JPS61129962A - Picture reader - Google Patents

Abstract

PURPOSE:To attain reading of a picture with an integer multiple of picture element density in comparison with that of the element by displacing relatively an original picture and a read sensor in the element arranging direction. CONSTITUTION:A signal from a read sensor 13 taking two positions in the own arranging direction by a position switch means is given to registers 19-22 via the 1st, 2nd and 3rd changeover switches 16, 17, 18 and the signal is stored in a prescribed timing. Registers 19, 20 and 21, 22 receiving respectively a signal from the switches 17, 18 are in pairs with each other and each pair stores alternately a signal corresponding to one scanning period. The registers 19, 20 and 21, 122 store respectively a signal corresponding to one read length at positions T1, T2 taking by the read sensor 13 and the signal is added by an adder circuit 23 after the end of write to the registers 19, 20 so as to be a signal read by a double reading density.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image reading device that reads original image information such as characters and figures recorded on a document.

[Technical background of the invention]

Generally, this type of reading device uses a reading sensor consisting of a plurality of reading elements such as photoelectric conversion elements arranged in a straight line.
The reading sensor and the original image are moved relative to each other in a direction perpendicular to the element arrangement direction to read image information projected onto the reading element array. In this case, the reading length of the reading element array is made to match the width of the original image, that is, the size of the original image in the direction that coincides with the element arrangement direction, thereby reducing the pixel density of the original image.

I try not to let it happen. The number of array elements of such a reading sensor currently on the market is 5,000 elements, and it is possible to read an original image approximately 300 mm wide at a pixel density of 16 dots per millimeter. be.

[Problems with background technology]

The conventional reading device described above has the disadvantage that it is more expensive than a sensor having a smaller number of elements arranged at a lower density.

Therefore, in order to avoid such cost problems, if the width of the original image is wider than the reading length of the reading element array, the gutter 4
A reduction type optical system is used between the reading element array and the original image to reduce and read the original image. However, the #*Kari f ratio reading sensor requires space for a circuit section to separate each pixel and store scanning and reading signals, so it cannot be arranged closely. Continuous dropouts may occur in the gaps, resulting in deterioration of image quality.

On the other hand, there are known reading devices that reduce the number of elements and achieve high image quality. Figure 8 shows a diagram of the principle of such a reading device, as published in Nikkei Electronics Magazine 1984゜9-10 No. 1.
It is described on page 79. That is, this reading device reads an original image using a plurality of one-dimensional COD image sensors, and is suitable for reading a large screen or reading a higher pixel density.

In the figure, reference numeral 1 denotes a recording paper (or manuscript) on which an original image is recorded, 2 an optical system consisting of three reduction type optical elements 2m, 2b and 2C, 3 an image sensor 3a,
3b and 3c.

The original image on the recording paper L is divided into three areas a, b, and C, and the area a is projected onto the COD image sensor 3a by the optical system 2a, and the other areas S and c are similarly divided into three areas 2b: 3b. and 2c:3c combination. As a result, a large screen area &, b, Q
The number of pixels of each of the sensors 3a, 3b, and 3c used to read the area is 1/1 of that when reading the entire area with one sensor.
3 can be used.

Although such a configuration is an effective means for solving the above problems, it is extremely difficult to accurately arrange the optical elements 2a to 2c, sensors 3a to 3c, etc. , the arrangement conditions change due to temperature changes, external forces, etc., and the joints of areas a, b, and c overlap (9) and become separated, resulting in loss of necessary information and distortion. There are very few drawbacks.

[Object of the Invention] □ The present invention has been made in view of the above points, and provides an image reading device that uses a single reading sensor and performs the reading function at a reading pixel density higher than that of this sensor. The purpose is to provide.

[Summary of the Invention] In order to achieve the above object, the present invention has a plurality of reading elements arranged in a constant direction, and receives image light based on an original image recorded on a document with the reading element and reads it. a reading sensor that reads sequentially in the element arrangement direction; a scanning unit that moves the original image and the reading sensor relative to each other so as to scan the original image so that image information of the entire document is acquired from the reading sensor; displacement means for displacing the relative position of the original image in the element arrangement direction in units of 1/n (n is an integer on 2J-1) of the arrangement pitch, and the original image at a position where it cannot be read due to the element gap. By reading, the reading density on the same scanning line is improved.

