JPS62176359A - Film image reader - Google Patents

Abstract

PURPOSE:To obtain the real magnification of a zoom optical system by permitting a photoelectric converter to read an image formed by a reference chart and expressing interms of the magnification from the size of the formed image and that of the reference chart. CONSTITUTION:A distance La from the reference chart 17 to the reflecting surface of a reflection mirror 19 is set to a one equivalent to an interval Lb from the film surface of a video film 9 to the reflecting surface of the reflection mirror 19 in two directions of an optical axis 2. A motor control signal is supplied to a motor drive circuit 13 to move a film scan stage 5 to the prescribed position, and the reflection mirror 19 with a magnification index mechanism is allowed to coincide with an optical axis 2. At that time, light from chart light sources 18 and 18 through the reference chart 17 is reflected by the reflection mirror 19, enlarged or reduced at the magnification of the zoom optical system 6, thereby forming the image of the reference chart 17 on an image forming surface 8. It ends up an image with l3 where the length of an light transmitting part 17a is l1. As l1 is given, the real magnification (n) can be obtained from n=l3/l1 by measuring l3, and a central control unit 12 carries out arithmetic operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a film image reading device that reads a film image reproduced by an optical system as electrical signal image information data using a photoelectric conversion device such as a COD. .

(Conventional example) Conventionally, this type of film image reading device irradiates the film surface of a positive film or negative film with light from a light source,
The light transmitted through the film is imaged by a zoom optical system on an imaging plane on a so-called photoelectric conversion device, and the formed image is converted into image information data in the form of electrical signals by the photoelectric conversion device. There is. □ The photoelectric conversion device uses a one-dimensional image sensor using COD or the like, and obtains image information data for one image by scanning the projection plane.

Here, in order to obtain high-quality image information data, it is necessary to form a reproduced image with excellent image quality. For example, the amount of light for imaging 1q by an image film having a film surface with a completely uniform density distribution must be uniform in all parts of the imaging surface.

Therefore, in the past, a diffuser plate or a condenser lens was provided between the light source and the video film, and a means was provided to uniformly irradiate the entire film surface of the video film with the light from the light source. There are means for finely adjusting the position of the light source as well as providing a lens.

However, with this method, there are problems such as a decrease in the amount of light from the light source, variations in characteristics due to the effects of the performance of the diffuser plate and condenser lens, and limits to the improvement of characteristics even if the position of the light source is delicately adjusted. In addition, there are problems such as an increase in the size of the device, an increase in the number of arms and legs, and an increase in costs.

Furthermore, there are methods for narrowing down the aperture of the lens and means for correcting the average distribution of light amount using a two-dimensional shading correction circuit, but the aperture means reduces the amount of light from the light source, so It becomes difficult to convert into image information data of image quality. Further, the two-dimensional shading correction circuit has problems such as a complicated structure and high cost.

Furthermore, in order to reduce the influence of such a problem, that is, the influence of light intensity inconsistency, conventionally, instead of performing so-called scanning by moving the photoelectric conversion device three times, on the contrary, by moving the image film side, the relative There are some methods (such as Japanese Unexamined Patent Publication No. 59-202774) that attempt to obtain the same effect as scanning by a photoelectric conversion device.

In this method of scanning video film (hereinafter referred to as film scanning method), the photoelectric conversion device is fixed and the relative position between the photoelectric conversion device and the zoom optical system does not change. Shading correction between the original image and the sensor can be done by one-dimensionally averaging the amount of light incident on each light-receiving element arranged one-dimensionally in a narrow width. This adjustment is simpler and can be averaged better than an adjustment that averages the average value.

(Problems to be Solved by the Invention) However, the film scanning method has the following problems.

As mentioned above, the photoelectric conversion device is fixed and the relative position between the photoelectric conversion device and the zoom optical system does not change, so if the magnification of the zoom optical system changes, the image formed on the photoelectric conversion device will shift with respect to the moving speed of the video film. The speed also changes. for example,
When the magnification is increased, an enlarged image is formed, so the speed at which the image is formed is faster than the speed at which the video film actually moves.

Furthermore, the imaging range also changes depending on the magnification. For this reason, it is necessary to change the speed and range of moving the video film accordingly according to the determined magnification, and in order to adjust the speed and range of moving this video film, it is necessary to detect the accurate zoom magnification. This is necessary.

