JPH01200344A - Printer focusing - Google Patents

Abstract

PURPOSE:To shorten converging time for obtaining an AF curve by performing fine adjustment in the way that error between an initial lens position coarsely adjusted and a lens position for the most suitable focus is converged, and correcting the AF curve based on the lens position after the fine adjustment. CONSTITUTION:When lens positioning is performed to magnification which is indicated in advance, for example if the positioning is performed by means of a non-corrected AF curve, the error between the lens position obtained by said operation and the lens position for the most suitable focus may be increased. Such bit error as this is, for example, judged by the visual observation of a workman, and much time may be spent for performing convergence from the initial lens position to the lens position for the most suitable focus. Therefore, the coarse adjustment of the focus of the initial lens position is performed based on a projected image after the lens positioning is performed. Thus, the error can be minimized and the converging time by the fine adjustment can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a focusing method used in a printer that determines the printing magnification by changing the position and conjugate length of a printing lens.

[Prior Art] Photographic films include 35 mm size film, Brownie film, 110 size film, etc. The same photographic film also comes in full size and half size.

In order to cope with these various sizes of photographic film, a printing apparatus is known that changes the printing magnification by moving the printing lens and changing the conjugate length of the printing optical path. The amount of movement and conjugate length of this lens can be obtained from the AF curve. A conventional method for determining an AF curve will be described below.

FIG. 3 shows a schematic diagram of the printing device.

The negative film 60 is illuminated by a light source (not shown),
The transmitted light is irradiated onto the photographic paper 64 through the lens 62 and printed. Here, the following equation holds true using the first lens formula.

Here, A: Distance between the lens and the negative film S: Conjugate length f: Focal length of the lens Next, when specifying the magnification m and focusing at this magnification m1, according to the above formula (1), the following is obtained. The formula is obtained.

... (2) Furthermore, when the magnification m2 is specified and the object is focused, the following formula can be similarly obtained.

... (3) Here, Ap: Distance between negative film and lens reference (correction value) Ao: Distance between lens reference and lens position Sp: Distance between negative film and photographic paper reference (correction value) S'' : Distance between photographic paper reference and photographic paper position A'm, ,
S'm, : A', S'''m2 when the magnification is m
, S'm2: A', S' when the magnification is m2. Note that A' and S' are the values obtained by actually measuring the distance (for example, the number of sending pulses of a pulse motor), and ApSSp is the value when the focus is achieved. , is a value obtained from calculation when it is assumed that the above formula (1) holds true.

Here, A'ffl+, S'fll+, A'm2,
Since S'm2 is the distance from each reference position, its value is known, and the focal length f is also determined by the lens, so from equations (2) and (3) above, Ap.

It is possible to obtain Sp.

If either Ap or Sp is determined by Ap and sp obtained above, as shown by the following formula, then Ap or Sp
The other can be easily obtained.

Ap+A'sp+s'-(Ap+A')
f... (4) By the way, general printing equipment requires accurate magnification as well as focus, so in actual printing work, it is possible to obtain accurate focus by inputting the magnification. is necessary.

That is, it is considered that the focus is correct if the blur is within the permissible circle of confusion, but since the magnification changes within the in-focus range, correction is required accordingly.

Therefore, A' at a predetermined magnification is calculated using the following procedure.
Find S'.

First, the following formula holds true as the second lens formula.

-A... (5) Here, as in the case of focusing, Am,
Find Sm.

By finding Am and Sm from equations (6) and (7), if either Am or Sm is determined as shown in the following equation, Am
Alternatively, the other of Sm can be obtained.

By the simultaneous equations of this equation (8) and the above equation (4), A
o and S'' are found.

Repeat the above focusing work to find the optimal Ap Ssp, Am
, Sm is calculated and stored in the memory of the control unit, then
Thereafter, by inputting the magnification m, it is possible to easily find A' and S' that are in focus at that magnification.

However, with this focusing method, when moving the lens near focus, the worker operates the fine adjustment screw attached to the lens holder to adjust the focus. This makes it difficult to return to the selected optimal focus position, resulting in poor workability. In addition, it is necessary to project and visually check the focus state, but this is difficult in the so-called royal type printing equipment where the negative film is at the top and the photographic paper is at the bottom; The scope of applicability is limited to a so-called inverted printing device in which the paper is placed above.

