Patent Publication Number: US-7719524-B2

Title: Pointing device and portable information terminal using the same

Description:
The present application is a continuation of application Ser. No. 09/930,207, filed Aug. 16, 2001, the contents of which are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a pointing device for moving a pointer (cursor) on a display screen used for a portable information terminal such as a cellular phone, and a portable information terminal using the pointing device. 
   Conventionally, a portable information terminal such as a portable type personal computer and cellular phone has an operation panel provided with a display screen on which a pointer for pointing to a desired position of an image is displayed and a pointing device for moving this pointer to a desired position. 
   As such a conventional pointing device, a track ball that moves a pointer by detecting the rotation of a ball and a dial type pointer that moves a pointer by detecting the rotation of a disk are known. Furthermore, as portable information terminals are being increasingly implemented with multi-functions and large-sized display screen, and in order to make it possible to arbitrarily and smoothly select more selection items with a pointer, a cross pointer having independent feed switches for upward/downward, rightward/leftward movements of a pointer and a stick pointer used for a game machine in particular that moves a pointer by tilting a stick or disk back and forth, right and left are also known. Furthermore, as used for a personal computer, etc., to continuously move a pointer on an image such as a map displayed on a display screen, a pointing device called a “track pad” is also known which consists of a flat table shaped sensor plate with a certain area and when a finger is moved continuously on this sensor plate, the continuously changing position of the finger is detected and the pointer is moved continuously according to this detection result. 
   On the other hand, since a portable information terminal must meet the need for portability, there is a demand for a smaller, lighter or thinner terminal. For the track ball or dial type pointing device above, meeting this demand is difficult because this pointing device includes a physical movable section such as a ball or disk, which puts a limit to reduction of the size. 
   With the pointing device such as the cross pointer and stick pointer above, the pointer basically moves one step by one operation, that is, the pointer moves by one item displayed on the display screen at a time, and therefore selecting an item at a considerable distance on the display screen requires more operations, which takes time and trouble. 
   Moreover, the track pad described above moves the pointer by touching the sensor plate with the finger and therefore the sensor plate must have an area sufficiently greater than the area of the finger that touches this and is not suited to miniaturization. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a pointing device capable of being small-sized and facilitating movement of the pointer, and a portable information terminal using such a pointing device. 
   In order to attain the above object, the pointing device according to the present invention includes a transparent plate having an outer surface to contact the surface of an object, image detecting means for detecting an image of the surface of the object that contacts the outer surface of the plate and optical means for forming an image on the outer surface of the plate on the detection plane of the image detecting means, in which the pointer is configured to be able to move according to the movement of the image on the outer surface of the plate detected by said image detecting means. 
   Furthermore, the portable information terminal according to the present invention is provided with the above-described pointing device and comprises means for detecting the movement of the image detected by the image detecting means and moving the pointer in the direction according to the direction of the detected movement. 
   When the user puts the finger on the plate and moves the finger from that position, the above configuration allows the fingerprint of this fingertip to be detected as a moving image and allows the pointer on the display screen to move in the direction according to the direction of this movement. This prevents the user from operating different operation switches according to the moving direction of the pointer and makes the operation easier. Moreover, the user only needs to detect the movement of the image on the plate, and therefore it is possible to narrow the range of image detection and reduce the size of the pointing device. 
   Furthermore, the portable information terminal according to the present invention provided with the above-described pointing device comprises means for determining the presence/absence of movement of the image on the outer surface of the plate detected by the image detecting means and switching the sensing frequency of the image detecting means according to the determination result. 
   When there is no movement of the image on the outer surface of the plate and no pointer movement operation, the above configuration makes it possible to reduce the sensing frequency of the image detecting means and suppress power consumption of the image detecting means accordingly. 
   In order to attain the above object, the pointing device according to the present invention further includes light emitting means for emitting light onto the outer surface of said plate in addition to the above configuration. 
   Furthermore, the portable information terminal according to the present invention is provided with the above-described pointing device and comprises first means for measuring a reflection factor of the plate on the outer surface from the quantity of light received of the image detecting means and the quantity of light emitted of the light emitting means, second means for designating the quantity of light emitted of the light emitting means as a first reference value when the reflection factor measured by the first means falls below a predetermined minimum reference value and adjusting the quantity of light emitted of the light emitting means when the reflection factor measured by the first means exceeds the minimum reference value so that the quantity of light received by the image detecting means becomes a predetermined second reference value which is larger than the first reference value, third means for detecting the movement of the image detected by the image detecting means and moving the pointer in the direction according to the direction of said detected movement and fourth means for determining the presence/absence of movement of the image detected by the image detecting means, setting the pointing device in an action mode when the movement is detected, moving the pointer in the direction according to the direction of the movement and setting the pointing device in a standby mode when the movement is not detected for a predetermined period of time, wherein the sensing frequency of the pointing device in the standby mode is smaller than the sensing frequency of the pointing device in the action mode. 
   Furthermore, the second means changes temporarily the quantity of light emitted of the light emitting means when the reflection factor measured by the first means falls below a predetermined minimum reference value and designates the quantity of light emitted of the light emitting means as the predetermined first reference value when the quantity of light received of the image detecting means does not change as the quantity of light emitted changes. 
   According to the configuration above, the light emitting means illuminates the image on the outer surface of the plate and the image detecting means can detect an image of high brightness and when no pointer movement operation is carried out without touching the outer surface of the plate with the fingertip, etc., this can be detected, which can suppress the quantity of light emitted by the light emitting means as standby mode and allows power saving. Moreover, whether the fingertip, etc. is touching the outer surface of the plate or not is judged from the reflection factor of the image on the outer surface of the plate and further a variation of the quantity of light received of the image detecting means is detected by temporarily changing the quantity of light emitted of the light emitting means, and therefore whether the fingertip, etc. is touching the outer surface of the plate or not can be judged more accurately. This configuration can provide detection of an image with necessary and sufficient brightness without being affected by personal differences such as the color of the fingertip or differences from one part to another, and even if the user wears gloves, this configuration can provide detection of an image with necessary and sufficient brightness without being affected by differences in color or material. 
   Furthermore, the portable information terminal according to the present invention in the above configuration allows the pointing device to push the plate and is provided with at least one operation switch that operates in accordance with this pushing operation and one of these operation switches is designated as an “ENTER” switch to enter the menu on the display screen indicated by the pointer. 
   Such a configuration allows the pointing device to have multi-functions, makes it possible to reduce the number of operation switches on the operation panel of the portable information terminal, further reduce the size of the portable information terminal, and add new operation switches enhancing the multi-functions of the portable information terminal. 
   Furthermore, the portable information terminal according to the present invention in the above configuration is configured so that the optical means of the pointing device can change the focal distance of the condensing lens. 
   Such a configuration allows the portable information terminal according to the present invention to also have functions as a digital camera or video camera. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front view showing an embodiment of a portable information terminal according to the present invention; 
       FIGS. 2A ,  2 B are configuration diagrams showing an embodiment of a pointing device according to the present invention; 
       FIGS. 3A ,  3 B are configuration diagrams showing another specific example of illuminating means of the pointing device shown in  FIG. 2 ; 
       FIGS. 4A ,  4 B are configuration diagrams showing another layout example of a fingerplate of the pointing device shown in  FIG. 2 ; 
       FIGS. 5A ,  5 B,  5 C,  5 D,  5 E,  5 F are perspective views showing a specific example of a configuration of an outer surface of the fingerplate shown in  FIG. 2  to  FIG. 4 ; 
       FIGS. 6A ,  6 B are configuration diagrams showing another specific example of the “ENTER” switch operating means shown in  FIG. 2 ; 
       FIGS. 7A and 7B  are configuration diagrams showing another embodiment of the pointing device according to the present invention; 
       FIGS. 8A ,  8 B,  8 C,  8 D are configuration diagrams showing a further embodiment of the pointing device according to the present invention; 
       FIGS. 9A ,  9 B,  9 C,  9 D are configuration diagrams showing a still further embodiment of the pointing device according to the present invention; 
       FIG. 10  is a block diagram showing a specific example of the circuit configuration of the embodiment shown in  FIG. 1 ; 
       FIGS. 11A ,  11 B are drawings to explain a method of detecting a variation of an image picked up from the pointing device of a controller in  FIG. 10 ; 
       FIG. 12  is a flow chart showing an operation of the pointing device shown in  FIG. 2  by the controller in  FIG. 10 ; 
       FIGS. 13A ,  13 B,  13 C,  13 D,  13 E illustrate layout examples of the pointing device according to the present invention on a portable information terminal; 
       FIGS. 14A ,  14 B,  14 C,  14 D,  14 E illustrate another layout examples of the pointing device according to the present invention on the portable information terminal; 
       FIG. 15  is a block diagram showing a specific example of a circuit configuration of another embodiment of the portable information terminal according to the present invention; 
       FIGS. 16A ,  16 B,  16 C,  16 D illustrate layout examples of an open/close detector, a contact sensor, an operation lock switch, a receiver section proximity sensor shown in  FIG. 15  on the portable information terminal; 
       FIG. 17  is a flow chart showing a control operation of the pointing device according to detection outputs of the open/close detector, the contact sensor, the operation lock switch, the receiver section proximity sensor of the controller shown in  FIG. 15 ; 
       FIGS. 18A ,  18 B illustrate other specific examples of misoperation preventing means of the pointing device according to the present invention; 
       FIGS. 19A ,  19 B,  19 C illustrate further specific examples of the misoperation preventing means of the pointing device according to the present invention; 
       FIG. 20  is a flow chart showing a specific example of an operation procedure for making a call with the embodiment of the portable information terminal according to the present invention; 
       FIGS. 21A ,  21 B,  21 C,  21 D,  21 E,  21 F,  21 G illustrate specific examples of screens displayed sequentially on the display screen according to the operation procedure shown in  FIG. 20 ; 
       FIG. 22  is a flow chart showing a specific example of the operation procedure for receiving a map service of the embodiment of the portable information terminal according to the present invention; 
       FIGS. 23A ,  23 B,  23 C,  23 D,  23 E,  23 F,  23 G,  23 H,  23 I,  23 J illustrate specific examples of the screens displayed sequentially on the display screen shown in  FIG. 22 ; and 
       FIGS. 24A ,  24 B are cross-sectional views showing a specific example of the pointing device when the embodiment of the portable information terminal according to the present invention is provided with a video camera function. 
