JPS62159138A - Photographing method for rotary camera - Google Patents

Abstract

PURPOSE:To increase the photographic speed of a rotary camera by making the illuminance of a part which is distant from a part where the optical axis of a photographic lens crosses an original at right angles and photographed at the same time higher than the illuminance of the latter part. CONSTITUTION:Arrangement intervals of lamps of a lighting device 13 are made irregular intentionally so that the center part is rough and peripheral parts (both end parts) are close, and consequently the original has such a illuminance distribution that the peripheral parts of the original are higher in illuminance than the center part. the photographic lens 18 uses an ideal lens having no eclipse and further lighting with which the illuminance at the peripheral parts of the original has a value obtained by dividing the illuminance of the original center part by the quadruplicate of the cosine of an incidence angle of an optical axis to an axis connecting the peripheral parts and lens. Then, a slit opening 17 is made completely rectangular to uniform the optical density in one frame of a photographed picture.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a photographing method using a rotary micro camera that performs reduced photographing while moving an original and a photographic film in synchronization.

Most of the photographic film used in rotary micro cameras is 16mm wide and 30m to 200m long (other sizes are also available). Continuous paper, bills, checks, etc. that are printed out continuously are 1724, 1/40.1/42,
Photographed at a reduction ratio of 1750 mag.

The feature of the rotary micro camera is high-speed photography, that is,
This is because a large amount of documents can be photographed in a short period of time, and because the photographic film taken is a micro image, its volumetric capacity is small. For the above reasons, rotary micro cameras are widely used throughout the world, and are often installed in banks, general offices, and the like.

The reason why rotary micro cameras are considered to be capable of high-speed photography is thought to be that the documents targeted by rotary micro cameras are moving and are often photographed while they are moving. This makes it easier to install an auto feeder (automatic continuous document insertion machine), and as a result, it is thought that there is no need for the time required to change documents as required with the Chidoko Ni micro camera.

"Prior Art: Problems to be Solved by the Present Invention" As mentioned above, there has been a recent demand for even higher speeds in rotary micro cameras, where high-speed photography is a major feature. The reason for increasing the photographing speed of rotary micro cameras is to shorten the time required to photograph microfilm.

In a rotary micro camera, the document photographing speed is often expressed as the number of checks photographed per minute or the document moving speed (M/m1n). Most of the original photographing speeds of rotary micro cameras in the prior art are between 20 M/min and 60 M/min, and no progress has been made in increasing the original photographing speed beyond this current level.

The following are possible reasons why progress has not been made in increasing the shooting speed of rotary micro cameras.

One reason is that progress in increasing the sensitivity of photographic film has been slow. The photographic film used in rotary micro cameras has different characteristics from ordinary 35 mm film, and requires characteristics such as high γ value, fine graininess, and constant sensitivity. This is thought to be because it is difficult to increase sensitivity.

Furthermore, even if a high-sensitivity photographic film were developed, the rotary micro-cameras currently in widespread use would not have a film sensitivity switching mechanism (for example,
Even if a high-sensitivity photographic film for rotary-type microcameras could be created, it would be necessary to develop a rotary-type microcamera compatible with high-sensitivity photographic film because it does not have a (like the A sensitivity switching mechanism).

Other major reasons for the slow progress in increasing the shooting speed of rotary micro cameras are as follows.

The reason is that increasing the photographing speed even higher than that of the current rotary micro camera will lead to deterioration in the image quality of reduced photographed images, deterioration in the safety of photographed originals, and the like. For example, if you use a brighter lens, you can increase the shooting speed, but a brighter lens will shorten the depth of field or lower the resolution. has the disadvantage of being very expensive.

In addition, increasing the illuminance of document illumination may be considered as an improvement plan for increasing the photographing speed of a rotary micro camera without causing deterioration of image quality. However, due to the problem of heat generation, the high illuminance of document illumination for current rotary micro cameras is nearing its limit. Considering the safety of documents when jamming (document jamming) occurs inside a rotary micro camera, countermeasures against heat generation due to high illuminance of document illumination become a very big problem.

The amount of light energy applied to form an image of a constant density on a photographic film is Lux*5ec (illumination heavy exposure time of the film imaging surface), and this amount needs to be controlled to be constant. The illuminance of the film imaging surface is proportional to the square of the illuminance of the document surface and the brightness of the lens, and is inversely proportional to the square of the reduction ratio.

In a conventional rotary micro camera, each part of the document surface is illuminated uniformly.

