DE2244705A1 - SELF-FOCUSING OPTICAL IMAGING DEVICE - Google Patents

Description

PATENT LAWYERS Dr.-Ing. Wolff

22ΑΛ705

fc *, T-T vv Dipl.-Chem. Dr. Brandes

br.-lng. hero
Diploma Phys. Wolff

7 Stuttgart 1, Lange Strasse 51

Tel. (0711) 296310 and 2972S5 ■

Telex 0722312 (patwo d)

Telegram address:

tlx 0722312 Wolff Stuttgart

Postal check account Stuttgart 7211 BLZ 60010070

Deutsche Bank AG, 14/28630 BLZ 60070070

Office hours: 8 a.m. to 12 p.m., 1 p.m. to 4.30 p.m. except Saturdays

Sept. 11, 1972 Our reference: 123 532/487375 kdk

Eastman Kodak Company »Röchester, New York State,
United States of America

Self-adjusting optical

The invention relates to a self-focusing optical imaging device with one between the object plane and Lens arranged in the image plane, which can be displaced along its optical axis for changing the magnification factor is arranged, and with a gear connected to the lens device for the automatic, the Adjustment resulting in the focus of the image as a function of the displacement movement of the lens the distance between the plane of the thing and the plane of the image.

Make changes to the enlargement factor during operation, is often required in the commercial production of photographic copies based on film negatives, if, for example, copies of different format sizes from a single negative or from a series of negatives are to be manufactured. In many cases, the desired magnification factors are both below and below also above the value one. If such an imaging device is in the form of a photographic copier or Once the magnifying device is in focus, it is extremely desirable to have this focusing automatically to be maintained if a different enlargement factor is used. However, it is a well-known one The fact that it is difficult to adjust the focus to be maintained when the enlargement factor is changed through the value one. This stems from it from the fact that the conjugate total distance (between thing plane and image plane) initially decreases when the magnification factor approaches the value one from above, however then increases again as one progresses from the value one to smaller enlargement factors. The kinematics to be applied Getriebelcher adjusting devices, for example

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in the form of cam control devices, designed for the range of magnification factors around the value one extremely complicated, so that most of such optical Imaging devices are designed either for magnification factors above the value one or for magnification factors below the value one.

Although it is one of US Pat. No. 3,408,145 Apparatus of the type mentioned is known that both magnification factors of more than one and magnification factors below the value one. However, this known device is in the process of being manufactured expensive, complicated to use and can only be removed over long periods of time with very careful handling keep in balanced state. With the latter known device is a fixed device arranged, a non-adjustable, stationary object plane forming a template holder is provided, and the lens and negative holder, which form the image plane are arranged so that they can be adjusted in position. In this known device, the lens and the negative holder adjusted at the same time, but independently of each other, in order to adjust the focus in the event of changes of the enlargement factor. The distance between the lens and the associated negative holder, So the image distance is in the known device by a crank and on the one hand on this and on the other hand adjusted push rod hinged to the associated negative holder. The distance between the lens and the template holder, so the thing width, is here by means of a crank, a control cam, a scanner for this and a rocker arm controlled by the scanner are set. The known device therefore has .zwei non-linear gear control devices, whereby an extremely complicated structure results.

3098 1 27 08 9 8 ■; '■.

The invention is based on the object of creating an imaging device of the type in question, which is particularly simple in construction and therefore inexpensive to manufacture.

Based on a device of the type mentioned, this object is achieved according to the invention in that the image plane is fixed to the device, that the lens is arranged adjustable in linear dependence on the setting of the desired magnification factor and that the lens is gear-connected device for setting the position of the object plane forming member displaceably arranged along the optical axis is coupled to this. As a result, as will be explained in more detail below with reference to the drawing, only a single non-linear device, which is geared to the lens, is provided to maintain the focus when the lens is longitudinally for a change in the magnification factor the optical axis is adjusted. In addition, in the device according to the invention, there is no such area restriction with regard to the magnification factors that can be achieved, as is the case with the known device mentioned.

The gear connected to the lens, in the case of the invention Device provided only nonvlinearc device serves only to depend on the respective magnification factor the distance between the lens and the object plane, i.e. the object width. This non-linear device can therefore be used in the device according to the invention be designed and constructed relatively simply.

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-ar-

The invention is explained in detail below with reference to an exemplary embodiment shown in the drawing explained.

Show it:

Fig. 1 is a schematically drawn representation of the beam path of an optical Imaging device in the form of a photographic copier and

Fig. 2 is a broken and partially cut side view of an embodiment an imaging device according to the invention.

In the following description, the invention will be explained using the example of a photographic copier. For the person skilled in the art, however, it is obvious that the invention is equally advantageous in camera systems is applicable where automatic focusing is desired.