Conventionally, a potentiometer linked to a zoom ring of a zoom lens is provided, and the magnification of the zoom optical system is calculated based on voltage changes detected from the potentiometer. However, since the characteristics between the magnification of the lens and the rotation angle of the zoom ring are nonlinear, they cannot be easily calculated, and a conversion table must be created. In addition, in order to perform accurate conversion, it is necessary to increase the number of points for conversion, which has the disadvantage of increasing the circuit scale.・Furthermore, since there are individual differences in zoom optical systems even if they have the same design, a conversion table must be created for each zoom optical system, which greatly reduces costs during production. It was difficult.

(Means for Solving the Problems) In view of the above conventional problems, the present invention provides a film image reading device using a film scanning method that appropriately adjusts the moving speed and range of an image film by changing the magnification of a zoom optical system. An object of the present invention is to provide a film image reading device that can perform accurate scanning according to the lens magnification by detecting the magnification of a zoom optical system with high precision.

In order to achieve this object, the present invention provides a slit-like reference chart that is pre-formed in a predetermined shape and is insertable at a position equivalent to the distance between the video film and the zoom optical system, and forms an image using the reference chart. Read with a photoelectric conversion device,
The technical point is that the actual magnification is accurately converted from the size of the image and the size of the reference chart.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of a film image reading device according to the present invention.

First, to explain the configuration, a diffuser plate 3, a condenser lens 4, a film scanning stage 5, a zoom optical system 6, and a photoelectric conversion device 7 are provided in this order along the optical axis 2 (indicated by a two-dot chain line) of a light source 1. , the light-receiving surfaces of the light-receiving elements arranged one-dimensionally in the photoelectric conversion device 7 are provided so as to serve as the image-forming surface 8 of the zoom optical system 6. Note that a description of the internal structure of the zoom optical system 6 will be omitted.

The film scanning stage 5 is provided with a film holder 10 on which the image film 9 is mounted so that the film surface is perpendicular to the optical axis 2. By moving in the axial direction (arrow Y), the video film 9 can be inserted into and removed from the optical axis 2.

Reference numeral 12 denotes a central control device using a microcomputer or the like, which instructs the motor drive circuit 13 to perform a predetermined operation of the drive motor 11, and also instructs the drive circuit 14 to perform a photoelectric conversion operation by causing the photoelectric conversion device 7 to perform a photoelectric conversion operation. Furthermore, command control is performed to cause the analog signal image information data detected by the photoelectric conversion device 7 to be converted into discrete image information data by the A/D converter 15 and stored in the storage device 16. or,
The central control device 12 can perform so-called image processing based on the image information data in the storage device 16.

Further, a magnification index mechanism including a slit-shaped reference chart 17, a chart light source 18, and a reflecting mirror 19 is provided on the end face of the film scanning stage 5 on the zoom optical system 6 side.

FIG. 2 shows an enlarged view of the structure of the magnification indicator mechanism.

A chart light source 1 consisting of two light emitting diodes (LEDs) etc. is placed in a so-called dark box fixed to a film scanning stage 5.
8 are housed in the same direction, and a reference chart 17 is vertically fixed to the front face of the light emitting direction, that is, a partial opening of the dark box.In front of the reference chart 17, there is a reflector tilted at a predetermined angle. 19 is fixed, and the light from the chart light source 18 that passes through the slit of the reference chart 17 is reflected by the reflecting mirror 1.
9, the light is reflected in a direction parallel to the optical axis 2.

When the film scanning stage 5 is advanced to a predetermined position by the drive motor 11, the reflected light from the chart light source 18 coincides with the optical axis of the zoom optical system 6, and an enlarged or reduced image of the reference chart 17 is formed. The image is formed on surface 8.

Note that the distance 1a between the reference chart 17 and the reflective surface of the reflective mirror 19 is a distance equivalent to the distance Lb from the film surface of the image film 9 to the reflective surface of the reflective mirror 19 in the two directions of the optical axis (in this embodiment, La = Lb).

Further, the image corresponding to the reference chart 17 is formed by the photoelectric conversion device 7.
The positional relationship among the chart light source 18, 18, reference chart 17, reflecting mirror 19, and photoelectric conversion device 7 is set so that the image is formed in accordance with the one-dimensional array of photoelectric conversion elements.

FIG. 3 is a plan view showing the structure of the reference chart 17 and the chart light source 18. The reference chart 17 is made of transparent glass with a slit-shaped light transmitting portion 17 having a length of 11 and a width of 12.
The entire surface except for part a is vapor-deposited with aluminum so that light can pass through the light transmitting part 17a. or,
Light transmitted from light source 18.18 for chart 17a
The light passing through is adjusted so that both the amount of light and the emission intensity distribution are equal.

As shown in FIG. 1, the magnification index and the film holder 10 are arranged at different positions, and when the film scanning stage 5 is moved so that the film holder 10 is aligned with the optical axis 2, The magnification index mechanism moves to a position off the optical axis 2, and conversely, when the magnification index mechanism is aligned with the optical axis 2, the film holder 10 moves to a position off the optical axis 2.

Next, the operation of the film image reading device having such a configuration will be explained.

First, a motor control signal is supplied from the central controller 12 to the motor drive circuit 13 to move the film scanning stage 5 to a predetermined position, and as shown in FIGS. 1 and 2, the reflection @19 of the magnification index mechanism is Align it with optical axis 2. At this time, the chart light source 18.18 passing through the reference chart 17
The light is reflected by the reflecting mirror 19, and is enlarged or reduced by the magnification of the zoom optical system 6, and is reflected on the reference chart 17 on the imaging plane 8.
Connect the @ (hereinafter referred to as chart image) and connect the light transmitting part 17.
There are 13 images for the length 11 of a, and 14 images for the width 12. If the magnification of the zoom optical system 6 at this time is n, then 11.3=n-fLl - (1) 14=n-
12...(2) Since 11 is known in advance, by measuring the length of m3, the true magnification n can be found from n=stop 3/11...(3>) , the central controller 12 executes the above formula (3
).

That is, the chart image on the imaging plane 8 is scanned by the photoelectric conversion device 7, and is stored in the storage device 16 as discrete image information data by the A/D converter 15, and the central control device 12 uses the stored data. Detect the length 13 of the chart image based on
The true magnification n is calculated by calculating the above equation (3). Note that data regarding the length 11 of the reference chart 17 is stored in the central control device 12 in advance.

4 and 5 show the sales distribution of the chart image in terms of the electrical signal level from the photoelectric conversion device 7, and also show it according to the difference in magnification.

For example, in FIG. 4, the magnification of the zoom optical system 6 is n=
In the case of 1, the length of the chart image is 13=11, and the light amount of the portions 18a and 18b corresponding to the chart light source 18.18 is projected with respect to the reference level BL.

In FIG. 5, when the magnification of the zoom optical system 6 is n=N, the length of the chart image is L3=N-11, and the light intensity of the portions 18a and 18b corresponding to the chart light source 18.18 is at the reference level BL. stand out against

Here, in FIGS. 4 and 5, the protruding portion 18a
, 18b intersect with the threshold T +-1 at four points 18c, 1
8d, 18'e, and 18f exist.

The light intensity distribution of such a chart image is photoelectric variable 1! It is stored as image information data in the storage device 16 from the A device 7. Here, the necessary points 18C and 18f are determined by sequentially reading data from the lower address of the image information storage part of the storage device 16, comparing it with the threshold value TH, and selecting the point that first exceeds the threshold value TH.
C1 Conversely, read data sequentially from the upper address and set the threshold value TH.
This can be determined by comparing this with 18f and setting the point at which the threshold value TH is exceeded for the first time.

The central controller 12 calculates the distance between the two points 18C and 18f in the part where the amount of light changes rapidly based on the length of the chart image 11.
, 3.

Specifically, since the position of the photoelectric conversion element corresponding to each pixel of the photoelectric conversion device 7 is associated with the so-called storage address of the recording/hiding device 16, data exceeding the threshold TH will not be stored. The address interval between the storage addresses in the memory address is detected as being equivalent to a length of 13. That is, the fourth
The interval P1 shown in FIG. P2 is the address interval, Pl corresponds to 11, and P2 corresponds to N-11.

In this way, by calculating the central controller 12 according to the above equations (1) and (3), the true magnification of the zoom optical system 6 can be obtained, and the moving speed and moving range of the video film in the film scanning method can be calculated. Be able to control accurately.

In this embodiment, two light emitting diodes with good directivity are used as the chart light source 18, but if a light emitting diode with strong light diffusivity is used, optical axis adjustment becomes unnecessary.

Also, if the relationship between the width 12 of the reference chart 17 and the width 14 of the chart image is n-fL2)11,4...(4), then the width is at the position of the reference chart 17 for detecting the magnification. This makes initial adjustment easier.

