| 摘要 |
PURPOSE:To obtain a correct ratio of brightness according to the sizes of an original and a copying magnification by providing a change-over device which changes the ratio of the brightness between the electric bulbs positioned in the end part of an arrangement and the electric bulbs positioned in the intermediate part. CONSTITUTION:An embodiment in which six pieces of the 1st kind of electric bulbs 1 each having plural filaments 12, 13 are arranged is illustrated. The electric bulbs 1b, 1c-1e provided in the intermediate part of the arrangement are so constituted as to have the equal outputs of both filaments (12b, 13b), (12c, 13c)- sealed thereon and the electric bulbs 1a, 1f provided at both ends are so constituted as to have the larger outputs of the 2nd filaments 13a, 13f than the outputs of the 1st filaments 12a, 12f. The outputs of 12a, 12f are further made larger than the outputs of 1b-1e. A change-over device 5 has the 1st contact 5a for lighting simultaneously the 1st filaments 12a, 12b-12f of all the bulbs 1a, 1b-1f and the 2nd contact 5b for lighting simultaneously the 2nd filaments 13a, 13b-13f. |
