Inspection apparatus with stroboscope intensity compensation features

• US 5,581,074 A
• Filed: 11/21/1994
• Issued: 12/03/1996
• Est. Priority Date: 11/29/1993
• Status: Expired due to Fees

• Current Assignee: Hajime Industries Limited
• Original Assignee: Hajime Industries Limited
• Inventors: Yoshida, Hajime
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): CALOGERO, STEPH
• Application Number:
  US08/342,701
• Time in Patent Office: 743 Days
• Field of Search: 250/205, 250/559.05, 250/559.07, 250/559.08, 250/559.4, 250/214 C, 250/214 DC, 250/214 PC, 250/223, 348/132, 348/131
• US Class Current: 250/205
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/89 in moving material, e.g. running paper or textiles G01N21/90, G01N21/91, G01N21/94 take precedence

Abstract

A stroboscope is employed as the lighting source for a video camera, the output of which is converted into a signal from which a fault in the object scanned is detected. The stroboscope is controlled in response to a portion of the output voltage of the video camera to insure that the luminous energy is constant.

Claims

1. An inspection apparatus having a stroboscope luminous energy correction function, comprising:

a conveyor means for conveying an inspected object;

a position detection means for detecting the position of said inspected object arriving at an inspection station to produce a position detection signal;

a stroboscope including a flash unit having a luminous energy, producing light irradiating said inspected object at the inspection station and a power source supplying an electric power to said flash unit;

a video camera means for picking up said inspected object as irradiated by said flash unit of the stroboscope to produce a video signal of said inspected object;

a signal processing circuitry which processes the video signal of said inspected object as picked up by said video camera means upon reception of said position detection signal from said position detection means;

a photoelectric conversion means for converting a part of the light from said stroboscope flash unit into a voltage; and

a luminous energy control system for controlling the luminous energy of the flash unit of said stroboscope to be constant in response to the voltage from said photoelectric conversion means, said luminous energy control system having an A/D converter means, a clock generator means, an adder means, and a mean value calculator means, said A/D converter means converting the luminous energy of the flash unit of said stroboscope to a predetermined number of digital values on tho basis of a clock from said clock generator means and supplying the same to said adder means, said adder means integrating the same predetermined number of outputs from said A/D converter means based on the clock from said clock generator means, and said mean value calculator means averaging a predetermined number of outputs from said adder means and supplying a mean value therefrom to said power source of said stroboscope.

2. The inspection apparatus as claimed in claim 1, in which said mean value calculator means obtains a mean value of integrated values of luminous energies of successive numbers of flashes of said flash unit to thereby control the luminous energy of said flash unit substantially constant.