JPS58217925A - Copying camera - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a platen for a contact screen and a photosensitive material, an optical system for projecting an original image onto the surface of the photosensitive material, a means for exposing the photosensitive material, and a method for exposing the photosensitive material. means for adjusting the original contact screen print, said exposure consisting of an imagewise main exposure through the contact screen, an imagewise additional exposure without the contact screen, and a non-imagewise additional exposure through the contact screen. This relates to a copy camera for making copies from.

In screen photography, the original is reproduced onto graph film through a contact screen.

The concept is generally to convert a continuous tone with a particular optical density on the original to a screen halftone with the same optical density on the film. For this purpose, halftones on the film are created by screen dots of different dimensions. A certain relationship exists between the screen dot size and the average optical density of the area containing the dot.

This is expressed as: where D is the optical density and a is the fraction of area occupied by dots.

Contact screens are used in many variations, differing in optical density gradient of one dot. The maximum optical density of the screens may also differ. If the original shows a large optical density variation, a contact screen with a high maximum optical density is used, and if the original has a small optical density variation, a contact screen with a small maximum optical density is used.

Every touch screen has a so-called "basic screen range", which indicates the original contrast range that can be replicated. For example, a standard screen has a basic screen range of 1.1. This means that an original with a contrast range of 1.1 can be adequately reproduced using this screen without any specific criteria to be made.

The original screen can be duplicated to contain a higher contrast range than the corresponding base screen range. A non-image additional exposure via the screen is used for this purpose, generally this is in the form of a flash exposure'1. ζ Again, when using a contact screen with a certain basic screen range &, a certain relationship exists between the maximum replicable contrast of the original and the amount of additional exposure. This relationship is expressed by the formula: [where R is the original contrast range and F
is the required flash exposure) and FO is the base flash exposure established in the particular system.

The condition is difficult if the original contrast range is much smaller than the basic screen range of the used screen. In this case, in addition to the main exposure, trial and error 111KI
Imagewise additional exposure can be given to the film without the presence of a screen (Bump).

Furthermore, for each original it is also possible to select a touch screen whose basic screen range corresponds to the contrast range of the original. In order to be able to properly reproduce any original as desired, a large number of touch screens are required and the procedure is extremely time consuming.

It is an object of the present invention to provide a camera that eliminates the need to select a screen and determines the exact main and additional exposures required to reproduce a particular original at the desired ttK.

To this end, according to the invention, the camera provides projections for one or more of the main and additional exposures after supplying the original minimum and maximum optical density, the optical data of the screen used and the necessary data of the camera and film. A combination machine is used to determine the amount of light and generate a screen print, and to make the specific dimensions of the highlight dots and the specific dimensions of the shadow dots correspond to the original minimum and maximum optical densities. In addition, the computer is equipped with an adjustable basic screen range adjuster to vary a specific main exposure while at the same time adapting at least one additional exposure to always or virtually match the original minimum at a specific dot size. and densities that continue to replicate the maximum optical density.

Other features and advantages of the invention will become apparent from the following description with reference to the drawings.

In Figures 1 to 3, the original optical density (OD
) is plotted with the horizontal axis KG. The lightest part of the original to be replicated is denoted by ODmln, and the darkest part to be replicated is denoted by ODmax. SR is the basic screen range of the contact screen used. The vertical axis shows the screen dot size (S) as the minus of the maximum screen dot size. In general, the original ODm
in, is preferably reproduced using positive film with a screen dot size of about 10-, the original ODm@x.

is preferably replicated using a screen dot size of about 90-. This is indicated in the figure by HD (highlight dot) and 8D (shaded dot) respectively. Original contrast range (ODmax,
-ODmin,) corresponds to the basic screen range (SR) of the screen used, then the imagewise (primary) exposure through the screen gives an image with a density gradient as shown in FIG. 1 by curve a. The exposure time of the main exposure depends on a number of constant actors, such as image ratio, diaphragm, and light source intensity. The only variable factor under these conditions is the original ODmin, according to the following equation: % (3) where T) I is the main exposure time and THo is the basic main exposure time. If an original is to be reproduced with a much smaller contrast range corresponding to the basic screen range of the screen, the main image exposure through the screen should be set to track II in FIG.
gives an image with a density gradient denoted by I&.

The darkest part of the original, ζ, is now reproduced with a dot size of about 60%, ie much brighter. Then, by applying additional image exposure without a screen, an image with a density gradient as shown by the curve is obtained. The screen dot dimensions of the original darkest part, 90, are then duplicated. The amount of additional image exposure without a screen (T, ) is determined by the following equation: where TB is the image base additional agricultural time p and SR is the base screen range of the contact screen. The sum of the main exposure and the additional exposure must be kept equal under these conditions to maintain accurate values of ODmin and related HD.

The resulting density gradient shown in the curve is identical to the curve as would be obtained if there was only a main exposure through the screen with a basic screen range of 5CR-1. By means of the imagewise additional exposure of the screen edge, any desired basic screen area can thus be selected practically.

In most cases, the contrast range of the [desired basic screen range] enlarged original, ie ODmax.

-onml, (curve b in Figure 2).

However, it is often desirable to have a displacement from this. In that case, [desired basic screen range J (S
CR) is substituted for the factor ODmax-ODmin,
must be introduced into Equation 4.

The formula for imagewise additional exposure without a screen is therefore: Figure 2 shows the resulting average gray ODg.

If the density gradient on the film is shown by the curve, ODg
is replicated with a dot size of approximately 30-. however,
It is desirable to replicate the original average gray color with a dot size of approximately 489g. ``If we set the desired base screen range J (SCR-2) and then give an imagewise additional exposure without a screen according to Equation 5, this additional exposure along with the main exposure creates a density gradient on the film shown by curve C. Give.This curve company, basic screen range 80
It corresponds to the curve as would be obtained if there was only a main exposure through a screen with R-2. If a non-image additional exposure by the screen is then used, the amount of which is calculated in a known manner, the density gradient on the film will be as shown by curve d. In this way, the original maximum and minimum optical densities are replicated on the film with specific screen dot dimensions for highlights and specific screen dot dimensions for shadow dots. The case is shown in which the screen is larger than the basic screen area.The main exposure line gives an image such that the density gradient is shown by curve a.In this case, no difference in contrast can be detected in the shaded dots.

The additional non-image exposure through the screen calculated as described above gives an image with a curved line and a density gradient. Again, the original maximum and minimum optical densities are replicated on the film with specific screen dot dimensions for highlight and shadow dots.

If it is desired to reproduce the midtones darker than in the original, an additional imagewise exposure without a screen can be performed again. For this purpose, [the desired basic screen range J 8CR-1 is introduced into Equation 5.

The density gradient obtained on the film by this exposure is plotted as curve C (FIG. 3). Non-image additional exposure through the screen is song #i! Give a density gradient as shown by d. All of these exposures are determined by a computer located within the copy camera.

FIG. 4 illustrates a computer 30 with input and output units. The computer 30 consists of a central processing unit (CPU) 10 (CPU), a path system 11, and a memory 13. Control board 12 pass system 1
1 to a central processing unit (CPU) 10. The combination camera 30 automatically controls all kinds of functions of the copy camera, such as the length of the main exposure 200, the length of the additional image exposure without the screen 21, and the additional non-image exposure with the screen 22. Data required for this control must be input. For example, an aperture in a diaphragm is automatically detected by a sensor at the location. for example.

Other data such as image ratios are entered via a keyboard located on the control board 12. The data is displayed to the operator on a display also located on the control board 12. Basic exposure time (F6 + TBo l T
uo) is determined by the computer 30 by data relating to the image ratio, lens, diaphragm, lamp, film sensitivity and basic screen range value of the screen. Original ODml. , and oI)max,
The relevant data is automatically entered into the computer by the exposure meter 23. If a non-automatic light meter is used, the ODmin and ODmBx values read therefrom can be entered via the keyboard on the front plate 12.

Original contrast range, i.e. ODmaX.

-ODmin, is smaller than the basic screen range of the screen (eg FIG. 2), a corresponding alarm appears on the display. The computer 30 can create by keying a "desired basic screen range" which is equal to the original contrast range. By means of columns 3 and 5 stored in memory 13, the computer is supplied with and displayed an additional exposure timer for the main exposure time and additional imagewise exposure without screen.

If the operator desires a different [desired base screen 17-y range] for the reason shown in the explanation of FIG. . The computer then again follows steps 2.3 and 5. and further executes formula 2.
Calculate the exposure time of the main exposure and the exposure time of the additional exposure.

The adjustable base screen range adjuster is created as a keyboard that works in conjunction with the computer. When new data about the original, screen, camera or film is entered, the basic screen range adjuster returns to its standard state.

The above examples are not intended to limit the invention.

→ For example, the adjustable basic screen range adjuster is
It may also take the form of an electrometer connected to a /D converter and provided with a suitable scale.

[Brief explanation of the drawing]

Fig. 1 is a graph in which the original contrast range is the same as the basic screen range of the m-circle tx screen, Fig. 2 is a graph in which the original contrast range is smaller than the basic screen range of the screen, and Fig. 3 is a graph in which the original contrast range is the same as the basic screen range of the screen. Figure 4 is a schematic diagram of a computer with input and conversion. 10... Central processing unit, 12... Control board, 13
...Memory, 20...Main exposure, "X,!5" Lilino, 28°°° exposure needle, 30...Computer. Fia, 1 JP-A-58-217925 (5) Fie, 3 Proceedings No. 1 Official Book July 22, 1980 Commissioner of the Japan Patent Office Mr. Kazuo Wakasugi 1 Indication of Case Patent Application No. 883298 of 1983
2. Title of the invention Copying camera 3. Relationship with the case of the person making the amendment Patent applicant name 7jt? -Edge A Print A Varnish 5
, Date of Amendment Order, Part 8, Contents of Amendment I, page 11, third line from the bottom [Figure 2 shows the resulting average gray ODo]. ], [Second
The figure does not show the average gray value occurring in the original in ODa. ” he corrected.

Claims (3)

[Claims] (1) comprising a contact screen and a platen for the photosensitive material, an optical system for projecting an original image onto the surface of the photosensitive material, means for exposing the photosensitive material, and means for adjusting the exposure; is the minimum and After providing the maximum optical density and the optical data of the screen used and the required data of the camera and film, the amount of light thrown for one or more of the main exposure and additional exposures is determined to produce a screen print and its highlight dots are determined. The computer is equipped with a computer that ensures that the specific dimensions and the specific dimensions of the shading dots always correspond to the original minimum and maximum optical densities, and this computer is equipped with an adjustable basic screen range regulator. , a reproduction camera characterized in that, at the same time as changing a particular main exposure, at least one additional exposure is adapted to constantly or virtually continue to replicate the minimum and maximum optical densities of the original at a particular dot size. . (2) For the standard condition of the adjustment device of the adjustable basic screen range, only if the minimum and maximum optical densities cannot be replicated at a particular dot size using two other exposures, or cannot be replicated exclusively; 2. A copying camera according to claim 1, wherein the computer determines the amount of light for the non-image additional exposure via the touch screen. (3) The adjustable basic screen range adjuster supplies original, screen, camera or film data, and returns to the standard state. copy camera.