JPH11252332A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader capable of reading an image with high image quality and at high speed. SOLUTION: A line period setting means 8 sets the line period of a drive signal, in accordance with the type of an original and drive waveform data corresponding to the period which is set is outputted to a drive means 6 in a drive waveform generation means 7. The drive means 6 generates the drive signal, based on drive waveform data outputted from the drive waveform generation means 7 and outputs it to a vibrating means 5. The vibrating means 5 vibrates a solid-state image-pickup element 4 to a main scanning direction in accordance with the driving signal. The solid-state image-pickup element 4 reads the image of the original in the respective moving positions of the main scanning direction. A signal processing means 9 composites, the image data of high resolution, based on the image data which is read from the solid- state image-pickup element and then outputs it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus for reading an original while vibrating an image input means such as a one-dimensional solid-state image sensor in the pixel column direction.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus has a scanner,
It is used as an image input unit of a facsimile, a copier, and the like, and recently, a demand for higher resolution is increasing.

As means for realizing high resolution, there is a method of increasing the number of pixels of a solid-state image sensor for reading an image.
However, if the number of pixels is increased, the cost of the solid-state imaging device increases. Therefore, as a method of obtaining a high-resolution image at a lower cost, a technique of obtaining information on a plurality of image forming positions by vibrating a solid-state image sensor in the direction of pixels arranged one-dimensionally, and combining and reading the information. (Swing method).

A conventional image reading apparatus based on the swing method will be described below. FIG. 11 is a configuration diagram of a conventional image reading apparatus. When the document 101 is irradiated by the light source 102,
The reflected light from the document 101 is imaged on the solid-state imaging device 104 by the lens 103. The solid-state imaging device 104 is vibrated by the vibration means 105 in the pixel column direction (hereinafter, horizontal direction). The solid-state imaging device 104 and the document 101 synchronize with the line synchronization signal, and the direction perpendicular to the pixel column direction becomes the traveling direction. The solid-state imaging device 104 reads the document by moving N lines in the traveling direction. The read image data is subjected to color conversion and MTF (Modulati
After performing processing such as on transfer function (correction), the data is stored in the data storage unit 108 and transferred to an external device in response to a transfer request from the external device 109.

As the vibration means 105, a piezoelectric element or the like is generally used. As shown in FIG. 12, the vibrating means 105 turns on / off the voltage for each line by the driving means 106.
FF is performed, and 1 / (width of the pixel) in the direction in which the pixels are arranged.
It is oscillated with an amplitude of 2 and reads left and right images line by line.

FIG. 13 is a diagram showing the relationship between the driving waveform and the reading area of the conventional image reading apparatus. FIG. 13A shows the reading area 110 and the driving waveform 112 of the solid-state image pickup device 104 at the phase A of the driving waveform 112. 13B shows a reading area 111 of the solid-state imaging device 104 in phase B, and FIG. 13B shows a driving waveform 112 of the driving unit 106. The reading areas 110 and 111 are displayed for each image.

The number of pixels of the solid-state imaging device 104 is N,
Assuming that the width of the document in the horizontal direction is D inches, an image of D inches is read by the sum of the number N of pixels read during the phase A and the number N of pixels read during the phase B, that is, 2N pixels. become. The reading resolution at this time is 2N /
Ddpi, and a resolution twice as high as that obtained when no vibration is obtained.

[0008]

However, in the above-described conventional method, when the vibration frequency of the solid-state imaging device 104 increases or the mass of the solid-state imaging device 104 increases,
As shown in FIG. 14, when the drive waveform is distorted, stable driving cannot be performed, and an image is read while the solid-state imaging device 104 is moving.

To prevent such a state, FIG.
The vibration means 105 may be driven by a drive signal having a drive waveform having a constant rising characteristic as shown in FIG. However, when the rising characteristic is always set to be constant, the following inconveniences occur at the time of low-speed reading and at the time of high-speed reading of a document. First, at the time of low-speed reading, as shown in FIG. 16A, the one-line cycle of reading becomes longer, and it takes more time than necessary to read in a stable state, and the reading time becomes longer.

At the time of high-speed reading, FIG.
As shown in (1), the one-line cycle of reading is shortened, so that the rising and falling times of the drive waveform cannot be sufficiently obtained, and reading in a stable state becomes difficult.

For example, a transparent original is read at a low speed in order to read at a high resolution. Therefore, if the same drive waveform as that of a reflection original read at a relatively low resolution is used, it takes more time than necessary to reach a stable state of the drive waveform, and the reading time becomes longer.

When driving is always performed using a drive signal having the same cycle irrespective of the type of a document or the like, as shown in FIG. As a result, the driving waveform is distorted, and the driving element is deteriorated.

An object of the present invention is to provide an image reading apparatus capable of quickly reading an image with high image quality.