Here, the exposure in the rotary micro camera is limited by a slit-shaped aperture between the lens and the photographic film or between the lens and the document surface, and the exposure time is limited by the slit-shaped aperture that is projected onto the photographic film. Determined by the width of the range (length in the direction of film movement) and film shooting movement speed, the reduced image (projected image of the slit-shaped aperture)
It is the value obtained by dividing the width of the film by the film photographing movement speed.

In general cameras, uniform illuminance illumination is necessary to obtain uniform image optical density within the frame, and is similar to the golden rule, but in rotary micro cameras, it is necessary to achieve uniform image optical density within the frame, but in rotary micro cameras, it is necessary to achieve uniform image optical density within the frame. Considering that (photographic film is exposed while constantly moving), it was found that this was not the case.

One is the distortion rate, which is one of the characteristics of the lens.
(rtion) is not a very important characteristic in general cameras, and if it was a factor of several tens of percent or more, there would be no problem. However, due to the special nature of the shooting method in rotary micro cameras (the photographic film is constantly moving while being exposed), the distortion rate is an important characteristic related to the resolution, which is one of the most important characteristics of the photographed reduced image. This characteristic requires the lens to have a low distortion rate, and its value is required to be one to two orders of magnitude lower than the distortion rate required for general camera lenses. − When a lens with a high distortion rate is used in a rotary micro camera, the image resolution shows a special tendency, and the resolution for a group of lines placed perpendicular to the direction of film travel is the same as the resolution of the lens. Although the deterioration is not so great compared to (without considering the deterioration caused by the film), the resolution for lines placed in the same direction as the film travel direction deteriorates, and the tendency is that the deterioration is worse in the surrounding area. Become. Furthermore, the deterioration in resolution becomes worse as the angle of incidence increases (that is, in the peripheral area).

One possible method for increasing the photographing speed of a rotary micro camera when the lens brightness and illuminance are constant is to increase the width of the slit-shaped aperture and lengthen the exposure time. The wider the range, the worse the distortion rate will be.
It cannot be used because the resolution becomes poor.

The shape of the slit-like aperture used in conventional rotary micro-cameras is approximately fan-shaped.

The reason for this is that the exposure time of each part is adjusted in order to make the optical density (0, D,) of each part of the photographed image constant.

A photographic lens has a characteristic that the larger the angle of incidence, the lower its ability to transmit light. At the same time, when an original is placed perpendicular to the optical axis of the photographic lens, the amount of light emitted by the original has the characteristic that the larger the incident angle, the lower the light output ability (the same thing applies to the film imaging surface). can be said),
When the illuminance of each part of the document is uniform, the illuminance of each part on the photographic film surface decreases as the angle of incidence increases. Therefore, in the past, in order to expose the photographic film to a certain amount of light energy in each area, by increasing the exposure time of the areas with low illuminance on the reduced image plane (the image forming area around the document), a fan-shaped slit-shaped opening was used. was used.

Currently, rotary micro cameras, like other machines, are required to be light, thin, and small. The opening angle of the slit-like openings in molds tends to increase.

There are three main reasons why the light transmission ability of a photographic lens decreases as the incident angle increases.One of them is the entrance pupil or exit pupil of the photographic lens, and the image formation of the document point being photographed or the photographic film. The solid angle formed between the two points becomes smaller as the incident angle increases.The second reason is that if the illuminated document is considered to be a completely diffused light source, the direction of the photographing lens will be smaller than the direction perpendicular to the document surface. This is because the ability to emit light decreases when tilted, and other reasons are due to lens performance (vignetting, etc.).

Lambert's law states that the amount of light emitted by a document decreases as the incident angle increases.

``Means for Solving the Problems'' The inventors of the present invention decided to overcome the above-mentioned limitations and somehow increase the photographing speed of the rotary micro camera5, and to improve the illuminance of the document illumination of the rotary micro camera. We departed from the conventional concept of uniform illumination and arrived at a method that provides non-uniform illumination. To explain further, generally when using non-uniform illumination intentionally, it is conceivable to make the illumination distribution non-uniform in order to make the image density of the breast meat uniform,
A feature of this invention is that non-uniform illumination is intentionally used to increase the photographing speed.

In other words, this invention can be used easily in a rotary micro camera without increasing the sensitivity of the photographic film, without deteriorating the image quality of the photographed micro images, and without significantly impairing the safety of the original. With the aim of increasing the shooting speed of a rotary micro camera, the optical axis of the photographing lens is photographed in the photographing method of a rotary micro camera, in which the document and photographic film are moved in synchronization while taking pictures in reduced size. The illuminance of the part that is far from the center of the original and is photographed at the same time (hereinafter referred to as the peripheral part of the original) is set higher than the illuminance of the part perpendicular to the original (hereinafter referred to as the central part of the original).

