JPS6245537B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a white subtractive color printer that adjusts the light source color by inserting Y (yellow), M (magenta), and C (cyan) filters into the optical path of a white light source. The present invention relates to a light source color adjustment device.

In this type of color printer, as shown in FIG. 1, white light from a light source lamp 1 passes through a light source color adjustment device 2, a light diffusion plate 3, a light pipe 4, and a light diffusion plate 5, and then is projected onto a negative 6. The light that has passed through the negative 6 passes through the enlarger lens 7 and the exposure control shutter 8 and is then projected onto the photographic paper 9, whereby the image on the negative 6 is enlarged and formed on the photographic paper 9.
The light receiving unit 10 has three primary colors B (blue), G (green), and R (red).
The amount of transmitted light of each negative 6 is measured, and when the amount of transmitted light reaches a predetermined constant value, control filters 11 for each color, that is, Y, M, and C filters are respectively inserted into the optical path to perform exposure control. The image is formed on the photographic paper 9 with good color balance,
Furthermore, the photographic paper 9 on which the image has been formed is chemically treated in a separate process to develop color, thereby creating a positive print. On the other hand, it was theorized by R. M. Evans in 1951 that the cumulative transmission density D of a negative and the amount of printing light F have the following relationship.

logFi=Ki+Di where K is a constant based on a combination of a certain printer and a certain photographic paper, and i represents one of B, G, and R color lights. When this equation is represented in a diagram, it becomes as shown in FIG. Therefore, in order to accurately control the amount of printing light F, the amount of each filter inserted into the optical path must be varied logarithmically with respect to the cumulative transmission density D of the negative. On the other hand, it is difficult to achieve ideal wavelength characteristics for each color filter, and the light source does not contain B, G, and R color light in a well-balanced manner, so Y, M,
If there is an extreme difference in the time each filter in C enters the optical path, light in other wavelength ranges leaking from each filter may become uncontrolled, resulting in poor print quality. be. Therefore, as described above, the light source color adjustment device 2 is required as a device for controlling the light in each wavelength range included in the light source to a well-balanced state. By the way, the conventional light source color adjustment device has a lead screw with a fixed pitch and changes the rotation speed of the lead screw to change the amount of insertion of each filter into the optical path. It is extremely difficult to vary logarithmically, and as a result, there is a problem in that it is difficult to accurately adjust the amount of printing light F.

In view of the above problems, the present invention aims to provide a light source color adjustment device that can logarithmically change the insertion amount of each filter into the optical path with high accuracy. To explain the case of adjusting the light quantity balance based on the embodiment shown in FIG. 3, 21 is a substrate provided with an opening 21a at a predetermined position through which the light from the light source 1 passes, and 22 is a substrate. 21 are the left and right bearing plates. Reference numeral 23 denotes a rotating shaft which is rotatably suspended horizontally between the bearing plates 22, 22, and is formed with symmetrical lead cam grooves 23a, 23a whose pitch changes from the center to both ends in proportion to the logarithmic value; is a bearing plate 22 parallel to the rotating shaft 23,
A pair of left and right movers 25 are mounted on the guide rod 24 so as to be movable in the axial direction, and rotatably hold a steel ball 26 that slides into the lead cam groove 23a. , 27 is a motor fixed to one end of the rotating shaft 23 and is adapted to be rotated in accordance with the amount of transmitted light of the standard negative of B measured by the light receiving unit 10, and 28 is fixed to the movers 25, 25, respectively. A pair of left and right filter holders, 29 is filter holder 2
The opening 21a is fixed to the tips of the filter holders 8 and 28, respectively.
These Y filters constitute the Y filter section 30.

It should be noted that it was only possible with the recent development of NC lathes and NC milling machines to form lead cam grooves on shafts whose pitch changes in proportion to logarithmic values.

Reference numeral 31 has basically the same structure as the Y filter section 30, and a pair of left and right M filters 32, 32.
is located below the Y filters 29, 29. M filter section, 33 is Y filter section 30
The C filter part has basically the same structure as the C filter part, in which the left and right pair of C filters 34, 34 are located below the M filters 32, 32, and 35 is a cover fixed to both bearing plates 22, 22. be.

Since the light source color adjustment device according to the present invention is configured as described above, the motor 27 rotates by a predetermined amount so that the transmitted light amount of, for example, a B standard negative measured by the light receiving unit 10 becomes a predetermined value. This causes the shaft 23 to rotate. Then, the left and right movers 25, 25 move into the lead cam grooves 23a, 23a.
The steel balls 26 and 26 cooperate with each other to move in the direction of the arrow in FIG. 3. In this way, the left and right Y filters 29, 29 are connected to the opening 21.
The light intensity of B gradually decreases as it gradually covers A, but since the pitch of the lead cam grooves 23a and 23a changes in inverse proportion to the logarithm from the end to the center, the Y filter 29 ,29
The insertion amount into the optical path is the transmission density D of the standard negative of B.
It changes logarithmically with respect to _B. Therefore, the amount of light F _B for printing B onto the photographic paper 9 can be adjusted in a well-balanced manner. In addition, in the M filter section 31 and the C filter section 33, by the same operating principle as above, the amount of insertion into the optical path of the M filters 32, 32 and the C filters 34, 34 is also changed to G and R, respectively.
The transmission densities of standard negatives D _G and D _R1 are changed logarithmically.
The amount of light used for printing F _G and F _R can also be adjusted in a well-balanced manner. Therefore, the printing time of each color can be balanced, and as a result, a good print can be obtained.

As described above, the light source color adjustment device for a color printer according to the present invention is extremely important in that it can control the amount of light for printing the three primary colors on photographic paper in a well-balanced manner, and as a result, it can obtain prints with good color balance. It has many advantages.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a color printer, FIG. 2 is a diagram showing the relationship between the cumulative transmission density of a negative and the amount of printing light, and FIG. 3 is a partially cutaway perspective view of a light source color adjusting device according to the present invention. 21... Board, 22... Bearing plate, 23... Rotating shaft, 24... Guide rod, 25... Mover, 26...
Steel ball, 27...Motor, 28...Filter holder, 29...Y filter, 30
...Y filter section, 31...M filter section,
32...M filter, 33...C filter section, 34...C filter, 35...cover.

Claims (1)

[Claims] 1. A rotary shaft in which a lead cam groove whose pitch changes logarithmically is formed, and a filter that rotatably holds a steel ball that slides into the lead cam groove and is arranged to be movable in the axial direction of the rotary shaft. A light source color adjustment device for a color printer, comprising: a filter, and a light source color adjusting device for a color printer, which inserts a filter into an optical path by rotating the rotation shaft, and logarithmically changes the amount of filter insertion.