FIG. 6 shows the structure of the magnification indicator mechanism in Haku's embodiment, and is a simplified version of the mechanism.

In this method, a rectangular hole 21 through which light passes is bored in the center of an opaque thin plate 20 of a size that can be attached to the film holder 10 shown in FIG. The image of the hole 21 is formed on the imaging plane 8 by the light from the light source 1 by moving the film scanning stage 5 shown in FIG. It is detected by the central control device 12. By storing the length of the hole 21 in advance in the central controller 12, the true magnification of the zoom optical system 6 can be calculated based on (3) above.

Furthermore, instead of the thin plate 20, a video film having an image pattern as shown in FIG. 6 may be used.

According to this embodiment, since the light source 1 is used, the pair of chart light emitting sources 18 and reflecting mirror 19 shown in FIG. 1 are unnecessary, and the structure can be simplified.

FIG. 7 shows still another embodiment, in which a hole 2 of a predetermined shape is formed at one end of the film scanning stage 5 on which the video film 9 is mounted.
2, and a reference chart 1-24 having transparent portions 23 at a predetermined interval 15 is directly fixed to the hole 22. Then, the film scanning stage 5 is moved to a predetermined position and an image formed by the transparent portion 23 is formed on the imaging plane 8 by the light from the light source 1 shown in FIG. Detected by central control unit @12. By storing the length of the transparent portion 23 in advance in the central controller 12, the true magnification of the zoom optical system 6 can be calculated based on the above equation (3).

According to this embodiment, since the light source 1 is used, the chart light emitting source 18 and the reflecting mirror 19 shown in FIG. 1 are unnecessary, and the structure can be simplified, and the structure can be simplified. Since there is no need to attach the thin plate 20 to the film holder 10, the operation becomes easy.

(Effects of the Invention) As explained above, according to the present invention, the size of the image is detected by enlarging or reducing the reference chart through the zoom optical system, and the size of the image and the size of the reference chart are detected. Since the magnification is calculated from , the true magnification of the zoom optical system can be obtained.

Further, since the structure is simple and a conventional mechanism can be used, the cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the film image reading device according to the present invention, FIG. 2 is an enlarged block diagram of the magnification indicator mechanism shown in FIG. 1, and FIG. 3 is a block diagram showing the reference chart and chart light source shown in FIG. FIG. 4 and FIG. 5 are explanatory diagrams showing an example of the light intensity distribution of a chart image, FIG. 6 is a plan view showing another embodiment, and FIG. 7 is a plan view showing still another embodiment. FIG. 1: Light source 2: Optical axis 3: Diffusion plate 4: Condenser lens 5: Film scanning stage 6: Zoom optical system 7: Photoelectric conversion device 8: Image forming surface 9: Image film 10: Film holder 11: Drive motor 12: Center Control device 13: Motor drive circuit 14 Drive circuit 15: A/D converter 16 Storage device 17.24: Base M chart 18 Chart light source 19: Reflector 20: Thin plate 21.22: Hole 23: Transparent part

Claims (4)

[Claims] (1) A light source that irradiates light onto an image film, a zoom optical system that forms an image of the light transmitted through the film on an image forming surface, and converts the image formed on the image forming surface into image information data consisting of electrical signals. A film image reading device comprising a photoelectric conversion device for converting the image and a moving means for moving the image film, further comprising means for forming an image of a reference chart indicating a reference length on the image forming plane by the zoom optical system. 1. A film image reading device comprising a reference magnification indicator mechanism. (2) The film image reading device according to claim 1, wherein the reference magnification indicator mechanism inserts the reference chart at the same position as the film with respect to the optical axis. (3) The reference magnification indicator mechanism includes a chart light source and a reflecting mirror that reflects the light emitted from the chart light source in the optical axis direction, and extends from the reflecting surface of the reflecting mirror to the image film surface. 2. A film image reading device according to claim 1, wherein said reference chart is set at a distance equal to a distance in an optical axis direction of said reference chart. (4) The size of the image formed with respect to the reference chart is detected based on the image information data converted by the photoelectric conversion device, and the size of the image formed with respect to the reference chart is detected based on the size of the reference chart stored in advance and the detected size of the image. 2. The film image reading device according to claim 1, further comprising a central control unit that calculates the magnification of the zoom optical system.