Fig. 1 shows a schematically simplified representation photographic system with a negative or ping plane il and an image or copy level 13> between which an objective 15 is located. When the lens has a focal length f then have to obtain μΐη a sharp image with the magnification m; along an optical axis 17 measured distances between the thing plane Ii lind the lens 15 (i.e. the diiigweito) and between the lens 15 and apr image level 13 jd.h. the distance) exactly correspond to the following words:

1 Q 9 B 1 ? / Π 8 there

Thing width = f (1 + = r) Image width = f (1 + m).

Without considering the main point distance of the lens 15 corresponds to the total conjugate distance O.A between the Thing plane 11 and the image plane 13 with a magnification m the following equation:

O.A.

If, for example, an objective has a focal length f of four length units, then this results for magnification factors from magnification 4 down to magnification 0.6, see the table below listed relationships between magnification, object width, image distance and conjugate total distance.

Thing width Table I. Total conjugate distance enlargement (L.E) Image distance (L.E.) 5 _t 000 (L.E.) 25,000 4th 5.333 20,000 Η 333 3 6 _t ooo 16,000 iSjooo 2 8,000 I2,000 16 * 000 1 8,444 Ö, 000 16 [Ö44 0.9 9,000 7,600 16.200 0.8 9.714 7,200 16,514 0.7 10,667 6,800 17.067 0.6 6,400

From the above it can be seen that with decreasing Increase the distance between the thing plane 11 and the Objective 15, i.e. the object width, increases. In contrast to this the distance between the Objective 15 and the image plane 13, from left to right the image distance.

The fact that causes difficulties is the course of the conjugate total distance O.A., which, as can be seen from the table above, decreases when the magnification approaches the magnification factor 1 from above, and which then increases again when the magnification drops further to values below the magnification factor 1.

It is this fact that makes the creation of self-focus

render devices with a fixed copy plane or negative plane extremely difficult, because the relationship between lens and object plane relative to the image plane, or vice versa, the relationship between lens and image plane relative to the object plane, is described by a complex hyperbolic equation, which is very difficult to understand can be reduced to a mechanical configuration. The main difficulty with this equation occurs when the magnification approaches a factor of 1, where the cam pitch becomes too steep for practical use . In some cases the cam pitch would be

one _o
at the magnification factor / 90, which means practical impracticability. The invention now recognizes that there is a direct relationship between the desired magnification and the image distance, ie the distance between the lens 15 and the image plane 13. Since the image distance can be set in a relatively simple manner, since no equation has to be solved which specifies the distance of the thing plane 11 from the image plane at a given magnification, as is the case when the thing plane or the image plane is first adjusted, in contrast to this, in the invention, the objective is first relative to the image plane 13 adjusted at a predetermined desired magnification. Then the thing plane 11 is brought into position relative to the lens 15. From the table above and the equations given, it can be seen that such a

3 0 9 8 1? / f) B 9 8

The procedure is relatively simple.

In Flg. 2 is a self-focusing copier Gentäe an embodiment of the invention shown in more detail. A negative carrier tray 21 and an objective slide 23 are on a common guide rod 25 stored. The upper ends of the negative carrier slide 21 and the lens slide 23 are permanently effective Tension spring 27 connected to one another in order to eliminate any play in the device mechanism. On the frame 29 of the copier a cam or guide groove 31 is provided. Integral with the negative carrier slide 21 is on the the lower end of a projection 33 in the form of a fork, the prongs of which extend downward. A Angle lever 35 is pivotably mounted on an arm 37 of the lens slide 23. An arm 39 of the bell crank 35 carries a cam button 41 which runs in the guide groove 31 '. On the other arm 43 there is another cam switch 45 stored, which is used for positioning the negative carrier slide 21 and in the projection 33 of the negative carrier slide 21 intervenes.

In the negative carrier slide 21 there is a holding device for the recording which defines a plane 47 of the object a film negative. A suitable objective made up of lens elements 49 is mounted in the objective slide 23. Its optical axis 51 passes through the central area of the object plane 47 and the lens elements 49 and hits onto the central area of a copy or image plane 53.

From Fig. 2 it can be seen that the guide groove 31 is progressively curved downward when one of the starting area on the left advances to the right,

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until one arrives at a knee denoted by 55 in FIG. From this point, the guide groove 31 then drops rapidly downwards. As below, even better can be seen, the knee 55 represents the position of the cam switch 41, which this assumes when the magnification factor 1 is. Positions to the left of knee 55 correspond to magnification factors greater than 1 are, while positions of the cam button to the right of the knee 55 correspond to magnification factors of less than 1.

