Translator for measuring amount of color correction for color

Abstract

A translator comprising a light receiving unit including three kinds of photocells having spectral sensitivities to red, green and blue colors respectively for receiving light from the optical projecting system of an enlarger equipped with color correction filters, arithmetic units for calculating ratios between the outputs of the photocells by taking one of the outputs as denominators and the other two outputs as numerators respectively, comparison output setting units having their outputs determined only by the conditions of a negative previously memorized for comparison with the outputs from the arithmetic units respectively, and comparison units for comparing the outputs from the arithmetic units with the corresponding comparison outputs individually to indicate the differences therebetween, whereby the amount of color correction given only by the conditions of the negative is adjusted for the enlarger actually used for color printing.

What is claimed is: 
     
       1. A translator for measuring the amount of color correction for color printing comprising: a light receiving unit including three kinds of photocells having spectral sensitivities corresponding to red, green and blue colors respectively for measuring light from the optical projecting system of an enlarger equipped with color correction filters,   arithmetic means for calculating ratios between the outputs of the light receiving unit responsive to the respective colors by taking one of the outputs as denominators and the other two outputs as numerators respectively, an amplifier for amplifying the output taken as the denominator,   reference voltage generating means for setting three comparison outputs for the three outputs of the arithmetic means respectively, the reference voltage generating means memorizing the comparison outputs previously set, and   comparison means for comparing the outputs of the arithmetic means with the outputs of the comparison output setting means in corresponding relation thereto, the comparison means having indicators for indicating the differences between the outputs of the arithmetic means and the corresponding set comparison outputs respectively.   
     
     
       2. The translator as set forth in claim 1 further comprising logarithmic converter means for converting the three outputs of the light receiving unit to logarithmic form respectively to apply the resulting logarithmic outputs thereof to the arithmetic means. 
     
     
       3. The translator as set forth in claim 1 further comprising means for setting an exposure multiplication number for an enlarging degree set on the enlarger, the exposure multiplication number setting means having changeover means for controlling one of the outputs of the light receiving unit that is fed to the amplifier of the arithmetic means and the corresponding comparison output set by the comparison output setting means. 
     
     
       4. The translator as set forth in claim 1 wherein the reference voltage generating means includes parallel translation means for controlling the comparison reference outputs to prevent any one of the set comparison outputs from becoming impossible to indicate. 
     
     
       5. A translator for measuring the amount of color correction for color printing comprising: a light receiving unit including three kinds of photocells having spectral sensitivities corresponding to red, green and blue colors respectively for receiving light from the optical projecting system of an enlarger equipped with color correction filters, the photocells being operative to produce outputs corresponding to the intensities of light of colors responsive thereto,   arithmetic amplifier circuits for calculating ratios between the outputs of the light receiving unit responsive to the respective colors by taking one of the outputs as denominators and the other two outputs as numerators respectively, the circuits being operative to produce calculated values of the ratios as outputs respectively individually,   comparison output setting circuits for setting two comparison outputs for the outputs of the arithmetic amplifier circuits respectively, the comparison output setting circuits having potentiometers for permitting the comparison outputs to be determined only by the conditions of a negative previously memorized,   comparison circuits for comparing the outputs of the arithmetic circuits with the outputs of the comparison output setting circuits individually in corresponding relation thereto, the comparison circuits having indicators for indicating the differences between the outputs of the arithmetic circuits and the corresponding set comparison outputs respectively,   an amplifier circuit for amplifying the output of the light receiving unit taken as the denominators for the aforesaid calculation,   another comparison output setting circuit for producing a comparison output corresponding to the output of the amplifier circuit, including a potentiometer for setting the comparison output, and   another comparison circuit for comparing the output of the amplifier circuit with the output of the second-mentioned comparison output setting circuit to indicate the difference therebetween.   
     
     
       6. The translator as set forth in claim 5 further comprising logarithmic converter circuits for converting the outputs of the light receiving unit to logarithmic form respectively to apply the resulting logarithmic outputs thereof to the arithmetic amplifier circuit and the amplifier circuit. 
     
     
       7. The translator as set forth in claim 5 further comprising means for setting an exposure multiplication number for an enlarging degree set on the enlarger, the exposure multiplication number setting circuit having changeover contacts for controlling the outputs of the amplifier circuit and the set comparison outputs of the other comparison output setting circuit and a plurality of resistance circuits of different resistance values changed at each contact. 
     
     
       8. The translator as set forth in claim 5 wherein the comparison output setting circuit and the comparison output setting circuit include parallel translation means for controlling the comparison reference voltages, the parallel translation means preventing any one of the set comparison outputs from becoming impossible to indicate by having its resistance values controlled. 
     
     
       9. The translator as set forth in claim 5 wherein the outputs of the red light receiving unit are taken as the denominators.