This is a photographing method characterized by the use of lighting that

If the angle between the optical axis and the line connecting the periphery of the document and the center of the photographing lens is the angle of incidence, then the illuminance at the periphery of the document is at least 4 times the cosine of the incident angle relative to the illuminance at the center of the document.
It is preferable to illuminate in such a manner that the light intensity is greater than or equal to the reciprocal of the power. More preferably, a rectangular slit opening is provided between the original and the photographic lens or between the photographic lens and the photographic film.

``Function'' In this invention, the effect of using illumination that increases the illumination intensity at the periphery of a document that is far from the center of the document is higher than the illuminance at the center of the document.

As mentioned above, in the case of a rotary micro camera, the limitations on image capture speed are concentrated around the document periphery due to limitations in image quality and exposure time, and there is plenty of leeway in other areas. This is the point of focus of the present invention, and furthermore, the general shape of the rotary micro camera makes it easy to remove heat generated locally (at the edges) by partial high-intensity illumination. In other words, in a rotary micro camera, the part with the worst resolution is the peripheral part (where the lens has a large distortion rate and the depth of field is shallow), and the part of the photographic film with low illuminance is also in the peripheral part.

- To make the image density of the breast meat uniform, the longest exposure time is the same peripheral area (the area where the light passes through the widest part of the fan-shaped slit).

Therefore, by increasing the illumination intensity of this area and making the slit width at the center closer to the slit width at the peripheral area, it is possible to easily increase the imaging speed. In other words, the amount of light increases at the periphery of the document, and the exposure time becomes longer at the center of the document, increasing the light energy exposed to the photographic film, so that the photographing speed can be increased.

Furthermore, since the image quality-related performance of the taking lens is better at the center of the document than at the periphery of the document, even if the width of the slit-shaped aperture at the center is wider than the width of the slit-shaped aperture at the periphery of the document. The image quality in the center area is wide enough that it does not deteriorate compared to the peripheral area, and the illumination matched to this inverse type slit-shaped aperture, that is, the illuminance of the peripheral area of the document, is adjusted to the angle of incidence multiplied by the fourth power of the cosine relative to the center area. By using illumination that is more than the reciprocal, it is possible to further increase the imaging speed.

On the other hand, it is preferable for the slit-like opening to have a rectangular shape in terms of machining, since it requires simple machining and reduces costs.

When using a photographic lens without a lens, etc., the illumination at the periphery of the document is equal to the illuminance at the center of the document, and the illumination at the center of the document is equal to 4 of the cosine of the angle of incidence.
By illuminating so that the value is divided by the power, uniform breast meat density can be obtained by using a slit-like opening with a rectangular shape.

Setting the illuminance at the periphery of the document to a value obtained by dividing the illuminance at the center of the document by the fourth power of the cosine of the incident angle means that the illuminance at the reduced image plane will be uniform in the partial area. , the use of a rectangular slit-shaped opening means that the exposure time is constant in a portion of the document.

The reason why the ratio of the illuminance at the periphery of the document to the illuminance at the center of the document is set to the fourth power of the cosine of the incident angle is to reduce the solid angle mentioned above.
And, when Zimbert's law is applied to both sides, the original side and the photographic film side.

Furthermore, due to the structure of the rotary micro camera, the increased amount of heat generated when the illumination around the document is increased to high illuminance is located in a location where the heat can be easily removed, making it possible to easily increase the imaging speed.

In particular, with Duplex and rotary micro cameras, the increase in heat generated when the surrounding area of the document is illuminated at high intensity is concentrated only on one side of the edge of the document due to its structure. It is very easy to add only one fan.

"Example" Examples of the present invention and comparative examples for comparison with the present invention will be described in detail below using simple drawings.

Embodiment 1 FIG. 1 shows a schematic configuration of a rotary micro camera to which the photographing method according to the present invention is applied.

In this figure, the number of reflecting mirrors is reduced for the sake of simplicity, and supports and moving mechanisms for each component are omitted.

The originals 11 are placed together in an auto feeder 12, and the auto feeder 2 automatically inserts the stacked originals 11 one by one into the original feeding mechanism.

The document 11 is moved to an illumination section (a portion where the document 11 is illuminated by the illumination device 13) by a document feeding mechanism (not shown).
and is transported to stocker 14.