[0014]

An image reading apparatus according to the present invention has a plurality of pixels arranged in a main scanning direction, and optically reads an image of a document. Signal generation means for generating drive signals having regions with different phases for moving in the forward direction and the sub direction along the direction, and the image input means in the main scanning direction based on the drive signals output from the signal generation means. And a setting unit for setting characteristic information of the driving signal. The signal generating unit generates the driving signal based on the characteristic information set by the setting unit.

In the image reading apparatus according to the present invention, the image input means is reciprocated in the main scanning direction by the driving means, and high-resolution reading can be performed by reading an image at each moving position. Further, a drive signal for reciprocating the image input means is generated based on characteristic information set by the setting means. Therefore, by generating an appropriate drive signal according to the type and resolution of the original and driving the image input unit, the waveform of the drive signal is distorted, and the movement operation of the image input unit becomes unstable, It is possible to prevent the load from acting on the driving means and to prevent the deterioration, thereby performing a stable image reading process.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reading apparatus according to a first aspect of the present invention includes an image input unit having a plurality of pixels arranged in a main scanning direction and optically reading an image of a document, and an image input unit. Signal generating means for generating a driving signal having regions having different phases for moving in the forward direction and the sub direction along the scanning direction, and main scanning of the image input means based on the driving signal output from the signal generating means. A driving unit for reciprocating in the direction; and a setting unit for setting characteristic information of the driving signal. The signal generating unit generates the driving signal based on the characteristic information set by the setting unit.

This makes it possible to generate an optimal drive signal for various image reading conditions and read the image while reciprocating the image input means in the main scanning direction. An image reading apparatus capable of performing the above can be obtained.

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect of the present invention, the setting unit sets the cycle of the drive signal as the characteristic information, and the signal generating unit sets the period. A drive signal having a period set by the means is generated.

Thus, the image is read while the image input means is reciprocated in the forward direction and the sub direction by the drive signal set to the optimum cycle. Thereby, a high-speed and high-quality image can be read.

According to a third aspect of the present invention, in the image reading apparatus according to the second aspect of the present invention, the setting means sets a different cycle to the drive signal in accordance with the original reading resolution. is there.

Thus, in the case of a high resolution, an image is read at a low speed using a drive signal having a long cycle, and in the case of a low resolution, an image is read at a high speed using a drive signal having a short cycle. And an efficient image reading operation can be performed according to the resolution.

According to a fourth aspect of the present invention, in the image reading apparatus according to the second aspect of the present invention, the setting means sets different periods of the drive signal in accordance with the type of the document. .

This makes it possible to read an image by using a drive signal having an optimum cycle according to the type of a document such as a transmission type or a reflection type.

According to a fifth aspect of the present invention, in the image reading apparatus according to the first aspect of the present invention, the drive signal includes a rising area and a falling area between one of the areas having different phases and the other. Region, and the setting unit sets, as characteristic information, gradients of different magnitudes in the rising region and the falling region of the drive signal, and the signal setting unit calculates the gradients of different magnitudes set by the setting unit. It generates a drive signal including a rising region and a falling region.

Thus, when the power is turned on or when reading is resumed from the reading stopped state, the image input means can be driven gently to read the image stably.

According to a sixth aspect of the present invention, in the image reading apparatus according to any one of the first to fifth aspects of the present invention, the signal generating means includes a drive signal waveform corresponding to the characteristic information. It includes a plurality of data storage means storing data, and a selection means for selecting a predetermined data storage means from the plurality of data storage means in accordance with the characteristic information provided from the setting means.

This makes it possible to select the waveform data of the drive signal from the predetermined data storage means in accordance with the characteristic information and generate an optimal drive signal, thereby reading a high-speed and high-quality image. Becomes possible.

Hereinafter, embodiments of the present invention will be described. (Embodiment 1) First, the configuration of the first embodiment of the present invention will be described. FIG. 1 is a schematic diagram of an image reading apparatus according to a first embodiment of the present invention. In FIG. 1, 1
Is a document, 2 is a light source for irradiating the document, 3 is a lens for forming reflected light from the document 1 on the solid-state imaging device 4, and 4 is a solid for converting the formed image to an electric signal. An image pickup device, 5 is a vibration unit for vibrating the solid-state image pickup device 4 in the horizontal direction, 6 is a drive unit for driving the vibration unit 5, 7 is a drive waveform generation unit for generating a drive signal, and 8 is a line cycle to be read. The line cycle setting means 9 performs signal processing such as shading correction, color correction, and resolution conversion on data output from the solid-state image sensor, and 10 generates timing for generating a signal for controlling the solid-state image sensor. Means.

FIG. 2 is a plan view of the solid-state imaging device of FIG. The solid-state imaging device 4 has pixel rows 11R, 11G, and 11B that read respective components of red (hereinafter R), green (hereinafter G), and blue (hereinafter B). In addition, the distance between each pixel column represented by the number of lines is denoted by L, and for example, L is 4 lines. Each pixel column is N
Pixels. The vibration unit 5 can be composed of, for example, a piezoelectric element, a voice coil, and the like.

FIG. 3 is a block diagram of the signal processing means.
In FIG. 3, analog / digital conversion means (hereinafter referred to as A
D conversion means) 12R, 12G, and 12B are solid-state imaging devices 4
Converts analog signals corresponding to the R, G, and B components of the document image, output from the pixel columns 11R, 11G, and 11B, into digital signals. Memory 13R,
13G stores the data output from the AD converters 12R and 12G. The image processing means 14 has a memory 13R, 1
The data output from the 3G and AD conversion means 12B is subjected to processing such as color processing and resolution conversion. The buffer memory 15 stores the data processed by the image processing means 14. The DMA unit 17 receives a transfer request from the external device 16 and transfers data from the buffer memory 15 to the external device 1.
6

As described above, the pixel rows 11R, 11G, 1
1B are arranged at intervals of L lines. Therefore, the pixel rows 11R, 11G, and 11B read positions separated by L lines.
To correct this, the data of the same line can be input to the image processing means 14 at the same time by delaying by a predetermined line in the memories 13R and 13G.

Here, the solid-state imaging device 4 corresponds to the image input means of the present invention, the driving waveform generating means 7 corresponds to the signal generating means, the driving means 6 corresponds to the driving means, and the line cycle setting means. 8 corresponds to a setting means.

Hereinafter, the reading operation will be described. The solid-state imaging device 4 includes 7000 pixels (elements) arranged one-dimensionally and has a resolution of 600 dpi (dots / inch). The size of each pixel is 10 μm × 10 μm, and the solid-state imaging device 4 reads an image while vibrating 5 μm, which is の of the pixel size, in the pixel alignment direction.

First, the resolution in the main scanning direction is 600 dpi.
Now, a case where a line cycle is read at 2 ms will be described.

As shown in FIG. 4, the driving waveform is desirably a trapezoidal wave or a sine wave having gentle rising and falling characteristics. Here, a trapezoidal wave is used as the drive waveform 18. The drive waveform 18 has two line periods (4 m
s), stops at a position shifted by half a pixel to the left in the next one line period, and the data read in this stopped state becomes valid. After that, it falls in the next two line periods, stops at the position shifted by half a pixel to the right in the next one line period, and the data read in this stopped state becomes valid. Hereinafter, this is repeated, and the solid-state imaging device 4 is driven at a cycle of 6 lines to read an image.

Next, the resolution in the main scanning direction is 1200 dp.
The case of reading with i will be described. The 600 dpi data read by the solid-state imaging device 4 is stored in the image processing unit 1.
As shown in FIG. 5, two pixels adjacent in the main scanning direction, for example, pixel A and pixel B are added and averaged to obtain an interpolated pixel Aa, as shown in FIG. Similarly, the resolution conversion from 600 dpi to 1200 dpi is performed by obtaining interpolation pixels Bb and Cc from adjacent pixels. After conversion, the number of pixels doubles per line to 1
Processed as 4000 pixel data.

Since the number of pixels is doubled, a processing time of 7000 pixels or more is insufficient in the same line cycle as 600 dpi. Therefore, when reading at 1200 dpi, 1
The line cycle is switched to a cycle (4 ms) that is twice as long as that at the time of reading at 600 dpi. Since the line cycle is doubled at 1200 dpi, the drive waveform has a 4-line cycle in which rising and falling occur in one line as shown in FIG. Therefore, in FIG. 7, when a line cycle 19 necessary for reading at 1200 dpi from an external device is set, the selector 21 of the drive waveform generation circuit 20 sets a ROM (Read Only Memory) in advance according to the line cycle 19.
(ry: read-only memory), and selects and outputs a drive waveform from a plurality of tables 1 to n prepared.

(Embodiment 2) Next, the configuration of a second embodiment of the present invention will be described. FIG. 8 shows a second embodiment of the present invention.
FIG. 3 is a configuration diagram of a drive waveform generation circuit according to the embodiment.

The CPU (Central Processing Unit) 26
When the power is turned on or when reading is resumed from the reading stopped state, the driving start direction selection signal 22 of the driving means 6 is set, the inclination of the driving waveform corresponding to the set direction is extracted from the table 23, and the driving waveform 18 is obtained. Occur.

FIG. 9A shows a driving waveform when the driving start direction is right (one of the main scanning directions). In this case, the drive start direction selection signal 22 becomes L level, and the table 23
Then, the drive waveform 18 having the rising slope shown in FIG. 9A is selected.

After that, in accordance with a drive waveform selection signal 25 generated by the CPU 26, the table is switched to a table 24 for generating a drive waveform according to the line cycle. This makes it possible to change either the rising or falling slope of the drive waveform.

FIG. 9B shows a driving waveform when the driving start direction is left. In this case, the drive start direction selection signal 22 becomes H level, and the drive waveform 18 having the falling slope shown in FIG.

Here, the tables 23 and 24 correspond to data storage means of the present invention, and the selector 21 corresponds to selection means.

(Embodiment 3) Next, the configuration of a third embodiment of the present invention will be described. FIG. 10 is a configuration diagram of a drive waveform generation circuit according to the third embodiment of the present invention. In the transmission original reading, higher resolution reading is set as compared to the reflection original. Therefore, it is necessary to drive at a lower speed than that of the reflection original, and it is necessary to perform reading at a longer line cycle than that of the reflection original.

Therefore, when the transparent original mode is selected by the transparent original mode signal 27 generated by the CPU 26,
In the line cycle setting means 8, the setting of the line cycle
The table is switched from the table 28 for the reflective original unit to the table 29 for the transparent original unit. The line cycle signal at the time of the selected transparent original is longer than the line cycle of the reflective original.

Here, the tables 28 and 29 correspond to data storage means of the present invention, and the selector 21 corresponds to selection means.

[0047]

As described above, according to the present invention, in an image reading apparatus for reading by vibrating image input means, a drive waveform according to a line cycle can be selected, and high-speed reading can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image reading apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view of the solid-state imaging device of FIG. 1;

FIG. 3 is a block diagram of a signal processing unit.

FIG. 4 is a timing chart of a drive waveform and a line synchronization signal.

FIG. 5 is an explanatory diagram of an operation of a resolution conversion process.

FIG. 6 is a timing chart of drive waveforms and line period signals at 1200 dpi.

FIG. 7 is a configuration diagram of a drive waveform generation circuit.

FIG. 8 is a configuration diagram of a drive waveform generation circuit according to a second embodiment of the present invention.

FIG. 9 is a timing chart of driving waveforms and line synchronization signals.

FIG. 10 is a configuration diagram of a drive waveform generation circuit according to a third embodiment of the present invention.

FIG. 11 is a configuration diagram of a conventional image reading apparatus.

FIG. 12 is a timing chart of driving waveforms and line synchronization signals.

FIG. 13 is a diagram illustrating a relationship between a driving waveform and a reading area of a conventional image reading apparatus.

FIG. 14 is a diagram illustrating distortion of a driving waveform of a conventional image reading apparatus.

FIG. 15 is a diagram showing a drive waveform generated in a cycle of 8 lines of the conventional image reading apparatus.

FIG. 16 is a diagram showing a relationship between a line cycle and a driving waveform of a conventional image reading apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 document 2 light source 3 lens 4 solid-state imaging device 5 vibrating means 6 driving means 7 driving waveform generating means 8 line cycle setting means 9 signal processing means 10 timing generating means 14 image processing means 15 buffer memory 18 drive waveform 19 line cycle signal 20 drive Waveform generator 21 Selector 23, 24, 28, 29 Table 26 CPU

Claims (6)

[Claims] A plurality of pixels arranged in a main scanning direction;
Image input means for optically reading an image of a document, and signal generating means for generating a drive signal having regions with different phases for moving the image input means in the forward direction and the sub direction along the main scanning direction, respectively. A driving unit that reciprocates the image input unit in the main scanning direction based on the driving signal output from the signal generation unit; and a setting unit that sets characteristic information of the driving signal. Generating a drive signal based on the characteristic information set by the setting unit. 2. The method according to claim 1, wherein the setting unit sets a cycle of the drive signal as the characteristic information, and the signal generation unit generates a drive signal having the cycle set by the setting unit. The image reading device according to claim 1. 3. The image reading apparatus according to claim 2, wherein said setting means sets a different cycle for said drive signal in accordance with a reading resolution of a document. 4. The image reading apparatus according to claim 2, wherein said setting means sets a different cycle for said drive signal in accordance with a type of the document. 5. The driving signal further comprises a rising region and a falling region between one and the other of the regions having different phases, and the setting means includes the rising region and the falling region of the driving signal as the characteristic information. A different slope is set for the falling area, and the signal generation unit generates a drive signal including a rising area and a falling area having different slopes set by the setting unit. The image reading device according to claim 1. 6. The signal generation means includes a plurality of data storage means storing waveform data of the drive signal corresponding to the characteristic information, and the plurality of data storage means storing the plurality of data according to the characteristic information provided from the setting means. 6. The image reading apparatus according to claim 1, further comprising a selection unit that selects a predetermined data storage unit from the units.