Title:
【発明の名称】画像読取装置
Document Type and Number:
Japanese Patent JP2981733
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To improve responsiveness to a weak signal by adding a bias to the input signal of a logarithmic amplifier to settle it within the desired range and correcting distortion generated in an output signal through an image processor having a correction table. SOLUTION: An analog signal current S(t), outputted from a photomultiplier 21 for receiving light expressing a radiograph, is inputted to an adder 25 and a fixed current S' is added. An added signal S(t)+S' is logarithmically amplified by a current input type logarithmic amplifier 26 and digitized by an A/D converter 27, and an image signal SQ is provided and stored in a storage means 283. An image processor 200 stores a correction value for correcting the distortion generated in the longarithnically compressed signal by bias addition, suitably corrects the signal Sq whenimage paocressing is perpirmed, provides an image signal SR and sends it to an image-reproducing device 300. Thus, only the input level within the range of satisfactory responsiveness of the logarithmic amplifier can be used, and throughput per unit time can be improved.
Inventors:
HORIKAWA KAZUO
Application Number:
JP16582697A
Publication Date:
November 22, 1999
Filing Date:
June 23, 1997
Export Citation:
Assignee:
FUJI SHASHIN FUIRUMU KK
International Classes:
A61B6/00; H04N1/00; H04N1/04; H04N1/40; G03B42/02; (IPC1-7): H04N1/40; A61B6/00; G03B42/02; H04N1/04
Domestic Patent References:
| JP6457878A | ||||
| JP5848573A | ||||
| JP6096957A | ||||
| JP1194747A | ||||
| JP54125049A | ||||
| JP5322815B1 |
Attorney, Agent or Firm:
Seiji Yanagida (1 person outside)