Patent Publication Number: US-9403401-B2

Title: Thermal eraser for tactile drawings

Description:
RELATED APPLICATION DATA 
     This application is a continuation of U.S. application Ser. No. 13/457,725, filed Apr. 27, 2012, and titled “Thermal Eraser For Tactile Drawings,” which application claims the benefit of priority of U.S. Provisional Application Ser. No. 61/482,175, filed on May 3, 2011. Each of these applications is incorporated by reference herein in its entirety. 
     This application is also related to U.S. patent application Ser. No. 13/684,993 entitled “Systems For and Methods of Digital Recording and Reproduction of Tactile Drawings,” which is being filed concurrently with the present application, and U.S. patent application Ser. No. 13/457,704, filed on Apr. 27, 2012, and titled “Systems For and Methods of Digital Recording and Reproduction of Tactile Drawings.” 
     All references, publications, patent documents, etc. mentioned herein are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to tactile drawings and in particular to a thermal eraser for erasing tactile features on tactile drawings. 
     BACKGROUND OF THE INVENTION 
     Tactile drawings, also called raised-line drawings or RLDs, are produced and used primarily by the blind and sight-impaired because they allow tactile sensing in a free-hand drawing. With reference to  FIG. 1 , tactile drawings are formed in one example by a stylus  10  that is moved and controlled by a user relative to a surface  22  of a locally deformable medium  20 , referred to hereinafter as a “tactile drawing medium.” Tactile drawing medium  20  is configured to permanently or semi-permanently display one or more tactile drawing features  30  on surface  22  when localized pressure is applied to the surface with stylus  10 . In particular, as a user moves stylus  10  over surface  22  of tactile drawing medium  20  with downward pressure, tactile feature  30  is formed thereon, with the tactile feature instantly revealing the stylus path. The resulting drawing is referred to herein as a tactile drawing  32 . 
     A typical tactile drawing medium  20  comprises a thin plastic sheet, which can be a thermoplastic material (also called thermosoftening plastic), among others. Tactile drawing medium  20  is placed and secured (e.g., via a clip  40 , as shown) on top of a pad of flexible or indentable material  24 , such as rubber. Stylus  10  can be a typical ballpoint pen (or other rolling contact device), or can simply be a rod with a rounded or otherwise effectively shape tip  12 . The force of stylus tip  12  on the flexible material  24  through tactile drawing medium  20  locally plastically deforms the tactile drawing medium to create a tactile feature  30 . In an example, the tactile drawing medium responds along the stretched line produced by the stylus by rising instantaneously to become a palpable raised feature. This system has the benefit of letting a user feel what they are drawing while they draw it, and provides a permanent hardcopy of their tactile drawing that others can tactilely sense. 
     One limitation of tactile drawing medium  20  is that tactile features  30  cannot be removed or erased in a practical manner. Thus, the user does not have the benefit of being able to readily refine tactile drawing  32  by erasing some or all of a given tactile feature  30 . Since making such changes is an essential part of the creative process of making a tactile drawing, the inability to erase some or all of a tactile drawing is a significant limitation on the state of the art. 
     SUMMARY OF THE INVENTION 
     An aspect of the disclosure is a thermal eraser for erasing a tactile feature from a tactile drawing medium. The thermal eraser includes a housing having a tip section and a back section. A voltage source is operably arranged within at least a portion of the back section. A thermal-tip assembly resides in the tip section and is in electrical contact with the voltage source. The thermal-tip assembly has a tip and a heating element. The voltage source provides a current to maintain the tip at a tip temperature sufficient to substantially flatten the tactile feature by the application of heat from the tip to the tactile feature. 
     Another aspect of the disclosure is the thermal eraser as described above, wherein the voltage source comprises one or more batteries. 
     Another aspect of the disclosure is the thermal eraser as described above, further comprising an activation switch configured to allow or interrupt the flow of current from the voltage source to the thermal-tip assembly. 
     Another aspect of the disclosure is the thermal eraser as described above, wherein the thermal-tip assembly includes a temperature-regulating circuit configured to control the flow of current from the voltage source to the heating element to that the tip can be maintained at a select temperature or within a select temperature range. 
     Another aspect of the disclosure is the thermal eraser as described above, wherein the temperature-regulating circuit includes a temperature sensor that senses the tip temperature. 
     Another aspect of the disclosure is the thermal eraser as described above, wherein the temperature-regulating circuit controls the flow of current from the voltage source to the heating element based on the measured tip temperature as compared to a set-point temperature that represents a select tip temperature. 