The light is irradiated onto the original 11 in the illumination section by the illumination device 13, and the light reflected by the original 11 has an optical path bent by the reflection mirror 15 and passes between the slit-shaped openings 170 in the slit plate 16, and is then reflected by the photographing lens. 18, and further reduced and projected onto photographic film 19.

As shown, the moving direction of the original 11 is opposite to the moving direction of the photographic film 19, and each moving speed is proportional to the reduction ratio. Although not shown in the figure, two exhaust fans are provided on both sides of the illumination device 130, located at a height above the slit plate 16.

The feature of this invention is remarkable in the slit-like opening 17 in the slit plate 16, which has a rectangular shape.

Although not shown, this is a result of using illumination in which the illuminance distribution of the document illuminated by the illumination device 13 is such that the illuminance at the periphery of the document is higher than the illuminance at the center of the document. The optical density of a whole breast meat is uniform.

According to the first embodiment shown in FIG.
Since an ideal lens without Kuraray etc. is used, the illuminance at the periphery of the document is adjusted to the center of the document using the angle between the optical axis and the axis where the periphery of the document is connected to the lens. By using illumination that divides the illumination intensity by dividing the cosine of the incident angle to the fourth power, and by using a perfect rectangular shape for the slit-shaped aperture 17, the optical density of the breast meat in the photographed image is uniform. I am able to obtain things.

FIG. 2 shows the illuminance distribution of the lighting device 13 used in this Example 1, and the lamp (halogen lamp, tungsten lamp) 2.
1 is a graph showing the arrangement of No. 1, a reflecting plate.

The lamp arrangement, light intensity of the lamp, positional relationship between the lamp and the document, positional relationship between the lamp and the reflector, and material of the reflector were entered into a computer, and the illuminance of the document illumination was calculated using a simulation program. The results are shown in FIG. 2, which agrees well with the actual illuminance distribution.

By intentionally making the arrangement intervals of the lamps of this illumination device 13 uneven, making the center part loose and the peripheral parts (both ends) dense, the illuminance distribution of document illumination is The illuminance of the surrounding area is the reciprocal of the fourth power of the angle of incidence, and according to actual measurements, the illuminance was within a range of +5% to 0 with respect to the target illuminance value.

Note that as the light source of this lighting device 13, a double-cap type halogen lamp in which the filaments of a large number of halogen lamps are housed in a single glass tube may be used, and in this case, the arrangement interval of the filaments is set to The spacing between the lamps may be the same as that shown in the figure.

Furthermore, since the illumination device 13 does not have lamps arranged to increase the illuminance at the center of the document (arrangement where the lamps are closely spaced in the center), the power consumption is reduced, the cost is reduced, and the amount of heat generated is increased. Embodiment 1 uses this illumination device 13 and a slit plate 16 having a rectangular slit-shaped opening 17, so that the optical density within the image taken is uniform, and the original The photographing speed is increased to the extent that the illuminance at the periphery is greater than that at the center.

The angle of view of the photographing lens 18 in Example 1 is 34, and the illuminance of the peripheral area of the document by the illumination device 13 is 20 degrees higher than that of the center of the document.

The photographing speed of Example 1 was actually measured at 48-72rrL/1r.
1 inch, and the maximum speed is the value at the maximum rated value of the lamp power supply.

Comparative Example 1 For comparison, FIG. 3 shows a schematic configuration diagram of a conventional rotary micro camera in a shape similar to FIG. 1.

Comparative Example 1 differs from Example 1 in that the lighting device 33,
and illuminance distribution, slit plate 34, original moving speed, and photographic film moving speed.

The illumination device 33 is designed to provide uniform illumination; - the slit plate 34 is designed to provide uniform illumination of the breast meat;
The inner slit opening 35 is fan-shaped. Since the photographing lens of Comparative Example 1 is the same as that of Example 1,
The angle of view of the photographic lens 11 is 34, and the maximum angle of incidence is 17.
It is.

The slit-shaped opening 35 is ideally a curved line (cosine to the fourth power)
is necessary, but since it requires a lot of cost in actual machining, a straight line close to this curve is used instead (the width at the center of the slit opening 35 is 80% of the width at both ends).
It is not possible to obtain a uniform optical density of a piece of breast meat in the photographed image.

Furthermore, the processing cost for forming a slit-like opening into a fan shape is higher than the processing cost for forming a rectangular opening.

