JPH0437251A - Picture reader - Google Patents

Abstract

PURPOSE:To prevent mis-copy due to an external light from a fluorescent lamp having periodicity by raising an alarm when the result of discrimination of an output level of an external light detection means is a prescribed level or over. CONSTITUTION:The reader is provided with an image pickup lens 3 forming an image of a picture of a transmission original 2 lighted by a lighting means 1 and an imaging device 5 applying photoelectric conversion to the picture formed via the image pickup lens 3 and reflecting mirror 4. Moreover, the reader is provided with a fluorescent lamp flicker detection circuit 6 detecting flicker of a fluorescent lamp based on a value subjected to photoelectric conversion by the imaging device 5, and a projector control circuit 7 discriminates a signal of the fluorescent lamp flicker detection circuit 6 and an alarm tone generator 8 warns an error when a level of a prescribed range or over is obtained. Thus, mis-copying due to uneven color or uneven density having periodicity being a cause to the light of a fluorescent lamp is prevented in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an image reading device, and particularly to an image reading device having a means for preventing copy errors caused by external light in a projector or the like.

<Conventional technology> In the past, in order to prevent copy errors due to external light, people carefully avoided external light or attached covers to block external light.

<Problem to be solved by the invention> By the way, even if humans try to carefully exclude external light,
It was difficult to judge how much outside light could be tolerated, such as accidentally letting in outside light and making mistakes in copying.

In addition, flicker noise from periodic fluorescent lights among outside light tends to affect images and cause copy errors.

SUMMARY OF THE INVENTION In view of the problems of the prior art described above, it is an object of the present invention to provide an image reading device that does not cause copy errors due to external light.

<Means for Solving the Problems> In order to achieve the above-mentioned object, an image reading device of the present invention includes: illumination means for illuminating a document; optical system means for guiding an illuminated image of the document to an image pickup device; It has an external light detection means for detecting periodic external light, a means for determining the output level of the external light detection means, and a means for issuing a warning when the determination result of the determination means is equal to or higher than a certain level. It is something.

<Operation> Image reading with the above configuration 1! The position is exposed to periodically changing external light,
For example, the flicker noise of a fluorescent lamp is detected by the external light detection means, and when the noise exceeds a certain level, a warning is issued by the warning generation means, thereby making it possible to prevent copy mistakes.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 1 to 12.

FIG. 1 shows the basic configuration of this embodiment. In the same figure, an image formed through a mirror 3 and a reflecting mirror 4 is photoelectrically converted.
It is a 1itt element. Reference numeral 6 denotes a fluorescent lamp flicker detection circuit which is connected to the image pickup element 5 and detects fluorescent lamp flicker based on the value obtained by photoelectric conversion by the image carrier element 5. 7 is a projector control circuit that judges the signal of the fluorescent lamp flicker detection circuit 6, and if a level exceeding a predetermined range is obtained, a warning sound generator M8 warns of an error;
If it is within a predetermined range, the color printer 11 starts a copying operation via the interface circuit 10, and roughly adjusts the focal position by moving the image lens 3 via the focus adjustment means 9.

Figure 2 shows a specific circuit configuration of a color image processing device to which this embodiment is applied. 11111L by photoelectric conversion with a color image sensor such as a charge element), digitize the obtained analog image signal with an A/D (analog/digital) converter, process the digitized full color image signal, It is applied to color image copying apparatuses and the like that output color images to various color printers and obtain color images.

In the figure, 21 (1 in Figure 1) is a light source lamp for illuminating a transparent original, 22 (2 in Figure 1) is a transparent original such as 35am photographic film, and 23 (3 in Figure 1) is a light source lamp for illuminating a transparent original. The imaging lens 24 (4 in FIG. 1) is the Ili image lens 23
Mirror 25 that reflects the optical path of the original image onto the imaging surface
(9 in FIG. 1) is a focus position adjustment motor that drives the III & lens 23, 26 (7 in FIG. 1) is a power source for the focus position adjustment motor 25, light source 21, etc.
27 is a home position switch that determines the home position of the imaging lens 23; 28 is a color image sensor 29 such as COD;
This is a self-hock lens that forms an image of the original document (5 in FIG. 1).