     Another aspect of the disclosure is the thermal eraser as described above, wherein the temperature-regulating circuit includes a control switch disposed between the voltage source and the heating element, and wherein the control switch responds to a control signal to conduct or interrupt the flow of current to the heating element to maintain the tip temperature at the select temperature or within the select temperature range. 
     Another aspect of the disclosure is the thermal eraser as described above, wherein the temperature-regulating circuit includes a comparator configured to compare first and second voltages corresponding to the measure temperature and the set-point temperature respectively, and provide the control signal in the form a control voltage to the control switch. 
     Another aspect of the disclosure is the thermal eraser as described above, wherein the temperature-regulating circuit provides a hysteresis that causes the tip temperature to stay within a controlled temperature range. 
     Another aspect of the disclosure is the thermal eraser as described above, wherein the tip is defined by a thermally conductive cap sized to fit over the heating element and the temperature-regulating circuit. 
     Another aspect of the disclosure is the thermal eraser as described above, wherein the temperature sensor resides within the thermally conductive cap and measures a temperature within the cap. 
     Another aspect of the disclosure is the thermal eraser as described above, wherein the tactile drawing medium is made of a plastic, and the tip temperature is maintained at about 170° F. 
     Another aspect of the disclosure is a method of erasing at least a portion of a tactile drawing feature formed in a surface of a tactile drawing medium. The method includes providing the tactile drawing medium with the tactile drawing feature formed thereon, with the tactile drawing medium made of a material such that the application of sufficient heat to the tactile drawing feature causes the tactile drawing feature to substantially flow back into the surface. The method also includes applying the heat with a heated tip disposed proximate to or in contact with the portion of the tactile drawing feature to cause the heated portion of the tactile drawing feature to substantially flow back into the surface of the tactile drawing medium. 
     Another aspect of the disclosure is the method as described above, further comprising the heated tip having a tip temperature of about 170° F. 
     Another aspect of the disclosure is the method as described above, wherein the heated tip has a tip temperature and is in thermal communication with a heating element, with the method further including controlling the tip temperature by controlling an amount of current flowing to the heating element. 
     Another aspect of the disclosure is the method as described above, wherein the act of controlling an amount of current flowing to the heating element is performed by comparing a measurement of the tip temperature to a set-point temperature. 
     Another aspect of the disclosure is the method as described above, further comprising using the comparison of the measured tip temperature to the set-point temperature to generate a control signal that controls a control switch that controls the flow of current to the heating element. 
     Another aspect of the disclosure is a method of erasing at least a portion of a tactile drawing feature formed in a surface of a thermoplastic tactile drawing medium. The method includes applying a select amount of heat from a thermal eraser having a heated tip to at least a portion of the tactile drawing feature by placing the heated tip proximate to or in contact with the portion of the tactile drawing feature. The method also includes moving the heated tip over at least the portion of the tactile drawing feature to cause the portion to become substantially flush with the surface of the tactile drawing medium. 
     Another aspect of the disclosure is the method as described above, further including providing downward pressure on the portion of the tactile drawing feature with the heated tip. 
     Another aspect of the disclosure is the method as described above, further including directing the thermal eraser with an electro-mechanical device, such as a tactile printer, operably connected to a computer. 
     Additional features and advantages of the disclosure are set forth in the detailed description that follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the disclosure as described herein, including the detailed description that follows, the claims, as well as the appended drawings. 
     It is to be understood that both the foregoing general description and the following detailed description are embodiments of the disclosure intended to provide an overview or framework for understanding the nature and character of the disclosure as it is claimed. 
     The claims are incorporated into and constitute part of the Detailed Description set forth below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS: 
         FIG. 1  is an elevated view of a prior art tactile system for creating a tactile feature in a tactile drawing medium in a conventional manner; 
         FIG. 2  is a side view of an example thermal eraser according to the disclosure, with certain internal components and structure shown in phantom; 
         FIG. 3  is a partially exploded and partially cut-away side view of the thermal eraser of  FIG. 2 ; 
         FIG. 4  is a partially exploded elevated view of an example thermal-tip assembly; 
         FIG. 5A  is an elevated view of the thermal-tip assembly of  FIG. 4 , showing the basic electrical connection to one or more batteries, the activation switch, and also showing heat being generated at the tip; 
         FIG. 5B  is a schematic diagram of an example configuration for the temperature-regulating circuit that constitutes part of the thermal-tip assembly; 
         FIG. 6A  shows an example tactile drawing feature on a tactile drawing medium; 
         FIG. 6B  shows the thermal eraser in the process of erasing a portion of the tactile drawing feature shown in  FIG. 6A ; and 
         FIG. 7  is a schematic diagram of an electro-mechanical device in the form of a tactile printer operably connected to a computer, with the tactile printer having a tactile drawing therein and holding the thermal eraser in place of a stylus to erase a portion of the tactile drawing feature. 
     
    
    
     The drawings are included to provide a further understanding of the disclosure, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description serve to explain the principles and operations of the disclosure. 
     DETAILED DESCRIPTION OF THE INVENTION: 
       FIG. 2  is a side view of an example embodiment of a thermal eraser  100  according to the disclosure.  FIG. 3  is a partially exploded and partially cut-away side view of the thermal eraser  100  of  FIG. 2  and shows additional internal components and structure. Thermal eraser  100  includes a housing  110  that includes a tip section  120  and a cylindrical back section  200 . Tip section  120  includes an open interior  122  and in an example has a wide end  124  and a narrow end  128 . Wide end  124  includes an engaging feature  106 , such as a lip or threads. Narrow end  128  includes an end wall  130  with a central aperture  134  formed therein. 
     Housing back section  200  includes an open front end  202  that includes a mating feature  206  configured to operably engage with engaging feature  106 . Housing back section  200  has an interior  212  sized to accommodate a voltage source  250 , such as one or more batteries  252 . In an example, the one or more batteries  252  are operably held in a battery holder  260  that includes front and back electrical contacts  262  and  264  and that is configured to fit within the front portion of interior  212  of housing back section  200  at open end  202 . Housing back section includes an activation switch  204  that is electrically connected to battery holder  260  and that allows the current from the voltage source  250  to be interrupted or to allow the current to flow, i.e., it turns the thermal eraser on and off. 
     In an example, activation switch  204  is configured to make a noise or otherwise trigger the generation of a sound so that a visually impaired user can know when thermal eraser  100  is on or off. 
     Tip section  120  is sized to accommodate a thermal-tip assembly  300  as well as a portion of voltage source  250 .  FIG. 4  is a partially exploded view of an example thermal-tip assembly  300 , while  FIG. 5A  is an elevated view of the thermal-tip assembly. Thermal-tip assembly  300  includes a printed circuit board (PCB)  310  having a top surface  312  and a bottom surface  314 . PCB  310  operably supports on top surface  312  a heating element  320  and a temperature-regulating circuit  330  electrically connected thereto. Temperature-regulating circuit  330  can be in the form of integrated circuit (IC), as shown by way of illustration. An electrical contact  316  (not visible in  FIG. 4 ; see  FIG. 3 ) resides on bottom surface  314 . Electrical leads  340  from electrical contact  326  pass through PCB to top surface  312  and to heating element  320  and temperature-regulating circuit  330 . 
     With continuing reference to  FIG. 4 , thermal-tip assembly  300  also includes a thermally conductive cap  350  having a closed front end  352  and an open back end  354 . Cap  350  is formed and sized to cover heating element  320  and temperature-regulating circuit  330  so that the cap open back end  354  rests on PCB top surface  312 . An example cap  350  is made of from aluminum, and in a specific example is formed from a piece of ⅜″ aluminum rod. Since cap  350  forms the heated tip of thermal eraser  100 , cap  350  is also referred to hereinafter as heated tip (or just tip)  350 . 
     Assembly  300  further includes an insulating sleeve  360  having a base  364  and a central aperture  368  sized to pass cap  350 . An example material for insulating sleeve  360  is Polytetrafluoroethylene (PTFE), also known by the brand name TEFLON (DuPont Co.). Base  364  rests upon top surface  312  of PCB  310  when cap  350  extends through aperture  368 . Insulating sleeve  360  serves to keep the heat  355  generated by heating element  320  within cap  350 , thereby minimizing the flow or diffusion of heat  355  (see  FIG. 5A ) to unwanted areas of thermal eraser  100 , and in particular to the portions of tip section  120  and housing back section  200  where a user would grip. 
     In an example embodiment, portions of tip section  120  and housing back section  200  can include an insulating (and preferably ergonomically designed) grip  220  (see  FIG. 6B ) to keep a user&#39;s hand (not shown) from being exposed to heat  355  generated by thermal-tip assembly  300 . An alternative embodiment incorporates ventilation ports (not shown) around the tip to produce convective flow of heated air away from the grip surface. 
