. The position coordinates P of the fingertips or the like to be detected, which are acquired by the position detection unit  3 , are stored as appropriate in the storage unit  9 . The CPU  4  reads the position coordinate P data from the storage unit  9  as necessary, and performs computations using such data. 
         [0048]    As shown in  FIG. 1 , the finger position detection unit  3  includes the pair of electrodes  3   a ,  3   b  for detecting the fingertip position coordinates P. One of the electrodes  3   a  is a transmitter electrode  3   a  (drive-side electrode), and has a frame shape surrounding a display area AA (active area) of the display surface  2   a . A transparent thin-film electrode member is used as the transmitter electrode  3   a . A transparent insulating layer  3   c  is formed on the transmitter electrode  3   a . The other electrodes  3   b  are receiver electrodes  3   b  that are disposed in the periphery of the display surface  2   a  so as to overlap the transmitter electrode  3   a  across the transparent insulating layer  3   c . In the present embodiment, there are four receiver electrodes  3   b , which are respectively disposed on all sides of the rectangular display surface  2   a . The electrodes  3   a  and  3   b  are set so as to face the same direction (Z axis direction) as the display surface  2   a.    
         [0049]      FIG. 3  is a descriptive drawing that schematically shows an electric field distribution formed to the front of the display surface  2   a . When a voltage is applied between the electrodes  3   a  and  3   b , an electric field having a prescribed distribution is formed to the front of the display surface  2   a .  FIG. 3  schematically shows electric force lines  3   d  and equipotential lines  3   e . In this manner, the space to the front of the display surface  2   a  where the electric field is formed is a region (detection region F) where a detection object such as a fingertip is detected by the finger position detection unit  3 . If a fingertip or the like to be detected enters this region, then the capacitance between the electrodes  3   a  and  3   b  changes. The capacitive sensor  30  including the electrodes  3   a  and  3   b  forms a prescribed capacitance between the electrodes  3   a  and  3   b  according to the entry of a fingertip in the region, and outputs an electric signal corresponding to this capacitance. The finger position detection unit  3  can detect the capacitance formed between the electrodes  3   a  and  3   b  on the basis of this output signal, and can additionally calculate the position coordinates P (X coordinate, Y coordinate, Z coordinate) of the fingertip in the detection region on the basis of this detection result. The detection of the position coordinates P of the fingertip by the finger position detection unit  3  is executed steadily, repeating at a uniform time interval. A well-known method is employed to calculate the fingertip position coordinates P from the capacitance formed between the electrodes  3   a  and  3   b.    
         [0050]      FIG. 4  is a descriptive drawing that schematically shows a signal strength of the capacitive sensor  30  in the Z axis direction. In the present embodiment, the display surface  2   a  has a 7-inch diagonal size, and if the drive voltage of the capacitive sensor  30  is set to 3.3V, then the signal value (S 1 ) at the detection limit is at approximately 20 cm (greater than 20 cm) in the Z axis direction from the display surface  2   a . In the present embodiment, the rectangular cuboid space measured out as the (length in the horizontal direction (X axis direction) of the display surface  2   a )×(vertical direction (Y axis direction) length of the display surface  2   a )×(length (20 cm) in the Z axis direction) is set as the detection region F. 
         [0051]    The detection region F has two virtual planes having, respectively, uniform Z axis coordinates. One of the virtual planes is a first virtual plane R 1  set at a position 9 cm from the display surface  2   a  in the Z axis direction, and the other virtual plane is a second virtual plane R 2  that is set at a position 20 cm from the display surface  2   a  in the Z axis direction. In the present embodiment, the second virtual plane R 2  is set at the Z coordinate detection limit. The first virtual plane R 1  is set between the display surface  2   a  and the second virtual plane R 2 . 
         [0052]    The detection region F is partitioned into two spaces by the first virtual plane R 1 . In the present specification, the space in the detection region F from the first virtual plane R 1  to the display surface  2   a  (between the display surface  2   a  and the first virtual plane R 1 ) is referred to as the first detection region F 1 . The space between the first virtual plane R 1  and the second virtual plane R 2  is referred to as the second detection region F 2 . The first detection region F 1  is used, for example, in order to detect click operations based on fingertip movements in the Z axis direction as will be described later. By contrast, the second detection region F 2  is used in order to detect input operations based on fingertip movements in the Z axis direction or operations based on fingertip movements in the X axis direction and Y axis direction (flick movements, for example) as will be described later. In this manner, the detection region F is divided into two detection regions F 1  and F 2  in sequential order according to distance from the display surface  2   a  (reference surface). 