In operation, the angle lever 35 when the lens slide 23 is moved from left to right,. counterclockwise around the end of the arm 37 of the lens slide 23 pivoted. This has the effect that the carriage for positioning the negative carrier carriage 21 is in the Approach 33 seated cam button 45 in the approach 33 is moved so that the negative carrier slide 21 of the lens slide 23 is moved away. This increase in distance takes place progressively until the cam probe 41 reaches the region of the knee 55 of the guide groove 31. The increase in distance decreases from this area between the lens carriage and the negative carrier rs cn lit ten to a greater extent than a reduction in the distance takes place between the objective slide 23 and the image plane 53. This has the consequence that the total conjugate distance between the negative carrier and the image plane increases when the magnification factor drops below 1. -

In the case of the in connection with the explanation of Fig. 1 .--., -. - ■ ■ ■ -. ■■ ·. (· ■: - ■ ^ uy -, ':, "■ .-;

In the above equations, the main point spacing in the case of the objective 15 was disregarded ⁵ . The configuration of the guide groove 31, however, can be in up displayed below catfish determine t

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Let X be the abscissa of the cam probe 41, i.e. its Distance from image plane 53;

Y is the ordinate of the cam sensor 41, i.e. its vertical distance from the lower end of the arm 37 of the Lens slide;

θ the angle between the arms 39 and 43 of the angle lever 35;

° c is the angle between the arm 43 of the angle lever and the horizontal axis;

R is the length of arms 39 and 43, then:

X = ME + F ₁ + L + F ₂ + k- cos ( * c + Θ) R and

Y = Sin («: + θ) R,
where mean:

M = enlargement of the system (enlargement factor); E = effective focal length of the lens; F. = front focal length of the lens;

F ₂ = rear focal length of the lens;

L = length of the lens and

k »a constant representing the horizontal distance between the rear of the rear focus of the lens and the pivot axis at the lower end of the arm 37 of the lens carriage 23 is equivalent to.

With such a configuration of the guide groove 31, it is found that the Megativcarrier slide 21 is automatically adjusted in the correct V / eise so that the focus of the device is given when the lens slide to a desired, a desired

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22U705

distance from the image plane resulting in the enlargement factor 53 sets. The configuration of the guide groove 31 is of a relatively simple shape, so that none are inconvenient parts of the device are exposed to great stress and there are no problems with the Keep the device in a balanced state.

From the simplified formula, as it was given above in the explanation of FIG. 1, it can be seen that that the object width, i.e. the distance between the lens and the plane in which the negative is located, approaches the focal length f of the lens "as the magnification factor approaches 1. Hence the course of the guide groove 31 of the device shown in FIG. 2 approaches a straight line when the magnification factor increases to larger values, and the maximum value of the achievable with the device according to the invention, Enlargement is only limited by the length of the frame in which the guide groove 31 is worked out.

An actuator in the form of a toothed belt drive can advantageously be provided for setting the position of the lens be, through which the lens slide 23 is displaceable along the guide rod (25).

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Claims (6)

Claims Self-focusing optical imaging device, with one arranged between the object plane and the image plane Objective which is arranged displaceably along its optical axis for changing the magnification factor, and with a device geared to the lens for the automatic focusing of the Image-yielding adjustment of the distance that takes place as a function of the displacement movement of the lens between the object plane and the image plane, characterized in that the image plane (53) is fixed to the device is that the objective (23, 49) is linearly dependent on the setting of the desired magnification factor is arranged adjustable and that the device (31, 35, 37, 39, 41, 43, 45) for adjusting the position of a plane (47) forming the object, displaceable along the optical axis (51) arranged member (21) is coupled to this. 2. Apparatus according to claim 1, characterized in that the with the thing plane (47) forming, displaceable arranged member (21) coupled device a control cam (31) and a cooperating with this, the lens (23, 49) with the element (21) that forms the plane of the thing (47) and the cam switch (35, 37, 39, 41, 43, 45). 3. Apparatus according to claim 1 or 2, characterized in that the objective (49) is arranged in a along the optical axis (51) displaceably arranged objective slide (23) and that as the thing plane (47) forming member along the optical axis _{(51) Slidably arranged negative carrier slide} (21) provided for holding a negative to be copied igt 3098 1 2/10 89 8 4. Apparatus according to claim 3, characterized in that that for the optional setting of the magnification factor with the objective slide (23) effectively coupled toothed belt drive is provided for the adjustment of the position of the lens slide (23). 5. Apparatus according to claim 4, characterized in that the control cam as in a wall (29) of the Device recessed curved guide groove (31-) is formed and that "as a cam button one is articulated on a protruding arm (37) of the lens slide (23) Angle lever (35) is provided, one arm (43) of which is articulated to the negative carrier slide (21) and whose other arm (39) is in the guide groove (31) has guided feeler member (41). 6. Apparatus according to claim 5, characterized in that that the arm (39) of the angle lever which interacts with the guide groove (31) has a cam button roller which engages in the guide groove (31) (41) and the other arm (43) of the angle lever one in the slot of a fork-shaped extension (33) of the negative carrier slide (21) have guided second cam feeler roller (45) and that the guide groove (31) in a wall (29) of the device that runs parallel to the optical axis (51) is recessed. 309812/0898