   

   DESCRIPTION OF THE EMBODIMENTS 
   With reference now to the attached drawings, embodiments of the present invention will be explained below. 
     FIG. 1  is a front view showing an embodiment of a portable information terminal using a pointing device according to the present invention. Reference numeral  1  denotes a portable information terminal;  2 , an operation panel;  2   a , a “Power/stop call” button;  2   b , “Start call” button;  2   c , a “Menu” button;  2   d , a “Return” button;  3 , a display screen;  4 , a pointing device. Here, this embodiment shows a case of a cellular phone, but this embodiment can also be other portable information terminals such as a portable type personal computer. 
   In the same drawing, the operation panel  2  including various operation components such as the pointing device  4  and the display screen  3  that shows an image and pointer (cursor, not shown) are provided on the front of the portable information terminal  1 . The operation panel  2  is provided with the “Power/stop call” button  2   a  to indicate the power button and the end of a call, the Start call” button  2   b  to indicate the start of a call, the “Menu” button  2   c  to display the menu screen on the display screen  3 , the “Return” button  2   d  to return to the screen displayed just before on the display screen  3  and a ten-key pad which can also be used to enter characters, etc. 
   The pointer displayed on the display screen  3  can be moved by stroking the surface of the pointing device  4  on the operation panel  2  with a fingertip. The pointing device  4  is also provided with an enter function which is not shown and pressing this pointing device  4  with the fingertip activates this enter function to enter an item indicated by the pointer on the display screen  3  or touch button, etc. 
     FIG. 2  shows an embodiment of the pointing device  4  according to the present invention used for the portable information terminal shown in  FIG. 1  and  FIG. 2A  is a vertical cross-sectional view and  FIG. 2B  is a top view to see through the pointing device  4  and reference numeral  4   a  denotes a fingerplate;  4   b , a light emitting device;  4   c , an image pick-up element;  4   d , a condensing lens;  4   e , a hinge;  5 , “ENTER” switch,  6 , a circuit board;  7 , a fingertip;  7   a , the thick of the fingertip;  8 , an outer case of the portable information terminal  1 ,  8   a , a through hole perforated in the outer case  8 . 
   By the way, the top surface of the outer case  8  in  FIG. 2A  is an outside of the portable information terminal  1 . 
   In  FIG. 2A  and  FIG. 2B , the fingerplate  4   a , light emitting device  4   b , image pick-up element  4   c , condensing lens  4   d  and hinge  4   e  constitute the pointing device  4  in  FIG. 1  and the transparent fingerplate  4   a  of these components is fitted in the through hole  8   a  perforated in the outer case  8  on the operation panel  2  ( FIG. 1 ) side of the portable information terminal  1 . This fingerplate  4   a  has a convex outer surface (that is, the surface of the fingertip  7  shown in the figure) and sticks out of the outer surface of the outer case  8  and can be easily touched by the thick  7   a  of the fingertip  7 . Furthermore, one end of this fingerplate  4   a  is supported by the hinge  4   e  and set in such a way as to be pivotable centered on the hinge  4   e  in the direction shown by the arrow. This fingerplate  4   a  can be pushed in the outer case  8  (that is, inside the portable information terminal  1 ) by the fingertip  7 . When the pushing by the fingertip  7  is released, the fingerplate  4   a  is returned to its original position shown in the figure by restoring means such as a spring (not shown). 
   Inside the outer case  8 , the light emitting device  4   b , condensing lens  4   d  and image pick-up element  4   c  are provided. The image pick-up element  4   c  is fixed to the circuit board  6  inside the outer case  8 . The normal in the center of the image pick-up surface of this image pick-up element  4   c , the optical axis of the condensing lens  4   d  and the central axis of the fingerplate  4   a  almost coincide and the condensing lens  4   d  is placed in such a way that the image of the object on the outer surface of the fingerplate  4   a  is focused on the image pick-up surface of the image pick-up element  4   c . Furthermore, the light emitting device  4   b  irradiates diagonally the outer surface of the fingerplate  4   a  from the inside of the outer case  8 . Therefore, when there is nothing on the outer surface of the fingerplate  4   a , the light beam from the light emitting device  4   b  passes through the fingerplate  4   a  and goes out of the portable information terminal  1 , but if the thick  7   a  of the fingertip  7  touches the outer surface of the fingerplate  4   a , the light beam from the light emitting device  4   b  illuminates this thick  7   a  and part of the reflected light is collected by the image pick-up element  4   c  via the condensing lens  4   d . In this way, when the pattern of the surface of an object that touches the fingerplate  4   a , for example, when the thick  7   a  of the fingertip  7  touches the fingerplate  4   a , the image of the finger print is taken by the image pick-up element  4   c . The image pick-up area of this image pick-up element  4   c  on the fingerplate  4   a  is part of the area such as the central area of the fingerplate  4   a , and therefore an image of part of the area of the thick  7   a  of the fingertip  7  that touches the fingerplate  4   a  is picked up. 
   Thus, when the light beam is applied diagonally to the surface of an object that touches the fingerplate  4   a , if the pattern of this surface of the object is a pattern made up of projections and depressions such as the finger print of the fingertip  7 , the variations of light and shade produced by this light beam becomes further noticeable and an image with a more distinctive pattern is picked up by the image pick-up element  4   c.    
   Furthermore, as shown above, by pushing the fingerplate  4   a  with the fingertip  7  in the direction shown by the arrow, the fingerplate  4   a  touches and activates the “ENTER” switch  5  to carry out an enter operation, which will be described later. 
     FIG. 3  is a block diagram showing another specific example of the illuminating means of the pointing device  4  shown in  FIG. 2  and reference numerals  4   f ,  4   f   1  and  4   f   2  denote optical path changing means and the same parts as those in  FIG. 2  are assigned the same reference numerals and overlapping explanations will be omitted. 
   A specific example shown in  FIG. 3A  describes a case where the light emitting device  4   b  is placed on the circuit board  6  face up (that is, the outgoing illumination beam is oriented perpendicular to the plane of the circuit board  6 ) and the illumination beam is emitted in the direction perpendicular to the plane of the circuit board  6 . Then, the optical path changing means  4   f  made up of a mirror or prism is provided between this light emitting device  4   b  and the outer case  8  so that the optical path changing means  4   f  changes the optical path of the illumination beam output from the light emitting device  4   b  and the fingerplate  4   a  is irradiated with this illumination beam diagonally from the lower part. 
   A specific example shown in  FIG. 3B  describes a case where the light emitting device  4   b  is placed on its side on the circuit board  6  (that is, the outgoing beam is oriented parallel to the surface of the circuit board  6 ) and the illumination beam is emitted in the direction parallel to the surface of the circuit board  6 . Moreover, on the circuit board  6  an optical path changing means  4   f   1  made up of a mirror or prism is provided facing the light emission port of this light emitting device  4   b  and an optical path changing means  4   f   2  made up of a mirror or prism is provided facing the optical path changing means  4   f   1  between the circuit board  6  and outer case  8  so that the light path of the illumination beam output from the light emitting device  4   b  is changed by these optical path changing means  4   f   1  and  4   f   2  and the fingerplate  4   a  is irradiated with this illumination beam diagonally from below. 
   Thus, placing the light emitting device  4   b , which is an electronic part, on the same circuit board as that of the image pick-up element  4   c  can simplify wiring support parts, etc., reduce manufacturing cost and shorten the operation time. 
     FIG. 4  is a configuration diagram showing another layout of the fingerplate  4   a  of the pointing device  4  shown in  FIG. 2  and the same parts as those in  FIG. 2  are assigned the same reference numerals and overlapping explanations will be omitted. 
   The specific example shown in  FIG. 4A  is configured to allow the fingerplate  4   a  to be placed inside the outer case  8 . In this case, the entire fingerplate  4   a  can be placed inside the outer case  8  or the fingerplate  4   a  can be placed so that the central part of the convex outer surface of the fingerplate  4   a  is placed inside the through hole  8   a  of the outer case  8  or the central part of the convex outer surface of the fingerplate  4   a  sticks out of this through hole  8   a.    
   In this case, the distance between the fingerplate  4   a  and circuit board  6  becomes shorter, and therefore it is possible to increase the above distance by making the thickness of the fingerplate  4   a  almost uniform and make the inner surface side have a concave shape. 
   The specific example shown in  FIG. 4B  is configured in such a way that the fingerplate  4   a  is placed outside the outer case  8 . In this case, the “ENTER” switch  5  is also mounted on the outer case  8  so that at least the operation part pressed by the fingerplate  4   a  also comes outside the outer case  8 . 
     FIG. 5  is a perspective view showing specific examples of configurations of the outer surface of the fingerplate  4   a  shown in  FIG. 2  to  FIG. 4 . Here, the fingerplate  4   a  has a true circle shape, but the present invention is not limited to this and any surface shape can be taken such as ellipsoidal, rectangular or other shapes. 
   The specific example shown in  FIG. 5A  shows the fingerplate  4   a  whose outer region is made up of an opaque outline section  10  and has a transparent section  9  inside this outline section  10  as the area through which light passes. The image pick-up element  4   c  ( FIG. 2 ) uses a predetermined area of this transparent section  9  as the image pick-up area. Such outline section  10  can reduce unnecessary incident light toward the image pick-up surface of the image pick-up element  4   c  from outside. 
   The specific example shown in  FIG. 5B  shows the fingerplate  4   a  with a shallow groove-like guide  11  provided in the radial direction passing its center, which makes it easier to move the fingertip  7  ( FIG. 2 ) while touching the fingerplate  4   a . It is this central part within this guide  11  that is the image pick-up area of the image pick-up element  4   c  and the area outside this image pick-up area can be opaque. 
   The specific example above is the case where the guide  11  is provided only in one direction, but as shown in  FIG. 5C , it is also possible to provide two guides  11   a  and  11   b , which intersect at right angles. In this case, the image pick-up area  12  of the image pick-up element  4   c  is set at the intersection of these guides  11   a  and  11   b.    
   The specific example shown in  FIG. 5D  shows the specific example in  FIG. 5C  with guides  11   a  and  11   b  further finished with a gloss and the other area  13  leather-grained. Applying leather-graining to this area  13  has an effect of making it easier to slide the finger and preventing sweat from sticking to the surface. 
   The specific example shown in  FIG. 5E  shows a case where a hollow section  14  is provided in the center of the outer surface of the fingerplate  4   a  and the image pick-up area of the image pick-up element  4   c  is set within this hollow section  14 . Setting the image pick-up area of the image pick-up element  4   c  within this hollow section  14  in this way prevents other objects from touching this image pick-up area and prevents this image pick-up area from being damaged when the portable information terminal  1  is put in, for example, a briefcase. In this specific example, it is also possible to make the area outside the hollow section  14  opaque or as shown in  FIG. 5F , provide guides  11   a  and  11   b  similar to those in  FIG. 5C  or as in the case of the specific example in  FIG. 5D , finish guides  11   a  and  11   b  and hollow section  14  with a gloss and apply leather-graining to the other area. 
     FIG. 6  illustrates another specific example of the operating means of the “ENTER” switch  5  shown in  FIG. 2  and the same parts as those in  FIG. 2  are assigned the same reference numerals and overlapping explanations thereof will be omitted. 
   The specific example shown in  FIG. 6A  shows a case where the fingerplate  4   a  is attached to the inner surface of the outer case  8  via the hinge  4   e  at a sufficiently large distance from the through hole  8   a  provided in the outer case  8 . This makes it possible to increase a distance L between the position on the fingerplate  4   a  pressed by the fingertip to carry out an ENTER operation and the position at which this fingerplate  4   a  is attached to the outer case  8  and realize a motion close to a pushing operation in the vertical direction though it is actually an arc-shaped motion centered on the hinge  4   e.    
   The specific example shown in  FIG. 6B  shows a case where the fingerplate  4   a  is attached to the inner surface of the outer case  8  via the hinge  4   e  at a position close to the through hole  8   a  provided in the outer case  8  and at the same time this fingerplate  4   a  extends beyond the position at which the fingerplate  4   a  is attached via this hinge  4   e  and the “ENTER” switch  5  is provided on the line of this extension. According to this configuration, when the fingerplate  4   a  is pressed by the fingertip, the “ENTER” switch  5  is lifted centered on the mounting section via the hinge  4   e  and the operating part thereof is pressed against the inner surface of the outer case  8  to perform an ENTER operation. In this case, the ENTER operation can be performed with a smaller force by applying the principle of leverage though this depends on a positional relationship between the hinge  4   e  and the “ENTER” switch  5 . 
     FIG. 7  is a configuration diagram showing another embodiment of the pointing device  4  according to the present invention.  FIG. 7A  is a top view and  FIG. 7B  is a cross-sectional view. Reference numeral  15  denotes a “RETURN” switch,  16   a  and  16   b  denote protrusions and reference numeral  17  denotes a rotation axis. The same parts as those in the above-described figures are assigned the same reference numerals and overlapping explanations thereof will be omitted. 
   This embodiment describes a case where the pointing device  4  described in  FIG. 2  to  FIG. 4  is provided with enhanced multi-functions. 
   In  FIG. 7A  and  FIG. 7B , the “ENTER” switch  5  and “RETURN” switch  15  are placed inside the outer case  8  with the through hole  8   a  placed in between and protruding pressing sections are formed toward the switches  5  and  15  on the fingerplate  4   a . The fingerplate  4   a  is placed by mounting means (not shown) in such a way as to be pivotable centered on the rotation axis  17 . Here, the rotation axis  17  is perpendicular to the straight line connecting the “ENTER” switch  5  and “RETURN” switch  15 . Of course, the mounting means above is made of a transparent material or provided in such a way as to bypass the image pick-up area so as not to prevent the image pick-up element  4   c  ( FIG. 2 ) from picking up an image on the outer surface of the fingerplate  4   a . Furthermore, a protrusion  16   a  and a protrusion  16   b  are provided toward the “RETURN” switch  15  and toward the “ENTER” switch  5  of the outer surface of the fingerplate  4   a , respectively. The image pick-up area of the image pick-up element  4   c  on the outer surface of this fingerplate  4   a  is the central part between the protrusions  16   a  and  16   b  on this outer surface. 
   When the pointing device  4  is provided with the “RETURN” function, providing the operation panel  2  with the “RETURN” switch  2   d  as shown in  FIG. 1  is not a necessary condition though doing so is not objected. 
   With this pointing device  4  in such a configuration, the image in the image pick-up area on the outer surface of the fingerplate  4   a  is taken by the image pick-up element  4   c  and pushing in the “ENTER” switch  5  of this fingerplate  4   a  with the fingertip causes the protruding pressing section of this fingerplate  4   a  to press and activate this “ENTER” switch  5  to carry out an ENTER operation. In this case, the fingertip is stopped by the protrusion  16   b , which makes it easier to push in the ENTER” switch  5  of the fingerplate  4   a . Moreover, by pushing in the “RETURN” switch  15  of this fingerplate  4   a  with the fingertip causes the protruding pressing section of the fingerplate  4   a  to press and activate this “RETURN” switch  15  to carry out the operation of returning to the display of the image displayed one step before on the display screen  3  ( FIG. 1 ). Thus, during a series of operations of browsing a menu in a hierarchic structure, it is possible to carry out operations without taking the finger off the pointing device. Moreover, once the operator places the finger on the pointing device, then the operator can concentrate on the display screen only without looking at the operating finger, which makes the operation easier. In this case, the fingertip is also stopped by the protrusion  16   a , which makes it easier to push in the “RETURN” switch  15  of the fingerplate  4   a.    
   By the way, this embodiment also describes the case where the pointer displayed on the display screen  3  is moved continuously or step by step by touching and moving the image pick-up area in the center of the fingerplate  4   a  with the fingertip (the pointer moves continuously when moving on a map and moves step by step when moving on the screen of a selection item such as a menu screen). Furthermore, the protrusions  16   a  and  16   b  are not always necessary. 
     FIG. 8  is a configuration diagram showing a further embodiment of the pointing device  4  according to the present invention and  FIG. 8A  is a top view,  FIG. 8B  is a cross-sectional view and  FIG. 8C  and  FIG. 8D  are functional schematic diagrams, and reference numerals  17   a  and  17   b  denote rotation axes;  18   a  to  18   d , functional switches; and  19 , protrusions. The same parts as those shown in the above-described drawings are assigned the same reference numerals and overlapping explanations thereof will be omitted. 
   This embodiment describes the pointing device  4  explained in  FIG. 2  to  FIG. 4  with enhanced multi-functions. 
   In  FIG. 8A  and  FIG. 8B , four functional switches  18   a ,  18   b ,  18   c  and  18   d  are spaced uniformly around the through hole  8   a  of the outer case  8  inside the outer case  8  and protruding pressing sections corresponding to these functional switches  18   a ,  18   b ,  18   c  and  18   d  are formed on the fingerplate  4   a.    
   Then, the fingerplate  4   a  is placed by mounting means (not shown) in such a way as to be pivotable on the two axes of the rotation axes  17   a  and  17   b  orthogonal, which are perpendicular to each other. Here, the rotation axis  17   a  is perpendicular to the straight line connecting the functional switches  18   c  and  18   d , while the rotation axis  17   b  is perpendicular to the straight line connecting the functional switches  18   a  and  18   b . Of course, the mounting means above of the fingerplate  4   a  is made of a transparent material so as not to prevent the image pick-up element  4   c  ( FIG. 2 ) from capturing the image on the outer surface of the fingerplate  4   a . Furthermore, protrusions  19  are provided toward the functional switches  18   a  to  18   d  on the outer surface of the fingerplate  4   a . The image pick-up area of the image pick-up element  4   c  on the outer surface of this fingerplate  4   a  is the central part between the protrusions  19  on this outer surface. 
   In this pointing device  4  having such a configuration, the image of the above-described image pick-up area on the outer surface of the fingerplate  4   a  is taken by the image pick-up element  4   c  and pressing the functional switch  18   a  side of this fingerplate  4   a  with the fingertip causes the fingerplate  4   a  to incline toward the functional switch  18   a  and the protruding pressing section of the fingerplate  4   a  presses and activates the functional switch  18   a . In this case, since the protrusion  19  is provided on the functional switch  18   a  side of the outer surface of the fingerplate  4   a , the fingertip is stopped by this protrusion, which makes it easier to push in the functional switch  18   a  side of the fingerplate  4   a . The same applies to other functional switches  18   b  to  18   d  sides and it is possible to push in the fingerplate  4   a  toward these switches and activate these switches. These switches are also provided with their respective protrusions  19 , which makes it easier to push in the fingerplate  4   a  towards these switches. 