         [0053]    The CPU  4  recognizes finger movements by the user by comparing fingertip position coordinates P detected by the finger position detection unit  3  with various preset thresholds (a, etc.), and receives processing content that has been placed in association with such movements in advance. Furthermore, in order to execute the received processing content, the CPU  4  controls respective target units (such as the display control unit  8 ). 
         [0054]    The display control unit  8  displays a prescribed image in the display unit  2  according to commands from the CPU  4 . The display control unit  8  reads appropriate information from the storage unit  9  according to commands from the CPU  4  corresponding to fingertip movements by the user (such as changes in Z coordinate of the fingertip), and controls the image displayed in the display unit  2  so as to switch to an image based on the read-in information. The display control unit  8  may be a software function realized by the CPU  4  executing a control program stored in the ROM  5 , or may be realized by a dedicated hardware circuit. The display operation device  1  of the present embodiment may include an input unit (button-type input unit) or the like that is not shown. 
         [0055]    The steps of the input process based on movements (Z axis direction movements) of a user U&#39;s fingertip in the display operation device  1  of the present embodiment will be described. The content indicated below is one example of an input process based on movements of the user U&#39;s fingertip (Z axis direction movements), and the present invention is not limited to such content. First, the steps of an input process based on two types of click operations (single click and double click) will be described. 
         [0056]    (Input Operation by Click Movement) 
         [0057]      FIG. 5  is a flowchart showing steps of an input process of the display operation device  1  based on a click operation by a fingertip,  FIG. 6  is a descriptive drawing that schematically shows a single click operation, and  FIG. 7  is a descriptive drawing that schematically shows a double click operation. Before entering an input by click operation, the user U first performs a prescribed operation on the display operation device  1  and causes the CPU  4  to execute a process of displaying a prescribed reception image (not shown) in the display surface  2   a  of the display unit  2 . 
         [0058]    In step S 10 , the finger position detection unit  3  acquires the fingertip position coordinates P of the user U according to a command from the CPU  4 . When a finger enters the detection region F, in step S 10 , the finger position detection unit  3  acquires the fingertip position coordinates P (X coordinate, Y coordinate, Z coordinate). In the present embodiment, as shown in  FIGS. 6 and 7 , the user U&#39;s hand is formed such that only the index finger extends towards the display surface  2   a  from a clenched hand. Thus, the position coordinate of the tip of the index finger is acquired by the finger position detection unit  3 . Regarding movements of the user U&#39;s hand (finger) for input operations on the display operation device  1 , a case in which the hand approaches the display surface  2   a  is referred to as “forward movement” and a case in which the hand moves away from the display surface  2  is referred to as “backward movement”. 
         [0059]    After the fingertip position coordinates P are acquired, the CPU  4  determines in step S 11  whether the Z coordinate among the acquired position coordinates P is less than or equal to a preset threshold α. The threshold α is the Z coordinate of the first virtual plane R 1 , and indicates a position 9 cm away from the display surface  2   a  in the Z axis direction. If the Z coordinate among the acquired position coordinates P is greater than the threshold α (Z&gt;α), then the process returns to step S 10 . If the Z coordinate among the acquired position coordinates P is less than or equal to the threshold α (Z≦α), then the process progresses to step S 12 . As shown in  FIGS. 6 and 7 , if the fingertip crosses the first virtual plane R 1  and enters the first detection region F 1 , then the Z coordinate (Z 1 ) among the fingertip position coordinates P 1  is less than or equal to α. 
         [0060]    The detection of the position coordinates P of the fingertip by the finger position detection unit  3  is executed steadily, repeating at a uniform time interval, regardless of the presence or absence of a detection object (finger) in the detection region F. Every time the detection of position coordinates P is performed, the process progresses to step S 11 , and as described above, the CPU  4  compares the detection results (Z coordinate) with the threshold α. 
