JPH1175121A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the image quality by preventing disturbance in an image specific to line sequential scanning. SOLUTION: A line sensor camera 1 as the image pickup device scans a subject image in line sequence. In this case, a camera shake sensor 52 detects a deviation between a regular scanning object position on a subject and an actual scanning position. A sensor moving device 17 moves minutely a line sensor 11 in a direction orthogonal to a pixel arrangement direction to displace the line sensor 11 with respect to a sub scanning device (rotary mirror device) 14. A CPU controls a displacement of the line sensor 11 during photographing of the object depending on the detected deviation to correct the actual scanning position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a line sensor (1).
A two-dimensional optical image is converted into an image signal by a two-dimensional image sensor.

[0002]

2. Description of the Related Art A digital camera which performs two-dimensional photographing using a line sensor and a mechanical sub-scanning mechanism has been put to practical use. The device of this means is capable of high-resolution imaging as compared with an imaging device using an area sensor. For example,
The entire document of about A4 size can be photographed so that characters of normal size can be read.

[0003]

However, line-sequential scanning requires a long shooting time for one frame. Therefore, in hand-held shooting, the influence of so-called camera shake is large. That is, the disturbance of the captured image such as “undulation” caused by the shake in the main scanning direction as shown in FIG. 8A and “pitch unevenness (dense / dense)” caused by the shake in the sub-scanning direction as shown in FIG. (Blurr) had occurred. These disturbances are phenomena peculiar to imaging with a line sensor, and do not occur with imaging with an area sensor.

Further, since the sub-scanning is mechanical, a response delay depending on the inertia force of the movable portion and the control processing speed is inevitable, causing uneven scanning speed. In particular, when the scanning speed on the subject is kept constant and the speed is changed during shooting in order to prevent image distortion, speed unevenness is likely to occur. Conventionally, there has been a problem that the speed unevenness appears as pitch unevenness like the hand shake in the sub-scanning direction.

An object of the present invention is to prevent image distortion peculiar to line sequential scanning and improve image quality.

[0006]

SUMMARY OF THE INVENTION In the present invention, a micro-movement technique of an optical system which is put into practical use in a video camera using an area sensor is applied to reduce a disturbance of an image which appears when a line sensor is used. .

According to a first aspect of the present invention, there is provided a photographing apparatus which includes a line sensor and a sub-scanning mechanism and scans a subject image in a line-sequential manner. Means for detecting the displacement of the line sensor, means for minutely moving the line sensor in a direction perpendicular to the pixel array direction and displacing the line sensor with respect to the sub-scanning mechanism. Means for controlling the displacement of the line sensor to correct the actual scanning position.

According to a second aspect of the present invention, there is provided an apparatus having means for minutely moving the line sensor in the pixel arrangement direction and displacing the line sensor with respect to the sub-scanning mechanism. , And is configured to detect the deviation and correct the actual scanning position.

In the apparatus according to the third aspect of the present invention, the means for detecting a shift comprises means for detecting a shake of the entire apparatus, and means for detecting a scanning speed unevenness of the sub-scanning mechanism.
A shift is detected based on the amount of the shake and the speed unevenness.

[0010]

FIG. 1 is a diagram showing the configuration of a line sensor camera 1 to which the present invention is applied, and FIG. 2 is a schematic diagram of a sensor moving mechanism.

The line sensor camera 1 is a handy type photographing apparatus, and is used as a high resolution digital image input means. A window 10a for guiding subject light to the inside is provided on the front surface of the housing 10, and a lens 12 for imaging is arranged behind the window 10a. Lens 12
Is reflected by the surface of the polygon mirror 15 and enters the line sensor 11. Housing 10
A photometric sensor 51 is mounted on the front surface of the device, and a release switch 63 is disposed on the upper surface. Further, an acceleration detector is mounted inside the housing 10 as a shake sensor 52 for preventing blur.

The lens 12 has a focusing actuator (not shown). Line sensor 11 is CC
A D imaging device, which is attached to a sensor moving mechanism 17 capable of minute movement in two directions, is disposed at a position where a subject image is formed. Another imaging device (for example, a MOS imaging device) can be used as the line sensor 11.

The polygon mirror 15 is a regular quadrangular prism-shaped optical member having four side surfaces each serving as a reflection surface, and is connected concentrically with the rotation axis of the motor 16. This rotation axis is parallel to the pixel array direction (main scanning direction) of the line sensor 11. As the polygon mirror 15 rotates, the subject light L is deflected in the sub-scanning direction, and the subject image is projected onto the light receiving surface of the line sensor 11 one line at a time. That is, the polygon mirror 15 and the motor 16 constitute the rotating mirror mechanism 14 as a sub-scanning unit.
One photographing (scanning for one frame) involves one reflecting surface. In other words, the polygon mirror 15 is set at 360 °
By rotating, four times of photographing can be performed. An optical rotation sensor (encoder) 56 for detecting a rotation angle position and a rotation speed is provided near the polygon mirror 15.