   Here, the functional switches  18   a  to  18   d  are provided with predetermined functions.  FIG. 8C  shows an example of this. Here, the functional switches  18   a  to  18   d  are provided with the function of moving the pointer displayed on the display screen  3  ( FIG. 1 ) one step at a time (that is, one item at a time when the menu screen is displayed on the display screen  3 ). More specifically, explaining this with reference to  FIG. 8A , the functional switch  18   a  is used to move the pointer one step rightward at a time, the functional switch  18   b  is used to move the pointer one step leftward, the functional switch  18   c  is used to move the pointer one step upward and the functional switch  18   d  is used to move the pointer one step downward. 
   When the function shown in  FIG. 8C  is provided, touching the image pick-up area in the central part of the fingerplate  4   a  with the fingertip and moving the fingertip allows the pointer displayed on the display screen  3  to move continuously. The protrusions  19  are not always necessary. 
   Furthermore,  FIG. 8D  shows another example of function. The portable information terminal  1  provided with the pointing device  4  with the image pick-up element  4   c  ( FIG. 2 ) and the display screen  3  can function as a video camera to take pictures of landscapes, etc. using the image pick-up element  4   c  and store signals of images taken by the image pick-up element  4   c  in a built-in storage device with an increased volume of storage or in a large-volume storage medium that can be attached to the apparatus and read and replay the image signals on the display screen  3 . 
   In this case, it is possible to provide the replay operation function as shown in  FIG. 8D . Explaining this with reference to  FIG. 8A , the functional switch  18   a  is provided with a fast-forward function, the functional switch  18   b  is provided with a rewind function, the functional switch  18   c  is provided with a replay/pause function and the functional switch  18   d  is provided with a stop function. 
   When the function shown in  FIG. 8D  is provided, touching the image pick-up area in the central part of the fingerplate  4   a  with the fingertip and moving the fingertip allows the pointer displayed on the display screen  3  to move continuously or step by step (the pointer moves continuously when moving on a map and moves step by step when moving on the screen of a selection item such as a menu screen). The protrusions  19  are not always necessary. 
     FIG. 9  is a configuration diagram showing another embodiment of the pointing device  4  according to the present invention and  FIG. 9A  is a top view,  FIG. 9B  and  FIG. 9C  are cross-sectional views along a line A-A′ and B-B′ of  FIG. 9A , respectively and  FIG. 9D  is a functional schematic diagram. Reference numeral  20  denotes an ENTER operation section;  21 , a functional operation section;  22 , an actuating part;  23 , a hinge. The same parts as those in  FIG. 8  are assigned the same reference numerals and overlapping explanations thereof will be omitted. 
   This embodiment is a case where an ENTER operation section is added to the pointing device  4  explained in  FIG. 8  to further enhance the multi-functions. 
   That is, in  FIG. 9A  to  FIG. 9D , the fingerplate  4   a  is divided into two areas; a central part and a peripheral part and the central part constitutes an ENTER operation section  20  and the peripheral part constitutes a functional operation section  21  to activate the functional switches  18   a  to  18   d . Since this functional operation section  21  is similar to the fingerplate  4   a  in the embodiment shown in  FIG. 8 , explanations thereof will be omitted. The ENTER operation section  20  is configured to be able to be pushed in. One end of the actuating part  22 , which is supported by a hinge  23  in a pivotable manner, is attached to the inner side of this ENTER operation section  20  and the other end of this actuating part  22  constitutes the operation section of the “ENTER” switch  5  provided on the inner surface of the outer case  8 . 
   Pushing in the ENTER operation section  20  of the fingerplate  4   a  with the fingertip makes the actuating part  22  rotate centered on the hinge  23  and the operation part at the end of this actuating part  22  acts on the “ENTER” switch  5  and activates it. When the pushing of the ENTER operation section  20  is released, the ENTER operation section  20  returns to its original position by means which is not shown. 
   By the way, the image pick-up area of the image pick-up element  4   c  ( FIG. 2 ) is set inside the ENTER operation section  20  in this embodiment, too and touching this image pick-up area with the fingertip and moving the fingertip allows the pointer displayed on the display screen  3  to move continuously. 
     FIG. 10  is a block diagram showing a circuit configuration of the portable information terminal  1  shown in  FIG. 1  and reference numeral  24  denotes an antenna;  25 , radio equipment that transmits/receives a radio signal;  26 , a modulator/demodulator that modulates a transmission signal and demodulates a received signal;  27 , a transmission/reception signal processor that processes a transmission signal or arriving signal;  28 , a sound processor that processes a speech signal from a speech transmitter  29  such as a microphone and a speech signal supplied to a speech receiver  30  such as a speaker;  31 , a controller that controls the entire portable information terminal  1 ;  32 , a storage device that stores information from a telephone directory, various set data or information from the Internet;  33 , a display that displays images or pointer, etc. on the display screen  3  ( FIG. 1 );  34 , a silent arrival annunciator such as a vibrator that produces vibration to notify the user of arrival of a call and the same parts as those in  FIG. 1  are assigned the same reference numerals. 
   In the same drawing, as explained in  FIG. 2 , when the pointing device  4  is touched with the fingertip  7 , an image of the pattern of the thick  7   a  thereof, that is, the fingerprint is taken by the image pick-up element  4   c  and the image signal is supplied to the controller  31 . The controller  31  reads image signals from this image pick-up element  4   c  at predetermined time intervals, compares images of image signals loaded before and after, such as time t 1  and time t 2  as shown in  FIG. 11 , detects a change and thereby detects the movement of the fingertip  7  on the pointing device  4 . Then, this controller  31  controls the position of the pointer displayed on the display screen  3  ( FIG. 1 ) by the display  33  according to this detection result. When no movement of the fingertip  7  is detected, the controller  31  holds this pointer in a halt state and when any movement of the fingertip  7  is detected, the controller  31  moves the pointer at a speed according to the movement of this fingertip  7  and in the direction according to the direction of the movement of this fingertip  7 . Thus, touching the fingerplate  4   a  of the pointing device  4  with the fingertip  7  and moving this fingertip  7  allows the pointer to move on the display screen  3 . 
   Thus, when the pointer reaches a predetermined position on the display screen  3  (for example, a position at which a predetermined item is displayed), pushing in the fingerplate  4   a  with the fingertip  7  activates the “ENTER” switch  5  and selects and specifies the position (for example, the predetermined item above). 
   Furthermore, the controller  31  detects the quantity of light received by the image pick-up element  4   c  of the pointing device  4  and controls the quantity of light emitted by the light emitting device  4   b , etc. 
   Parts other than those described above are the same as those in the conventional portable information terminal. 
   On the other hand, when the display  3  in  FIG. 2  is large and when the pointer is moved in one direction, if it is impossible to move the pointer to a desired position with a single operation of the fingertip  7 , the fingertip  7  must move on the fingerplate  4   a  repeatedly and the movement of the fingertip  7  at this time is a reciprocating motion. In this case, if this reciprocating motion is performed with the fingertip  7  contacting the fingerplate  4   a , the controller  31  ( FIG. 10 ) assumes that the fingertip  7  is performing a reciprocating motion and makes the pointer also perform a reciprocating motion accordingly, which prevents the pointer from moving to a desired position. Therefore, when it is not possible to move the pointer to a desired position without moving the fingertip  7  a plurality of times, it is necessary to take this fingertip  7  off the fingerplate  4   a  when returning the fingertip  7 . 
   However, this occurs in the case where the display screen  3  is large. However, such a problem does not occur when the display screen  3  is small as in the case of a cellular phone and it is possible to move the pointer from one side of the display screen  3  to the opposite side by a single motion of the fingertip  7  on the fingerplate  4   a.    
   In such a pointing device  4 , it is only necessary to take an image of part of the thick  7   a  of the fingertip  7 , that is, it is only necessary to detect a change of the image read by the controller  31  before and after. This makes it possible to reduce the area of the surface of the fingerplate  4   a , and hence the size of the fingerplate  4   a  and as a result, reduce the size of the pointing device  4 . 
     FIG. 12  is a flow chart showing a control operation of the pointing device  4  by the controller  31 . 
   In the same drawing, when the “Power/stop call” button  2   a  is operated on the operation panel  2  of the portable information terminal  1  shown in  FIG. 1 , power is turned on, or when the pointing device  4  gets ready for operation by opening the cover of the portable information terminal  1  in a configuration described later, or unfolding the folded portable information terminal  1 , the pointing device  4  is set in a standby mode (step  100 ). In this standby mode, the controller  31  makes the light emitting device  4   b  emit illumination light with a predetermined quantity of light emission and the image pick-up element  4   c  repeats picture taking with the frequency (sensing frequency) of approximately 10 times a second. When the image pick-up element  4   c  takes pictures, the quantity of light received by the image pick-up element  4   c  is detected from the output thereof and the reflection factor (=quantity of light received/quantity of light emitted) on the outer surface of the fingerplate  4   a  is calculated based on the quantity of light received and the quantity of light emitted of the light emitting device  4   b  (step  101 ). The quantity of light received is assumed to be, for example, the integrated value of the output signal value corresponding to one screen from the image pick-up element  4   c  and the quantity of light emitted of the light emitting device  4   b  is assumed to be a drive power value of this light emitting device  4   b.    
   Then, this reflection factor calculated is compared with a preset minimum reflection factor (minimum reference value) (step  102 ). This step  102  is intended to determine whether the fingertip  7 , etc. is touching the fingerplate  4   a  or not and this minimum reference value can be obtained by, for example, an experiment, etc. 