Furthermore, when visually confirming a projected image of a negative film, the image illuminance is too low to make accurate determination.

For this reason, the applicant has determined that the optimum AF concave curve correction is performed by changing the lens position within a predetermined range and performing a printing process at each position to obtain the optimum focus based on the lens position and the actual magnification. It is proposed that the true AF concave curve be obtained by repeating the process until the focal point reaches the center of the processing range (Japanese Patent Application No. 172381/1981).

According to this, AF concave curve correction is almost automatically performed,
It is possible to reduce operations by the worker and prevent errors caused by manual work by the worker.

[Problem to be solved by the invention]

However, in such automatic focusing methods, focusing and magnification are performed simultaneously, and it takes a considerable amount of time to converge to obtain the optimal focus position at a given magnification, making it difficult to work efficiently. do not have. One of the causes of this is that there is a large error between the lens position according to the AF concave curve calculation result based on the predetermined conjugate length and the optimal lens position. In other words, since calculations are performed using an uncorrected AF concave curve at the initial stage, the convergence operation is performed from this point on, regardless of the degree of error and even if the lens position clearly deviates from the optimal focus position. (operation for finding the true AF concave curve) must be started.

In this way, a shift in the lens position that can be seen by the operator's visual inspection does not improve work efficiency since magnification and focusing are performed simultaneously as described above.

In consideration of the above facts, the present invention aims to provide a printer focusing method that can place the initial lens position near the focus point and shorten the convergence time for finding the AF concave curve. be.

[Means for Solving the Problems] A method for focusing a print according to the present invention performs coarse focus adjustment using a projected image at an initial lens position positioned based on a predetermined magnification. Fine adjustment is made to converge the error between the initial lens position and the lens position that becomes the optimum focus, and the AF concave curve is corrected based on the finely adjusted lens position, and the lens position and conjugate length are adjusted using this AF concave curve. It is characterized by calculating the focus at a set magnification.

[Operation] When positioning at a predetermined magnification, for example, when positioning is performed using an uncorrected AF concave curve, the error from the optimal focus position may become large.

Such a large error can be determined, for example, by visual inspection by an operator, and it takes a great deal of time to converge from this lens position to the lens position that provides optimal focus. In the present invention, after the positioning, the focus of the initial lens position is roughly adjusted based on the projected image, so that the error can be made as small as possible, and the convergence time due to fine adjustment can be shortened. Can be done.

[Embodiment FIG. 1 shows a Royal type photographic printing apparatus 10 to which the present invention is applied.
It is shown. The housing 12 has a base plate 1
A negative carrier 18 can be mounted on the negative carrier 16, and a negative film 18 is loaded into the negative carrier 16.

Inside the housing 12, a light source 20, an MMC filter 21, a mirror 21A, and a light softening section 22 are provided coaxially with the negative carrier 16, and the printing light is sent to the photographic paper 28 through a printing lens 24 and a shutter 26. There is. The drive of the shutter 26 is controlled by a signal from a control device 29 via a driver 27. In addition, MMC
The movement of the filter 21 onto the optical axis is also controlled by signals from the control device 29.

The housing 12 is attached to a part of a belt 34 that passes over a pulley 30.32, and the pulley 30.32 is movable in the vertical direction in FIG. 2 by receiving the driving force of a motor (not shown).

The printing lens 24 is attached to a turret 38, which is connected to the housing 12 by a screw shaft 36.
It is mounted on a lifting platform 40 that is pivotally supported. The turret 3 is driven by the mower 41 attached to this lifting platform 40.
8 is rotated so that another printing lens can be placed on the optical axis. Further, the lifting table 40 is prevented from rotating, and when the screw shaft 36 is rotated by the driving force of the motor 43, it moves up and down together with the turret 38, so that the position of the printing lens 24 can be changed.