         [0061]    In step S 12 , the CPU  4  starts the timer  7  and measures the time. Then, in step S 13 , detection of the fingertip position coordinates P is performed again, as in step S 10 . After detection of the position coordinates P, the CPU  4  determines whether or not a preset prescribed time Δt has elapsed since the timer  7  has started. If the CPU  4  has determined that the prescribed time Δt has not elapsed, then the process returns to step S 13  and detection of the position coordinates P of the finger is once again performed. By contrast, if the CPU  4  has determined that the prescribed time Δt has elapsed, then the process progresses to step S 15 . In other words, after the timer  7  has started with the fingertip entering the first detection region F 1 , the finger position detection unit  3  repeatedly performs detection of the fingertip position coordinates P until the prescribed time Δt has elapsed. In the present embodiment, the prescribed time Δt, the detection interval and the like for the position coordinates P are set such that the detection of the fingertip position coordinates P in step S 13  is performed a plurality of times (twice or more). 
         [0062]    In step S 15 , after the Z coordinate among the fingertip position coordinates P reaches α&lt;Z within the prescribed time Δt, the CPU  4  once again determines whether Z has reached Z≦α. As shown in  FIG. 6 , if the fingertip crosses the first virtual plane R 1  and enters the first detection region F 1  for a period of Δt, then the Z coordinate among the position coordinates P is always less than or equal to α. In such a case, the process progresses from step S 15  to S 16 , and the movement of the user U&#39;s fingertip (Z axis direction movement) in the detection region F is recognized as a single click operation, and a process associated therewith in advance is executed. In the present embodiment, by such a click operation (single click operation), a command is inputted to the display operation device  1  so as to switch the above-mentioned reception image (not shown) to another image (not shown), for example. 
         [0063]    By contrast, as shown in  FIG. 7 , if during the prescribed time Δt the fingertip moves backward towards the second detection region F 2  (position coordinate P 2 ) and then once again crosses the first virtual plane R 1  and enters the first detection region F 1  (position coordinate P 3 ), the Z coordinate of the fingertip position coordinates P, after attaining α&lt;Z, once again becomes Z≦α. In other words, the Z coordinate (Z 2 ) among the position coordinates P 2  is at α&lt;Z 2 , and the Z coordinate (Z 3 ) among the position coordinates P 3  is at Z 3 ≦α. In such a case, the process progresses from step S 15  to S 17 , and the movement of the user U&#39;s fingertip (Z axis direction movement) in the detection region F is recognized as a double click operation, and a process associated therewith in advance is executed. In the present embodiment, by such a click operation (double click operation), a command is inputted to the display operation device  1  so as to switch the above-mentioned reception image (not shown) to another image (not shown), for example. 
         [0064]    In such a display operation device  1 , the Z coordinate of the first virtual plane R 1  set in the detection region F is used as the threshold α for recognizing a click operation (movement of user U&#39;s finger in the Z axis direction). Thus, the user U can use the first virtual plane R 1  as the “click surface” to input clicks, and by movement back and forth of the fingertip (movement along the Z axis direction), it is possible to perform input operations with ease on the display operation device  1  without directly touching the display unit  2 . In the display operation device  1  of the present embodiment, the amount of data that the CPU  4  needs to process is less than in conventional devices where user gestures were recognized by analyzing image data. 
         [0065]    (Input Operation by Forward Movement) 
         [0066]    Next, the steps of the input process based on forward movement of the user U&#39;s fingertip will be described. In the present embodiment, a command in which the image displayed in the display unit  2  is switched to an enlarged image is inputted to the display operation device  1  by forward movement of the fingertip.  FIG. 8  is a flowchart showing steps of an input process of the display operation device  1  based on a forward movement operation by a fingertip,  FIG. 9  is a descriptive drawing that schematically shows a state in which a fingertip is held still in the second detection region F 2  prior to forward movement, and  FIG. 10  is a descriptive drawing that schematically shows a state in which the fingertip moves forward to the first detection region F 1 . 
         [0067]    Before entering an input by forward movement to increase magnification of the display, the user U first performs a prescribed operation on the display operation device  1  and causes the CPU  4  to execute a process of displaying a prescribed image (not shown) in the display surface  2   a  of the display unit  2 . 
         [0068]    Next, in step S 20 , the finger position detection unit  3  acquires the fingertip position coordinates P of the user U according to a command from the CPU  4 . After the fingertip position coordinates P are acquired, the CPU  4  determines in step S 21  whether the Z coordinate among the acquired position coordinates P is within a preset range (α&lt;Z&lt;β). The threshold α is as described above. The threshold β is the Z coordinate of the second virtual plane R 2 , and indicates a Z coordinate corresponding to a distance of 20 cm away from the display surface  2   a  in the Z axis direction. By using such thresholds α and β, it can be determined whether the fingertip position coordinates P are within the second detection region F 2 . 
         [0069]    If as shown in  FIG. 9  the user U&#39;s fingertip is within the second detection region F 2 , for example, then the Z coordinate of the fingertip among the position coordinates P 11  satisfies α&lt;Z&lt;β. If the Z coordinate among the acquired fingertip position coordinates P is within this range, then the process progresses to step S 22 . By contrast, if the Z coordinate among the acquired fingertip position coordinates P is outside of this range, then the process progresses to step S 20 , and detection of the finger position coordinates P is once again performed. 
         [0070]    The detection of the position coordinates P of the fingertip by the finger position detection unit  3  is, as described above, executed steadily, repeating at a uniform time interval, regardless of the presence or absence of a detection object (finger) in the detection region F. Every time the detection of position coordinates P is performed, the process progresses to step S 21 . 
         [0071]    In step S 22 , the CPU  4  starts the timer  7  and measures the time. Then, in step S 23 , detection of the fingertip position coordinates P is performed again, as in step S 20 . After detection of the position coordinates P, the CPU  4  determines whether or not a preset prescribed time Δt 1  (3 seconds, for example) has elapsed since the timer  7  has started. If the CPU  4  has determined that the prescribed time Δt 1  has not elapsed, then the process returns to step S 23  and detection of the position coordinates P of the finger is once again performed. By contrast, if the CPU  4  has determined that the prescribed time Δt 1  has elapsed, then the process progresses to step S 25 . In other words, after the timer  7  has started with the fingertip entering the second detection region F 2 , the finger position detection unit  3  repeatedly performs detection of the fingertip position coordinates P until the prescribed time Δt 1  has elapsed. The timer  7 , in addition to being used to measure the prescribed time Δt 1 , is also used to measure the prescribed time Δt 2  to be described later. 
         [0072]    In step S 25 , the CPU  4  determines whether or not the Z coordinate among the plurality of position coordinates P detected within the prescribed time Δt 1  is within an allowable range D 1  (±0.5 cm, for example) for which a change amount ΔZ 1  is set in advance. The change amount ΔZ 1  is determined in step S 21  by taking the difference between the Z coordinate (reference value) determined to satisfy the range α&lt;Z&lt;β, and the Z coordinate among the position coordinates P detected within the prescribed time Δt 1 . If all change amounts ΔZ 1  for Z coordinates of all position coordinates P detected after the timer  7  has started are within the allowable range D 1 , then the process progresses to step S 26 . By contrast, if the change amount ΔZ 1  of even one Z coordinate exceeds the allowable range D 1 , then the process returns to step S 20 . In other words, in step S 25 , it is determined whether or not the fingertip of the user U is within the second detection region F 2  and has stopped moving at least in the Z axis direction. 
         [0073]    In step S 26 , detection of the fingertip position coordinates P is performed again. As indicated in step S 27 , such detection is repeated until the prescribed time Δt 2  has elapsed since the timer  7  has started. The prescribed time Δt 2  is longer than the prescribed time Δt 1 , and if Δt 1  is set to 3 seconds, then Δt 2  is set to 3.3 seconds, for example. If the CPU  4  has determined that the prescribed time Δt 2  has elapsed, then the process progresses to step S 28 . 
         [0074]    In step S 28 , the CPU  4  determines whether the Z coordinates among the plurality of position coordinates P detected within the prescribed time Δt 2  have become less than or equal to α (Z≦α). In other words, in step S 28 , it is determined whether the user U&#39;s fingertip has moved (forward) from the second detection region F 2  to the first detection region F 1  within Δt 2 −Δt 1  (0.3 seconds, for example). If as shown in  FIG. 10  the user U&#39;s fingertip is within the second detection region F 2  for the prescribed time Δt 1  and then moves forward and enters the first detection region F 1  by Δt 2 , for example, then the Z coordinate of the fingertip among the position coordinates P 12  becomes less than or equal to α (Z≦α). In another embodiment, it may be determined whether the Z coordinates among the plurality of position coordinates P detected during Δt 2 −Δt 1  (0.3 seconds, for example) have become less than or equal to α (Z≦α). 
         [0075]    In step S 28 , if the CPU  4  determines that there are no Z coordinates at or below α (Z≦α), then the process progresses to step S 20 . By contrast, if in step S 28  the CPU  4  determines that there is at least one Z coordinate at or below α (Z≦α), then the process progresses to step S 29 . In step S 29 , the CPU  4  receives a command to switch the image displayed in the display unit  2  to an enlarged image. A command in which the image displayed in the display unit  2  is switched to an enlarged image can be inputted to the display operation device  1  by such forward movement of the user U&#39;s fingertip (example of a gesture). When the CPU  4  receives such an input, the display control unit  8  reads information pertaining to an enlarged image from the storage unit  9  and then switches from an image displayed in advance in the display unit  2  to the enlarged image on the basis of the read-in information, according to the command from the CPU  4 . In such a display operation device  1 , it is possible for an input operation to be performed with ease by forward movement of the user U&#39;s fingertip (movement of fingertip in Z axis direction) without directly touching the display unit  2 . 
         [0076]    (Input Operation by Backward Movement) 
         [0077]    Next, the steps of the input process based on backward movement of the user U&#39;s fingertip will be described. In the present embodiment, a command in which the image displayed in the display unit  2  is switched to a shrunken image is inputted to the display operation device  1  by backward movement of the fingertip.  FIG. 11  is a flowchart showing steps of an input process of the display operation device  1  based on a backward movement operation by a fingertip,  FIG. 12  is a descriptive drawing that schematically shows a state in which a fingertip is held still in the first detection region F 1  prior to backward movement, and  FIG. 13  is a descriptive drawing that schematically shows a state in which the fingertip moves backward to the second detection region F 2 . 
         [0078]    Before entering an input by backward movement to decrease magnification of the display, the user U first performs a prescribed operation on the display operation device  1  and causes the CPU  4  to execute a process of displaying a prescribed image (not shown) in the display surface  2   a  of the display unit  2 . 
         [0079]    Next, in step S 30 , the finger position detection unit  3  acquires the fingertip position coordinates P of the user U according to a command from the CPU  4 . After the fingertip position coordinates P are acquired, the CPU  4  determines in step  31  whether the Z coordinate among the acquired position coordinates P is within a preset range (Z≦α). The threshold α is as described above. By using such a threshold α, it can be determined whether the fingertip position coordinates P are within the first detection region F 1 . 
         [0080]    If as shown in  FIG. 12  the user U&#39;s fingertip is within the first detection region F 1 , for example, then the Z coordinate of the fingertip among the position coordinates P 21  satisfies Z≦α. If the Z coordinate among the acquired fingertip position coordinates P is within this range, then the process progresses to step S 32 . By contrast, if the Z coordinate among the acquired fingertip position coordinates P is outside of this range, then the process progresses to step S 30 , and detection of the finger position coordinates P is once again performed. 
         [0081]    The detection of the position coordinates P of the fingertip by the finger position detection unit  3  is, as described above, executed steadily, repeating at a uniform time interval, regardless of the presence or absence of a detection object (finger) in the detection region F. Every time the detection of position coordinates P is performed, the process progresses to step S 31 . 
         [0082]    In step S 32 , the CPU  4  starts the timer  7  and measures the time. Then, in step S 33 , detection of the fingertip position coordinates P is performed again, as in step S 30 . After detection of the position coordinates P, the CPU  4  determines whether or not a preset prescribed time Δt 3  (3 seconds, for example) has elapsed since the timer  7  has started. If the CPU  4  has determined that the prescribed time Δt 3  has not elapsed, then the process returns to step S 33  and detection of the position coordinates P of the finger is once again performed. By contrast, if the CPU  4  has determined that the prescribed time Δt 3  has elapsed, then the process progresses to step S 35 . In other words, after the timer  7  has started with the fingertip entering the first detection region F 1 , the finger position detection unit  3  repeatedly performs detection of the fingertip position coordinates P until the prescribed time Δt 3  has elapsed. The timer  7 , in addition to being used to measure the prescribed time Δt 3 , is also used to measure the prescribed time Δt 4  to be described later. 