     Temperature-regulating circuit  330  is configured to regulate the tip temperature (i.e., the temperature of tip  350 ) by controlling the amount of electrical power provided to the heating element  320  from voltage source  250 . In an example, the temperature of tip  350  (the “tip temperature”) is maintained at about 170° F. by simply providing either a set or fluctuating amount of current to heating element  320 , or via the action of temperature-regulating circuit  330 . 
       FIG. 5B  is a schematic diagram of an example layout of temperature-regulating circuit  330 . Temperature-regulating circuit  330  includes an internal temperature sensor  332  for sensing the tip temperature of conductive cap  350 . Temperature-regulating circuit  330  is configured to regulate the amount of electrical power being delivered to the heating element from voltage source  250 . In an example, this regulation function involves turning on and off the electrical current being delivered to heating element  320  to maintain a select tip temperature, or to maintain the tip temperature within a temperature range (e.g., a few degrees F.). 
     In an example, this is accomplished by providing a control switch  326  (e.g., a thermistor switch) between voltage source  250  and heating element  320 . Temperature sensor  332  generates a temperature sensor signal S T  corresponding to the measured tip temperature T M  (i.e. the temperature of conductive cap  350 ). A comparator (e.g., an op-amp comparator or like element)  345  is disposed downstream of temperature sensor  332  and is operably connected to control switch  326 . One input to comparator  345  is a voltage corresponding to set-point temperature T S  while another input to the comparator is a voltage associated with temperature sensor signal S T  corresponding to the measured tip temperature. 
     If the measured tip temperature T M  from temperature sensor  332  exceeds the set-point temperature T S , then comparator  345  generates a control voltage signal S 2  that provided to control switch  326 . Voltage signal S 2  acts to open switch  326 , thereby interrupting the flow of current. When the measured temperature T M  drops below the set-point temperature T S , then comparator  345  generates a voltage signal S 1  that acts to close control switch  326 , thereby allowing current to flow from voltage source  250  to heating element  320  to heat the tip  350 . 
     In an example, PCB  310  includes two resistors R 1  and R 2  (not shown) electrically connected to temperature-regulating circuit  330 . Resistor R 1  controls the set-point temperature T S , and resistor R 2  controls a hysteresis that defines an amount of deviation from the set-point temperature T S  that will be tolerated when regulating the flow of current from voltage source  250  to heating element  320 . 
     Thermal-tip assembly  300  is operably supported by tip section  120  (see  FIG. 2 ) so that cap  350  extends beyond narrow end  128  of the tip section and defines the heated tip of thermal eraser  100 . With thermal-tip assembly  300  in place, voltage source  250  is inserted to housing back section  200  using, for example, the aforementioned battery holder  260  and batteries  252 . An example battery holder  260  is cylindrical and configured to hold three batteries  252 , such as three AAA batteries. Battery holder  260  is configured to fit into the interior  212  of housing back section  200  and in an example also extends into the interior  122  of the tip section  120  so that top electrical contact  262  of the battery holder comes into contact with bottom electrical contact  316  on PCB bottom surface  314 . In another example, voltage source  250  could be inserted into the opposite end of housing back section  200  by removing thermal-tip assembly  300 . 
       FIG. 6A  shows a tactile drawing medium  20  that includes a tactile drawing feature  30  drawn thereon.  FIG. 6B  shows the same tactile drawing feature, but with a portion  30 E having been erased by tracing heated tip  350  of thermal eraser  100  over a portion of the tactile drawing feature. In an example, the heated tip  350  causes the heated portion of tactile drawing feature  30  to soften, allowing the user to flatten the tactile drawing feature with very little downward pressure. 
     Depending on the material composition of tactile drawing medium  20 , the process by which a raised line is flattened can vary. For example, the flattening process may be due to heat shrinking if tactile drawing medium is made of nylon or polyolefin. It is noted here that the terms “erase” and “erased” as used herein also include substantially removing as well as entirely removing an erased portion  30 E of tactile drawing feature  30  so that it either can be slightly tactilely sensed and thus distinguishable from a non-erased tactile drawing feature  30 , or cannot be tactilely sensed at all. 
