JPS6158374A - Image reader - Google Patents

Abstract

PURPOSE:To correct the quantity of light illuminating an image in accordance with the situation of a read image and to read the image in a proper condition constantly by providing an observing plate a light passage switching mirror or the like with respect to the light passage of a projection optical system. CONSTITUTION:A microfilm frame image 3 as a read image is illuminated by an illumination means 4 and a transmission light from the film forms an image on an image sensor 6 by a projection optical system 5. On the light passage between the optical system and the sensor 6, a light passage switching mirror 8 rotating on an axis 9 and an observing plate 7 constantly observing the light passage of the optical system 5 are provided. The read image based on a reference quantity of illuminating light from the mirror 8 in a light passage switching process from the observing plate 7 to the sensor side 6 is received on a light receiving sensor 10. The read images from the sensors 6, 10 are processed by calculation circuits 15, 19 and a dimmer control circuit 16 or the like and an illuminating means 14 is controlled. In accordance with the condition of the read image, the quantity of illuminating light is controlled to read the image in a proper condition constantly.

Description

[Detailed description of the invention] B1 Purpose of the invention [Industrial application field] The present invention relates to an image reading device.

More specifically, the present invention relates to an image reading apparatus that converts an image to be read into an electrical signal (time-series electrical pixel signal) using a one-dimensional or two-dimensional image sensor such as a CCD array, and reads and processes the converted image.

[Conventional technology]

This type of image reading apparatus is well known, and FIG. 3 shows, as an example, a very schematic configuration of an apparatus for reading and processing required frame image information on a microfilm.

Reference numeral 1 denotes a film frame illumination unit, in which the required three film frames to be read and processed in the film 2 (roll microfilm, microfiche film, microstrip film, etc.) are detected by an automatic search mechanism (not shown). Or located by manual search. Reference numeral 4 denotes an illumination system that illuminates the film frame 3 from below, and the illumination light transmitted through the film is imaged on the light receiving surface of the image sensor 6 via the projection optical system 5. When the image sensor 6 is a two-dimensional image sensor, the entire imaged image is read and processed as time-series electrical pixel signals by the sensor's own electrical main scanning and sub-scanning functions. Image sensor 6
When the image sensor is a one-dimensional image sensor, the entire image formed by the electric main scanning function along the length of the sensor 6 and the mechanical relative sub-scanning movement between the sensor 6 and the film frame 3 are used to create a time-series electrical image. It is read and processed as a pixel signal.

A time-series electrical pixel signal, which is an image reading signal output from the image sensor 6, is input to an image reproducing device or recording device (not shown) such as a laser beam printer mechanism, display device, facsimile receiving device, etc., and is outputted from the image sensor 6 to generate a signal corresponding to the read image. To reproduce the image, please refer to t! ! will be done.

[Problem that the invention seeks to solve]

By the way, in this type of image reading device, the image reading signal level output from the image sensor 6 is the same as that of each image to be read, regardless of the difference in image density level and base density level of each image to be read. The amount of illumination light for each image to be read is automatically controlled so as to maintain an approximately constant appropriate output level throughout.

Specifically, in the reading processing cycle of each image to be read, the illumination system 4 illuminates the image to be read g13 with a preset standard illumination light intensity, and the image sensor 6 reads the image with that light intensity. let This image reading process is called pre-reading. During this pre-reading process, the image reading signal level output from the image sensor 6 is compared with a reference signal level, and the amount of illumination light from the illumination system 4 is adjusted based on the comparison. Automatically corrects and controls the amount of illumination to be appropriate. Thereafter, the image sensor 6 reads the image 3 to be read illuminated with the appropriate illumination light amount after the correction (normal reading process of the image to be read), and inputs the read signal to a reproduction device or the like. It is something.

However, this had the following problems.

That is, the image sensor 6 is in a saturated state (
There are some images that have a base density state that is outside the sensitivity range (outside the sensitivity range), and in such cases, the image illumination at a certain standard illumination light amount that has been set in advance may be inappropriate (Illumination light amount excess/deficiency condition 8). Therefore, the self-effect correction control of the image elucidation light amount by the above-mentioned pre-scanning reading cannot be performed properly.

The present invention aims to solve the above problems.

Summary: Structure of the Invention [Means for Solving Problems] The present invention provides an illumination means for an image to be read, a projection imaging optical system for the image to be read, a projection observation plate for the image to be read, and a light receiving surface. an image sensor that converts a projection-formed image to be read into an electrical signal and reads it; and a projection optical path of the projection optical system that is normally on the projection observation plate side and is operated by a read command signal and switched to the image sensor side. an optical path switching movable mirror, a light receiving sensor that receives image light to be read based on a reference illumination light amount from the mirror in the process of switching the optical path of the movable mirror from the projection viewing plate side to the image sensor side; a control circuit system that determines an appropriate illumination light amount during a pre-reading process of the image sensor to be read based on the light amount of the image to be read, and corrects the image illumination light amount of the illumination means to the determined light amount; Based on the image reading signal level output from the image sensor during the pre-reading reading process using the image illumination light intensity, the appropriate illumination light intensity during the regular reading process by the image sensor of the image to be read is determined, and the image of the illumination means is determined. a control circuit system that re-corrects the illumination light amount to the determined light amount;
The gist of the present invention is an image reading device comprising:

[Effect]

That is, with the above configuration, the image illumination light amount of the illumination means is adjusted so that the illumination light amount of the image to be read in the pre-reading process of the image to be read is individually appropriate depending on the image condition of the image to be read. Correction is automatically controlled.

