Light sources for digital pen
Motion of a writing instrument is tracked from sensors located in the vicinity. The signals generated from the sensors are processed and used in a wide variety of ways.
1 . Apparatus comprising:
a writing instrument including,
an elongated housing configured to be hand-held,
a light source in the housing, and
a lens in the housing configured to receive light from the light source and convey the light through a free-air path to optical sensors spaced from the writing instrument, the lens being configured to enable light to be directed parallel to the writing surface no matter what the orientation or position of the writing instrument to the writing surface.
2 . Apparatus comprising:
a writing instrument including,
an elongated housing configured to be hand-held, and
a light source in the housing, the light source comprising an array of light sources arranged around an axis of the writing instrument and configured to emit light in a direction normal to the axis.
3 . The apparatus of claim 1 in which the lens is configured to internally reflect and concentrate the light and to emit it by reflection from a reflective external surface of the lens.
4 . The apparatus of claim 3 in which the reflective external surface comprises a conical surface oriented at a certain degree angle to a longitudinal axis of the writing instrument.
5 . The apparatus of claim 1 in which the lens comprises a cylindrical body having an upper surface that receives the light and a lower annular surface that reflects the light toward the optical sensors.
6 . The apparatus of claim 1 in which the light source emits light in a direction toward a writing end of the writing instrument.
7 . The apparatus of claim 1 in which a light guide delivers light to the tip of the pen and conveys it outwardly in a disk-like pattern.
8 . Apparatus comprising:
a writing instrument including,
an elongated housing configured to be hand-held, and
a light source in the housing, the light source being arranged to emit light in a direction parallel to a longitudinal axis of the writing instrument.
9 . The apparatus of claim 8 in which the light source comprises one or more LEDs.
10 . The apparatus of claim 8 in which the light source comprises a ring of light sources.
11 . Apparatus comprising:
a writing instrument;
a light-source in the writing instrument configured to convey light to sensors spaced from the writing instrument; and
a device configured to turn the light source on and off in response to a user applying pressure from the writing instrument to a writing surface, the switch being configured so that an amount of pressure required to trigger the switch is not so large as to disrupt normal writing motion of the writing instrument on the writing surface.
12 . The apparatus of claim 11 in which the writing instrument includes a ballpoint cartridge having a writing point and the device is positioned at the opposite end of the cartridge from the writing point.
13 . The apparatus of claim 12 in which the device could comprise a switch.
14 . The apparatus of claim 12 in which the device could comprise a pressure sensor.
15 . Apparatus comprising:
a writing instrument and a sensor,
the writing instrument including a reflective element configured to reflect light received from outside of the writing instrument to the sensor for use in tracking motion of the writing instrument.
16 . The apparatus of claim 15 also including a mechanism to enable the reflective element to reflect the light to the sensor when the writing instrument is being used for writing and to disable the reflective element from reflecting light to the sensor when the writing instrument is not being used for writing.