A reflective mirror 42 is disposed within the housing 12 and is slidable in the horizontal direction. A portion of the mirror 42 is also attached to a belt 44. The belt 44 is wrapped around the pulleys 46 and 48, and these Boo!
When J46.48 receives the rotational force of a motor (not shown), the mirror 42 moves in the left-right direction in FIG. 1 and can advance and retreat onto the optical axis.

This mirror 42 reflects the printing light from the light source 20 and sends it to two image sensors 56 and 58 via a zoom lens 52 and a beam splitter 54. In the image sensors 56 and 58, a negative image having a thickness corresponding to the negative size is formed by the zoom lens 52, and each point of this negative image is scanned and photometered. This photometric data is supplied to the control device W129, and the exposure time is calculated.

The control device 29 includes a microcomputer 68, and the microcomputer 68 has a manual port door 0, an output port door 2, a CPU 74, a RAM 76, and a ROM.
78 and a bus 80 such as a data bus or a control bus that connects them. A keyboard 82 is connected to the input port door 0 of the control device 29, and by operating the keys on the keyboard 82, the magnification, the size of the negative film, etc. can be input. In addition, from this keyboard 82, manual input of the number attached to the photographic paper after the printing process, which will be described later, and manual input of the lens position when specifying the current position of the printing lens 24 (for example, the lens position can be automatically determined by key operation). (remembered) is also being carried out.

By the way, in the printing apparatus 10 of this embodiment, before performing a series of printing processes, the housing 12 is positioned at one location each at a high magnification position and at a low magnification position, and predetermined positions are determined to obtain the lens position and conjugate length. (The AF convex curve is corrected. In other words, once the printing lens 24 is determined, A
Based on the lens position and conjugate length obtained from the F convex curve, a motor 43 is driven to adjust the focus.

The control device 29 stores in advance a plurality of types of focus fine adjustment pitch dimensions (resolutions), and moves the lifting platform 40 to each of the four upper and lower positions in FIG. 1 based on the focused lens position. Position and select each position (
9 locations). At this time, numbers 1 to 9 are attached to the back side of the photographic paper 28 by a printing machine (not shown) in order from the lower lens position (lower side in Figure 1). This number can correspond to each lens position.

Here, the worker performs the above-mentioned printing process at two predetermined positions, high magnification and low magnification, selects the optimal focus position,
The number assigned to the selected photographic paper 28 is input to the control device 29. Here, since the minimum resolution differs depending on the applied printing lens 24, the above-mentioned resolution is made finer one after another as necessary, and the above-mentioned printing process is repeated.

Further, prior to this, the housing 12 is positioned at the predetermined high magnification and low magnification positions, an image is projected, and the projected image is visually checked to manually adjust the focus. That is, the in-focus position at the above magnification may be determined using the AF convex curve before correction, but if the calculation result based on the AF convex curve deviates greatly from the actual focus position, the correction will take time. Therefore, in this embodiment, the convergence time is shortened by focusing within a range that can be determined visually by the worker and applying the focused position as the initial position.

Next, the operation of this embodiment will be explained.

First, the operation of normal printing processing will be explained.

The printing light emitted from the light source 20 is diffused by the light diffusion tube 22 and illuminates the negative film 18. The light transmitted through the negative film 18 passes through the opening of the turret 38 and is laterally reflected by the mirror 42. Further, the reflected light passes through a zoom lens 52, is split by a beam splitter 54, and enters image sensors 56 and 58, respectively. A negative image of a size corresponding to the negative size is formed on these image sensors 56 and 58 by the zoom lens 52, and each point of this negative image is subjected to scanning photometry.

The image sensors 56 and 58 measure the density of each point on the negative image, and the printing exposure amount is calculated based on the obtained density values.

During printing, the turret 38 is rotated by the drive of the motor 41, and the printing lens 24 corresponding to the printing magnification is inserted on the optical axis. At the same time, the mirror 42 moves rightward in FIG. 1 and is retracted from the printing optical axis. Here, the shutter 26 is opened for a time corresponding to the printing exposure amount, and the image on the negative film is printed onto the photographic paper 28.

