Ink washing device for a printing machine

Abstract

An ink washing device is disclosed, for use in a printing machine having a deposit roller with a variable luminance outer surface. The washing device includes a blade disposed adjacent to the deposit roller, for removing excess deposit of ink on the outer surface of the deposit roller, thus causing its luminance to vary. A luminance sensor detects changes in the luminance of the outer surface. The washing operation is interrupted or continued based on the detected luminance changes.

What is claimed is: 
     
       1. An ink washing device, for performing a washing operation in a printing machine, the printing machine including a plurality of ink rollers for supplying ink to a cylinder plate, a deposit roller having an outer surface where excess ink from the ink rollers is deposited, said outer surface having a luminance that varies with the amount of the deposited ink, and a spraying device for spraying washing fluid on at least one ink roller to initiate a washing operation, the ink washing device comprising: scraping means, disposed adjacent to said deposit roller, for removing the deposited ink on said outer surface; and   operating detection means for determining the completion of the washing operation, said operating detection means including a luminance detector means responsive to said luminance of said outer surface during removal of the deposited ink, said operating detection means indicating completion of the washing operation when a luminance signal from the luminance detector means exhibits substantially no change.   
     
     
       2. The ink washing device according to claim 1, wherein said luminance signal includes red, green and blue luminance signals. 
     
     
       3. The ink washing device according to claim 2, wherein said operation detection means includes selector means for selecting one of said red, green or blue luminance signals. 
     
     
       4. The ink washing device according to claim 1, including means supplying pressurized air and washing fluid to the spraying device; and further including:   a first solenoid valve for selectively interrupting the air supply to the spraying device;   a second solenoid valve for selectively interrupting the washing fluid supply to the spraying device; and   delay timer means for causing said first solenoid valve to remain open for a predetermined period of time after said second solenoid valve is closed.   
     
     
       5. The ink washing device according to claim 4, including means operating said second solenoid valve intermittently, in order to control the amount of washing fluid sprayed from the spraying device. 
     
     
       6. The ink washing device according to claim 1, wherein the printing machine includes a plurality of printing units, the operation detection means includes a selector means for selecting one of said printing units, and each of said printing units includes luminance detection means for generating corresponding luminance signals. 
     
     
       7. An ink washing device, for performing a washing operation in a printing machine, the printing machine including a plurality of ink rollers for supplying ink to a cylinder plate, a deposit roller having an outer surface where excess ink from the ink rollers is deposited, said outer surface having a luminance that varies with the amount of the deposited ink, and a spraying device including an air supply and a washing fluid supply for spraying washing fluid on at least one ink roller to initiate a washing operation, the ink washing device comprising: scraping means, disposed adjacent to said deposit roller, for removing the deposited ink on said outer surface;   operating detection means for determining the completion of the washing operation, said operating detection means including a luminance detection means responsive to said luminance of said outer surface during removal of the deposited ink, said operating detection means indicating completion of the washing operation when a luminance signal from the luminance detector remains substantially constant for a predetermined period of time;   a first solenoid valve means for selectively interrupting the air supply to the spraying device; and   a second solenoid valve means for selectively interrupting the washing fluid supply to the spraying device.   
     
     
       8. The ink washing device according to claim 7, wherein said luminance detection means includes a color detector for generating a plurality of different luminance signals. 
     
     
       9. The ink washing device according to claim 8, wherein said operation detection means includes selector means for selecting at least one of said plurality of luminance signals. 
     
     
       10. The ink washing device according to claim 7, further including: delay timer means that causes said first solenoid to remain open for a predetermined period of time after said second solenoid valve is closed.   
     
     
       11. The ink washing device according to claim 7, wherein said second valve means is operated intermittently in order to control the amount of washing fluid sprayed from the spraying device. 
     
     
       12. The ink washing device according to claim 7, wherein the printing machine includes a plurality of printing units, the operation detection means includes a selector means for selecting one of said printing units, and each of said printing units includes luminance detection means for generating corresponding luminance signals. 
     
     
       13. A method for performing a washing operation in a printing machine, the method comprising the steps of: spraying washing fluid on at least one roller of the printing machine to initiate a washing operation;   scraping excess ink deposited on an outer surface of a deposit roller, which causes the luminance of said outer surface to change;   detecting changes in the luminance of said outer surface during said scraping, and generating a signal indicative of said changes; and   determining the completion of the washing operation responsive to said signal remaining substantially constant.