Patent Publication Number: US-2005140652-A1

Title: Track ball

Description:
TECHNICAL FIELD  
      The present invention relates to a track ball and, more particularly, to a track ball capable of preventing foreign matters such as water and dust from intruding into a case containing a sensor board.  
     BACKGROUND ART  
      A track ball, which is a pointing device for a computer and other various types of digital equipment, is configured so that by rotating a ball in an arbitrary direction with a palm or fingers, rotation is detected smoothly and continuously, and hence precise position control can be carried out easily.  
       FIG. 3  is an explanatory view showing a side sectional construction of a conventional track ball. In  FIG. 3 , the conventional track ball has: a ball support structure  37  having a rotating shaft  3  which supports a ball and transmits the rotation of the ball and a rotating element  34  for causing a rotation sensor  35 , described later, to read the rotation of the rotating shaft  3 ; the rotation sensor  35  which generates a pulse signal by detecting the rotation of the rotating element  34  in the ball support structure  37  and transmits the pulse signal to a sensor board  6 , described later; the sensor board  6  for arithmetically operating the transmitted pulse signal to detect the rotational displacement; a case  32  which is a housing structure for the track ball and protectively contains the sensor board  6  therein; and the ball (not shown), which is an input operation part. By this configuration, the rotation of ball produced by the operation of a palm or the like is transmitted to the rotating shaft  3  and is changed to the rotation of the rotating element  34 . The rotation of the rotating element  34  is changed to a pulse signal by the rotation sensor  35 , which can be detected as rotational displacement including direction after being subjected to processing by the sensor board  6 .  
      In  FIG. 3 , the rotating element  34  of a disc shape formed with a slit is provided at the end of the rotating shaft  3  for transmitting the rotation of ball so that a part of the rotating element  34  enters a case interior space SI in the case  32  containing the sensor board  6  from a ball-side space SB through a notch  8  provided in the case  32 .  
      The rotation sensor  35 , which is a transmission photosensor, has paired portions serving as a light emitting portion and a light receiving portion provided with the rotating element  34  being held therebetween, and the rotating element  34  is provided so as to be positioned between the paired portions. By this configuration, the ball-side space SB and the case interior space SI existing with the case  32  being a boundary therebetween are configured so as to communicate with each other through the notch  8  provided in the case  32 .  
      A problem with the conventional track ball is that the presence of notch allows water, dust, dirt, and the like to intrude into the case from the ball-side space continuous with the environment on the outside of the track ball through the notch (X 3  in  FIG. 3 ), and these foreign matters adhere to the sensor board, and exert an adverse influence on the performance and normal operation of the sensor board, which results in a decrease in detection accuracy of track ball.  
      The present invention has been made to solve the problem with the prior art, and an object thereof is to provide a track ball capable of preventing foreign matters such as water and dust from intruding into the case containing the sensor board.  
     DISCLOSURE OF THE INVENTION  
      The inventor conducted studies earnestly on the above-described problems, and resultantly concluded that the isolation of the case interior space from the ball-side space is effective in preventing the intrusion of foreign matters, and therefore, the above-described problems can be solved by taking measures capable of detecting the rotation expressed in the rotating element even in such a construction. The invention claimed in this application as measures for solving the above-described problems is as follows:  
      (1) A track ball having a ball; a ball support structure having a rotating shaft which supports the ball and transmits the rotation of the ball and a rotating element which is provided at the end of the rotating shaft to cause a rotation sensor, described later, to read the rotation of the ball; the rotation sensor which generates a pulse signal by detecting the rotation of the rotating element that expresses the rotation of the rotating shaft and transmits the pulse signal to a sensor board, described later; the sensor board for arithmetically operating the transmitted pulse signal to detect the rotational displacement; and a case which is a housing structure for the track ball and protectively contains the sensor board therein, characterizedinthattherotatingelementandtherotationsensorareprovided so as to be isolated from each other, and of the case, at least a portion, which forms a part of an electromagnetic wave transmission path for the rotation sensor to detect an electromagnetic wave to be detected, has a construction capable of transmitting an electromagnetic wave that can be detected by the rotation sensor.  
