JPH04296742A - Image data reader - Google Patents

Abstract

PURPOSE:To measure accurate density in each wavelength band at each point on a photographic film by displacing a small aperture on an object frame of light measurement in two dimensions. CONSTITUTION:A light shield plate 15 is arranged below a mirror box 13 in contact with the reverse surface of a negative film 10 and the small aperture 14 is formed in the light shield plate 15. A shift part 16 moves the light shield plate 15 intermittently in the breadth direction of the film 10 to put the small aperture 14 in main scanning motion on the photometric object frame. A film feed roller couple 11 sends the film 10 in the subscanning direction by the breadth of the small aperture 14. A collimator 20, a spectroscope 21, a cylindrical lens 22, and a line sensor 23 are arranged below the small aperture 14 and moves in synchronism with the light shield plate 15. The line sensor 23 consists of a CCD where many photodetecting elements are linearly arranged and detects light intensity in each wavelength band of spectral light. The photodetection signal from the line sensor 23 is sent to a characteristic value calculation part 30 arranged on a printer side.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data reading device used in determining the printing exposure amount of a photographic printer or the like.

0002

2. Description of the Related Art In a photographic printer, an image of a frame to be photometered is illuminated by a light source, the transmitted light is spectrally resolved, and the intensity of this spectral light is measured.
Devices for determining the printing exposure amount have been proposed (e.g.
JP-A-1-142719).

0003

[Problems to be Solved by the Invention] In the above device, the transmitted light from the slit is split into spectra using a spectroscope, and the split light is split into two-dimensional CCDs.
The spectral intensity is calculated for each wavelength and used to control the exposure amount. However, in this method, since the slit is formed to span the entire width of the frame to be photometered, there is a possibility that light in the longitudinal direction of the slit may be mixed on the CCD light receiving surface. In this case, there is a problem in that it becomes difficult to accurately measure the density at each point of the frame to be photometered.

The present invention is intended to solve the above-mentioned problems, and provides an image data reading device that can accurately measure the concentration of each wavelength band after spectroscopy for each point of a frame to be photometered. The purpose is to provide

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a light source for illuminating a frame to be photometered on a photographic film, a small aperture, and a light source that illuminates the frame to be photometered in a two-dimensional manner. a collimator that converts the transmitted light of the frame to be measured from a small aperture into parallel light, a spectroscope that spectrally decomposes the parallel light from the collimator, a lens that forms a line-shaped image of the spectral light, and a lens. and a line sensor placed at the imaging position. Another invention uses a liquid crystal panel in which small liquid crystal shutters are arranged in a matrix instead of the means for displacing the small opening in two-dimensional directions.

[0006]

[Operation] The frame to be measured on the photographic film is illuminated by a light source. The light shielding plate is displaced in a two-dimensional direction with respect to the frame to be photometered. As a result, the small aperture scans the frame to be photometered. The transmitted light of the frame to be measured through the small aperture is collimated by a collimator and then spectrally decomposed by a spectrometer. The light intensity of this spectrum light is detected by a line sensor. In this way, the density of each wavelength band of the spectral light is detected for each point of the frame to be photometered, so the accuracy of determining the exposure amount is improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing an image data reading apparatus embodying the present invention. This data reading device is used not only by being placed on the entrance side of a film carrier of a photographic printer, but also by a negative verification machine and the like. The negative film 10 is intermittently fed by a pair of film feeding rollers 11. Above this film transport path, a photometric light source 12 is provided.
A mirror box 13 is arranged to uniformly diffuse this light and illuminate the frame to be photometered. Further, a light shielding plate 15 is arranged below the mirror box 13 so as to be in contact with the lower surface of the negative film 10. A small rectangular opening 14 is formed in the light shielding plate 15. Note that this small opening 14 may have a pinhole instead of a rectangular shape. The shift unit 16 intermittently moves the light shielding plate 15 in the width direction of the film 10, and main scans the small aperture 14 over the frame to be photometered in the film width direction. After this main scanning, the film feed roller pair 11 feeds the film 10 by the width of the small opening 14 and performs a sub-scanning. As a result, the small aperture 14 moves in a two-dimensional direction with respect to the frame to be photometered.

