Patent ID: 6474770
Filing Date: 2002-11-05
Classification: B41J

Abstract:
A testing device to test whether or not ink droplets are expelled from a print head in a printer, comprising:a photo-emitter unit configured to emit light such that the light crosses a locus of the ink droplets; a photo-receptor unit configured to receive the light that has crossed the locus of the ink droplets, and a controller configured to control the photo-emitter unit and the photo-receptor unit; wherein the photo-receptor unit includes: (i) a photo sensor having a gain adjustment terminal and an output signal terminal; and (ii) a variable voltage supply unit configured to supply a variable voltage signal to the gain adjustment terminal, and wherein the controller detects an output signal from the output signal terminal of the photo sensor while changing a voltage level of the variable voltage signal output from the variable voltage supply unit, and sets the variable voltage signal to an appropriate level for the ink droplet expulsion test before the test is carried out, in accordance with the relationship between the voltage level of the variable voltage signal and the output signal of the photo sensor.