[Embodiments of the Invention] The present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 is a configuration diagram showing an embodiment of an image reading device according to the present invention, FIG. 2 is an explanatory diagram for explaining the operating principle of the same device, and FIG. 3 is a time chart showing operation timing. FIG. 4 is a schematic diagram showing the reading area when reading diagonal information according to the present invention, and the fifth factor is an explanatory diagram for explaining the operating principle of another embodiment of the present invention. The figure is a schematic configuration diagram showing a specific example of a means for switching the position of the potato master.

First, in FIG. 1, reference numeral 11 is a recording paper, 12 is a projection optical means (lens), and 13 is a one-dimensional reading sensor.The original image on the recording paper 11 illuminated by an illumination means (not shown) is The image is reduced in size through the optical means 12 and projected onto the reading sensor 13. Here, Ll indicates the reading length of the reading sensor 13, and L2 indicates @ of the recording paper 11. The reading sensor 13 is firmly supported by a support stand 14, and the support stand 14 is configured to be movable by a position switching means 15, so that the reading sensor 13 can be moved in two directions in its own arrangement direction with respect to the original image on the same scanning line. It is possible to take two positions. As is well known, the reading sensor 13 is constructed by dividing a photoelectric conversion surface used for photo-resistive or photo-electromotive force phenomena into pixel units, and the constituent elements are arranged in chronological order. A scanning circuit is added. There are two methods for reading signals: (1) a method that reads the element resistance and electromotive force at the moment the reading element is scanned, and (2) a method that reads information from the time of the previous scan to the next scan in the form of electric charge. There is a system in which the integrated signal is stored and then read out at the time of scanning, and ``2'' is typified by a light guide 11IL element such as CdS, and ``2'' is typified by COD. The present invention is applicable to any of these.

Next, the signal read from the reading sensor 13 is selectively guided to the input terminal C of the first changeover switch 16 - ,
The first switch 16. Second output terminal a.

Further, through the above 2.b. 3rd changeover switch 17°18
is introduced into the input terminal C of. Each of these changeover switches 17.
18 each 1st. The second output terminals a and b are connected to each register 19,
20, 21. The connection 18 to and 22 uses a semiconductor element for high speed switching.

Each of the above registers 19 to 22 is connected to the second changeover switch 1.
A set of registers 19.20 that receives signals from the third switch 18 and a set of registers 21.22 that receive signals from the third changeover switch 18 form a pair. are memorized alternately. Registers 19 and 20 and 21 and 22 are read registers 1 and 22, respectively.
Signals corresponding to one reading length at three positions are alternately stored. That is, in this embodiment, the reading sensor 13 is
Since the device is switched between two positions in the direction of the element arrangement, two V registers t-2 are required to obtain data corresponding to the sensor reading weir length at each position as a signal for one scanning period. That's why I do it.

The signals thus accumulated in the registers 19, 20 and 21, 22 are added by adder circuits 23 and 24, respectively. Signals from these adder circuits 23 and 24 are supplied to an image display device (not shown) via, for example, a signal processing circuit 25.

The position switching means 15, which is the most unique feature of the present invention, will be explained in detail in FIGS. 6 and 7, so its specific configuration has been omitted. However, in the embodiment shown in FIG. Based on the configuration using the corresponding piezoelectric element 26, (in the figure, reference numeral 27 indicates the voltage 1 as a driving power source for the element 26). Further, a clock pulse signal generation circuit for driving each circuit means is omitted.

The apparatus of the present invention is constructed as described above, and its operation will be explained next by dividing it into main operational blocks.

(1) Scanning of the original image Scanning is performed electrically within the reading sensor 13 (hereinafter referred to as
There are two types: main scanning (main scanning), and mechanical scanning (sub-scanning) in which the recording paper 11 and reading sensor 13 are moved relative to each other. In the main scanning, each element of the reading sensor 13 is driven to a reading state. In addition, the sub-scanning is performed in the element arrangement direction of the reading sensor 13 (
The original image and the reading sensor 13 in a direction perpendicular to the main scanning direction).
and move relative to each other. Thereby, the signals of each reading period of the reading sensor 13 are read out in time series.