A collimator 20, a spectroscope 21, a cylindrical lens 22, and a line sensor 23 are arranged in this order below the small aperture 14. These are attached so as to be integrated with the light shielding plate 15, and as the light shielding plate 15 moves, these also move in the film width direction. As is well known, the collimator 20 converts the transmitted light that has passed through the small aperture 14 into parallel light. The spectrometer 21 uses a prism or a diffraction grating, and decomposes the parallel light that has passed through the collimator 20 into spectra. The cylindrical lens 22 forms a line image of the spectral light on the light receiving surface of the line sensor 23 . The line sensor 23 is composed of a CCD in which a large number of light receiving elements 24 are arranged in a straight line, and detects the light intensity of each wavelength band of the spectral light. The light reception signal from the line sensor 23 is sent to a well-known characteristic value calculation unit 30 located on the printer side. The characteristic value calculation section 30 is composed of a microcomputer, and processes the light reception signal to calculate various characteristic values such as LATD, maximum density, and minimum density necessary for calculating the printing exposure amount. Note that when calculating these characteristic values, the spectral intensity is weighted with respect to its wavelength band to match the spectral sensitivity of the color paper. The exposure calculation unit 31 calculates the printing exposure from various characteristic values using a well-known exposure calculation formula.

[0009] In the above embodiment, the negative film 10
I made it possible to sub-scan the photometry target frame by sending
Alternatively, the small opening 14 may be displaced in the film feeding direction by a shift section in the same way as in the main scanning. Also,
The scanning area may be reduced by projecting the photometric target frame of the negative film using a reduction optical system. In this case, a general-purpose two-dimensional CCD sensor can be used, the cost of the apparatus can be reduced, and a cylindrical lens is not required. Further, instead of shifting the line sensor together with the light shielding plate, the line sensor may be fixedly arranged in the film width direction. In this case,
Each light-receiving element of the line sensor is formed long enough to correspond to the main scanning range of the small aperture, and the light-receiving element of the line sensor is selectively used in synchronization with the main scanning of the small aperture. Moreover, instead of mechanical scanning, as shown in FIG. 2, a liquid crystal panel 51 in which minute liquid crystal shutters 50 are arranged in a matrix is used,
The image of the frame to be photometered on the negative film 53 may be scanned. In this case, the driver 54 sequentially opens the liquid crystal shutter 50 to scan the frame to be photometered in a two-dimensional direction. Further, a large number of microlenses 52 are arranged in a matrix in correspondence with each shutter 50, and the light passing through each shutter 50 is made into parallel light.

0010

[Effects of the Invention] As explained above, according to the present invention,
Since the small aperture is displaced two-dimensionally on the frame to be photometered, the transmitted light does not overlap in the longitudinal direction of the slit, which is the case with slits that are long in the width direction of the film, and each point on the photographic film is Accurate concentration measurements can be made in each wavelength band.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an image data reading device embodying the present invention.

FIG. 2 is a schematic diagram showing another embodiment using a liquid crystal panel.

[Explanation of symbols]

10 Negative film 14 Small opening 15　Light shielding plate 16 Shift part 20 Collimator 21 Spectrometer 22 Cylindrical lens 23 Line sensor 50 LCD shutter 51 LCD panel

Claims (2)

[Claims] 1. A light source for illuminating a frame to be photometered on a photographic film, a means having a small aperture and displacing the small aperture in a two-dimensional direction with respect to the frame to be photometered, and transmission of the frame to be photometered from the small aperture. It is characterized by having a collimator that converts light into parallel light, a spectrometer that spectrally decomposes the parallel light from the collimator, a lens that forms a line image of the spectral light, and a line sensor placed at the imaging position of the lens. image data reading device. 2. A light source that illuminates a frame to be measured on a photographic film, a liquid crystal panel in which small liquid crystal shutters are arranged in a matrix, a driver that sequentially opens the liquid crystal shutters and scans the frames to be measured in two dimensions, and a liquid crystal shutter. It has a collimator that converts the transmitted light that has passed through the collimator into parallel light, a spectrometer that spectrally decomposes the parallel light from the collimator, a lens that forms a line image of the spectral light, and a line sensor that is placed at the imaging position of the lens. An image data reading device characterized by: