Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
  • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
  • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
  • G06F3/042—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by opto-electronic means
  • G06F3/0421—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by opto-electronic means by interrupting or reflecting a light beam, e.g. optical touch-screen
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
  • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
  • G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
  • G06F3/0354—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor with detection of 2D relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
  • G01P3/36—Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light
  • G01P3/366—Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light by using diffraction of light
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
  • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
  • G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
  • G06F3/0354—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor with detection of 2D relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks
  • G06F3/03543—Mice or pucks

Definitions

• This invention relates to a relative movement sensor for use in an optical input device, in which movement of the input device and an object relative to each other along at least one measuring axis is measured by illuminating an object surface with a measuring laser beam, and converting a selected portion of the measuring beam radiation reflected by the object surface into an electrical signal, which is representative of the movement along the measuring axis.
• the input device may be an optical mouse, which is used in a computer configuration to move a cursor across the computer display or monitor, for example, to select a function of a displayed menu.
• Such an optical mouse is moved across a mouse pad by hand, like, for example, the conventional mechanical mouse.
• EP-A-0942285 discloses several embodiments of the optical measuring module, in all of which homodyne or heterodyne detection is used.
• optical input devices require the provision of an opening in the base plate to enable the light to travel from the light source to a table, mouse mat or other surface, and then back to the detector.
• a typical optical mouse 10 comprises a housing 12, within which is housed the optical measuring module 14.
• the mouse 10 is further provided with a base plate 16 having a plurality of spacers 18 by means of which the mouse 10 can glide across a surface 20.
• An opening 22 is provided in the base plate 16 to enable light to travel from the optical measuring module 14 to the surface 20, and then back to the detector (in the module 14).
• a disadvantage of the opening 22 in the base plate 16 is that the electrostatic discharge (ESD) shielding of the electronics (14) within the housing 12 is difficult. Electrostatic discharge (ESD) is caused by the build-up of electrical charge on one surface that is suddenly transferred to another surface when it is touched. This discharge is typically several thousand volts, and the components of the optical measurement module 14 are especially sensitive to ESD.
• One of the ways of dealing with ESD is to drain it away so it cannot cause any damage, and in the case of the optical mouse 10 of Figure 1, an ESD shielding plate 24 in the form of a special insert in the base plate 16, is provided for this purpose. This results in a more complex and more expensive base plate.
• an optical input device comprising a relative movement sensor for measuring movement of said device relative to a surface
• the device comprising a housing defining an enclosure within which is provided an optical measuring module, said optical measuring module comprising at least one laser, having a laser cavity, for generating a measuring beam, said housing comprising a base at least a portion of which comprises a material transparent to said measuring beam through which said surface is illuminated by said measuring beam, wherein at least some of the measuring beam radiation reflected by the surface re-enters said laser cavity, said optical measuring module further comprising measuring means for measuring changes in operation of said laser cavity caused by interference of reflected measuring beam radiation re-entering said laser cavity and the optical wave in said laser cavity, and means for providing an electric signal representative of said changes for use in determining movement of said device relative to said surface.
• the optical measuring module uses an optical measuring beam, there is no need to provide an opening in the base of the housing to allow the measuring beam to illuminate the surface and allow reflected measuring beam radiation to return to the detector.
• the base may include a transparent window, either formed integrally therewith or mounted therein.
• the base may actually be formed of a material transparent to the measuring beam, which configuration has the additional advantage of reducing the number of components of the device.
• the base of the housing is arranged and configured such that, in use, the transparent material is in spaced apart relation to said surface.
• one or more spacers or gliders may be provided which, in addition to making it easier for the device to glide across the surface, also have the effect of maintaining the base of the device in spaced apart relation to the surface.
• the transparent portion may be at least partially non-planar, e.g. curved or faceted, in which case the need for the spacers may be eliminated.
• the present invention extends still further to a method of manufacturing an optical input device comprising a relative movement sensor for measuring movement of said device relative to a surface, the method comprising providing within a housing defining an enclosure an optical measuring module, said optical measuring module comprising at least one laser, having a laser cavity, for generating a measuring beam, said housing comprising a base at least a portion of which comprises a material transparent to said measuring beam, said optical measuring module being arranged such that said surface is illuminated by said measuring beam through said transparent portion and at least some of the measuring beam radiation reflected by the surface re-enters said laser cavity, said optical measuring module further comprising measuring means for measuring changes in operation of said laser cavity caused by interference of reflected measuring beam radiation re-entering said laser cavity and the optical wave in said laser cavity and means for providing an electric signal representative of said changes for use in determining movement of said device relative to said surface.
• Fig. 1 is a schematic cross-sectional view of an optical input device according to the prior art
• Fig. 2 is a schematic cross-sectional view of an optical input device according to a first exemplary embodiment of the present invention