The transparent original 22 is first irradiated by the illumination lamp 21, and the transmitted image is read by the sensor 29 after color separation, and is amplified to a predetermined level by the analog processing circuit 30, and the amplified signal is /H&A/D
The conversion circuit 31 performs shading correction and analog-to-digital conversion, and the deviation correction circuit 32 corrects the deviation.
G.

Each signal of B is output. Next, black correction/white correction circuit 3
3, only the G signal is read by the fluorescent lamp flicker detection circuit 47 (6 in FIG. 1), and if the value is above a predetermined level, the warning reputation generator is activated by a command from the projector control circuit 26. 46 (8 in FIG. 1) alerts you to the error.

By the way, the fluorescent lamp flicker detection circuit 47 examines the frequency characteristics of the average value of the 11 degree level of one pixel or multiple pixels in the main scanning direction of the G signal, and determines whether the G signal is 100 Hz or 120 Hz.
Configure a bandpass filter with a peak frequency around z using a digital signal processing system, or calculate its output by numerical calculation, determine whether the power is above a certain value or below a certain value, and output it. .

The color reading sensor 29 is a color reading sensor 29 which is divided into 5 parts 29a to 29e in the main scanning direction and reads 62.5 lines (62.5 lines).
1/16jw) is taken as one pixel, and there are 1024 pixels, that is, the pixels are divided into three in the main scanning direction by G, B, and R as shown in the figure, so the total number of effective pixels is 1024X3=3072.

On the other hand, each chip 29a to 29e is formed on the same ceramic substrate, and the 1st, 3rd, and 5th chips of the sensor <29a, 29c
, 29e) are on the same line LA, the 2nd and 4th (29b
, 29d) is 4 lines (62,5
4=250 lines) on the line LB, and when reading a document, it scans in the direction of the arrow.

Of the five CODs, the 1st and 3.5th CODs are driven by the drive pulse group 0DRVI 18, and the 2.4th COD is driven by the EDRv119, independently and synchronously.

In Figure 3(b), ○φ included in 0DRV118
1A, Oφ2A, OR3 and EφIA, Eφ2A, and ER8 included in EDRVI 19 are charge transfer lock and charge reset pulses in each sensor, respectively, and 1.3
．． Due to mutual interference and noise limitations between the fifth and second and fourth signals, they are generated in synchronization with each other without jitter. Therefore, these pulses are generated from one reference oscillator source 03C58 (FIG. 2).

FIG. 4(a) shows the drive pulse 0DRV118. of the color reading sensor 29. FIG. 4 is a circuit block diagram of the pulse generator 57 that generates the EDRVl 19 (bl is its timing chart, and is included in the system control pulse generator 57 in FIG. 2).

The original clock CLKO generated by a single 08C58 is divided by the frequency divider 63. ○135 is the reference signal 5YNC2 that determines the generation timing of 0DRV and EDRV.
, 5YNC3. 5YNC2,
5YNC3 is the signal line 139 connected to the CPU42 bus
The output timing is determined according to the set value of the presettable counter 64, 65, and the frequency divider 66, 67 and the drive pulse generator 68, 69 are initialized. In other words, H3YNC1 input to this block
15 as a reference, all of them are generated by one oscillation 1 [CLKO output from 1O8c58 and the minute rotation lock that is generated synchronously, so 0DRVI 18
．． ! : Each pulse group of the EDRV 119 is obtained as a periodic signal with no jitter at all, and signal disturbances due to interference between sensors can be prevented.

Here, the sensor drive pulses 0 obtained in synchronization with each other are
The DRVI 18 is connected to the 1st, 3.5th sensors 29a via the CCD driver 56 (FIG. 2).

29G, 29e, EDRV119 has CCD driver 5
6 through 2.4th sensor 29b.

29d. Video signals 1 to V5 are independently output from each sensor+j29a to 29e in synchronization with the drive pulse, and are adjusted to a predetermined voltage value by independent analog processing circuits 30-1 to 305 for each channel shown in FIG. 0O81 in FIG. 3(b) is amplified and passed through the coaxial cable 101.
29 timing rV1. V3. V5 is EO3134
(7) A signal of V2.4 is sent out at timing and input to the sample hold (S/H) circuit 31.

The color image signal obtained by dividing the original input into this S/l-1 circuit 31 into five parts and reading it is separated into three colors: G (green), B (blue), and R (red). . Therefore, after S/H, 3×5=15 signals are processed.

Further, the analog color image signals sampled and held for each color R, G, and B by the S/H circuit 31 are sent to the next stage A.
Each of the 1st to 5th channels is digitized by the /D conversion circuit, and each of the 1st to 5th channels are independently paralleled and output to the next stage.

Now, in this embodiment, as mentioned above, 4 lines (62,
Since the document is read using five staggered sensors that have an interval of 5m x 4 = 250 lines in the sub-scanning direction and are divided into 5 areas in the main-scanning direction, the channels 2 and 4 that are scanning in advance and the remaining 1 , 3°5, the reading position is off. Therefore, in order to connect these lines correctly, a shift correction circuit 32 having memory for a plurality of lines corrects the shift.

Next, the blue signal black level correction circuit 77 in FIG. 5(a)
The black correction operation will be explained using the block diagram of FIG. As shown in FIG. 5(b), when the amount of light input to the sensor is small, the black level outputs of channels 1 to 5 vary greatly between chips and between pixels. If this is output as is and an image is output, streaks and unevenness will occur in the data portion of the image. Therefore, it is necessary to correct this variation in the output of the black portion, and this circuit is designed to correct this. In other words, the black level data O to be thermally corrected
For K m, for example, in the case of a blue signal, B ! n
(ri - D K (ri = Bcu (ri), and the same control is performed for green G10. red R1n. Also, this control is controlled via Ilo of the CPU 42, and furthermore, it is necessary to access the RAM 78. This allows the thermal correction data CI K m to be read and written.

Next, white level correction (shading) in the thermal correction/white correction circuit 33 will be explained with reference to FIG.

White level correction is carried out by moving the document scanning unit containing a self-hook lens and a COD image sensor to the center of a screen (not shown) attached to the mirror 24, and applying shading correction filters corresponding to negative and positive films respectively. Illumination system based on white data, which is a transmitted image.

Corrects sensitivity variations in the optical system and sensor.

FIG. 6(a) shows the basic circuit configuration of the thermal correction/white correction circuit 33, which is the same as the blue signal black level correction circuit 77B shown in FIG. In contrast, in color correction, the multiplier 79'
The only difference is that .

During color correction, when the COD image sensor 29 for reading the original is at the reading position at the center of the screen, that is, before the copying or reading operation, the original illumination lamp 21 is turned on to obtain image data 1 at an even white level. It is stored in the line correction RAM 78'. Needless to say, as a pre-processing for this shading correction, the light amount of the lamp 21 is set to an appropriate value.

For example, if the projected image has a width in the longitudinal direction of A4 in the main scanning direction, then 161) el/ms+ is 16X297m=47
52 pixels, that is, at least the capacity of RAM 78' is 4
It is 752 bytes. As shown in FIG. 6(b), if the i-th pixel white board data Wi (i=1 to 4742) is shown, the RAM 78' stores data for the white board for each pixel as shown in FIG. 6(c) F. is stored.

On the other hand, regarding Wi, the corrected data Do=DiXFFh/W for the read value Qi of the normal image of the i-th pixel
It should be i. Therefore, the latch 8 is set by the CPU 42.
Gate 80' for ■l, @l, ◎'@' of 5'
Open 81' and select selectors 82' and 83'.
, 86' so that B is selected, and the RAM
78' is made accessible to CPtJ. Next, in the procedure shown in FIG. 6(d), the CPLI 42 performs FFH/WO on the first pixel Wo.

Data replacement is performed by sequentially calculating FFH/W1 . . . for Wl. Once the blue component of the color component image has been corrected [5 tep B in FIG. 6(d)], the green component (5 tep G) and the red component (5 tep R) are similarly corrected in sequence.

Here, the algorithm for automatic focus position adjustment will be explained using FIG. 11.

Generally, autofocus (AF) evaluates (detects) the degree of focus (degree of focus) by some means,
Based on this degree of focus, the position of the lens distance ring is controlled to achieve focus. The edges of both images are sharper in an in-focus image than in an out-of-focus image. This corresponds to the fact that there are many high frequency components in the image signal when the image is read. In general, there is a method of performing 8F by detecting from the image signal how much the image is in focus (or conversely, how blurry it is), such as by using the appearance of high frequency components of the image signal as an evaluation quantity. In the field of cameras, this is called the blur amount detection method. Other methods that utilize the principle of triangulation include an active method that projects spot light or pattern light, and a shift detection method that detects the amount of shift in the pattern of images carried by multiple sensors.

In this embodiment, the aforementioned blur detection method with a simple mechanical configuration is used.

That is, for evaluating the degree of focus (sharpness), for example, a G (green) image signal read out from the COD image sensor 29 is used, and an AF image signal at the center of a screen (not shown) attached to the mirror 24 is used. The sharpness is determined for both image reference area image signals. It is known that the evaluation of the sharpness P at this time can be obtained, for example, by an arithmetic expression as shown in the following (1).

P=Σ(Xj X j-1) 2...-
(1)-2a Levels a and b are the numbers of the second pixel from the beginning and the last pixel in the main scanning direction in the AF image reference v4 area. ) Now, when trying to focus an image based on the amount of blur, unfortunately there are not many high-frequency components such as edges in the AF image reference area on the subject document, for example, as shown in Figure 11. As shown by a broken line curve 3103, the peak value (maximum value) Sl of the sharpness P is small, and the lens extension amount at the in-focus point may not be detected with high accuracy.

Next, as shown in FIG. 12, the AF operation, that is, the motor 2
While moving the lens 23 multiple times according to step 5,
There is a possibility that the focal point may shift due to various factors such as mechanical backlash or movement of the mounting position of the projector body. Therefore, we developed a method to calculate the rate of change based on previous focal position data and calculate the current focal position from there. The simplest method for calculating the rate of change is to select two points and find the slope, but here we adopted a method of calculating the rate using the least squares method.

When the maximum value Si is sufficiently large, the above-mentioned operation is not performed and the focus position is moved to the maximum value Si.

As described above, the black level and white level are corrected based on various factors such as the black level sensitivity of the image input system, the COD dark current variation, each sensor sensitivity variation, the optical system light amount variation, and the white bell sensitivity. The color image data proportional to the input light amount, which is uniform over the scanning direction, is input to a logarithmic conversion circuit 35 (FIG. 2) that performs processing to match the luminous efficiency characteristics of the human eye.

Here, white = OOH and black = FFH are converted as much as possible,
Furthermore, the image source input to the image reading sensor 29 is a transparent original, or even if the same transparent original is a negative film,
Since the input gamma characteristics differ depending on the sensitivity and exposure state of the positive film or film, as shown in Figure 7(a), (
As shown in b), it has a plurality of LUTs (look-up tables) for logarithmic conversion, which are used depending on the purpose.

The CPU 42 connects the signal line IQo, 1g1.1g2 (16
0 to 162) to switch the LUT. Here, each B
, G, and R correspond to the density values of the output image, and the data output for B (blue), G (green), and R
(Red) signals correspond to toner amounts of yellow, magenta, and cyan, respectively, so the subsequent color image data are associated with Y, M, and C.

