JPH0865451A - Still image input device - Google Patents

Abstract

PURPOSE: To obtain a still image input device receiving a still image with high precision even from an original of a thick book simply by controlling a focus adjustment mechanism and a magnification adjustment mechanism so as to pick up an image with a prescribed magnification based on an in-focus detection signal obtained from each line. CONSTITUTION: Light made incident from an image pickup lens 7 having a zoom mechanism is photoelectric-converted by a CCD line sensor 11. The zoom mechanism and the focus adjustment mechanism of the image pickup lens 7 are driven by an exclusive magnification adjustment motor 8 and an exclusive focus adjustment motor 9 respectively to make in-focuse and magnification adjustment based on a signal from a signal processing circuit. The CCD line sensor 11 is driven by a read screw 10 integrated with a stepping motor 19 and receives an image by one line each. The focus adjustment mechanism and the magnification adjustment mechanism are controlled so as to pick up an image at a prescribed magnification based on the in-focus detection signal in this way and they are picked up for each line to obtain an image focused to the entire screen with small distortion.

Description

Detailed Description of the Invention

[0001]

The present invention relates to, for example, a CCD (char
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a still image input device suitable for use in an electronic filing system that images a document such as a book as a subject using a linear image sensor and records the signal on a recording medium such as a magneto-optical disk.

[0002]

2. Description of the Related Art Conventionally, a flat bed type or handy type scanner (image input device) has been used for image input of an electronic filing system.

The flat head type scanner is a system in which an original is placed on a flat glass surface and a sensor is used to scan the lower surface. The scanning includes a document table moving type in which a document table is moved while fixing a sensor, and a document fixed type in which an optical unit scans a fixed document surface. Since the original can be input from a book, for example, it is easy to use and is most commonly used.

On the other hand, the handy type scanner is a device for manually scanning the original surface of a figure or an image to be read and inputting image data. For example, it is mainly used for inputting a partial image such as an illustration of a document or a part of an image by connecting to a word processor or a computer device, and is small in size because it is manually scanned.

[0005]

By the way, in the flat bed type scanner, when inputting, an original is pressed against a glass surface to take an image. In addition, the handy-type scanner moves an image while pressing the scanner body against the document at the time of input.

However, when considering an electronic filing system, it is important that a document can be input quickly and easily, but both types are troublesome because the document and the scanner need to be in close contact with each other.

In addition to the above, a line sensor camera is also used as a part of a high-definition still image input device in a scanner for an electronic filing system. This line sensor camera has a structure in which a CCD line sensor is moved step by step in the sub-scanning direction, and images are taken line by line, and are used to capture highly detailed images.

However, even when a still image is input by utilizing this, a thick book deformed more than the depth of field cannot focus on the entire image.

Therefore, the present invention has been proposed in view of the above situation, and an object thereof is to provide a still image input device which can easily capture a highly detailed still image even when a thick book is used as an original. And

[0010]

In order to solve the above-mentioned problems, a still image input device of the present invention includes a CCD line sensor camera having a magnification adjusting mechanism and a focus adjusting mechanism, and focus detecting means for each line. This is a configuration including a control unit that uses a focus signal to focus without changing the magnification.

[0011]

According to the present invention, the control means controls the focus adjusting mechanism and the magnification adjusting mechanism so that an image is picked up at a constant magnification based on the focus detection signal obtained from the focus detecting means. By capturing this while performing this for each line, it is possible to obtain an image focused on the entire screen with little distortion.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described below with reference to the drawings.

FIG. 1 shows an overall view of an embodiment of a scanner for an electronic filing system to which the still image input device of the present invention is applied. In this example, the purpose is that the user can use the scanner without feeling uncomfortable, and the structure is integrated with a desktop proof device in consideration of use in an extremely ordinary work space such as an office desk.