   Then, if the reflection factor obtained in step  101  is below this minimum reference value, it is determined that the fingertip, etc. is not touching the fingerplate  4   a  for the operation of moving the pointer on the display screen  3  (hereinafter referred to as “pointer operation”) (if the reflection factor is below this minimum reference value, the quantity of light emitted of the light emitting device  4   b  is temporarily increased and the quantity of light received by the image pick-up element  4   c  at this time is detected, and if there is almost no change in the quantity of light received even if the quantity of light emitted is increased in this way, it can also be determined that the fingertip, etc. is not touching the fingerplate  4   a ), the quantity of light emitted of the light emitting device  4   b  is set to a preset small reference value (step  103 ) and the process moves on to step  105 . This allows power saving in the standby mode. On the other hand, when the reflection factor obtained in step  101  exceeds this minimum reference value, it is determined that the fingertip, etc. is touching the fingerplate  4   a  for a pointer operation (step  102 ), the quantity of light emitted of the light emitting device  4   b  is set to a value according to this reflection factor and the quantity of light received by the image pick-up element  4   c  is adjusted to a predetermined constant value (step  104 ). Therefore, if, for example, the reflection factor of an image of the fingertip covered with a glove is low and the quantity of light received is not enough to take the image on the image pick-up surface by the image pick-up element  4   c  with favorable brightness, the quantity of light emitted of the light emitting device  4   b  is increased so as to increase the output level of the image pick-up element  4   c , or on the contrary, if the reflection factor of the fingertip  7  touching the fingerplate  4   a  is high and the quantity of light received on the image pick-up surface by the image pick-up element  4   c  is too much, the quantity of light emitted of the light emitting device  4   b  is decreased so that the light emitting device  4   b  does not output the quantity of unnecessary light to save power consumption. After this quantity of light emitted is adjusted, the process moves on to step  105 . 
   In this step  105 , the image pick-up element  4   c  takes pictures with low frequency in a standby mode (that is, sensing frequency is 10 times/sec, etc.), and every time an image is taken, the image pick-up element  4   c  compares the image with the previous image and detects whether there is any change (movement) of the image. Then, if no change is detected for one sec or more (step  106 ), unless the “Power/stop call” button  2   a  ( FIG. 1 ) on the operation panel  2  is operated again and power is turned off (step  110 ), the process returns to step  100  and detects the reflection factor as shown above and adjusts the quantity of light emitted of the light emitting device  4   b . If the “Power/stop call” button  2   a  on the operation panel  2  is operated and power is turned OFF or the cover is put on the portable information terminal  1  as will be described later and the use of the portable information terminal  1  is completed (step  110 ), the pointing device  4  is set in a halt state. 
   Moreover, if there is any change (movement) with the image (step  105 ), it is judged that the pointer is operated, and the pointing device  4  is changed to an action mode (step  107 ). In this action mode, the sensing frequency of the image pick-up element  4   c  is set to a high speed, for example, 1000 times/sec, and this makes smooth the change of the image obtained from the image pick-up element  4   c  for the movement of the fingertip  7 . The controller  31  picks up each image taken and detects a change from the image taken previously and changes the position of the pointer according to the change, that is, the movement of the fingertip  7  (step  108 ). The operations in step  107  and  108  are repeated as long as such an operation of the pointing device  4  continues (step  109 ). 
   In the above action mode, the image pick-up element  4   c  takes pictures (sensing) with a frequency as high as 1000 times a second, for example, compared to a normal video camera, but since the picture taking range of this image pick-up element  4   c  is extremely narrow, detection of images can be performed with high resolution even if the number of pixels is set to a small value compared to an image pick-up element used for an ordinary video camera, and this ability to reduce the number of pixels makes it possible to increase the sensing frequency as shown above. On the other hand, increasing the sensing frequency in this way will shorten the time of exposure of each pixel, and by increasing the quantity of light emitted so that the necessary quantity of light is obtained in that short exposure time (this will be done in step  104 ), the quantity of light received at each pixel increases and an image signal with a sufficient level is obtained from the image pick-up element  4   c . Furthermore, it is also possible to use a device such as a light emitting diode that can emit light in pulses and generate a necessary sufficient quantity of light in a short time. 
   Moreover, in the standby mode above, when the fingertip  7 , etc. is not touching the fingerplate  4   a , the quantity of light emitted of the light emitting device  4   b  is reduced (step  103 ) and the sensing frequency of the image pick-up element  4   c  is reduced considerably compared to the action mode (step  100 ), and it is therefore possible to suppress power consumption considerably, and even if the fingertip  7 , etc. is touching the fingerplate  4   a , the sensing frequency of the image pick-up element  4   c  is reduced considerably (step  100 ), which makes it possible to expect suppression of power consumption. When the fingertip  7 , etc. touches the fingerplate  4   a , however, the fingertip  7  moves and an action mode starts almost immediately in that condition, and therefore, it is rather more important to adjust the quantity of light emitted of the light emitting device  4   b  (step  104 ), move the fingertip  7  and transition to the action mode immediately. 
   Then, when an ENTER operation is performed by pushing in the fingerplate  4   a  of the pointing device  4  with the fingertip  7  or when the operation of the pointing device  4  is finished by operating the operation switches other than the pointing device  4  (step  109 ), unless the “Power/stop call” button  2   a  ( FIG. 1 ) on the operation panel  2  is operated and power is turned OFF or the use of the portable information terminal  1  is finished by putting the cover to the portable information terminal  1 , which will be described later (step  110 ), the process returns to step  100  and starts the operation from there and the pointing device  4  is set in a standby state until it is operated next. 
     FIG. 13  illustrates layout examples of the pointing device  4  in the embodiment of this portable information terminal  1  and  FIG. 13A  shows an example of placing the pointing device  4  on the operation panel  2 ,  FIG. 13B  shows an example of placing the pointing device  4  on the back  1   a  of portable information terminal  1 ,  FIG. 13C  shows an example of placing the pointing device  4  on one side  1   b  of the portable information terminal  1  (here, the pointing device  4  is placed on the side  1   b , but can also be placed on the opposite side  1   b ) and  FIG. 13D  shows an example of placing the pointing device  4  next to the display screen  3 . Moreover, a specific example in  FIG. 13E  shows an embodiment in which numerical keys to enter telephone numbers are eliminated and numbers are entered only through operations of the pointing device. To enter numbers, a number list and a pointer are displayed in the peripheral section of the display screen  3  and it is possible to enter a number by moving the pointer to the number to be entered using the pointing device  4  and performing an ENTER operation. With such a portable information terminal  1 , it is also possible to place the pointing device  4  at an appropriate position. 
   Thus, the pointing device  4  can be placed in any location of the portable information terminal  1  taking into account the ease of operation, etc. For example, in the layout examples shown in  FIG. 13B  and  FIG. 13C , most areas of the back  1   a  and side  1   b  of the portable information terminal  1  are not used and placing the pointing device  4  in easy-to-use locations makes it possible to effectively use the surface of the portable information terminal  1 , reduce the size of the operation panel and implement a further reduction in size of the portable information terminal  1 . 
     FIG. 14  illustrates layout examples of the pointing device  4  of another embodiment of the portable information terminal  1 . 
     FIG. 14A  to  FIG. 14C  relate to a folding portable information terminal  1  in which a case  1   d  provided with the display screen  3  is connected with a case  1   e  having the operation panel  2  in a pivotable manner by a hinge  1   c  and when the portable information terminal is not used, overlapping the case  1   d  over the case  1   e  makes it possible to prevent the display screen  3  and operation panel  2  from exposing to the outside. 
   In the portable information terminal  1  in such a configuration, the specific example in  FIG. 14A  shows the pointing device  4  placed on the operation panel  2  and the specific example in  FIG. 14B  shows the pointing device  4  placed on a hinge  1   c . In both specific examples, by placing the pointing device  4  on the operation panel  2 , it is possible to protect the pointing device  4  when the portable information terminal  1  is not used. 
   Moreover, the specific example in  FIG. 14C  shows a case where the case  1   d  is provided with a notch section  1   f  facing the case  1   e  so that part of the case  1   e  is exposed to the outside through this notch section  1   f  also when the terminal is folded and the pointing device  4  is placed in that exposed section. In such a specific example, when the terminal is folded, it is possible to change the function of the pointing device  4  to a function different from the original function (that is, the function of moving the pointer on the display screen  3 , that is, pointer operation function) and use the pointing device  4  even when the portable information terminal  1  is folded. Such a function can be a function of display of arrival, etc. allowing the light emitting device  4   b  of the pointing device  4  ( FIG. 2 ) to emit light when there is an incoming call while the terminal is folded. 
   The specific example shown in  FIG. 14D  shows a case where a flip (open/close cover)  1   g  is provided on the operation panel  2  and the specific example shown in  FIG. 14E  shows a case where a slide cover  1   h  is provided on the operation panel  2 . In these specific examples, it is also possible to protect the pointing device  4  when the portable information terminal  1  is not used by placing the pointing device  4  on the operation panel  2 . 
   By the way, in the specific examples in  FIG. 14 , the pointing device  4  performs the operation shown in  FIG. 12  and when the terminal is folded in the specific examples in  FIG. 14A  to  FIG. 14C , or when the covers  1   g  and  1   h  are closed in the specific examples in  FIG. 14D  and  FIG. 14E , it is determined in step  110  that the portable information terminal  1  has finished the operation and the pointing device  4  is set in a halt state. Furthermore, when the terminal is unfolded in the specific examples in  FIG. 14A  to  FIG. 14C , or when the covers  1   g  and  1   h  are opened in the specific examples in  FIG. 14D  and  FIG. 14E , the pointing device  4  starts to operate in the standby mode in step  100 . In this case, it goes without saying that a sensor (not shown) to detect the folding state or the open/closed state of the covers  1   g  and  1   h  is provided in each portable information terminal  1  shown in  FIG. 14 . 
   As shown above, the pointing device  4  is placed at an appropriate location of the portable information terminal  1 , and it goes without saying that the location is the one which allows the user to easily operate the portable information terminal  1  by the thumb or forefinger when the user holds the portable information terminal  1  by hand. Of course, it is also possible to design so that the pointing device  4  is operated with the finger of the hand different from the hand that holds the portable information terminal  1 , but it goes without saying that it is more convenient to operate the pointing device  4  with the finger of the hand that holds the portable information terminal  1 . 
     FIG. 15  is a block diagram showing a circuit configuration of another embodiment of the portable information terminal. Reference numeral  35  denotes an open/close detector;  36 , a contact sensor;  37 , an operation lock switch;  38 , a receiver section proximity sensor, and the same parts as those in  FIG. 2  will be assigned the same reference numerals and overlapping explanations thereof will be omitted. 
   This embodiment in  FIG. 15  is the circuit configuration shown in  FIG. 2  with all or at least one of the open/close detector  35 , contact sensor  36 , operation lock switch  37  and receiver section proximity sensor  38 . 
   The open/close detector  35  is provided for the portable information terminal  1  of a folded type or with the cover as shown in  FIG. 15 . In the case of the folded type portable information terminal  1  as shown in  FIG. 16A , the open/close detector  35  is placed on either the surface of the case  1   d  or  1   e  (here, the side next to the display screen  3  of the case  1   d ). This open/close detector  35  can be a push-type switch or optical sensor. When the cases  1   d  and  1   e  overlap with each other in a folded state, the open/close detector  35  detects this and supplies this detection output to the controller  31 . The controller  31  determines whether the portable information terminal  1  is opened or not in the case of the folded type portable information terminal  1  and whether the cover is opened or closed in the case of the portable information terminal  1  with a cover. 
   The contact sensor  36  is placed on the side  1   b  of the portable information terminal  1  to detect whether the palm of the hand of the user touches or not, as shown in  FIG. 16B . This detected output is supplied to the controller  31  and the controller  31  determines from this detected output whether the portable information terminal  1  is held by the hand of the user or not. This contact sensor  36  can be placed on one side  1   b  of the portable information terminal  1  or can also be placed on both sides of the portable information terminal  1 . 
   In order to distinguish the case where the user holds the portable information terminal  1  by hand to operate the terminal from other cases (for example, when the portable information terminal  1  is put in a briefcase in contact with objects around), it is preferable to have the contact sensor  36  of an electrostatic capacitive type capable of distinguishing the human hand from other objects when the sensor is placed on one side  1   b  or a type of contact sensor  36  using the electrical resistance value of the human hand as a detection reference when the sensor is placed on both sides. 
   The operation lock switch  37  is provided on one side  1   b  of the portable information terminal  1  as shown in  FIG. 16C  and operating the operation lock switch  37  locks the operation switches on the operation panel  2  and pointing device  4  preventing them from operating. 
   The receiver section proximity sensor  38  is placed close to the location of the sound receiver  30  such as a speaker of the portable information terminal  1  as shown in  FIG. 16D  to detect any object that approaches this (for example, within a range of 1 cm) and send the detected output to the controller  31 . The controller  31  determines from this detected output that the ear of the user approaches the sound receiver  30  and determines that a call is being received. 
     FIG. 17  is a flow chart showing the control operation of the controller  31  in response to detected outputs from the open/close detector  35 , contact sensor  36 , operation lock switch  37  and receiver section proximity sensor  38 . Here, this flow chart will be explained assuming that the portable information terminal  1  is provided with all or some of these open/close detector  35 , contact sensor  36 , operation lock switch  37  and receiver section proximity sensor  38 . 
   In  FIG. 17 , in the case of portable information terminal  1  as shown in  FIG. 16C , if the operation lock switch  37  is ON (step  201 ), the operation switches on the operation panel  2  are locked so that they cannot be operated, and at this time the controller  31  sets the pointing device  4  in a halt state (that is, the light emitting device  4   b  and image pick-up element  4   c  in  FIG. 2  are not operating. Step  200 ). Furthermore, in the case of the folded type portable information terminal  1  as shown in  FIG. 16A , if the cases  1   d  and  1   e  overlap with each other in a folded state, the open/close detector  35  is in an open state (step  202 ) and the controller  31  also sets the pointing device  4  in a halt state (step  200 ). Furthermore, in the case of the portable information terminal  1  with a receiver section proximity sensor  38  as shown in  FIG. 16D , during a conversation, this receiver section proximity sensor  38  supplies a detected output indicating that the user&#39;s ear is close to the sound receiver  30  and a conversation is in progress to the controller  31  (step  203 ) and the controller  31  sets the pointing device  4  in a halt state (step  200 ). Furthermore, in the case of the portable information terminal  1  with the contact sensor  36  as shown in  FIG. 16B , while this contact sensor  36  senses no contacting object (step  204 ), the controller  31  determines from the detected output from this contact sensor  36  that the portable information terminal  1  is not held by the hand of the user and is not used and sets the pointing device  4  in a halt state (step  200 ). 
   In this way, when it is detected in steps  201 ,  202  and  204  that the portable information terminal  1  is not used, the pointing device  4  is set in a halt state and in this way even if the user touches the fingerplate  4   a  ( FIG. 2 ) of the pointing device  4  unintentionally, or when the portable information terminal is put in a briefcase or handbag and other objects touch the fingerplate  4   a  ( FIG. 2 ) of the pointing device  4 , the pointing device  4  does not operate, thus making it possible to prevent misoperation of the pointing device  4 . This also makes it possible to suppress power consumption of the pointing device  4  and realize power saving. 
   While the open/close detector  35  is used for a folded type portable information terminal or a portable information terminal  1  provided with a cover as shown in  FIG. 14 , while the contact sensor  36 , operation lock switch  37  or receiver section proximity sensor  38  can be used for any one of the types of portable information terminal  1  shown in  FIG. 13  and  FIG. 14 . Therefore, the portable information terminal  1  can have any one of the open/close detector  35 , contact sensor  36  and operation lock switch  37  in combination with the receiver section proximity sensor  38  and in this case, the detection operation in any one of steps  201 ,  202  and  204  in combination with step  203  is carried out as the operation shown in  FIG. 17 . 
   In the case where the detection result in any one of steps  201 ,  202  and  204  shows that the portable information terminal  1  is ready to be used by the user and at the same time the receiver section proximity sensor  38  detects no approaching object, the operation from step  100  on shown in  FIG. 12  is carried out. In the case of “Yes” in steps  106  and  109  in  FIG. 12 , the process goes back to step  201  in  FIG. 17  (this  FIG. 17  includes the flow chart shown in  FIG. 12 , but does not include step  110  in  FIG. 12 ). 
     FIG. 18  illustrates other specific examples of the misoperation preventing means of the pointing device  4 . Reference numeral  39  denotes a crown and the same parts as those in the aforementioned figures will be assigned the same reference numerals and overlapping explanations thereof will be omitted. 
     FIG. 18A  shows a folded type portable information terminal  1  and the pointing device  4  is placed on the hinge  1   c  that connects the cases  1   d  and  1   e . This hinge  1   c  can be made pivotable and when the pointing device  4  is operated, the entire pointing device  4  is exposed so that it can be operated as shown in the figure at left and when the pointing device  4  is not used, at least part of the pointing device  4  is hidden as shown in the figure at right. 
   Of course, the folded type portable information terminal  1  is intended to prevent misoperation of the pointing device  4  by folding the portable information terminal, which is applicable when the portable information terminal  1  is not used. When the portable information terminal  1  is in use, the specific example in  FIG. 18A  is intended to also prevent misoperation of the pointing device  4  even when the cases  1   d  and  1   e  are completely exposed. 
     FIG. 18B  shows a case of the portable information terminal  1  with the display screen  3  and operation panel  2  exposed all the time. In this case, one end of a rotation axis (not shown) inside the case sticks out of the side  1   b  of the outer case  8  (see  FIG. 2 ) and the crown  39  is attached to it and the pointing device  4  is attached to the other end of this rotation axis within the case. When the pointing device  4  is used, the crown  39  is operated as shown in the figure at left to allow the fingerplate  4   a  to be operated by touching it with the fingertip from the through hole  8   a  provided on the outer case  8  as shown in  FIG. 2  and when the pointing device  4  is not used, the fingerplate  4   a  is hidden as shown in the figure at right of  FIG. 18B  by turning the crown  39  to rotate the pointing device  4 . 
   This makes it possible to prevent misoperation of the pointing device  4  while not in use. 
   Of course, the means shown in  FIG. 18B  is also applicable to the portable information terminal  1  with a structure shown in  FIGS. 14A and 14C  to  14 E. Of course, in the specific examples shown in  FIGS. 14A ,  14 D and  14 E, misoperation of the pointing device  4  is prevented by closing the cases  1   d  and  1   e  and closing the covers  1   g  and  1   h . This is the case where the portable information terminal  1  is not in use and when the portable information terminal  1  is in use, the cases  1   d  and  1   e  are open or covers  1   g  and  1   h  are open and the specific example in  FIG. 18B  makes it possible to prevent misoperation of the pointing device  4  even in such a case. 
     FIG. 19  shows a further specific example of the misoperation preventing means of the pointing device  4 .  FIG. 19A  shows an overall view of the portable information terminal  1 , while  FIG. 19B  and  FIG. 19C  show sectional views of the fingerplate  4   a  of the pointing device  4  viewed from the split line of  FIG. 19A , respectively and the same parts as those in the aforementioned figures will be assigned the same reference numerals and overlapping explanations thereof will be omitted. 