         [0083]    In step S 35 , the CPU  4  determines whether or not the Z coordinate among the plurality of position coordinates P detected within the prescribed time Δt 3  is within an allowable range D 2  (±0.5 cm, for example) for which a change amount ΔZ 2  is set in advance. The change amount ΔZ 2  is determined in step S 31  by taking the difference between the Z coordinate (reference value) determined to satisfy the range Z≦α, and the Z coordinate among the position coordinates P detected within the prescribed time Δt 13 . If all change amounts ΔZ 2  for Z coordinates of all position coordinates P detected after the timer  7  has started are within the allowable range D 2 , then the process progresses to step S 36 . By contrast, if the change amount ΔZ 2  of even one Z coordinate exceeds the allowable range D 2 , then the process returns to step S 30 . In other words, in step S 35 , it is determined whether or not the fingertip of the user U is within the first detection region F 1  and has stopped moving at least in the Z axis direction. 
         [0084]    In step S 36 , detection of the fingertip position coordinates P is performed again. As indicated in step S 37 , such detection is repeated until the prescribed time Δt 4  has elapsed since the timer  7  has started. The prescribed time Δt 4  is longer than the prescribed time Δt 3 , and if Δt 3  is set to 3 seconds, then Δt 4  is set to 3.3 seconds, for example. If the CPU  4  has determined that the prescribed time Δt 4  has elapsed, then the process progresses to step S 38 . 
         [0085]    In step S 38 , the CPU  4  determines whether or not there is at least one case in which a difference ΔZ 3  between the Z coordinate among the plurality of position coordinates P detected within the prescribed time Δt 4  and the Z coordinate of the first virtual plane R 1  (that is, α) is greater than or equal to a predetermined prescribed value D 3  (3 cm, for example). In other words, in step S 38 , it is determined whether the user U&#39;s fingertip has moved (forward) from the first detection region F 1  to the second detection region F 2  within Δt 4 −Δt 3  (0.3 seconds, for example). In another embodiment, it may be determined whether there is at least one case in which a difference ΔZ 3  between the Z coordinates among the plurality of position coordinates P detected during Δt 4 −Δt 3  (0.3 seconds, for example), and α is greater than or equal to a predetermined prescribed value D 3 . 
         [0086]    After the fingertip of the user U stays in the first detection region F 1  for the prescribed time Δt 3  as shown in  FIG. 12 , the fingertip moves back by Δt 4  to a position (position coordinate P 22 ) that is at a distance of the prescribed value D 3  or greater from the first virtual plane R 1  along the Z axis direction as shown in  FIG. 13 , for example. In step S 38 , if the CPU  4  determines that if there are no cases in which the difference ΔZ 3  is greater than or equal to the prescribed value D 3 , then the process progresses to step S 30 . By contrast, if in step S 38  the CPU  4  determines that if there is at least one case in which the difference ΔZ 3  is greater than or equal to the prescribed value D 3 , then the process progresses to step S 39 . 
         [0087]    In step S 39 , the CPU  4  receives a command (input) to switch the image displayed in the display unit  2  to a shrunken image. A command in which the image displayed in the display unit  2  is switched to a shrunken image can be inputted to the display operation device  1  by such backward movement of the user U&#39;s fingertip (example of a gesture). When the CPU  4  receives such an input, the display control unit  8  reads information pertaining to a shrunken image from the storage unit  9  and then switches from an image displayed in advance in the display unit  2  to the shrunken image on the basis of the read-in information, according to the command from the CPU  4 . In such a display operation device  1 , it is possible for an input operation to be performed with ease by backward movement of the user U&#39;s fingertip (movement of fingertip in Z axis direction) without directly touching the display unit  2 . 
       Embodiment 2 
       [0088]    Next, a display operation device  1 A of Embodiment 2 will be described with reference to  FIGS. 14 to 17 .  FIG. 14  is a descriptive drawing that schematically shows the outer appearance of a display operation device  1 A of Embodiment 2, and  FIG. 15  is a function block diagram showing main components of the display operation device  1 A of Embodiment 2. The display operation device  1 A of the present embodiment includes a three-dimensional image display unit  2 A instead of the display unit  2  of the display operation device  1  of Embodiment 1, and has a three-dimensional image display control unit  8 A instead of the display control unit  8 . Furthermore, the display operation device  1 A of the present embodiment stores information corresponding to three-dimensional images in the storage unit  9 . Other components are similar to those of Embodiment 1, and therefore, the same components assigned the same reference characters and descriptions thereof are omitted. 