• Fig. 3 is a schematic cross-sectional view of an optical input device according to a second exemplary embodiment of the present invention.
• an optical input device 110 comprises a housing 112 and a base plate 116, together defining an enclosure 123 within which the optical measuring module 114 is housed.
• the method for measuring the relative movement of the input device 110 relative to the surface 120 employed by the optical measuring module 114 uses the so-called self-mixing effect in a diode laser. This is the phenomenon that radiation emitted by a diode laser and re-entering the cavity of the diode laser induces a variation in the gain of the laser and thus in the radiation emitted by the laser.
• the input device 110 is moved relative to the surface 120 such that the direction of movement has a component in the direction of the laser beam.
• the radiation scattered by the surface 120 gets a frequency different from the frequency of the radiation illuminating the object, because of the Doppler effect.
• Part of the scattered light is focused on the diode laser by the same lens that focuses the illumination beam on the object. Because some of the scattered radiation enters the laser cavity through the laser mirror, interference of the light takes place in the laser. This gives rise to fundamental changes in the properties of the laser and the emitted radiation. Parameters which change due to the self-coupling effect are the power, the frequency and the line width of the laser radiation and the laser threshold gain. The result of the interference in the laser cavity is a fluctuation of the values of these parameters with a frequency that is equal to the difference of the two radiation frequencies. This difference is proportional to the component velocity of the object. Thus, the velocity of the objects and, by integrating over time, the displacement of the object can be determined by measuring the value of one of said parameters. This technique is described in detail in International Patent Application No. WO02/037410.
• the optical measuring module 114 provides a carrier for the diode lasers, which may be of the VCSEL type, and the detectors, for example, photo diodes.
• a single integrated wafer 3 including a diode laser and corresponding photo diode is visible, but in practice, one or more further diode lasers and associated detectors may be provided.
• the diode laser 3 emits a laser, or measuring beam 13, which may, for example, be visible or infrared laser light, which measuring beam 13 needs to reach the surface 120.
• no opening is required to be provided in the base plate 116.
• the base plate 116 is provided with a small area 124 which is transparent to the laser light used to generate the measuring beam 13. Since the laser light has a small spectral bandwidth, the area or window 124 needs only to be transparent to that small spectral bandwidth; it can be opaque, absorbing or reflective in respect of all other wavelengths. This area 124 is only required to be of limited optical quality.
• the measuring beam 13 is incident on the surface 120 and the surface 120 reflects and/or scatters the beam 13.
• a part of the beam 13 is scattered in the direction of the illumination beam 13 and this part is converged by a lens (not shown) on the emitting surface of the diode laser and re-enters the cavity of this laser.
• the radiation returning to the cavity induces changes in this cavity, which results in, inter alia, a change in the intensity of the laser radiation emitted by the diode laser.
• This change can be detected by the photo diode, which converts the radiation variation into an electric signal, which signal is processed by electronic circuitry (not shown), to determine the relative movement of the measuring beam 13 with respect to the surface 120 and, therefore, displacement of the input device 110 relative to the surface 120.
• an optical input device is similar in most respects to that of the embodiment described with reference to Figure 2 of the drawings, and like components thereof are denoted by the same reference numbers.
• the transparent area 124 is curved, faceted or otherwise at least partially non-planar.
• the spacers 118 (which may be made of, for example, Teflon ®) could be omitted.
• a curved window 124 in particular can contribute to the optical power of the system. The laser can travel closer to the perpendicular through such a window than if the window were planar.
• the optical path through the window 124 is smaller (so there is less chance of absorption, birefringence, etc) and any aberrations are smaller. Additionally, there is a larger distance between the surface and the bottom of the device, so the effects of scratches or dust on the window can be reduced. Also, the likelihood of scratches occurring is less.
• the spacers or gliders 118 are primarily provided so the device can glide more easily over the working surface. However, these are not essential. In the illustrated examples, the gliders 118 serve the additional purpose of providing some space between the transparent window 124 and the surface, especially in the case where the window 124 is planar. However, this is not essential; instead the window 124 could simply be mounted slightly inwardly relative to the base plate surface, or the window can be curved or faceted, as in the embodiment illustrated in Figure 3.
• the device comprises a base plate 116 in which is provided a transparent window 124.
• the base plate 116 itself could simply be made of a material which is transparent to the wavelength of the measuring beam. This provides the advantage that the number of components for the device is reduced.
• the present invention is applicable to optical input devices generally, including an optical mouse for a desktop computer, in a keyboard of a desktop or laptome computer, in a remote control for different apparatus, in a mobile telephone, etc, and the present invention is not intended to be limited in this regard.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Theoretical Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Human Computer Interaction (AREA)
• Electromagnetism (AREA)
• Power Engineering (AREA)
• Position Input By Displaying (AREA)
• Length Measuring Devices By Optical Means (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (2)

Family

ID=36021736

Family Applications (1)

Country Status (6)

Cited By (2)

Families Citing this family (1)

Citations (1)

• 2005
  • 2005-12-12 EP EP05825658A patent/EP1831777A2/en not_active Withdrawn
  • 2005-12-12 JP JP2007546264A patent/JP2008524690A/ja not_active Withdrawn
  • 2005-12-12 KR KR1020077016152A patent/KR20070100941A/ko not_active Application Discontinuation
  • 2005-12-12 WO PCT/IB2005/054184 patent/WO2006064450A2/en active Application Filing
  • 2005-12-12 CN CNA2005800432860A patent/CN101080690A/zh active Pending
  • 2005-12-13 TW TW094144098A patent/TW200634608A/zh unknown

Patent Citations (1)

Also Published As

Similar Documents

Legal Events