When changing the burning magnification, a burning magnification designation key (not shown) is operated. Δ depending on this specified burning magnification
The lens position and conjugate length are calculated using the F curve, and the screw shaft 36 is rotated to move the turret 38 up and down. At the same time, the belt 34 is driven to move the housing 12 up and down by a predetermined amount, changing the positions of the negative film 18 and the printing lens 24, and changing the conjugate length of the printing optical path.

Before performing the above-described printing process, it is necessary to correct the AF/curve to determine the lens position and conjugate length according to a predetermined magnification to obtain a true AF curve. Below, according to the flowcharts in Figure 2 (A) and (B), this true A
How to determine the F curve will be explained. .

First, in step 200, a lens to be applied is selected from among a plurality of printing lenses, and then in step 20
The housing 12 is moved and positioned based on the conjugate length on the high magnification side predetermined in step 2. In the next step 204, an image is projected in this state, and the lens is manually moved while visually observing the projected image to roughly adjust the focus. This focus adjustment may be determined by the operator, and may not actually be the optimum focus position. That is, the above operation can bring the camera closer to the optimal focus position to some extent. In the next step 206, the lens position of the in-focus point is input to the control device 29 and stored.

Next, when the input of the lens position at the high magnification position is completed in step 206, the process moves to step 208, and the housing 12 is adjusted based on the predetermined conjugate length on the low magnification side.
is moved and positioned, and the process moves to step 210.

In step 210, the same operation as in step 204 is performed, and when the lens is in focus, in step 212 the lens position at that time is input to the control device 29 and stored.

By performing the above operations, the initial lens position when correcting the AF curve can be brought as close as possible to the optimal position, and the convergence time for correcting the AF curve can be shortened.

Next, when the process of step 212 is completed, FIG. 2(B)
The process moves to step 214 to read out the initial resolution. A plurality of resolutions are stored in advance, and the initial resolution is a relatively coarse pitch dimension.

In the next step 216, the housing 12 is repositioned to the high magnification side that was positioned in the step 204, and then in the step 218, the lens position stored in the step 208 is used as the center for each pitch dimension of the resolution read out. Perform the baking process in places. In this case, numbers 1 to 9 are printed in order from the bottom of the lens position in FIG. Next, proceeding to step 220, the housing 12 is repositioned to the low magnification side positioned in step 210,
The process moves to step 222 and the same burning process as step 218 is performed. After the printing process is completed, it is developed and the worker selects the optimal print number (hereinafter referred to as "best print") N.
o,). In the next step 224, the selected best print No. is input, and in step 226 it is determined whether or not the set resolution is the minimum resolution of the applied printing lens 24. Here, in the case of a negative determination, the process moves to step 228 to read out a resolution one step finer than the previous one, and then moves to step 216, whereupon steps 218, 220, 222, 224, and 226 are applied. This is repeated until the minimum resolution of the printing lens 24 is reached, and when an affirmative determination is made in step 226, the process moves from step 226 to step 238 to input the magnification, and in the next step 240, this magnification and the best print N are input.
The AF curve is corrected based on the lens position based on o.

In this way, in this example, focus is emphasized, and the magnification is entered when the focus is finally achieved without changing the magnification, which shortens the convergence time until the focus is achieved and improves work efficiency. will improve.

[Effects of the Invention] As explained above, the printer focusing method according to the present invention allows the initial lens position to be placed near the in-focus point, thereby shortening the convergence time required to obtain the AF curve. It has this excellent effect.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a printing apparatus to which the present invention is applied, Figs. 2 (A) and (B) are flowcharts showing the focusing procedure, and Fig. 3 is a diagram of the printing apparatus to explain the focusing method. It is a schematic diagram. DESCRIPTION OF SYMBOLS 10... Printing device, 18... Negative film, 24... Lens, 28... Photographic paper, 29... Control device.

Claims (1)

[Claims] (1) Coarsely adjust the focus using the projected image at the initial lens position, which is positioned based on a predetermined magnification, and converge the error between the coarsely adjusted initial lens position and the optimal lens position. Make fine adjustments so that
A method for focusing a printer, comprising correcting an AF curve based on a lens position after fine adjustment, calculating a lens position and a conjugate length using this AF curve, and performing focusing at a set magnification.