      (2) The track ball described in item (1), characterized in that the whole of the case has a construction capable of transmitting the electromagnetic wave.  
      (3) The track ball described in item (1) or (2), characterized in that the case has no notch for the rotation sensor to detect the rotation of the rotating element.  
      (4) The track ball described in any one of items (1) to (3), characterized in that the electromagnetic wave is visible rays, and the construction of the case for transmitting the electromagnetic wave is a transparent or semitransparent visible ray transmitting construction.  
      (5) The track ball described in any one of items (1) to (3), characterized in that the electromagnetic wave is infrared rays, and the construction of the case for transmitting the electromagnetic wave is an infrared ray transmitting construction.  
      (6) The track ball described in item (4) or (5), characterized in that the rotating element has a disc shape, the rotation sensor is a transmission photosensor, and the side sectional shape of the case in a portion in which the case is opposed to the peripheral edge portion of the rotating element (hereinafter referred to as “element portion”) is substantially in a U shape having a U-shaped portion.  
      (7) The track ball described in item (4) or (5), characterized in that the rotating element has a drum shape, and the rotation sensor is a reflective photosensor.  
      (8) A dustproof and waterproof track ball characterized in that foreign matters are prevented from intruding into the interior of the case containing the rotation sensor by the track ball described in any one of items (1) to (7).  
      In the present invention, as a material for the case of track ball, there is used a material capable of transmitting an electromagnetic wave, which is an object to be detected by the rotation sensor, such as a transparent or semitransparent visible ray transmitting material or an infrared ray transmitting material. Therefore, there is no need for providing a notch, the rotation sensor and the sensor board are provided so as to be isolated completely from the support structure for supporting the ball, and foreign matters such as water, dust, and dirt are prevented from intruding to the sensor board side, by which the durability and reliability of track ball are improved, and the above-described problems are solved. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an explanatory view showing a side sectional construction of a track ball in accordance with the present invention;  
       FIG. 2  is an explanatory view showing a side sectional construction of another example of a track ball in accordance with the present invention; and  
       FIG. 3  is an explanatory view showing a side sectional construction of a conventional track ball. 
    
    
      Symbols used in these figures designate the followings.  2 ,  22 ,  32  . . . case,  2 A,  2 B,  22 C . . . case portion,  3  . . . rotating shaft,  4 ,  24 ,  34  . . . rotating element,  5 ,  25 ,  35  . . . rotation sensor,  5 A,  5 B . . . rotation sensor portion,  6  . . . sensor board,  7 ,  27 ,  37  . . . ball support structure,  8  . . . notch, E . . . light emitting portion, L, L′ . . . path of visible light etc., R . . . light receiving portion, SB . . . ball-side space, SI . . . case interior space, X 1 , X 2 , X 3  . . . movement flow of foreign matters.  
     BEST MODE FOR CARRYING OUT THE INVENTION  
      The present invention will now be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiment described below. In the figures, the same symbols are applied to the same elements to give explanation.  
       FIG. 1  is an explanatory view showing a side sectional construction of a rotating element and its surrounding portion of one example of a track ball in accordance with the present invention.  FIG. 1  shows an example in a case where a transmission photosensor is used as a rotation sensor  5 . In  FIG. 1 , the track ball in accordance with the present invention has a ball support structure  7  having a rotating shaft  3  which supports a ball (not shown), being an input operation part, and transmits the rotation of the ball and a rotating element  4  which is provided at the end of the rotating shaft  3  to cause the rotation sensor  5 , described later, to read the rotation of the ball; the rotation sensor  5  which generates a pulse signal by detecting the rotation of the rotating element  4  that expresses the rotation of the rotating shaft  3  and transmits the pulse signal to a sensor board  6 , described later; the sensor board  6  for arithmetically operating the transmitted pulse signal to detect the rotational displacement; and a case  2  which is a housing structure for the track ball and protectively contains the sensor board  6  therein. The rotating element  4  and the rotation sensor  5  are provided so as to be isolated from each other by the case  2  so that foreign matters such as water and dust can be prevented from intruding into a case interior space SI containing the sensor board  6  etc. from a ball-side space SB, which is a space continuous with the environment on the outside of the track ball. Also, of the case  2 , at least case portions  2 A and  2 B (both  2 A and  2 B are closely hatched portions in  FIG. 1 ), each of which isolates the rotating element  4  from the rotation sensor  5  and forms a part of an electromagnetic wave transmission path for the rotation sensor  5  to detect an electromagnetic wave to be detected, has a construction capable of transmitting an electromagnetic wave that can be detected by the rotation sensor  5 .  