(2) Position switching operation In this example, the scanning of the reading sensor 13 is performed twice on the same scanning line by switching the position of the reading sensor 3. Figure g2 (JL) shows an example of the arrangement of the reading window (light receiving part of the reading element) of the reading sensor 3 for this purpose.
As shown in , the reading windows X marked with diagonal lines are separated by a pitch P between them, which is set to the length in the column direction when the two windows are aligned without a gap. T2 indicates the position of the reading sensor 3 after position switching, and when compared with the TI position, the amount of movement Sr is τ. In other words, the reading window cl before the movement is the same element as the reading window x2 after the movement, and x2 is placed between xl and the adjacent window "11".This relationship is The same applies to other reading windows.Here, the reading sensor 1 shown at Tl
3 is the first position, and the position of the reading sensor 3 shown at T2 is the second position. Note that the symbol B indicates the sub-scanning direction.

(3) Circuit operation after signal reading Here, the route of the signal derived from the reading sensor 3 will be explained, but before that, Fig. 2 (Fig. 2) will be explained. 2) shows the signal based on the original image (#) read out by the reading sensor 3, (I) is the signal waveform at the leg position, (
I[) is the Kel signal waveform in the second position, (m) is (
This is the waveform obtained by adding I) and (II).

First, when the reading sensor 13 is in the first position, the read signal is delivered to the input terminal C of the first changeover switch 16. At this time, the first changeover switch 16 is set so that, for example, c and a are connected, and the second
Assuming that the 6 second changeover switch 17 led to the input end C of the changeover switch 17 is also in a conductive state between c and a, the first
A signal for one scanning period from the reading sensor 13 at the position is stored in the register 19. This register 1
The signal led to 9 corresponds to (I).

Subsequently, when the reading sensor 13 is switched to the second position, the setting state of the first changeover switch 16 remains unchanged.
The setting state of the second changeover switch 17 is changed. Therefore, the signal from the reading sensor 13 at the second position is stored in the register 20. The signal at this time is
Corresponds to (II).

When the writing to both registers 19.20 is completed, pulse generation means (not shown) sends data to both registers 19.2.
While a read pulse is applied to register 21.2
2 is set to write state. At this time, the first changeover switch 16 is switched to conduction between c and b.

In this way, when the 22 signals read from the registers 19 and 20 are added by the adder circuit 23, they become a signal as if the reading sensor 13 had read it at twice the reading density, as shown in (■). . This signal (m) corresponds to a signal for one main scanning period according to the present invention. Finally, the reading device according to the present invention can read information in the window X of the reading sensor 13, the gap between songs, in the second position. Note that the other registers 21 and 22 similarly store signals in the first and second positions, respectively, and read them while the registers 19 and 20 are in the write operation.

The above is an example in which the reading sensor 13 continuously reads document information and reads out image signals arranged in order for one scanning line from the registers 19 to 22, but the present application is not limited to this embodiment. It's not something you can do. For example, if a slow reading speed is acceptable, the configuration of the third changeover switch 18, registers 21, 22, and adder circuit 24 is omitted, and when writing to one register, reading from the other register is not performed. If one register is configured so that writing is not performed while the other register is being read, the number of registers can be reduced by half, and the circuit can be simplified. However, the reading of the original and the reading from the register become intermittent.

In addition, special considerations are required when applying to the present application an element such as a COD image sensor, in which read information is accumulated between the previous scan and the next scan, as the image reading element array. The reason for this is that, for example, if the reading sensor 13 is moved to the second position after reading the original at the first position and starts reading from x2 immediately, most of the signal read at x2 will come from the element at the position rl. This is because the information accumulated at 6 and 2 contains only a small amount of information at position 2. To eliminate this inconvenience, shift the reading sensor 13 to a predetermined position and Clear the stored information by performing a pre-scan at the same speed as the
After that, regular reading scanning is performed.

FIG. 3 is a timing chart when scanning is performed using the COD image sensor as described above. In FIG. 3, (I) shows the scanning timing of the reading sensor 13,
tl indicates a pre-scanning period for clearing unnecessary information, and t2 indicates a main scanning period for image reading. (n
) indicates the position of the reading sensor 13, T1. This shows that T2 takes two positions. (III) indicates the gate timing for cutting off the clearing signal among the signals from the reading element and extracting only the reading signal, during the main scanning period t2.
Gate with gate pulse G synchronized with . (IV) shows the read signal S gated as described above. As can be seen from the figure, after the reading sensor 13 moves to a predetermined position, the accumulated information is first cleared by pre-scanning,
After that, main scanning is performed to obtain a correct image signal. Then, by gate operation based on the pulse G, only the signal at t2 during the main scan is extracted.

Even if a reading element that reads the photoelectric conversion signal as it is without accumulating it is applied to the main residence, after the reading sensor 13 is moved to a predetermined position, the element will adapt to its original position at the same position. If it takes time to show a stable output, the reading scan must be started after the stabilization time.
It does not require pre-scanning like the COD sensor described above.

(4) When reading diagonal information When using the reading sensor 13 as described above to read line information that is inclined at an angle of 45 degrees with respect to the main scanning direction, in this embodiment, as shown in FIG. 4(a), It is possible to read row 9. The symbols x1/ and x2/ in the figure are as shown in Figure 2(a)
If the reading window Jl,,2!2 shows the readable area and the position is not changed, the information in the area z2/2 cannot be read, but according to this embodiment, To provide information that can be accurately read without overlapping diagonal information and without successively dropping information.

However, in FIG. 4(a), the relative movement pitch between the reading sensor 3 and the M image is set at once. This has the effect of matching the pixel density in the main scanning direction indicated by arrow C and the pixel density in the sub-scanning direction indicated by arrow C, and the effect of preventing the above-mentioned reading of diagonal information from being omitted. achieved.

Next, FIG. 5 shows the principle operation of another embodiment of the present invention in which the amount of movement by the position switching means 15 is set to END, the main scanning is switched to t-3 positions, and is repeated three times. FIG. In this figure, (a) corresponds to FIG. 2(a), and Φ) corresponds to (in FIG. 2).

First, in No. 5-(a), 3 indicates the arrangement of each reading window Y at the reference position, and yl corresponds to zl. T4 indicates the arrangement of the reading window Y in the intermediate position shift by one degree from the reference position, y
2 corresponds to yl. T5 is the reading window Y at the final position, which is further shifted by one knife from the intermediate position.
y3 corresponds to y2, that is, 'Il.

That is, the pitch S2 between yl and y2 is 1, and the pitch S3 between yl and y3 is 2p.

(in Figure 5) shows the signal waveform obtained based on the reading sensor 3 as described above, (I) shows the signal waveform obtained from the reading sensor 3 set at the base fishing point, and (n
) is the signal waveform obtained at the intermediate position, (III)
respectively show the signal waveforms obtained at the final position. Therefore, when this practical example is realized using the configuration shown in FIG. 1, three registers are required. Also, (I
V) indicates a waveform obtained by adding the waveforms (I), (IF), and (III).

In this way, when switching to three positions, the obtained signal (IV) is equal to 3 of the element arrangement density of the reading sensor 3.
This is equivalent to a signal read with twice the pixel density. Also in this embodiment, the operation when reading diagonal information is shown below.
The result will be as shown in Figure 4). In this figure, the symbols yl', yz' and ya' represent the reading window'/
1. y2 and y3 indicate areas that can be read, C is the main scanning direction, and D'd is the sub-scanning direction. In this case, the regions y1' and y2' and y2' and y3' partially overlap in positive alignment, but it is effective for high-density reading if the overlapping area is 501 or less of one pixel. Also in this case, by adjusting the movement pitch in the D direction to match the positional shift in the C direction, the pixel density in the sub-scanning direction can be made equal to the pixel density in the main scanning direction.

As is clear from the above two embodiments, the reading sensor 3
By checking the element spacing P in the element arrangement direction, reading at a pixel density n times higher than the original reading density of the reading sensor 3 is achieved.

Next, a detailed configuration of the position switching means 15 will be described with reference to a specific example shown in FIGS. 6 and 7.

6(a) and (6) show a piezoelectric element 26 corresponding to FIG.
FIG. 2 is a sectional view and a plan view showing a configuration using the same, and parts common to those in FIG. 1 are denoted by the same reference numerals. In these figures,
The reading sensor 3 is firmly fixed to a socket 29 attached to a holder 28, and this holder 28 is attached to a fixing member 3.
It is placed in the recess 0' and is sandwiched between an elastic body 31 on one side and a piezoelectric element 26 on the other side, and is movable in the element arrangement direction E of the reading sensor 13. Incidentally, the socket 29 and the holder 28 correspond to the support body 14 in Fig. WJ1.

According to such a configuration, the piezoelectric element 26 is connected to the driving power source 27.
It takes a compressed state and an expanded state depending on the electrical signal from the
When in a compressed state, the assembly including the sensor 13 assumes a position moved toward the piezoelectric element by the pressure of the elastic body 31, and when in an expanded state, it assumes a position moved toward the elastic body.

Thus, by switching the signal applied to the piezoelectric element 26 to a plurality of levels, it is possible to cause the reading sensor 13 to take a plurality of positions.

Incidentally, if a sufficient amount of displacement cannot be obtained with the above configuration, it is better to use a configuration as shown in FIG. 6(C).
In Figure (C), a plurality of piezoelectric elements 26' are provided in parallel, and one end of each piezoelectric element 26' is connected to a connecting member 32, 32...
1. In addition to being mechanically coupled, eight transmission members 33 and 33e are attached to the end faces of the piezoelectric element at both ends. Therefore, by providing such a structure in the amount of the piezoelectric element 26 shown in FIGS. 6(a) and 6(b), for example, the reading sensor 13 is displaced.

Further, the position switching means 15 may have a configuration as shown in FIG. 7. In the specific example shown in this figure, a mirror 34 is interposed in the optical path of the optical image in order to move the projected image from the original (recording paper 11), and parts common to those in FIG. 1 are given the same reference numerals. That is, the configuration shown in FIG.
The image light from is applied to the mirror 34 via the optical means 12',
The image light reflected by this mirror 34 is projected onto the entire reading length of the reading sensor 13. The mirror 34 is configured to be able to rotate by a predetermined amount f around arrow F as an axis.

According to the configuration in which the mirror 34 is rotated in this way, the configuration is simpler than in the other embodiments described above, and there is an effect that high speed can be obtained. In addition, in the above position switching means, @! In addition to 34, an optical polarizing element such as a prism can also be used.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to read with a pixel density that is an integral multiple of the number of elements using a reading sensor with a limited number of elements, and when reading a screen of the same width,
This has the effect of improving the pixel density (per unit length).

Furthermore, when the pixel density per unit length is made the same, there is an effect that the screen width that can be read can be increased.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of an image reading device according to the present invention, FIG. 2 is an explanatory diagram for explaining the operating principle of the same device, and FIG. 3 is a time chart showing the operation timing of the present invention. , FIG. 4 is a schematic diagram showing a reading area when reading diagonal information according to the present invention, FIG. 5 is an explanatory diagram for explaining the operating principle of another embodiment of the present invention, and FIGS. 6 and 7. 8 is a block diagram showing a specific example of a position switching means, and FIG. 8 is a schematic diagram showing an example of a conventional image reading device. 11...Recording paper, 12...Optical means, 13.
...reading sensor, 14...support stand, 15...position switching means, 16 to 18...changeover switch, 19 to 22...register, 23...addition circuit, 26...piezoelectric element , 27...
・Drive power supply, X, Y...reading window, 34...mirror. Agent Patent Attorney Susumu Ito Figure 6 (b) Figure 7

Claims (1)

[Scope of Claims] A reading sensor having a plurality of reading elements arranged in a fixed direction, the reading element receiving image light based on an original image recorded on a document and sequentially reading it in the element arrangement direction; a scanning unit that moves the original image and the reading sensor relative to each other so that image information of the entire document is acquired from the reading sensor; and arranging the relative position of the original image and the reading sensor in the element arrangement direction. 1. An image reading device comprising: displacement means for displacing in units of 1/n (n is an integer of 2 or more) of the pitch.