JPS634990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image input display device that reads an image or the like on an input side and visualizes it on an output side.

[Technical background of the invention and its problems]

In devices that input an image and visualize the image as an output, such as facsimile machines, copiers, and TV cameras, the number of input pixels and the number of display pixels are often the same. Such devices have the disadvantage that moiré occurs when an image whose display pixels are nearly synchronized is input. Moiré is a low frequency;
It was very sensitive to human vision and was very obtrusive on output images.

Furthermore, Japanese Patent Application Laid-Open No. 104114/1984 discloses a technique for making M reading pixels correspond to N recording pixels, where M>N, that is, a technique for making a plurality of reading pixels correspond to one recording pixel. is disclosed.

However, in order to reduce the effects of noise and other factors when reading images, this technology refers to signals from multiple reading pixels and supplies the most accurate signal to the recording pixels. Read signals such as moiré, which are different from noise, are accurately read signals and cannot be prevented.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image input display device that eliminates the above-mentioned drawbacks and does not cause moiré phenomena.

[Summary of the invention]

In this invention, a plurality of input pixels of an input device for reading an image are provided for one display pixel for forming an image in a visualization device that is an output device. Then, processing called addition or integration is performed on the signals from these input pixels. It is characterized in that the signal obtained as a result is supplied to display pixels as a single image signal.

〔Effect of the invention〕

In this invention, when inputting an image that is approximately equal to the period of display pixels, multiple samplings are performed in one period of the input image, and a type of averaging operation called adding or integrating these signals is performed. The obtained signal has a constant value and no moiré occurs.

This effect is more noticeable when input pixels are multiplexed and a color input system is used. It is also resistant to noise.

[Embodiments of the invention]

Before describing embodiments of the invention, the principle of the invention will be explained.

The detection element has an aperture a as shown in FIG. In FIG. 1, the shaded area is necessary for separating each detection element, and the entire element is not necessarily an effective area. Furthermore, for the following discussion, it is assumed that the direction in which the detection elements are arranged is the x direction, and that detection elements of the same size are arranged.

For such a group of detection elements, the spatial frequency ξ ₀ which changes sinusoidally as shown by the following equation (1)
The output signal of the detection element when the image f(x) of is input is evaluated.

f(x)=cos2πξ _0x +1 ...(1) First, the number of input pixels on the input device and the number of display pixels on the display device are the same, and as shown in FIG. Let us examine the case where the period is T. (This is the conventional example itself.) The output signal I (mT) of the m-th detection element from the endmost (first) detection element is becomes.

Next, the output signal Im' when an image with a spatial frequency ξ' close to the reciprocal of the display pixel period T is input is evaluated. Let the spatial frequency ξ' be ξ'=1/T±1/T・△r...(3). However, Δr represents the difference from (1/T), and is a minute amount here. By substituting this ξ′ into equation (2), the output signal Im′ can be found. That is, Im′=sin(πξ′a)/πξ′a・cos[2π(1/
T±1/T・△r)mT)+1 = sin(πξ′a)/πξ′a・cos[2π(m±
m△r)]+1=sin(πξ′a)/πξ′a・cos(2πm
△r)+1...(4) This formula shows information about "moiré". That is, the output signal Im' shown by equation (4) has almost the same value when mΔr=(integer). In other words, when a waveform with a spatial frequency that differs by Δr from the reciprocal of the display pixel period T is input, the output signal of the detection element has a period of (1/Δr). This is nothing but moiré.

This moiré pitch becomes (T/Δr) on the display surface. Since Δr is a very small amount, this value becomes very large, indicating that moiré occurs at low frequencies. As mentioned in [Technical background of the invention and its problems], this is something that is easily perceived by the human eye and is very easy to see. For example, when the surface pixel pitch is 0.1 mm and △r=0.1, that is, (3)
As can be confirmed using the formula, the period is 0.099 mm to
When a 0.11 mm pattern is input, the moiré pitch on the display screen has a period of 1 mm.

Now, the amplitude of moire is cos(2πm△
r). a=0.83T and a=
The value of this coefficient at T is illustrated in FIG. 2.

As can be seen from Fig. 2, the amplitude value (the curve shown by the dotted line in Fig. 2) when a = 0.83T is ξ
=1/T is not zero but a finite value. This confirms the occurrence of moiré.