The illuminance of the illumination device 33 is the same as the illuminance of the central part of the illumination device 13 of the first embodiment, so that the illuminance is uniform. Since the width is the same as the width of the opening 170, the original moving speed and film moving speed (imaging speed) are slower by the narrowing of the central part of the slit-like opening 35 in the slit plate 34 (80%). The actual measurement value of the photographing speed in Comparative Example 1 was 40 m to 607 IL/min.

FIG. 4 shows a graph of the lamp arrangement of the lighting device 330 used in Comparative Example 1 and the illuminance distribution. According to the illumination device 33 of the conventional rotary micro camera, the lamps 21 are arranged almost evenly, as shown in FIG. 4, so that illumination with a uniform illuminance distribution is performed.

In addition, since Example 1 and Comparative Example 1 do not have the peripheral light intensity reduced by graphs, etc., the shooting speed of Comparative Example 1 is about 80 times slower than that of Example 1. However, if a low-cost photographic lens is used, the photographing speed will be slower.

Example 2 FIG. 5 shows a second embodiment of the invention.

Embodiment 32 differs from Embodiment 1 in the imaging mode, and is a simultaneous front and back imaging system (Duplex).

The flow of documents in the second embodiment is the same as in the first embodiment, but the illumination device 53, the reflecting mirror 52, the number of slit openings 59 in the slit plate 54, the photographing lens 58, etc. are different.

When the document 11 passes through the illumination unit, it is exposed to two illumination devices 5.
3, the front and back surfaces are illuminated simultaneously, and the reflected light has its optical path bent by two reflective mirrors 52, passes through two slit-shaped openings 59 in a slit plate 54, and is guided to a common photographic lens 58, where it is photographed. The image is formed on the film 19 to form a latent image.

The original illuminance distribution of the illuminating device 53 is different from the illuminance distribution of the illuminating device 13 of the first embodiment (FIG. 2).

FIG. 6 shows the lamp arrangement, illuminance distribution (the illuminance distribution is high on one side), etc. of the illumination device 53 used in Example 2.

Since the photographing lens 58 used in this example has some graphs, the illumination device 53 for creating the illuminance distribution is adjusted according to the graph of the lens body in accordance with the attenuation proportional to the fourth power of the cosine of the incident angle. The illuminance due to dimming is corrected.

In Example 2, the illuminance distribution is controlled by the arrangement density of the lamps, so the illumination device (
13, 53) where the lamp arrangement density is high, the heat generation is large, and the heat generation in other parts is not so different compared to the conventional lighting device 33.

Since the high-intensity illumination part of the illumination device 53 of the second embodiment is concentrated on one side due to the simultaneous front and back imaging system, one cooling fan for heat removal is installed on one side (that is, the part above the slit plate 54). It has the advantage of being simple and low cost since it only requires one piece.

Furthermore, the photographing lens 1 used in Example 1 is used as the photographing lens 58.
When using the same lens as 8, if the reduction ratio is the same,
The angle of incidence is more than double that of Example 1 compared to Comparative Example 1.
It will be larger than the value compared with the shooting speed.

In the second embodiment, the angle of view of the photographing lens 58 is 40 degrees, and in order to correct the light reduction due to the lens cran, the illuminance distribution of the illumination device 53 changes the illuminance of the document periphery from that of the center of the document. is illuminated with high illuminance of 40 or more.

The photographing speed of Example 2 was actually measured to be 44 m to 66 m.

"Effects of the Invention" As described above with reference to the drawings, examples, and comparative examples, the present invention overcomes the above-mentioned limitations in the conventional art and can realize an increase in the photographing speed of a rotary micro camera.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the photographing method of a rotary camera according to the present invention, FIG. The figure is a schematic configuration diagram for explaining a conventional rotary micro camera, FIG. 4 is a diagram showing the illuminance distribution, lamp arrangement, etc. by the illumination device 33 in FIG. 3, and FIG. FIG. 6 is a schematic configuration diagram showing another embodiment of the camera photographing method, and is a diagram showing the illuminance distribution, lamp arrangement, etc. by the illumination device 53 used in the second embodiment. 11: Document, 12: Auto feeder, 13゜53: Lighting device, 14: Stocker, 15.52 Two reflection mirrors,
16,54 Nislit plate, 17°59 Nislit opening, 18.58: Photographic lens, 19: Photographic film.

Claims (1)

[Claims] (1) In a photographing method using a rotary micro camera in which an original and a photographic film are moved in synchronization and are reduced in size using a photographing lens, the illuminance of the part where the optical axis of the photographing lens intersects perpendicularly to the original being photographed is A photographing method using a rotary micro camera characterized by using illumination that increases the illumination of a part that is distant from this part and is photographed at the same time.