   The specific example shown in  FIG. 19B  shows the fingerplate  4   a  of the pointing device  4  having a concave outer surface whose depth is largest in the center. This pointing device  4  has the same configuration as that in  FIG. 2  except the fingerplate  4   a  and the condensing lens  4   d  is placed so that the image close to the central part on the concave outer surface of the fingerplate  4   a  converges onto the image pick-up surface of the image pick-up element  4   c . Then, when the fingerplate  4   a  in the configuration shown in this  FIG. 19B  is used, if, for example, the portable information terminal  1  is put in a briefcase, even if other objects touch the operation panel  2  of the portable information terminal  1  and move on the pointing device  4 , since the surface of these objects is separate from the central section of the outer surface of the fingerplate  4   a , this surface image on the image pick-up plane of the image pick-up element  4   c  is out of focus and the controller  31  ( FIG. 15 ) cannot detect this surface image (that is, a pattern). For this reason, even if this object moves with respect to the pointing device  4 , the controller  31  cannot detect this, cannot move on to step  107  in  FIG. 12  after the operation of  FIG. 17  or prevent misoperation of the pointing device  4 . 
   The specific example shown in  FIG. 19C  shows the fingerplate  4   a  of the pointing device  4  having a flat outer surface with protrusion  8   b  provided around the through hole  8   a  of the outer case  8  in which this fingerplate  4   a  is fitted. The circumference of the fingerplate  4   a  is placed lower than this protrusion  8   b . In this specific example, the rest of the configuration of the pointing device  4  is the same as the configuration in  FIG. 2  and the condensing lens  4   d  is placed so that the image on the outer surface of the fingerplate  4   a  converges onto the image pick-up plane of the image pick-up element  4   c.    
   According to such a configuration, as in the case of the specific example shown in  FIG. 19B , when the portable information terminal  1  is put in a briefcase and even if another object touches the operation panel  2  of the portable information terminal  1  and moves on the pointing device  4 , the pointing device  4  does not operate erroneously. 
   Then, an operation example of the embodiment of the portable information terminal  1  described above will be explained. 
     FIG. 20  is a flow chart showing an operation procedure when a telephone call is made. When a telephone call is made to a person whose telephone number is registered, operating almost only the pointing device  4  can perform this operation.  FIG. 20  shows this case. 
     FIG. 21  shows screens displayed on the display screen  3  according to this operation. Reference numeral  40  is a pointer (cursor). 
   In  FIG. 1 ,  FIG. 20  and  FIG. 21 , when power is turned ON by operating the “Power/stop call” button  2   d , the initial screen appears on the display screen  3  as shown in  FIG. 21A . In this state, operating the “Menu” button  2   c  (step  300 ) shows the menu screen shown in  FIG. 21B  on the display screen  3 . On this menu screen, it is possible to select a menu (selection item) such as “Telephone directory”, “Mail”, “Map service”, “Shopping”, and so on. A frame-shaped pointer  40  is also displayed on this screen. This pointer  40  can be moved by touching the aforementioned fingerplate  4   a  of the pointing device  4  with the fingertip and moving the fingertip one step at a time (one selection item at a time) in the direction (that is, upward or downward) according to the movement of the fingertip. 
   On this menu screen, if an pointer operation is performed in such a way that the pointer  40  is moved to a desired selection item, here, a selection item “Telephone directory” (step  301 ) and the fingerplate  4   a  of the pointing device  4  is pushed in with the fingertip to perform an ENTER operation (step  302 ), then the telephone directory screen shown in  FIG. 21C  is displayed on the display screen  3 . This telephone directory screen displays the names of people whose telephone numbers are registered and the pointer  40  to select one of them. Then, by performing a pointer operation using the fingerplate  4   a  of the pointing device  4  (step  303 ), the pointer  40  is moved on the telephone directory screen to indicate the person to whom a telephone call is made. Here, if the name of the person in question does not appear, the pointer  40  is moved to the end of the telephone directory screen as shown in  FIG. 21D , and if the pointer operation is continued in the same direction, this telephone directory screen scrolls (step  304 ) and the name of the desired person can be displayed. The telephone directory screen shown in  FIG. 21E  shows this state and this makes it possible to point the pointer  40  to the desired person (here, “Kinoshita XX”) (step  305 ). Then, if the ENTER operation above is performed on the pointing device  4  with the pointer  40  placed on the desired person (step  306 ), the telephone directory screen changes to the telephone number screen as shown in  FIG. 21F  showing the telephone number of the selected person, selection item “Make a call”, “Edit telephone directory”. When a telephone call is made to this person, pointing the pointer  40  to “Make a call” and performing the ENTER operation above using the pointing device  4  (step  307 ) shows a call screen as shown in  FIG. 21G  to make a call to the other party (step  308 ). 
   This call screen also displays an item “Stop call” as shown in  FIG. 21G  and the pointer  40  points to this item. For example, when the other party does not come on the line and the user wants to stop the call, the user may perform the ENTER operation above using the pointing device  4  while the call screen is displayed, then the call is stopped and the initial screen in  FIG. 21A  is displayed again. 
   When a call is made while the call screen shown in  FIG. 21G  is displayed (step  308 ) and then the other party answers the phone, a conversation starts and the name and telephone number of the other party are displayed on the display screen  3  at that time. When the conversation with the other party ends and the “Power/stop call” button  2   a  is operated, the initial screen in  FIG. 21A  is displayed again. 
   Thus, by operating the pointing device  4 , it is possible to call the other end of communication. 
   When a call is made to a person whose telephone number is not registered, the “Power/stop call” button  2   a  is operated to display the telephone number input screen as in the case of the conventional art, the telephone number is entered in this input screen by operating the ten-key pad, and then the “Start call” button  2   b  is pressed, which starts a call to the other party. 
   Furthermore, operating the “Power/stop call” button  2   a  in any step of  FIG. 20  can return to the initial screen in  FIG. 21A  and operating the “Return” button  2   d  on the display screen  3  in any step of  FIG. 20  can return to the previously displayed screen. 
     FIG. 22  is a flow chart showing another operation example in the above embodiment of the portable information terminal according to the present invention, that is, the operation procedure for receiving a map service.  FIG. 23  illustrates screens displayed on the display screen  3  according to this operation. Reference numeral  41  denotes a map;  42 , a pointer (cursor);  43 , scroll icons. 
   In  FIG. 1 ,  FIG. 22  and  FIG. 23 , step  400  is the same as step  300  in  FIG. 20  and operating the “Menu” button  2   c  while the initial screen in  FIG. 23A  is displayed on the display screen  3  displays the same menu screen as that shown in  FIG. 21B  on the display screen  3  as shown in  FIG. 23B  (step  400 ). When the pointer is operated on this menu screen and the frame-shaped pointer  40  is pointed to a desired selection item, here a selection item “Map service” shown in  FIG. 23C  and the fingerplate  4   a  of the pointing device  4  is pushed in with the fingertip to perform an ENTER operation (step  401 ), then the geographic name selection screen shown in  FIG. 23D  is displayed on the display screen  3 . 
   Then, through pointer operation, the pointer  40  is pointed to a target geographic name (here “Shibuya”) on this geographic name selection screen and the target geographic name is selected, and the above ENTER operation is performed (step  402 ), then the selected town as shown in  FIG. 23E , that is, the map screen of Shibuya appears. This map screen shows a map  41  of Shibuya selected, an arrow-shaped pointer (cursor)  42  and white triangular scroll icons  43 . A total of 8 scroll icons  43  are displayed; four for 4 corners of the map  41 , four for midpoints of these icons. These scroll icons  43  indicate the scrolling directions of the map  41  and it is possible to select one of them by the pointer  42 . 
   While the map screen shown in  FIG. 23E  is displayed, through pointer operation using the pointing device  4 , the pointer  42  is moved and pointed to the scroll icon  43  indicating a desired scroll direction in the map  41  (step  403 ), the above ENTER operation is carried out on the pointing device  4 , then, the map  41  scrolls in the direction indicated by this scroll icon  43  as shown in  FIG. 23G  (step  404 ). In this case, scrolling continues as long as the fingerplate  4   a  of the pointing device  4  is depressed and when the depressing is finished, the scroll icon  43  selected by the pointer  42  changes to a black triangular shape as shown in  FIGS. 23F and 23G  to define the scroll direction. 
   When the scrolling advances and a desired location appears on the map  41 , for example, a shop whose information the user wants to see appears, the user stops the ENTER operation and stops scrolling and moves the pointer  42  through pointer operation and when the user points this pointer  42  to the desired location as shown in  FIG. 23H  and carries out the above ENTER operation (step  405 ), then the detailed information screen indicating detailed information of the desired location appears on the display screen  3  (step  406 ). 
     FIG. 23I  and  FIG. 23J  show an example of the detailed information screen schematically. Detailed information of the shop selected in  FIG. 23H  with the information of interest, for example, the name of the shop (Italian restaurant), service time (10:00 to 20:00), regular holidays (Tuesday), telephone number (03-1111-XXXX) is displayed. 
   Furthermore, this detailed information screen shows two selection items “Make a call” and “Return to map display” and the frame-shaped pointer  40  and by moving the pointer  40  through pointer operation of the pointing device  4 , it is possible to select either one of the selection items (step  407 ). Then, to make a call to this shop according to the detailed information on this detailed information screen, the user selects the selection item “Make a call” using the pointer  40  and performs the above ENTER operation using the pointing device  4  and thereby a call is automatically made to this telephone (step  408 ) and when the stop calls and the user operates the “Power/stop call” button  2   a , the screen returns to the map screen in  FIG. 23H  or  FIG. 23E . Furthermore, even if the user does not want to make a call to this shop after seeing the detailed information on this detailed information screen, by selecting the selection item “Return to map display” as shown in  FIG. 23J  using the pointer  40  and performing the above ENTER operation using the pointing device  4 , it is possible to return to the map screen shown in  FIG. 23H  or  FIG. 23E . From this display screen, it is possible to carry out operations starting from step  405  to step  403  and re-specify a desired location. If the user wants to stop the map service (step  409 ), it is possible to return from the map screen to the geographic name selection screen shown in  FIG. 23D  or the menu screen shown in  FIGS. 23B and 23D  or the initial screen shown in  FIG. 23A  by operating the “Return” button  2   d.    
   By the way, by operating the “Power/stop call” button  2   a  in the display condition of each step except the case where the line is busy in step  408 , it is possible to directly display the initial screen in  FIG. 23A . When the line is busy in step  408 , by operating the “Power/stop call” button  2   a , the call finishes and the above-described map screen is displayed but by operating the “Power/stop call” button  2   a  again, the initial screen in  FIG. 23A  is displayed directly. 
   In such a “Map service”, through the control of the controller  31  ( FIG. 10 ,  FIG. 15 ), the arrow-shaped pointer  42  displayed on the map  41  moves continuously according to the pointer operation of the pointing device  4 . This makes it possible to specify precisely the desired location on the map  41 . Furthermore, on the screen on which selection items are shown, the frame-shaped pointer  40  is displayed, but this pointer  40  moves step by step under the control of the controller  31 . This makes it possible to select a desired selection item smoothly without the need for fine positional adjustment of the pointer  40 . In this way, while using the same pointer operation method using the pointing device  4 , the present invention can automatically change the mode of moving the pointer according to the type of the screen displayed and allow the pointer to move in a manner that fits each screen. 
     FIG. 24  shows sectional views showing further embodiments of the pointing device  4  used for the above-described embodiments of the portable information terminal according to the present invention. Reference numerals  4   d   1 ,  4   d   2  and  4   d   3  denote condensing lenses;  4   g , a lens replacement mechanism;  4   h , a lens zooming mechanism, and the same parts as those in the aforementioned figures are assigned the same reference numerals and overlapping explanations will be omitted. 
   Since each embodiment above of the portable information terminal  1  is provided with an image pick-up element  4   c , this embodiment also provides this image pick-up element  4   c  with the function of a digital camera or video camera. 
   The embodiment shown in  FIG. 24A  is intended to allow the lens replacement mechanism  4   g  to switch between the condensing lenses  4   d   1  and  4   d   2  and the condensing lens  4   d   1  is a lens for pointer operation with a short focal distance and the condensing lens  4   d   2  is a lens for picture taking such as landscapes with a long focal distance. The lens replacement mechanism  4   g  consists of a slide plate or rotation plate and the condensing lenses  4   d   1  and  4   d   2  are mounted on this slide plate or rotation plate. Furthermore, the lens replacement mechanism  4   g  is also provided with an operation section to operate the lens replacement mechanism  4   g  associated with the operation is panel  2  or the side  1   b  of the main unit shown in  FIG. 1 , etc. 
     FIG. 24A  (a) shows a status of pointer operation in which the condensing lens  4   d   1  with a short focal distance is placed between the fingerplate  4   a  and image pick-up element  4   c . When the portable information terminal  1  is used as a video camera, the lens replacement mechanism  4   g  is slid or rotated so that the condensing lens  4   d   2  with a long focal distance is placed between the fingerplate  4   a  and image pick-up element  4   c  as shown in  FIG. 24A  (b). 
   The embodiment shown in  FIG. 24B  is a case where the condensing lens  4   d   3  with a variable focal distance is used. This condensing lens  4   d   3  is a lens that can expand/contract in the direction perpendicular to the optical axis and the lens zooming mechanism  4   h  can change the thickness of the condensing lens  4   d   3  by applying uniform forces in the radial direction at a plurality of points evenly spaced on the circumference of the lens simultaneously or releasing the forces and thereby change the focal distance of the condensing lens  4   d   3 . This changes the focal distance of the condensing lens  4   d   3 . For such a lens zooming mechanism  4   h , for example, an aperture mechanism used for a camera can be used. 
     FIG. 24B  (a) shows a status of pointer operation in which the condensing lens  4   d   3  is thick and has a sufficiently short focal distance. When the portable information terminal  1  is used as a video camera, the lens zooming mechanism  4   h  functions so that the condensing lens  4   d   3  becomes a lens with a long focal distance as shown in  FIG. 24B  (b). 
   The same applies to a case where the portable information terminal  1  is used as a digital camera. 
   By the way, in such an embodiment having also the function as a digital camera or video camera, the display panel  2  of the portable information terminal  1  is provided with a video camera operation button, recording or replay button (for a replay operation, the pointing device  4  can also be provided with the function as shown in  FIG. 8D ) and when the portable information terminal  1  is used as a video camera, in  FIG. 10  and  FIG. 15 , the controller  31  instructs a processing circuit (not shown) to process the output signal of this image pick-up element  4   c  as appropriate, record the output signal in an external recording medium (not shown) such as the storage device  32  or a floppy disk, perform a replay operation and thereby display the reproduced image on the display screen  3 . 
   Furthermore, in order to make the portable information terminal  1  function as a digital camera or video camera as shown above, an image pick-up element normally used for a digital camera or video camera is used as the image pick-up element  4   c . When the pointing device  4  is used for pointer operations using this image pick-up element  4   c  as in the case of the embodiment above, part of the picture taking plane of the image pick-up element  4   c  is used as a scanning target and images are detected with high sensing frequency as shown above. Furthermore, when the portable information terminal  1  is used as a digital camera or video camera as shown above, the entire picture taking plane of the image pick-up element  4   c  is used as the scanning target. The scanning area used for such a picture taking plane can be changed by, for example, changing the cycle and amplitude of the scan signal used for the image pick-up element  4   c.    
   As described above, the pointing device and the portable information terminal using the same according to the present invention can move the pointer displayed on the display screen according to the movement of images on the outer surface of the plate detected by the image detecting means, and therefore when the user touches the plate with the fingertip and moves the fingertip, the fingerprint of this fingertip is detected as a moving image and the pointer moves on the display screen in the direction according to the direction of this movement. Therefore, it is not necessary to operate different operation switches according to the direction in which the pointer moves, which makes operations easier. Moreover, since it is only necessary to detect the movement of the image on the plate, it is possible to narrow the range of image detection and reduce the size of the pointing device. 
   The portable information terminal according to the present invention determines the presence or absence of movement of an image on the outer surface of the plate detected by the image detecting means and switches the sensing frequency of the image detecting means according to the determination result, and therefore when there is no movement of the image on the outer surface of the plate and the pointer is not moved, it is possible to reduce the sensing frequency of the image detecting means and suppress power consumption of this image detecting means accordingly. 
   Furthermore, the pointing device and portable information terminal using the same according to the present invention is further provided with light emitting means for irradiating the outer surface of the plate with illumination light, first means for measuring a reflection factor of the plate on the outer surface from the quantity of light received of the image detecting means and the quantity of light received of the light emitting means, second means for designating the quantity of light emitted of the light emitting means as a first predetermined reference value when the reflection factor measured by the first means falls below a predetermined minimum reference value and adjusting the quantity of light emitted of the light emitting means when the reflection factor measured by the first means exceeds the minimum reference value so that the quantity of light received by the image detecting means becomes a predetermined second reference value which is larger than the first reference value, third means for detecting the movement of the image detected by the image detecting means and moving the pointer in the direction according to the direction of the detected movement and fourth means for determining the presence/absence of movement of the image detected by the image detecting means, setting the pointing device in an action mode when the movement is detected, moving the pointer in the direction according to the direction of the movement and setting the pointing device in a standby mode when no movement is detected for a predetermined period of time, wherein the sensing frequency of the pointing device in the standby mode is smaller than the sensing frequency of the pointing device in the action mode and the second means changes temporarily the quantity of light emitted of the light emitting means when the reflection factor measured by the first means falls below a predetermined minimum reference value and designates the quantity of light emitted of the light emitting means as the predetermined first reference value when the quantity of light received of the image detecting means does not change as the quantity of light emitted changes, and since the light emitting means illuminates the image on the outer surface of the plate, the image detecting means can detect an image of high brightness and when no pointer movement operation is carried out without touching the outer surface of the plate with the fingertip, etc., this can be detected, which can suppress the quantity of light emission by the light emitting means in the standby mode, thus realizing power saving. Moreover, whether the fingertip, etc. is touching the outer surface of the plate or not is judged from the reflection factor of the image on the outer surface of the plate and a variation of the quantity of light received of the image detecting means is detected by temporarily changing the quantity of light emitted of the light emitting means, and therefore whether the fingertip, etc. is touching the outer surface of the plate or not can be judged more accurately. 
   Furthermore, the portable information terminal according to the present invention allows the pointing device to push in the plate and is provided with at least one operation switch that operates in accordance with this pushing operation and one of these operation switches is designated as an “ENTER” switch to determine the menu on the display screen which is pointed by the pointer. This allows the pointing device to have multi-functions, makes it possible to reduce the number of operation switches on the operation panel of the portable information terminal, further reduce the size of the portable information terminal, and add new operation switches, thus further enhancing the multi-functions of the portable information terminal. The operator can perform a series of selection/determination operations without casting the eyes aside from the pointing device (or without moving a large distance). 
   Furthermore, the portable information terminal according to the present invention is configured so that the optical means of the pointing device can change the focal distance of the condensing lens allowing the optical means to also have the functions as a digital camera or a video camera.