Therefore, even if the image to be read is in an image state that is outside the sensitivity range of the image sensor, the forward scanning of the image to be read is always performed in the appropriate light amount state.

〔Example〕

FIG. 1 is a very schematic configuration diagram of one embodiment of the apparatus of the present invention, and FIG. 2 is a block diagram of an example of a control circuit. Components common to those in the device shown in the example shown in FIG. 3 are designated by the same reference numerals and will not be described again.

In the figure, 7 is a projection observation plate (opalescent plate, etc.) for checking the image to be read, and 8 is a movable mirror that can rotate freely around axis 9. Image optical system 5
The mirror 8 is held in a first position in which it intervenes in the optical path at an angle of 45°, and in this position, the image light to be read from the optical system 5 is reflected and deflected in the direction of the observation plate 7 by the lower surface of the mirror 8. The image to be read 3 of the illumination unit 1 is projected onto the observation plate surface. When an image reading signal is input to the control circuit, the mirror 8 is rotated clockwise around a shaft 9 by a drive mechanism (not shown), and the mirror 8 escapes from the optical path of the projection imaging optical system 5.
It is held in the second posture shown by the dotted chain line. In this attitude, the image light to be read from the optical system 5 is projected onto the light receiving surface of the image sensor 6 to form an image.

10 is a light receiving sensor, and the mirror 8 changes from the first attitude to the second attitude.
During the rotational process of changing the posture, the image light to be read is received from the mirror through the slit 7l-11a of the slit plate 11 and the diffuser plate 12. The slit plate 11 functions to improve light reception accuracy. The diffuser plate 12 functions to illuminate the light receiving sensor 10 with the average amount of image light to be read. The light receiving sensor 10 has a dynamic range, that is, a ratio between the minimum amount of received light and the maximum (saturated) amount of received light, which is larger than that of the image sensor 6'.

Next, the control system will be explained.

(1) The first movable mirror 8 in response to the image reading command signal
During the rotation process from the posture to the second posture, the light receiving sensor 10 receives a light amount that is an average of the image density level of the image to be read based on the reference illumination light amount and the base density level, which is photoelectrically converted and sent to the amplifier circuit. It is amplified by 13.

(2) The amplified signal is digitally converted by the A/D converter 14 and input to the comparison/arithmetic circuit 15.

(3) Comparison and arithmetic circuit 15 performs a comparison with a reference level value, and calculates and determines an appropriate amount of illumination light during the pre-reading process of image 3 to be read by image sensor 6.

(4) The dimming control circuit 16 of the illumination means 4 is controlled by the output of the calculation result, and the amount of illumination light of the illumination means 4 is corrected to the amount of light determined by the calculation.

(5) Then, +ii7 scan reading of the image to be read using the corrected illumination light amount is executed by the image sensor 6.

(6) The image reading signal output from the image sensor 6 in the pre-reading process is input to the amplifier circuit 17 and amplified.

(7) The amplified signal is digitally converted by the A/D converter 18 and input to the comparison/arithmetic circuit 19.

(8) This comparison/calculation circuit 19 performs a comparison with a reference level value, and calculates and determines the appropriate amount of illumination light during the regular reading process of the image to be read by the image sensor 6.

(8) The dimming control circuit 16 of the illumination means 4 is controlled by the output of the calculation result, and the amount of illumination light of the illumination means 4 is re-corrected to the amount of light determined by the calculation.

(lO) Then, the image sensor 6 performs normal image reading of the image to be read using the above-mentioned re-corrected illumination light intensity, and the read signal is input to the control circuit of the image reproduction device (not shown). .

(Step 1) When the regular image reading process is completed, the movable mirror 8 is changed to the first attitude by the signal, and the illumination means 4
returns to the initial reference illumination light amount state.

C. Effects of the Invention As described above, the present invention corrects the image illumination light amount during the pre-reading process to an appropriate light amount according to the image condition of the image to be read, so that image reading processing is always performed in an appropriate state. is executed.

[Brief explanation of the drawing]

Fig. 1 is a very schematic configuration diagram of an embodiment of the device of the present invention;
The figure is a two-dimensional blow diagram of the control circuit system, and FIG. 3 is a very schematic configuration diagram of the conventional device. 3 is a microfilm frame image as an image to be read;
4 is an illumination means, 5 is a projection optical system, 6 is an image sensor,
7 is an observation plate, 8 is an optical path switching mirror, and 10 is a light receiving sensor. Figure 3 Figure 1 Figure 2

Claims (1)

[Claims] (1) An illumination means for the image to be read, a projection imaging optical system for the image to be read, a projection observation plate for the image to be read, and converting the image to be read projected and formed on the light receiving surface into an electrical signal and reading it. an image sensor; an optical path switching movable mirror that normally sets the projection optical path of the projection optical system to the projection observation plate side and switches to the image sensor side when operated by a reading command signal; a light receiving sensor that receives image light to be read based on a reference illumination light amount from the mirror in the process of switching the optical path to the sensor side; and a light receiving sensor that receives image light to be read based on the reference illumination light amount from the mirror; A control circuit system that determines the appropriate amount of illumination light during the pre-reading process and corrects the image illumination light amount of the illumination means to the determined light amount; a control circuit system that determines an appropriate amount of illumination light during a normal reading process of the image to be read by the image sensor based on the image reading signal level of the image sensor, and re-corrects the amount of image illumination of the illumination means to the determined light amount; An image reading device comprising: