Title:
LIGHT SPOT POSITION DETECTOR
Document Type and Number:
Japanese Patent JPS63150605
Kind Code:
A
Abstract:
PURPOSE:To detect an accurate light spot position by arranging a means which detects the appearance of disturbing light corresponding to the modulated light of a light pen, etc., and inhibiting the output signal of a light position detecting element from being generated while the disturbing light is present. CONSTITUTION:The light spot position detector consists of the light pen 2 which is turned on with the output of an oscillation circuit 1, a semiconductor light position detecting element 3 which detects the indication position of the light pen 2, processing circuits S1-S4 which process the output signals of four electrodes of the element 3, and a switching circuit 5. In this constitution, if a photodiode 51 detects a noise originating from the disturbing light containing a higher harmonic component WH, it is led out as a higher harmonic component signal through a 2nd low-pass filter 53 and a comparator 54. Then only when this signal is at high level, analog switches SW1-SW4 are opened.
Inventors:
HIROOKA MASATAKE
Application Number:
JP29797586A
Publication Date:
June 23, 1988
Filing Date:
December 15, 1986
Export Citation:
Assignee:
KOMATSU MFG CO LTD
International Classes:
H01L31/16; G01B11/00; G06F3/041; G06F3/042; (IPC1-7): G01B11/00; G06F3/037; H01L31/16
Attorney, Agent or Firm:
Kimura Takahisa