Note that the first color correction circuit 34 is a circuit that detects a specific color from input color image data R, B, and G and replaces it with another color. For example, it realizes a function of converting a red part in a document to any other color other than blue.

Next, the second color correction circuit 36 performs color correction as described later on each color component image data from the original image obtained by logarithmic conversion, that is, the yellow component, magenta component, and cyan component. The spectral characteristics of the color separation filters arranged for each pixel in the color reading sensor 29 have an unnecessary transmission area shown in the shaded area as shown in FIG.
For example, it is well known that color toners (Y, M, C) transferred to transfer paper have unnecessary absorption components in the shaded areas shown in FIG. Therefore, the color component image data Yi,M:,C
Masking correction is well known in which color correction is performed by calculating a linear equation for each color for i. Furthermore, Yi, Mi.

Min by Ci (Yi, Mi, C1) (Yi.

Calculate IVli, (:, the minimum value of i), use this as a smear (black), and then add black toner (smear insertion)
Undercolor removal (UCR) operations, which reduce the amount of each coloring material added depending on the added black component, are also commonly performed.

FIG. 10(a) shows the circuit configuration of the second color correction circuit 36 that performs masking, smearing, and UCR. The features of this configuration are (1) It has two systems of masking matrices, and can be switched at high speed by one signal line "Ilo".

(2) The presence or absence of UCR is determined by one signal line "I/'O",
Can be switched quickly.

(3) It has two circuits that determine the amount of smear, and “I/
You can switch quickly by pressing ``O''.

That's the point.

First, prior to image reading, a desired first matrix coefficient M1 and a desired second matrix coefficient M2 are set via a bus connected to the CPU 42.

In this embodiment, Ml is set in registers 87-95, and M2 is set in registers 96-104.

In addition, 111 to 122, 135, 131° and 136 are selectors, respectively, and select A when the S terminal is -1''.
Select B when it is “0”. Therefore, when selecting matrix M1, the switching signal MAREA364-"1N,
When selecting matrix M2, it is set to 0''.

Further, 123 is a selector, and selection signals Co, C
+ (366, 367), the outputs a, b, and c are obtained based on the truth table of FIG. 10(b). Selection signal Co
, C+ and C2 correspond to color signals to be output,
For example, in the order of Y, M, C, Bk (C2, C, +, Co
)-(0,0,O).

(0,0,1), (0,1,O), (1,'0°O),
Furthermore, by setting (0, 1, 1) as a monochrome signal, a desired color-corrected color signal is obtained. Now, (Co,
C+, C2)=(0,O.

O), and MAREA-"1", selector 1
23 outputs (a, b, c) have registers 87, 88 .
89 contents, therefore (aYl, -b111+.

Ccl) is output.

On the other hand, Mln(Yi, M
The black component signal 374 calculated as i, C1)=Y=ak-b (a, b are constants) in the primary conversion circuit 137
The -order transformation becomes (passes through the selector 135) and is input to the B input of the subtracter 124°125.126. In each subtractor 124 to 126, Y=Y(a
k-b), M=M i -(ak-b), C-C1
-(ak-b) is calculated and the signal line 337°378.3
79, a multiplier 127 for masking operations;
128.129 is input.

The selector 135 is controlled by the signal UAREA365, and the UAREA365 selects the presence or absence of UCR (undercolor removal).
The configuration allows for rapid switching between ■ and ○''.

Multipliers 127, 128, and 129 each have eight inputs (ay+, bhl+, -Cc+), and the aforementioned [Y i −<ak−b), M(ak−b)
, Ci −(ak−b) ] = [YIvN,C
i] is input, so as is clear from the figure, the output Dotx has the condition C1=O (Y.

Selection of M and C>, Ycu = Y i X (aYl)
+M + X (-bx+) +Ci X (-Cc,)
is obtained, and yellow image data that has been subjected to masking color correction and undercolor removal processing is obtained. Similarly, Moh, = YiX (-ay2) + MiX (b
M2) +Cix (-CC2)Cax -Yix (
-ay3) +Mix (bM3) +Cix (CC
3) is output to DQJL. Color selection is done according to the order of output to the color printer (Co, (,
+02 ), the CPU 42 according to the table in FIG. 9(b)
controlled by Register 105~107°108~
Reference numeral 110 is a register for forming a monochrome image, and based on the same principle as the above-mentioned masking color correction, 1 is applied to MONO=.
Weighting of each color is obtained by addition using Y i +ff11M i +m+ C+.

As mentioned above, the switching signal MAREA364 is a high-speed switching of the masking color correction matrix coefficients M1 and M2, and the UAREA365 is a high-speed switching of the presence/absence of UCR, K
AREA387 switches the primary conversion of the black component signal (signal line 369 → output to Dcu through selector 131),
That is, for −Min(Yi, Mi, Ci), Y=
This is a signal that quickly switches the characteristics of ck-d or Y=ek-f (c, d, e, f are constant parameters).

FIG. 13 shows another embodiment of the invention. In order to simplify the explanation, the same parts as in the previous embodiment are given the same reference numerals, and only the different points will be explained.

In this embodiment, a CCD separate from the color image sensor 29 is used.
A sensor 29' is installed on the projection surface, and this CCD sensor 2
9' is connected to a fluorescent lamp flicker detection circuit 47. The other configurations and configurations are the same as those of the conventional example described above.

In this embodiment with the above configuration, when the CCD sensor 29' is irradiated with light from an external fluorescent lamp, the fluorescent lamp flicker detection circuit 47
Detects fluorescent light flicker. The value is determined by the projector power source and control circuit, and if it is equal to or greater than a predetermined value, the warning sound generating device 46 issues an error warning.

<Effects of the Invention> As explained above, the present invention provides external light detection means, means for determining the output level of the external light detection means, and means for issuing a warning when the determination result of the determination means is equal to or higher than a certain level. For example, by detecting fluorescent light flicker as external light and warning of errors based on the value,
This has the effect of reliably preventing copy errors caused by periodic color unevenness and density unevenness caused by fluorescent light.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of an image reading device according to an embodiment of the present invention, FIG. 2 is a circuit configuration diagram for its operation, and FIGS. Explanatory diagram showing the reading sensor configuration diagram and drive palace, Figure 4 (
a), (b) are circuit block diagrams and timing charts for generating each drive pulse, and FIG. 5(a),
(b) is a circuit block diagram for thermal correction and its dynamic diagram, Figures 6 (a) and (b), (C), (
d) is a circuit block diagram for white correction and an explanation diagram of its operation, FIGS. 7(a) and (b) are a circuit block diagram for logarithmic conversion and an explanation diagram of its operation, and FIG. 8 is a diagram of a color separation filter. 9 is a characteristic diagram of color toner, FIGS. 10(a) and 10(b) are circuit block diagrams for color correction and their dynamic diagrams, and FIG. 11 is a diagram showing the control algorithm of this embodiment. FIG. 12 is a diagram similarly showing the relationship between focus operation and focal position, and FIG. 13 is a circuit configuration diagram of an image reading apparatus according to another embodiment of the present invention. 1.21...Illumination means, 2.22...Transparent original, 3
゜23...Imaging lens, 5...Imaging element, 29...
・Color image sensor (imaging device), 6.47...
Fluorescent lamp flicker detection circuit (external light detection means), 7.26.
-・Projector control circuit, 8.46... Warning sound generating device. Figure 1'' Figure (a) Figure (b) Figure (a) Figure (d) 1=0 ND Figure (b) (c) Figure (a) (b) Figure 400500600700400': ffl u'
AXJ 4UtJ Figure 10 (b)

Claims (1)

[Claims] 1. An illumination means for illuminating a document, an optical system means for guiding an image of the illuminated document to an image sensor, an external light detection means for detecting periodic external light, and an output level of the external light detection means. An image reading device comprising: means for determining; and means for issuing a warning when the determination result of the determining means is equal to or higher than a certain level.