JPS61150457A - Film reader - Google Patents

Abstract

PURPOSE:To always read films with a proper light quantity by rewinding a film set to a film reader when the power supply of the reader is applied, detecting the light quantity of the light source by a photoelectric converting means and controlling the light quantity of the light source based on the detection output of said light quantity. CONSTITUTION:A control part 41 drives a motor 39 to rewind a microfilm if set to a film reader. Then the part 41 produces a pulse LP for setting start of light quantity after the microfilm is rewound and then this film is removed from a reading position of an image sensor 27. The count value of an up-counter 36 undergoes the D/A conversion to increase the electric power supplied to a lamp 24 from a lamp power supply 38. Thus the light quantity is gradually increased and then detected by the sensor 27. This detected light quantity is amplified by an amplifier 31 and converted into the digital value of a prescribed bit by A/D conversion. this A/D conversion value is gradually increased to produce an overflow. The part 41 decides the end of the setting of light quantity by an overflow signal and is through with a light quantity setting program.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film reading device that photoelectrically reads images recorded on a film.

2. Description of the Related Art Conventionally, documents have been recorded on microfilm for the purpose of reducing storage space for large amounts of documents and facilitating data retrieval.

In addition, with recent improvements in electrical image processing technology, images recorded on microfilm (a tCOD
2. Description of the Related Art It has been proposed to perform reading using an image sensor having a photoelectric conversion function such as an image sensor, and displaying and recording an image based on the read signal, or storing and transmitting the image signal.

Generally, reading images recorded on microfilm is done by
This is done by exposing a desired frame of the microfilm to light from a light source and photoelectrically converting the amount of transmitted light using an image sensor as described above. Therefore, the density of the read image is affected by the amount of light from the light source used to expose the microfilm, and in order to obtain good reading results, it is necessary to set the amount of light from the light source to an optimum value.

On the other hand, image sensors that photoelectrically convert transmitted light from microfilm have characteristics determined by each element, and it is desirable to use the light amount that provides the highest sensitivity for good image reading. . Therefore, the light amount of the light source is set according to the characteristics of the image sensor. However, the light source: - The amount of light changes over time and differs from the initially set amount of light, resulting in image reading being performed with an amount of light that is not appropriate for the image sensor.

The present invention has been made in view of the above points, and an object of the present invention is to provide a film reading device that can always perform film reading with an appropriate amount of light. rewind the film,
Thereafter, the amount of light from the light source is detected by a photoelectric conversion means, and the amount of light from the light source is fully controlled based on this detection output.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a microfilm reading device (microfilm reader) to which the present invention is applied. In the figure, a round strip-shaped microfilm 23 stored in a first cartridge 21 is wound onto a second cartridge 22, and thereby a frame 20 desired to be read is set at a predetermined reading position.

The frame 20 set at a predetermined reading position is exposed to light from a halogen lamp 24 that enters through a lens 25. The light transmitted through the microfilm 23 is focused by a lens 26 onto an image sensor 27 such as a 9CCD line sensor. The image sensor 27 has a plurality of light-receiving elements arranged in a row, and these light-receiving elements separate the image on the microfilm 23 into a plurality of pixels and photoelectrically read each line.

Further, the image sensor 27ti is moved in the direction of the arrow by a drive mechanism (not shown), thereby reading the entire image of the desired frame 20 on the microfilm 23 set at a predetermined position. The read output of the image sensor 27 is transmitted to the signal processing unit 28, and after predetermined processing is performed, it is output as an image signal VD to an output device such as a printer, an electric file, or a display.

FIG. 2 shows an example of the characteristics of the output voltage with respect to the amount of input light of the image sensor 27.

In order to bring out the performance of the image sensor 27 most effectively, it is preferable to set the light amount so that the brightest part of the image has a light amount of Em, which is slightly lower than the saturation exposure amount SE. On the other hand, if it is too bright, the output voltage will saturate,
If it is too dark, the sensitivity/SN ratio will deteriorate.

To achieve this, when the film is not at the reading position of the image sensor 27, the saturation output voltage v8^! The amount of light may be gradually increased until a voltage V, which is lower by a predetermined amount, is output, and then stopped at around VA.

FIG. 3 shows an example of the configuration of the light amount control circuit in the microfilm reader shown in FIG. 1. Further, FIG. 4 shows a control procedure related to light amount control. This is programmed in advance in the memory of a microcomputer that constitutes the control section 41i, which will be described later.