As shown in FIG. 2, the sensor moving mechanism 17
It is composed of a plurality of small moving tables 710 and 720 and a magnetic sensor (not shown) for controlling their positions. The micro movable table 710 includes a U-shaped arm 711 and an electromagnetic coil 7.
12, and the minute moving table 720 also includes a U-shaped arm 721 and an electromagnetic coil 722. Micro moving table 72
The micro movable table 710 is attached to the distal end of the zero arm 721, and the line sensor 11 is attached to the distal end of the arm 711 of the micro movable table 710. Electromagnetic coil 7
12 is energized, the line sensor 11
When a minute movement is performed in the pixel arrangement direction (main scanning direction) M1 which is the longitudinal direction of “a” and the electromagnetic coil 722 is energized, the line sensor 11 is moved together with the minute movement table 710 in the pixel arrangement direction M.
A minute movement is made in a direction M2 orthogonal to 1. Here, the micro-movement means a movement of a stroke of about several pixels of a photograph.

FIG. 3 is a functional block diagram of the line sensor camera 1. As described above, the line sensor camera 1 includes an imaging system 1a for scanning a subject image line-sequentially by the line sensor 11 and the rotating mirror mechanism 14, a signal processing system 1b for outputting photographing data of a predetermined format, and a microprocessor. And a control system 1c composed mainly of a CPU 90 having

The CPU 90 has a CCD drive circuit 91, a mirror drive circuit 94, an arm drive circuit 97 in accordance with operation information from the switch group 60 and detection information from various sensors.
And other appropriate instructions. A control memory 98 is used as a work area for this control. The output of the rotation sensor 56 is binarized by a comparator 96 and input to the CPU 90. In response to a start request from the CPU 90, the CCD drive circuit 91 outputs a signal that defines the timing of CCD integration (charge accumulation) to the line sensor 11. The line sensor 11 latches the electric charge of each pixel in response to the integration end signal, and the photoelectric conversion signal S1 in the pixel arrangement order.
The signal is output as 1 to the signal processing system 1b. This main scanning is repeated at a constant cycle (= imaging time T / number of lines n). The mirror driving circuit 94 drives the motor 16, and the arm driving circuit 97 operates the coils 712, 7 of the sensor moving mechanism 17.
22 is driven.

In the signal processing system 1b, the photoelectric conversion signal S
Reference numeral 11 denotes an AD converter 81, which is sampled and held in synchronization with a pixel clock, and has a predetermined number of bits (for example, 8 bits).
Is converted to shooting data DG. The photographing data DG is sequentially stored in the image memory 82, and is transferred to the image processing circuit 83 in the pixel arrangement order after photographing for one frame is completed. The image processing circuit 83 performs predetermined image processing including image quality correction on the input photographing data DG. The processed imaging data is output to an external device via the interface 84. As an external device, an image editing device represented by a computer system, a storage medium including an IC card,
There are image output devices such as printers and displays. It should be noted that a storage medium may be built in and the line sensor camera 1 may store shooting information. In that case,
The stored information is transferred to the external device by data communication or transfer of the recording medium as appropriate.

The line sensor camera 1 having the above configuration has a function unique to the present invention for preventing the image quality from deteriorating by slightly displacing the line sensor 11 with respect to the rotating mirror mechanism 14 during photographing. I have. Hereinafter, this function will be described.

The line sensor camera 1 detects camera shake and uneven speed in sub-scanning during photographing, and minutely moves the line sensor 11 in a direction to cancel the shake and uneven speed. The direction and amount of camera shake are detected by a shake sensor (acceleration detector) 51 using a piezoelectric effect or an electrostatic effect. Velocity unevenness is detected by a rotation sensor (encoder) 56 using light transmission and diffraction.

FIG. 4 is a diagram showing an example of unevenness in the speed of sub-scanning. When the rotation speed of the polygon mirror 15 is uneven, the cycle of the output waveform of the rotation sensor 56 changes. If the sensor output is binarized using a threshold th corresponding to half the amplitude, pulse waveforms having different pulse widths can be obtained. By detecting the rise or fall of the pulse waveform, the period of the waveform, that is, the unevenness in the sub-scanning speed can be detected. This pulse is output at least for the number of lines in the sub-scanning direction during the one-surface scanning.

FIG. 5 is a schematic diagram of correction for unevenness in the speed of sub-scanning. If the rotation speed of the polygon mirror 15 becomes uneven, a certain position on a subject (not shown) is photographed (scanned).
At this point, the rotation angle differs from the original angle. That is, the normal scanning target position on the subject and the actual scanning position are shifted. In the figure, the original mirror angle position and the optical path of the subject light are indicated by chain lines. Therefore,
The line sensor camera 1 corrects image distortion due to uneven rotation speed by moving the line sensor 11 slightly in the sub-scanning direction M2 to a position where the subject light deviated from the original optical path is correctly received.

FIG. 6 is a schematic diagram of correction for camera shake in the sub-scanning direction. In the figure, the original positions (relative positions with respect to the subject) of each part of the line sensor camera 1 are indicated by chain lines.