      Herein, the electromagnetic wave transmission path is a path through which an electromagnetic wave such as visible rays or infrared rays travels.  
      In  FIG. 1 , this track ball can be configured so that the whole of the case  2 , not limited to the case portions  2 A and  2 B, can have a construction capable of transmitting the electromagnetic wave. Also, unlike the conventional example, the case  2  need not be provided with a notch (refer to  FIG. 3 ) for the rotation sensor  5  to detect the rotation of the rotating element  4 .  
      In  FIG. 1 , the track ball has a construction such that the rotating element  4  has a disc shape formed with a slit, the rotation sensor  5  is a transmission photosensor, and the side sectional shape of the case  2  in a portion in which the case  2  is opposed to the peripheral edge portion of the rotating element  4  (hereinafter referred to as “rotating element portion”) is substantially a U shape having a U-shaped portion.  
      In the track ball shown in  FIG. 1 , the rotation sensor  5 , which is the transmission photosensor, has portions  5 A and  5 B provided with a light emitting portion and a light receiving portion that are opposed to each other with the rotating element  4  being held therebetween, and the rotating element  4  is provided so as to be positioned between the portions  5 A and  5 B. The ball-side space SB in which the ball support structure  7  is provided and the case interior space SI in which the rotation sensor  5  and the sensor board  6  are provided are isolated from each other with the case  2  being a boundary. Therefore, the rotating element  4  and the rotation sensor  5  are provided in a state of being isolated from each other by the case  2 , and the rotation sensor  5  and the sensor board  6  are constructed so as not to communicate with the ball-side space SB, that is, so as to be isolated from the space. SB.  
      When visible rays are utilized as the electromagnetic wave, the track ball shown in  FIG. 1  can be constructed so as to transmit the electromagnetic wave by making the case  2  have a transparent or semitransparent visible ray transmitting construction. To obtain such a construction, the whole of the case  2  or at least the case portions  2 A and  2 B can be constructed by using a transparent or semitransparent material.  
      The term “semitransparent” in the present invention includes a large degree of transparency as long as visible rays of a degree enough to keep the function of track ball can be transmitted.  
      When infrared rays are utilized as the electromagnetic wave, the track ball shown in  FIG. 1  can be constructed so as to transmit the electromagnetic wave by making the case  2  have an infrared rays transmitting construction. To obtain such a construction, the whole of the case  2  or at least the case portions  2 A and  2 B can be constructed by using an infrared ray transmitting material. When other electromagnetic waves are utilized, similarly by making the case  2  have a construction capable of transmitting that electromagnetic wave, the same effect can be achieved.  
      In  FIG. 1 , since the track ball in accordance with the present invention has the above-described construction, the rotation of the rotating element  4  of the ball support structure  7  provided in the ball-side space SB is detected through the case portions  2 A and  2 B capable of transmitting an electromagnetic wave that can be detected by the rotation sensor  5 , for example, visible rays or infrared rays, or through the case  2 . Specifically, in  FIG. 1 , when the portion  5 A of the rotation sensor  5 , which is a transmission photosensor, is the light emitting portion and the portion  5 B thereof is the light receiving portion, the electromagnetic wave such as visible rays or infrared rays emitted from the light emitting portion  5 A enters the disc-shaped rotating element  4  existing in the ball-side space SB region through the case portion  2 A of the case  2 , being processed by the slit provided in the disc, and is received and detected as a pulse signal by the light receiving portion  5 B through the case portion  2 B. In  FIG. 1 , for example, on a straight line L, there exists a path (electromagnetic wave transmitting path) through which visible rays etc. go from the light emitting portion  5 A to the light receiving portion  5 B through the case portions  2 A and  2 B.  
      Since the rotating element  4  need not be provided so as to enter the case interior space SI for the rotation sensor  5  to detect the rotation of the rotating element  4 , the case  2 , which is the boundary between both of the spaces SB and SI, need not be provided with a notch for causing these spaces SB and SI to communicate with each other. Specifically, the ball-side space SB in which the ball support structure  7  is provided is isolated from the case interior space SI containing the rotation sensor  5  and the sensor board  6  by the case  2 . Therefore, foreign matters such as water and dust can be prevented from intruding into the case interior space SI from the ball-side space SB continuous with the environment on the outside of the track ball.  
      In other words, even if foreign matters such as water and dust, which are originated from the environment on the outside of the track ball, are present in the ball-side space SB, the foreign matters do not intrude into the case interior space SI, which is isolated from the ball-side space SB by the case  2  (X 1 ). Therefore, the foreign matters are prevented from intruding into the sensor board  6  and the rotation sensor  5 , which are provided in the space SI.  
      The rotation of the rotating element  4  is detected by the rotation sensor  5  provided in the case interior space SI, and a pulse signal is generated by the rotation sensor  5 . The pulse signal is transmitted to and arithmetically operated by the sensor board  6 , by which the rotational displacement of ball is detected.  
       FIG. 2  is an explanatory view showing a side sectional construction of a rotating element and its surrounding portion of another example of a track ball in accordance with the present invention.  FIG. 2  shows an example in a case where a reflective photosensor is used as a rotation sensor. In  FIG. 2 , the track ball in accordance with the present invention has a ball support structure  27  having a rotating shaft  3  which supports a ball (not shown), being an input operation part, and transmits the rotation of the ball and a rotating element  24  which is provided at the end of the rotating shaft  3  to cause a rotation sensor  25 , described later, to read the rotation of the rotating shaft  3 ; the rotation sensor  25  which generates a pulse signal by detecting the rotation of the rotating element  24  that expresses the rotation of the rotating shaft  3  and transmits the pulse signal to a sensor board  6 , described later; the sensor board  6  for arithmetically operating the transmitted pulse signal to detect the rotational displacement; and a case  22  which is a housing structure for the track ball and protectively contains the sensor board  6  therein. The rotating element  24  and the rotation sensor  25  are provided so as to be isolated from each other by the case  22  so that foreign matters such as water and dust can be prevented from intruding into a case interior space SI containing the sensor board  6  etc. from a ball-side space SB that is a space continuous with the environment on the outside of the track ball. Also, of the case  22 , at least a case portion  22 C (a closely hatched portion in  FIG. 2 ), which isolates the rotating element  24  from the rotation sensor  25  and forms a part of an electromagnetic wave transmission path for the rotation sensor  25  to detect an electromagnetic wave to be detected, has a construction capable of transmitting an electromagnetic wave that can be detected by the rotation sensor  25 .  
      In  FIG. 2 , this track ball can be configured so that the whole of the case  22 , not limited to the case portion  22 C, can have a construction capable of transmitting the electromagnetic wave. Also, the case  22  need not be provided with a notch for the rotation sensor  25  to detect the rotation of the rotating element  24 .  
      In  FIG. 2 , the track ball has a construction such that the rotating element  24  has a drum shape, and the rotation sensor  25  is a reflective photosensor.  
      Unlike the track ball using a transmission photosensor as shown in  FIG. 1 , the case  22  need not have a substantially U-shaped side cross section. Specifically, in the track ball using the reflective photosensor as shown in  FIG. 2 , the case  22  needs neither a notch nor a substantially U-shaped portion, which achieves an effect that the number of processes can be decreased, and accordingly the manufacturing cost can be reduced.  
      In the track ball shown in  FIG. 2 , the rotation sensor  25 , which is the reflective photosensor, is provided at a position facing to the rotating element  24  with the case  22  being held therebetween, and has a light emitting portion E for emitting an electromagnetic wave to a reflector provided on the drum-shaped rotating element  24  and a light receiving portion R for receiving an electromagnetic wave reflected by the reflector. The ball-side space SB in which the ball support structure  27  is provided and the case interior space SI in which the rotation sensor  25  and the sensor board  6  are provided are isolated from each other by the case  2  with the case  22  being a boundary. Therefore, the rotating element  24  and the rotation sensor  25  are provided in a state of being isolated from each other by the case  22 , and the rotation sensor  25  and the sensor board  6  are constructed so as not to communicate with the ball-side space SB, that is, so as to be isolated from the space SB.  
      When visible rays are utilized as the electromagnetic wave, the track ball shown in  FIG. 2  can be constructed so that the construction of the case  22  for transmit the electromagnetic wave is made a transparent or semitransparent visible ray transmitting construction. To obtain such a construction, the whole of the case  22  or at least the case portion  22 C can be constructed by using a transparent or semitransparent material. When other electromagnetic waves are utilized, similarly the case  22  can be constructed by using the electromagnetic wave transmitting material.  
      When infrared rays are utilized as the electromagnetic wave, the construction of the case  22  for transmit the electromagnetic wave is made an infrared ray transmitting construction. To obtain such a construction, the whole of the case  22  or at least the case portion  22 C can be constructed by using an infrared transmitting material.  
      In  FIG. 2 , since the trackball in accordance with the present invention has the above-described construction, the rotation of the rotating element  24  of the ball support structure  27  provided in the ball-side space SB is detected through the case portion  22 C capable of transmitting an electromagnetic wave that can be detected by the rotation sensor  25 , for example, visible rays or infrared rays, or through the case  22 . Specifically, in  FIG. 2 , when the portion E of the rotation sensor  25 , which is a reflective photosensor, is the light emitting portion and the portion R thereof is the light receiving portion, the electromagnetic wave such as visible rays or infrared rays emitted from the light emitting portion E enters the drum-shaped rotating element  24  existing in the ball-side space SB region through the case portion  22 C of the case  22 , being processed by the reflector provided on the drum-shaped rotating element  24 , and is received and detected as a pulse signal by the light receiving portion R through the case portion  22 C. In  FIG. 2 , for example, on a straight line L′, there exists a path through which visible rays etc. go from the light emitting portion E to the light receiving portion R via the case portion  22 C through the reflector on the drum-shaped rotating element  24 .  
      Since the rotating element  24  need not be provided in the case interior space SI for the rotation sensor  25  to detect the rotation of the rotating element  24 , the case  22 , which is the boundary between both of the spaces SB and SI, need not be provided with a notch for causing these spaces SB and SI to communicate with each other. Specifically, the ball-side space SB in which the ball support structure  27  is provided is isolated from the case interior space SI containing the rotation sensor  25  and the sensor board  6  by the case  22 . Therefore, foreign matters such as water and dust can be prevented from intruding into the case interior space SI from the ball-side space SB continuous with the environment on the outside of the track ball.  
      In other words, even if foreign matters such as water and dust, which are originated from the environment on the outside of the track ball, are present in the ball-side space SB, the foreign matters do not intrude into the case interior space SI, which is isolated from the ball-side space SB by the case  22  (X 2 ). Therefore, the foreign matters are prevented from intruding into the sensor board  6  and the rotation sensor  25 , which are provided in the space SI.  
      The rotation of the rotating element  24  is detected by the rotation sensor  25  provided in the case interior space SI, and a pulse signal is generated by the rotation sensor  25 . The pulse signal is transmitted to and arithmetically operated by the sensor board  6 , by which the rotational displacement of ball is detected.  
     Industrial Applicability  
      According to the track ball in accordance with the present invention, foreign matters such as water and dust can be prevented from intruding into the case containing the sensor board. Further, there is no need for providing a notch in the case, so that the manufacturing cost can be reduced.  
      Also, according to the track ball using the reflective photosensor, there is no need for partially forming the case substantially into a U shape, so that the manufacturing cost can further be reduced.