In FIG. 3, numeral 24 is a lamp which is a light source with variable light intensity, numerals 25 and 26 are lenses, and numeral 27 is an image sensor having a photoelectric conversion function for image reading.

The automatic light amount setting operation will be explained using FIGS. 3 and 4. When the operator turns on the device power of the microfilm reader by operating the power switch 40, the control section 41 drives the motor 39t to rewind the microfilm if it is set in the device. Incidentally, if the microfilm is not set yet or is already being rewound, the motor 39 will not operate.

When the microfilm is rewound and removed from the reading position of the image sensor 27, the controller 4
1 is a light amount setting start pulse LPt- generated. When the light amount setting start pulse LP is input, the UP counter 36 and the 7-lip flop 34 are reset. Then, the clock generator 35 starts and generates a clock of a predetermined period. The UP counter 36 counts the clock of the clock generator 35, and its count value increases. The count value of the UP counter 36 is converted into digital/analog (D/A)
The lamp power supply 3 is converted by D/A conversion by the converter 37.
The power supplied to the lamp 24 from the lamp 8 increases, thereby gradually increasing the amount of light. This amount of light is detected by the image sensor 27, amplified by the amplifier 31, and then analog
A digital (A/D) converter 32 performs AD conversion into a digital value of a predetermined pit. This AD conversion value gradually increases, and eventually an overflow occurs. When an overflow occurs, the 7-lip flop 34 is reset and the clock generation from the clock generator 35 is stopped. Therefore, the count value of the UP counter 36 at this point is held, and the output of the D/A converter 37 is also held, so that the amount of light is fixed.

Further, based on the over 7cI signal, the control unit 41 determines that the light amount setting is completed, and ends the light amount setting program. Thereafter, in order to search for a desired frame on the microfilm according to the search data from the operator, the microfilm is loaded, the desired frame is exposed to the next light amount set as described above, and the image sensor 27
The image is then read. The read power source signal is input to a binarization circuit 33 via an amplifier 31 and an A/D converter 32t, where it is converted into a binary stroke signal and output to an output device such as a printer. Ru.

Here, if the amplification factor of the amplifier 31 is set in advance so that the maximum full scale value of the A/D converter 32 is at a level slightly lower than the saturated output voltage of the image sensor 27, the image sensor 27 The light intensity will be set to the optimum level to bring out the best performance.

In the above embodiment, the microfilm was rewound and the light intensity setting was performed in synchronization with the power switch being turned on. The above operation may also be started.

In this example, the light intensity of the lamp is gradually increased,
It is also possible to determine that the over 70 signal from the A/D converter 32 has disappeared and set the light amount at this point to an appropriate value. Also,
Rather than increasing or decreasing the amount of light, the appropriate amount of light may be determined while performing both.

Further, in consideration of the delay in the response time of the amount of light emitted to a change in the supply voltage of the lamp, data obtained before the output of the image sensor reaches a predetermined value may be used as the set value of the optimum light setting.

Further, the present invention can be applied not only to reading images of microfilms but also to reading images of ordinary 35W1I films, and furthermore, to reading color films.

As explained above, according to the present invention, it is possible to always set the light intensity of the light source that is used for reading images of microfilm to the optimum value without any manual effort, and therefore, it is possible to set the light intensity of the light source that is a companion to the microfilm image reading system to the optimum value, and therefore, it is possible to set the light intensity of the companion light source to the optimum value without any manual effort. Corresponding reading operations can be executed.

(9) Since the light amount is controlled by the output of the photoelectric conversion means for reading 1111g1, it is possible to perform a compensation operation involving not only the light source but also the optical system such as a lens.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a microfilm reader to which the present invention is applied, Fig. 2 is a diagram showing an example of the characteristics of the output voltage with respect to the input light amount of the image sensor, and Fig. 3 is a diagram showing an example of the configuration of the light amount control circuit. FIG. 4 is a flowchart showing the light amount control procedure, in which 23 is a microfilm, 24 is a halogen lamp, 27 is an image sensor, and 36 is an UP counter.

Claims (1)

[Claims] In a film reading device that reads a film by detecting the amount of light transmitted through the film exposed by a light source using a photoelectric conversion means, the film set in the device is rewound when the device is powered on, and then the amount of light from the light source is changed to A film reading device characterized in that the light quantity of the light source is controlled based on the detection output by a photoelectric conversion means.