Even when camera shake occurs, the regular scanning target position on the subject is shifted from the actual scanning position. Therefore, the line sensor camera 1 moves the line sensor camera 1 to a position where the subject light deviated from the original optical path is correctly received. The sensor 11 is slightly moved in the sub-scanning direction M2. When a camera shake in the main scanning direction is detected, the image sensor is corrected by slightly moving the line sensor 11 in the pixel array direction (main scanning direction). When both the camera shake and the scanning speed unevenness occur, the shift amount is added to obtain the movement amount, and the line sensor 11 is moved to the optimum position.

FIG. 7 is a flowchart showing the general operation of the line sensor camera 1. When the start of shooting is instructed by operating the release switch 63, the motor 16 is started to start the rotation of the polygon mirror 15 (# 1,
# 2). Rotation unevenness detection (# 3), camera shake detection (#
If the scanning position is shifted in either the sub-scanning direction or the main scanning direction, the line sensor 11 is slightly moved so that a normal position on the subject can be photographed, and one line is photographed. (# 5-7). Until the photographing of the predetermined number of lines is completed, the position of the line sensor 11 is corrected and photographing of one line is repeated for each line as necessary (# 8). When the photographing of one frame is completed, various image processing is performed on the obtained photographing data DG (#
9). At this time, illuminance fluctuation is corrected as needed.
Then, data output to the outside is performed (# 10).

In the above embodiment, the configuration for correcting the unevenness in the speed of the sub-scan and the camera shake has been described.
A configuration may be adopted in which only correction for speed unevenness is performed. In this case, the minute movement of the line sensor 11 in the main scanning direction M1 becomes unnecessary. The sub-scanning mechanism is not limited to the rotating mirror mechanism 14, but may be a mechanism for moving the line sensor 11 in parallel. Also in this case, in order to correct the scanning unevenness due to the inertia of the movable body, a minute moving mechanism in the sub-scanning direction is provided separately from the parallel moving mechanism having a long stroke of the number of lines or more.

Regardless of the presence or absence of camera shake or speed fluctuation during photographing, the line sensor 11 moves the pixel in the main scanning direction to 1/2 to 1 pixel.
By moving by the pitch, a high-definition image can be obtained. By controlling the rotation speed of the polygon mirror 15 to be constant and moving the line sensor 11 slightly in the sub-scanning direction, the scanning speed on the subject may be made constant. The present invention is applicable not only to a portable type but also to a stationary type photographing apparatus.

[0027]

According to the first to third aspects of the present invention,
It is possible to prevent image distortion peculiar to line sequential scanning and improve image quality.

According to the second aspect of the present invention, the disturbance of the image in the main scanning direction can be reduced, and a high-quality photographed image can be obtained even when the apparatus shakes in hand-held photographing or the like. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a line sensor camera to which the present invention is applied.

FIG. 2 is a schematic diagram of a sensor moving mechanism.

FIG. 3 is a functional block diagram of the line sensor camera.

FIG. 4 is a diagram illustrating an example of uneven speed in sub-scanning.

FIG. 5 is a schematic diagram of correction for unevenness in the speed of sub-scanning.

FIG. 6 is a schematic diagram of correction for camera shake in the sub-scanning direction.

FIG. 7 is a flowchart showing a schematic operation of the line sensor camera.

FIG. 8 is a diagram showing a disturbance of an image peculiar to line sequential scanning.

[Explanation of symbols]

 Reference Signs List 1 line sensor camera (photographing device) 11 line sensor 14 rotating mirror mechanism (sub-scanning direction mechanism) 17 sensor moving mechanism (means for displacing) 52 shake sensor (means for detecting misalignment) 56 rotation sensor (means for detecting misalignment) 90 CPU (means for correcting the scanning position) 720 Micro movable table (means for displacing in the pixel array direction) M1 main scanning direction (pixel array direction) M2 sub-scanning direction (direction orthogonal to the pixel array direction)

Claims (3)

[Claims] 1. A photographing apparatus comprising a line sensor and a sub-scanning mechanism for scanning a subject image in a line-sequential manner, comprising: means for detecting a deviation between a regular scanning target position on a subject and an actual scanning position. Means for minutely moving the line sensor in a direction orthogonal to the pixel array direction and displacing the line sensor with respect to the sub-scanning mechanism; and displacing the line sensor during photographing of the subject according to the detected displacement. Means for controlling to correct the actual scanning position. And a means for slightly displacing the line sensor in the pixel array direction and displacing the line sensor with respect to the sub-scanning mechanism, and detecting the displacement in two directions, a main scanning direction and a sub-scanning direction. The photographing apparatus according to claim 1, wherein the actual scanning position is corrected. 3. A means for detecting a shift comprises means for detecting a shake of the entire apparatus and means for detecting a scan speed unevenness of the sub-scanning mechanism, based on the amount of the shake and the speed unevenness. The photographing apparatus according to claim 1, wherein the shift is detected.