     Thus, thermal eraser  100  flattens the portion of tactile drawing feature  30  to which heated tip  350  is applied. In an example, temperature-regulating circuit  330  is configured to maintain the temperature of tip  350  at about 170° F., which allows for tactile drawing feature  30  to be flattened by heat  355  from tip  350  without damaging tactile drawing medium  20 . Other tip temperatures can be employed and will depend on the material making up tactile drawing medium  20 . A suitable tip temperature is one that cause the tactile drawing feature  30  to substantially recede back into surface  22  of tactile drawing medium  20  without inducing thermal damage, especially the kind of thermal damage (e.g., blistering) that can be tactilely sensed by a visually impaired user and confused with the actual tactile drawing feature. 
     Additional Embodiments 
     Tip  350  is shown (e.g., see  FIG. 5A ) has having a flat front end  352 . However, tip  350  can have a variety of suitable shapes, such as rounded or an angled flat surface, and can have a variety of surface areas, including surface areas large enough to erase more than one tactile feature  30  at a time. 
     Tactile drawing features  30  can be created and erased repeatedly with thermal eraser  100  much in the way that graphite pencil lines on paper can be created and removed repeatedly with a rubber eraser. In another example, if areas of raised lines or tactile drawing features are in place, selective erasing can be to draw or create new tactile drawing features  30  on a tactile drawing medium  20 . Such new tactile drawing features  30  can be made to have a different texture than the original tactile drawing feature. 
     In an example embodiment, the tip temperature of thermal eraser  100  is selected (e.g., via the set-point temperature) to be suitable for the particular tactile drawing medium  20 . Also, though the embodiment of thermal eraser  100  shown above utilizes an internal voltage source  250 , a power cord that plugs into AC wall power can also be employed as the power (voltage) source. 
     Thermal eraser  100  can be used in a variety of ways. In one example, it can be picked up in the hand of the user, and directed (slid) along all or a portion of tactile drawing feature  30  while turned on. In an example, the application of pressure also assists in flattening the treated portions of tactile drawing feature  30 . 
     In an example illustrated in  FIG. 7 , instead of a human user handling thermal eraser  100 , it can be held and then moved and controlled by an electro-mechanical device  400 , such as a tactile printer. Tactile printer  400  is shown in  FIG. 7  as being connected to a computer  460  via a cable  462  or a wireless connection (not shown). Computer  462  includes a visual representation  30 GR (i.e., a visible graphics image) of tactile drawing feature  30 , as shown on computer display  464 . In an example, information for tactile drawing  32  is provided to computer  460  via a flash drive  466  or by any one of a number of known data transfer techniques. 
     In this embodiment, thermal eraser  100  can be selected by tactile printer  400  (either manually or automatically) and then used in a manner similar to how it uses stylus  10  to erase some or all of tactile drawing feature  30 , as shown by the erased portion  30 E. 
     Thermal-tip assembly  300  can also include a variety of different types of heating elements  320 . In an example, heating element  320  is self-regulating, and does not require a closed-loop control circuit to maintain the tip temperature. In a more specific example, the heating element  320  comprises a self-regulating Positive-Temperature-Coefficient (PTC) heating element that maintains a constant tip temperature largely independent of the applied voltage from voltage source  250 . 
     In another example, the heating element  320  is a conventional resistive heating element, and the heat  355  generated by thermal-tip assembly  300  is regulated only by a fixed voltage supplied to the heating element. If relatively constant ambient conditions prevail, a feedback circuit may not be necessary to control the tip temperature, as it would instead be controlled by a voltage source  250  in the form of a fixed-voltage power supply. 
     Aspects of the disclosure include method of erasing at least a portion of tactile drawing  30  feature formed in surface  22  of tactile drawing medium  20 . One example method includes providing tactile drawing medium  20  with the tactile drawing feature  30  formed thereon, with the tactile drawing medium made of a material such that the application of sufficient heat  355  to the tactile drawing feature causes the tactile drawing feature to substantially flow (recede) back into surface  22  of tactile drawing medium  20 . The method also includes applying the heat  355  with heated tip  350  disposed proximate to or in contact with the portion of tactile drawing feature  30  to cause the heated portion of the tactile drawing feature to substantially flow (recede) back into surface  22  of tactile drawing medium  20 . 
     Another method of erasing includes applying a select amount of heat  355  from a thermal eraser  100  having a heated tip  350  to at least a portion of tactile drawing feature  30  by placing the heated tip proximate to or in contact with the tactile drawing feature. The method also includes moving heated tip  350  over at least a portion of tactile drawing feature  30  to cause the portion to become substantially flush with surface  22  of tactile drawing medium  20 . 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.