Imaging device 1 using CCD line sensor
Is fixed to the fluorescent lamp illumination 2, and is fixed to the desk 5 by the pillar 3 and the clamp 4. Then, this imaging device 1
Scans the document 6 placed on the desk 5 in the direction indicated by arrow A in the figure to input an image.

2 and 3 show the structure of the image pickup apparatus 1. Light incident from the image pickup lens 7 having a zoom mechanism is photoelectrically converted by the CCD line sensor 11. The zoom mechanism and the focus adjustment mechanism of the image pickup lens 7 are driven by a dedicated magnification adjustment motor 8 and a focus adjustment motor 9, respectively, and perform focusing and magnification adjustment based on a signal from the signal processing circuit.

The CCD line sensor 11 is driven by the lead screw 10 integrated with the stepping motor 19 and is synchronized with the pulse given from the signal processing circuit to 1
Capture images line by line.

FIG. 4 shows a block circuit diagram of the signal processing system. When a start signal comes from a start switch not shown in FIG. 4, the CPU 16 causes the clock generator 15
To move.

The image formed by the image pickup lens 7 is converted into an electric signal by the CCD line sensor 11,
It is written in the memory 14 through the A / D converter 12 and the shading correction circuit 13.

Using this data, the hill climbing method is used to adjust the focus adjusting motor 8 and the magnification adjusting motor 9 so that the magnification is constant.
To move the focus to complete the image input for one line.

The CPU 16 transfers the data in the memory 12 from the parallel port 17 to a filing system (not shown) and controls the sensor drive motor 18 to move the CCD line sensor 11 by one line. An image can be input by repeating this.

FIG. 5 shows the relationship between the shooting distance and the magnification. To make things easier to understand, consider thin lenses. Assuming that the height a of the object, the height a ′ of the image, the distance S from the object to the lens principal point, the distance S ′ from the lens principal point to the line sensor, and the image magnification β, β = a / a ′ = S ′ / S = const.・ ・ ・ ・ Equation (1) Further, when the focal length of the lens is f, as shown in the equation (2), f = SS '/ (S + S') = βS / (β + 1) ... (2) Therefore, if the distance S from the subject to the lens principal point is obtained, the focal length f can be obtained. The distance S from the subject to the lens principal point is obtained by counting the number of pulses of the stepping motor, and the lens focal length is adjusted based on this.

[0022]

As described above, according to the present invention,
In the still image input device having the above-mentioned configuration, a control unit for controlling the focus adjustment mechanism and the magnification adjustment mechanism based on the focus detection signal obtained from the focus detection unit for each line so that the image is captured at a constant magnification. By having such a document, it is possible to easily obtain an image focused on the entire screen with little distortion, even in a document such as a book which is thick and has large deformation.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a basic configuration of a scanner to which a still image input device according to the present invention is applied.

FIG. 2 is a vertical sectional view of an image pickup apparatus.

FIG. 3 is a cross-sectional view of the image pickup device.

FIG. 4 is a block diagram of a signal processing system.

FIG. 5 is a diagram showing a relationship between a shooting distance and a magnification.

[Explanation of symbols]

 1 Imaging Device 2 Fluorescent Lamp Illumination 3 Support 4 Clamp 5 Desk 6 Document 7 Imaging Lens 8 Magnification Adjustment Motor 9 Focus Adjustment Motor 10 Lead Screw 11 CCD Line Sensor 12 A / D Converter 13 Shading Correction Circuit 14 Memory 15 Clock Generator 16 CPU 17 Parallel port 18 Sensor drive motor

Claims (3)

[Claims] 1. A still image input device for capturing an image obtained through an image pickup optical system while moving a one-dimensional sensor, and having a focus detection means for each line, a magnification adjustment mechanism and a focus adjustment mechanism. A still image input device comprising: means and a control means for controlling the image pickup means. 2. The still image input device according to claim 1, wherein the control means is adapted to focus on each line. 3. The still image input device according to claim 1, wherein the control means controls the focus adjusting mechanism and the magnification adjusting mechanism to correct a change in magnification due to the thickness of the document.