On the other hand, the amplitude value when a=T (the curve shown by the solid line in FIG. 2) is zero at the value of ξ=1/T. This shows that moiré does not occur. However, this means that a=T, that is, the aperture ratio
In 100% of cases, it is possible. In many cases, a=0.83T is a typical example with an aperture ratio of about 80%.

In contrast, in the present invention, the aperture is the same as the conventional one, and one display pixel is associated with a plurality of input pixels. For example, adding or integrating output signals from detection elements forming n input pixels at equal intervals,
This signal is supplied to one display pixel as an image signal.

For example, when two input pixels correspond to one display pixel, the two input pixels correspond to the pitch T of the display pixel, as shown in FIG. At this time, the aperture of the input pixel is still a, and the area indicated by diagonal lines is the area necessary to separate the detection elements.

Therefore, the output signal Im from one detection element is (1)
It is expressed as the formula. At this time, the pitch T of display pixels is taken as a unit distance, and the output signal Gm from the m-th input pixel group, that is, the input pixel group corresponding to the m-th display pixel from the end of the display pixels, is Gm=1/n{ I(mT)+I(mT+1/nT)+……+
I(mT+n-1/nT)} =1/n{α〓βmT+α〓β(mT+1/nT)+
...+α〓β(mT+n-1/nT)+n} (However, α=〓(πξa)/πξa, β=
Let it be 2πξ. ) =α/n _o-1 〓 ^l=0 〓(βmT+lβT/n)+1 =〓(βmT+n-1/2 βT/n)〓n/2・β
T/n〓ecβT/2n+1 (from the formula) =α/n・〓βT/2/〓βT/2n・〓βmT(1+
n-1/2mn)+1 =〓(πξa)/nπξa-〓(πξT)/〓(πξ
T/n)・〓[2πξmT(1+n-1/2mn)]+1...
…(5) becomes.

Gm expressed by this equation (5) becomes approximately zero near ξ=1/T. Therefore, moiré does not substantially occur.

In order to better understand this effect, a case will be explained in which two input pixels correspond to one display pixel.

In equation (5), if n=2, Gm=〓(πξa)/2πξa・〓(πξT)/〓(πξT
/2)・〓[2πξT(1+1/4m)]+1 =〓(πξa)/πξa・〓(πξT/2)・〓〓[2
πξmT(1+1/4m)]+1……(6) When the amplitude value of this output signal Gm is plotted with ξ on the horizontal axis, it becomes as shown in FIG. In Figure 4, the curve shown by the solid line is a=T/2 (aperture ratio 100%), and the curve shown by the dotted line is a=0.83・T/2.
It is 2. As you can see from this figure, ξ=1/
Near T, both curves are zero, indicating that moiré does not occur regardless of the aperture ratio of the detection element.

The above will be explained qualitatively. Let us consider the case where the number of input pixels and the number of display pixels are the same, and a sinusoidal image having a period approximately equal to the pitch T of the input pixels and display pixels is input.

At this time, since the period of the image and the pitch of the input pixels and display pixels are the same, the sine wave is sampled at a constant interval T, and a constant value is displayed.

However, the pitch T of input pixels and display pixels
On the other hand, when a sine waveform having a minute difference is input, the output value changes little by little with respect to sampling at a constant interval T. That is, low frequency moiré occurs.

On the other hand, for example, two input pixels (preferably equally spaced) are made to correspond to the display pixel pitch T.
When a sine waveform having a minute difference with respect to the display pixel pitch T is input, the input pixel pitch becomes
Since it is half the display pixel pitch T, the sampling period is approximately half the period of the sine waveform. Then, the output signals from one input pixel and the other input pixel corresponding to the same display pixel become signals with opposite signs and substantially the same amplitude. After such signals are added, they are supplied to display pixels as image signals, so no moiré occurs.

In the above principle, the input pixels themselves do not necessarily have to be arranged at equal intervals. Even if input pixels are irregularly arranged with respect to one display pixel, the effect can be achieved by performing signal processing on signals from input pixels arranged at the same interval. Furthermore, even if the input pixels are not provided at the same interval, it is sufficient to appropriately weight the signals from the input pixels.

Next, embodiments of the invention based on such a principle will be described with reference to the drawings.

As shown in FIG. 5, the apparatus of this embodiment has a linear light source 51 that irradiates light, and the reflected light from this light source 51 is formed into an erect real image with a one-to-one size. A convergent rod lens array 53 that guides the light to the convergent rod lens array 53 and a CCD (charge
Coupled Device) 54 (The above is the image input section 40
It is. ) and the electrical signal from this CCD54.
A first integrating circuit 55 integrates in the arrangement direction of the CCD 54, a storage device 56 stores the signal from the first integrating circuit 55, and a storage device 56 stores the signal from the storage device 56 in the paper feeding direction of the original 52 (arrow A second integrating circuit 58 that integrates (indicated by
is signal processing 41. ), the recording head 59 generates heat in response to the signal from the second integrating circuit 58.
and an ink ribbon 60 coated with heat-softening ink on the opposite surface of the surface that contacts the heat generating surface of the recording head 59 (the recording head 59 and the ink ribbon 6
0 is the image output section 42. ), the recording paper 6 in contact with the heat-softening ink-coated surface of the ink ribbon 60
Consists of 1.

The CCD 54 is connected to the substrate 6 as shown in FIG.
1, eight CCD chips 54a to 54h are provided in a staggered manner. Each of these CCD chips 54a to 54h has 2048 elements on one chip, and each element is provided at a pitch of about 14 μm. In other words, the number of input pixels is basically 72/
mm.

Also, as you can see from Figure 6, CCD chip 5
4a to 54h have a length l = 210 mm, which is enough to cover the width of A4 size paper, and the overlap d =
Arranged to allow 2.38mm.

For such a CCD 54, two plate-shaped focusing rod lens arrays 53 are arranged in a V-shape, as shown in FIG. This focusing rod lens array 13 forms an image on the original 12 on the CCD 54 as an erect real image with a one-to-one size.

The CCD 54 transfers charges according to the amount of received light,
The signal is supplied as an image signal to a recording head 59 via a first integrating circuit 55, a storage device 56, and a second integrating circuit 58.

The recording head 59 is a collection of resistors, and a collection of heating resistors is provided on a ceramic substrate. In this embodiment, the heating resistors are provided at 8 pieces/mm.

On the other hand, the detection elements on the CCD chips 54a to 54h described above form input pixels. The pitch of this input pixel changes depending on how the signal from the detection element is handled. For example, if the average of the signals from 9 detection elements is taken as an image signal, the number of input pixels is 8.
book/mm. If the average of the signals from the three elements is taken as an image signal, it will be 24 lines/mm.

In this embodiment, CCD chips 54a to 54
The signals from the three detection elements of h are sent to the recording head 59.
correspond to one heating resistor.

Here, the arrangement direction of the CCD 54 and the scanning direction of the original 52 will be explained. CCD54a to 54
h are arranged in a staggered manner as described above. However, the optical path of the reflected light from the scanning area on which light is irradiated on the original 52 is
Since it is divided by CCD54a to 5
4h is equivalent to being arranged in a straight line in the width direction of the document 52.

With this configuration, the signals output from the CCD 54 are signals read sequentially in the width direction of the original 52. However, as mentioned above
Since the CCD chips 14a to 14h overlap, it is necessary to remove signals from this overlapping region. Since this signal is output at a constant cycle in the output signal group, it may be removed at a constant cycle.

Actually, the signals from which the overlap has been removed in this manner are integrated three by three in the first integrating circuit 55. In this way, three integrated signals are stored in the storage device 56 as a single image signal for one line. If the image signal stored in the storage device 56 is used, moiré in the width direction of the document 52 will not occur.

On the other hand, the original 52 and the image input unit 40 are in relative motion. The speed of this phase velocity movement is the recording paper 61
Set to 1/2 of the movement speed. When such settings are made, there is a possibility that moiré as described above may occur also in the moving direction of the document 57, as shown by the arrow 57 in FIG. This is because the detection element has a separation area in its arrangement direction, and the aperture ratio is
The reason why it is not 100% is that a separation area actually exists also in the direction of relative movement between the original 52 and the image input unit 40, that is, in the direction perpendicular to the direction in which the detection elements are arranged.

Therefore, in this embodiment, the relative speed between the original 52 and the image input unit 40 is set to 1/2 of the moving speed of the recording paper 61.
Therefore, in this direction, one recording pixel on the recording paper 61 corresponds to two input pixels of the image input unit 40, that is, the detection element.

This will be explained using FIG. 8. FIG. 8 is a schematic diagram of the arrangement of the detection element arrays constituting the CCD chips 14a to 14h projected onto the original 52. A detection element 81 that transferred an output signal at a certain time and a detection element array 82 that transferred an output signal corresponding to the next scan are shown. The shaded area is an area for separating the detection elements.

As mentioned above and as shown in Figure 8,
Separation regions exist in the row direction of the detection element rows 81 and 82, and moiré occurs. In this embodiment, as shown by arrow 83, three responses are integrated in the column direction to prevent moiré from occurring in this direction.

Next, attention will be paid to the direction of relative movement of the document 52, which is perpendicular to the column direction, as indicated by an arrow 57. Also in this direction, there is a region that is missed due to the aperture of the detection element. In other words, a separated region exists, and moiré may occur.

In this embodiment, as mentioned above, two input pixels correspond to one recording pixel in this direction, and if the signals from these two input pixels are added or integrated, moiré in this direction can be eliminated. does not occur either.

This signal processing is performed by the second integration circuit 58. However, the signal input to the second integrating circuit 58 has already been subjected to integration processing in the column direction by the first integrating circuit 55. Therefore, in the second integration circuit 58, the 2
It is sufficient to simply add the signals for scanning. At that time, signals from the same detection element are added. That is, addition is made in the direction shown by arrow 84 in FIG.

The signal obtained in this way is sent to the recording head 5.
9, the heating resistor generates heat in response to these signals and an image is formed on the recording paper 61.

This image has no moiré in either the moving direction of the recording paper 61 or the width direction, and there is no visual disturbance.

[Other embodiments of the invention]

In the above embodiment, the original 52 and the image input unit 40
The relative speed with the second integrating circuit 5 is set to 1/2.
8, the occurrence of moire in the direction of relative movement of the original 52 has been eliminated, but the occurrence of moire in this direction can be prevented simply by appropriately controlling the amount of relative movement between the original 52 and the image input section 40. That is, in FIG. 8, the inside of the diagonal line corresponds to the opening, and the amount of relative movement may be controlled so that this opening corresponds to and continues with the document 52.

FIG. 9 schematically shows this. This figure is a schematic diagram of the array state of the detection element rows projected onto the original 52, similar to FIG. 8. However, parts of two sets of detection element arrays 81 and 82 are shown to clarify the relationship between the opening ends. As can be seen from this figure, the lower end 91 of the aperture defined by the detection element array forming the scan at a certain time and the upper end 92 of the aperture defined by the detection element array forming the next scan.
If the detection element array and the document 52 are moved relative to each other so that they match, there will be no separation area in this direction of movement. That is, the aperture ratio is 100%, and no moiré occurs in the direction of relative movement between the original 52 and the image input unit 40.

[Other embodiments of the invention]

Next, as another embodiment, the input system is multiplexed,
A device that can read color images will be explained.

In this embodiment, the pitches of the detection elements on the CCD chips 14a to 14h are different from those in the previous embodiment. In this example, 48 detection elements/mm are provided. The number of heating resistors is 8/mm. Therefore, one display pixel formed by the heating resistor corresponds to input pixels formed by six detection elements.

Furthermore, a yellow filter is placed on the detection element.
Y _o , magenta filter M _o , cyan filter
C _o are pasted in order. As shown in FIG. 10, for one display pixel pitch T, Y ₁ , M ₁ ,
Detection elements to which C ₁ , Y ₂ , M ₂ , and C ₂ filters are attached correspond.

The signal from such a detection element becomes a signal obtained by color-separating the input image. Among these signals, the signals from filters Y ₁ and Y ₂ , the signals from filters M ₁ and M ₂ , and the signals from filters C ₁ and C ₂ are integrated or added, respectively. Perform this operation. The resulting image signal for each color is supplied to one display pixel.

Therefore, when considering display pixels, two detection elements are set for each color as input pixels. Therefore, the response from one detection element is basically the same as in equation (6), and it is sufficient to specify a=T/6·α (7) as the aperture a in this equation. However, α is the ratio of the effective detection element area (area of the region excluding the area of the region necessary for element integral) to the surface area of one detection element, and is the aperture ratio.

From the above, the first integrating circuit 55 in this embodiment
When α=0.8, the output signal from the output signal becomes the curve shown by the solid line in FIG.

Here, in order to see the effect of this example, it is meaningful to compare the results with the case where no signal processing is performed in this example. CCD chip 54a when no signal processing is performed in this embodiment
It is necessary to take into consideration that one display pixel corresponds to one input pixel and that the arrays 54h to 54h are multiplexed. Then, as shown in FIG. 12, three detection elements are provided for each bit T of one display pixel. A yellow filter Y, a magenta filter M, and a cyan filter C are attached to these detection elements.

In this case, the response from one detection element is the (4th)
It can be found by setting the aperture a to a=T/3・α in the formula (8).

Based on the above, α=0.8 and the response from one detection element is illustrated as shown by the dotted line in FIG. As can be seen from this curve, the response in the spatial frequency region near (1/T) where moiré may occur is finite and exhibits a fairly large value.

This shows that the moire amplitude is large and the moire is very noticeable. When spatially multiplexed in this way, it is impossible to increase the aperture ratio of the detection element for each separated color, so moire is inevitably noticeable.

On the other hand, in this embodiment, 1
Input pixels are divided into display pixels into solid numbers that are twice or more the number of color-separated pixels. Moiré can be prevented by applying a signal obtained by adding or integrating signals from detection elements corresponding to the same color to one display pixel.

In the above embodiments, making a plurality of input pixels correspond to one display pixel can generally be achieved by increasing the number of input pixels. If the actual number of display pixels and the number of input pixels are the same, the input pixels may be duplicated to correspond to the display pixels. For example, output signals from two input pixels are added (integrated) to obtain half the number of display pixels.
Even if you create the same signal as each signal and make it the same number of signals as the number of display pixels and then supply it to the display pixels,
Moire can be prevented.

Input devices are not limited to CCD one-dimensional sensors, but can also include CCD two-dimensional sensors and TV cameras (especially spatially multiplexed color cameras).
It is also applicable to other matters. Further, the output device is not limited in any way as long as it is a device that expresses an image as a set of pixels.

For example, it is also applicable to cathode ray tube displays.

As described above, it is natural that any modifications are included in the present invention as long as they do not depart from the spirit of the invention.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between a conventional display pixel and an input pixel, and Figure 2 shows a signal supplied to one display pixel in the case of the relationship between the display pixel and input pixel shown in Figure 1. 3 is a diagram showing the relationship between the display pixel and the input pixel in an embodiment of the present invention, and FIG. 4 is a diagram showing the relationship between the display pixel and the input pixel shown in FIG. 3. FIG. 5 is a diagram showing the configuration of a device according to one embodiment, and FIGS.
8 and 9 are schematic diagrams showing the relative movement between the original 52 and the image input device 40, and FIGS. 10 and 11 are diagrams showing a part of the apparatus shown in the figure.
A diagram illustrating an example of a color input system,
FIG. 12 is a diagram showing a conventional example of a color input system. 40... Image input section, 41... Signal processing section, 42...
Image output section.

Claims (1)

[Claims] 1. An image input section that includes a plurality of detection elements whose aperture ratio is 1 or less and that reads an image and obtains image information using this detection element group, and an image that visualizes the image information from this image input section. An image input display device comprising: an output section; a reading density defined by a detection element in the image input section is set to a value greater than a recording density defined by a recording element in the image output section; By setting, an input pixel defined by a plurality of detection elements in the image input unit is assigned to one display pixel defined by a recording element in the image output unit, and An image input display device comprising: a signal processing means for averaging signals from the plurality of detection elements and then supplying the signal obtained by the averaging to a recording element defining one display pixel. 2. The image input display device according to claim 1, wherein the image input section is constituted by a contact sensor. 3. The image input unit includes a light source, a board provided facing the original onto which light from the light source is irradiated, and a plurality of parts arranged in a staggered manner on the board so as to cover the width of the original without any gaps. an IC image sensor chip, and the plurality of IC image sensor chips image the reflected light from the irradiated scanning line portion on the document as a substantially one-to-one erect real image on the plurality of IC image sensor chips. 2. The image input display device according to claim 1, comprising an optical system and a processing circuit that performs predetermined processing after reading out the output signals of the IC image sensor chip in parallel. 4. The image input display device according to claim 3, wherein the image input section is provided with three types of color filters in a row.