         [0089]    As shown in  FIG. 14 , the display operation device  1 A displays a three-dimensional image  100  to the front of the three-dimensional image display unit  2 A. The three-dimensional image display unit  2 A displays the three-dimensional image  100  by the parallax barrier mode, and is constituted by a liquid crystal display panel, a parallax barrier, and the like. The three-dimensional image  100  is perceived by the user U to be floating in front of the display surface  2 Aa of the three-dimensional image display unit  2 Aa. The three-dimensional image display control unit  8 A displays a prescribed three-dimensional image  100  in the three-dimensional image display unit  2 A according to commands from the CPU  4 . The three-dimensional image display control unit  8 A may be a software function realized by the CPU  4  executing a control program stored in the ROM  5 , or may be realized by a dedicated hardware circuit. 
         [0090]    The display operation device  1 A of the present embodiment also includes a finger position detection unit  3  similar to the above-mentioned display operation device  1 , and as shown in  FIG. 16 , a detection region F similar to that of Embodiment 1 is formed to the front of the display operation device  1 A. The three-dimensional image  100  is displayed at the first virtual plane R 1  in front of the three-dimensional image display unit  2 A. In other words, the three-dimensional image  100  is perceived by the user U to be floating 9 cm (Z=α) from the display surface  2 Aa of the three-dimensional image display unit  2 A. 
         [0091]    Next, the steps of the input process based on a click operation (single click operation) by the user U&#39;s fingertip will be described.  FIG. 17  is a flowchart showing steps of an input process of the display operation device  1 A based on a click operation by a fingertip. 
         [0092]    First, in step S 40 , the user U performs a prescribed operation on the display operation device  1 A, and causes the CPU  4  to execute a process in which the three-dimensional image display unit  2 A displays the prescribed three-dimensional image  100  on the first virtual plane R 1 . 
         [0093]    Next, in step S 41 , the CPU  4  determines whether or not there has been a click input. The processing content in step S 41  is the same as the processing content for the click operation of Embodiment 1 (steps S 10  to S 16  in the flowchart of  FIG. 5 ). However, in the case of the present embodiment, the user U can perform click input using the first virtual plane R 1  while experiencing the sense of directly touching the three-dimensional image  100 . 
         [0094]    In step S 41 , if the CPU  4  determines that an input by click operation (single click operation) has been received, it progresses to step S 42 , and a new three-dimensional image (not shown) that has been placed in association with the click input in advance is displayed by the three-dimensional image display unit  2 A. The three-dimensional image  100  of the rear surface of a playing card shown in  FIG. 14  may be switched to the front surface of the playing card by click input, for example. In this manner, in the display operation device  1 A, the three-dimensional image  100  displayed by the three-dimensional image display unit  2 A is arranged on the first virtual plane R 1  (click surface), and thus, it is possible for the user U to perform an input operation to switch to another three-dimensional image while experiencing the sense of directly touching the three-dimensional image  100  with his/her fingertip. In the display operation device  1  of Embodiment 1, it would be difficult for the user U to recognize the object to be operated (click surface of the first virtual plane R 1 ), but such a problem is solved in the display operation device  1 A of the present embodiment. 
       OTHER EMBODIMENTS 
       [0095]    The present invention is not limited to the embodiments shown in the drawings and described above, and the following embodiments are also included in the technical scope of the present invention, for example. 
         [0096]    (1) In a display operation device of another embodiment, the display unit may include touch panel functionality. In other words, the display operation device may include both a non-contact-type input method and a contact-type input method. 
         [0097]    (2) There is no special limitation on the arrangement of electrodes (transmitter electrode, receiver electrode) included in the capacitive sensor as long as a prescribed detection region as illustrated in the embodiments above can be formed to the front of the display unit (towards the user). 
         [0098]    (3)  FIG. 18  is a front view that schematically shows Modification Example 1 of electrodes  3 Aa and  3 Ab included in the capacitive sensor, and  FIG. 19  is a cross-sectional view along the line A-A of  FIG. 18 . In Modification Example 1, one of the electrodes  3 Aa (transmitter electrode) is arranged to overlap the display area AA (active area) of the display unit  2 , and the other electrodes  3 Ab (receiver electrodes) are arranged to overlap the electrode  3 Aa across a transparent insulating layer  3 Ac. The electrodes  3 Ab are constituted by four parts, each of which is triangular in shape. The electrodes  3 Aa and  3 Ab may be arranged to overlap the display area AA as in Modification Example 1. In such a case, the electrode material forming the electrodes  3 Aa and  3 Ab would be a transparent conductive film. 
         [0099]    (4)  FIG. 20  is a front view that schematically shows Modification Example 2 of electrodes  3 Ba and  3 Bb included in the capacitive sensor, and  FIG. 21  is a cross-sectional view along the line B-B of  FIG. 20 . In Modification Example 2, one of the electrodes  3 Ba (transmitter electrode) has a frame shape surrounding a display area AA (active area) of the display unit  2 . In other words, the electrode  3 Ba is arranged in the non-display area (frame region). A frame-shaped insulating layer  3 Bc is formed on the electrode  3 Ba. By contrast, the other electrodes  3 Bb (receiver electrodes) are arranged so as to overlap the electrode  3 Ba across an insulating layer  3 Bc. The electrodes  3 Bb form a frame shape overall, but include four portions that are disposed, respectively, at the sides of the rectangular display area AA. The electrodes  3 Ba and  3 Bb may be arranged only in the non-display area (frame region) surrounding the display area AA as in Modification Example 2. 
         [0100]    (5) The display operation device of the embodiments received input operation by the finger position detection unit detecting the position coordinates of the user&#39;s hand (fingertip), but the present invention is not limited thereto, and in other embodiments, a detection object such as a stylus may be what is detected by the finger position detection unit. 
         [0101]    (6) In the embodiments, the second virtual plane is set as the position in the Z axis direction where the signal strength was at the detection limit, but in other embodiments, the position of the second virtual plane may be set closer to the display operation device than the detection limit. 
         [0102]    (7) There is no special limitation on the first virtual plane as long as the first virtual plane is set between the display surface (reference surface) of the display unit and the detection limit position in the Z axis direction. However, for purposes such as ensuring a large second detection region, it is preferable that the first virtual plane be set closer towards the display surface (display operation device) than the midway point between the display surface and the detection limit position. By setting the first virtual plane closer towards the display surface in this manner, it is easier for the user to move his/her fingertip in and out of the first detection region, and for the user to more easily perform an input operation (click operation) on the first virtual plane (click surface). 
         [0103]    (8) In Embodiment 1, the displayed image was switched to an enlarged image by an input operation based on forward movement of the fingertip, and then by an input operation based on backward movement thereafter, the displayed image was switched to a shrunken image, but in other embodiments, a configuration may be adopted in which an input operation based on forward movement results in the displayed image being switched to a shrunken image, and an input operation based on backward movement results in the displayed image being switched to an enlarged image. Alternatively, forward and backward movement by a fingertip may be associated with a command to the display operation device to perform another process besides enlarging or shrinking the displayed image. 
         [0104]    (9) In the embodiments, the displayed image was switched by an input operation based on fingertip movement, but in another embodiment, fingertip movement can result in a process for another component (such as volume adjustment for speakers) besides the switching of displayed images being executed. 
         [0105]    (10) In the embodiments, only the Z coordinate was used among the acquired position coordinates P of the fingertip, and only fingertip movement in the Z axis direction was recognized, but in other embodiments, fingertip movement may be recognized using not only the Z coordinate but furthermore, as necessary, the X coordinate and Y coordinate. It is preferable that a capacitive sensor be used as the sensor for the finger position detection unit for reasons such as being able to detect with ease movement of the fingertip, which is the detection object, in the Z axis direction. 
         [0106]    (11) In Embodiment 2, the three-dimensional image was switched to another three-dimensional image (static image) according to movement of the user&#39;s fingertip (click operation), but the present invention is not limited thereto, and the display operation device may be configured such that after receiving the fingertip movement (click operation) by the user, the three-dimensional image (such as a globe) undergoes movement such as rotation, for example. Furthermore, a configuration may be adopted in which a switch image is displayed as the three-dimensional image, with the user being able to recognize the image as a virtual switch. 
       DESCRIPTION OF REFERENCE CHARACTERS 
       [0000]    
       
         
           
               1  display operation device (input device) 
               2  display unit 
               2   a  display surface (reference surface) 
               3  finger position detection unit (position detection unit) 
               3   a ,  3   b  electrode 
               30  sensor 
               4  CPU (determination unit, comparison unit, standby detection unit, change amount detection unit) 
               5  ROM 
               6  RAM 
               7  timer 
               8  display control unit (display switching unit) 
               9  storage unit 
               10  bus line 
             F detection region 
             R 1  first virtual plane (virtual plane) 
             R 2  second virtual plane 
             U user 
             P position coordinate of detection object