JPS5817795A - Color image pickup device - Google Patents

Abstract

PURPOSE:To widen the transmissive wave length range, and to remove noise, and to improve the color reproducibility, by installing an infrared filter in the image pick-up optical path and, at the same time, by using a sharp cut filter which cuts light having shorter wave length than red out of the filters. CONSTITUTION:Plural infrared filters are arranged on a filter disk 3 of a color image pickup device, and a sharp cut filter which cut light having shorter wave lenghts than red is adopted for at least one of the filters, and then, the disk 3 is rotated by a motor 4 synchronously to a clock pulse from a synchronism controlling circuit 8. The change-over of the filter of the disk 3 is detected by a synchronism detector 7 and inputted into the circuit 8. Images formed in an image pickup element 5 through the filter are binary coded at an A/D comparator 10 and added to a channel selector 11. The element 5, the comparator 10, and the selector 11 are controlled by the circuit 8 and the output of the selector 11 is read out to digital memories 100-102. Then, the transmissive wave length range is widened and the color reproducibility is improved, and then, the output is stored in a memory 103.

Description

[Detailed description of the invention] FIELD OF THE INVENTION This invention relates to field sequential color-imaging devices.

Conventionally, for example, in a field sequential type video camera, R (red), q [with], BC) band pass filters were sequentially inserted into the imaging optical path to obtain color No. 14, so it was not possible to handle each color. Moreover, band-pass filters have a low maximum transmittance, so they have the disadvantage that they do not provide enough light for low-luminance objects.

In addition, in the case of a bandpass filter, the transmittance is large in a long wavelength region in addition to a predetermined wavelength region, so that there is a drawback that light in the infrared region becomes noise.

By appropriately selecting the color filter of the present invention, sufficient light can be obtained even for low-luminance objects, noise in the infrared region can be completely removed, and even better colors can be easily obtained. The purpose of this invention is to provide a color whale photography device that provides high reproducibility, and also to reduce the number of filter types that need to be changed.

In order to achieve such an objective, in the embodiment of the present invention, a sharp cut filter is employed as a color filter at least in part, and the 1d number obtained by adding 5゛ to the filter insertion is easily calculated to υ↓ by 1. Through processing, it is made into a form that can be used as a color signal.

Next, the present invention will be specifically explained with reference to the drawings.

FIG. 1 is an IIA diagram of a field sequential cuff-imaging device. In addition, the imaging device referred to here includes a copying machine, a facsimile, etc. in addition to a camera.
l a photographing lens; 2 is a color filter; 3 is a filter disk; 4 is a motor that rotates ij3; 5 is an image sensor; 6 is an electric circuit for outputting the #i cut signal to the output terminal 6a; 7 is a color synchronous signal and a filter. The desk 3 is rotated by a motor 4, different color filters are sequentially inserted into the imaging optical path, and color signals are also taken out from the imaging device 6 in time series. However, in the past, as a color filter, three types of band-pass filters that transmit only R (red), G (green), and B (blue) colors were arranged on a filter disk, resulting in various drawbacks as described above. It is something.

FIG. 2 is a diagram showing the characteristics of a band-pass filter conventionally used in the filter disk 3. In the figure, curves R, G, and B are R filter, Q filter A/Y+, and B, respectively.
It shows the transmission characteristics of the filter.

FIG. 3 is a diagram showing the characteristics of the first practical example of the sharp cut filter configuration according to the present invention, in which (&) is a characteristic diagram of the first filter IPl, and (b) is the characteristic diagram of the second filter P2. Characteristic diagram of (0) II third filter B'
3, (d) is a characteristic diagram of the infrared cut filter 14 that is always placed in front of the light receiving element.

By forming a filter disk using a combination of filters with the characteristics shown in the figure, the transmission efficiency is improved even when each R%G, B signal is obtained using multiple filters, so it is suitable for dark subjects. It also becomes possible to capture images. Furthermore, a brighter image can be formed even for objects of the same brightness.

Also, according to the embodiment of the present invention, the sharp-cut filter 4' to be switched is determined by considering the spectral characteristics of the sharp-cut filter and the combination thereof. I! 4 types
Since there are three types, the time required to obtain one frame image is reduced, and the amount of memory required can also be reduced, and many other effects can be achieved.

That is, in the example shown in FIG. 3, the filter disposed on the filter disk 3 is an IFl having the spectral characteristics shown in FIG.
- Three filters shown in F3, among which filter Fi
It can be used for both purposes due to the external ray cutting characteristics of the photographic lens.

In that case, one of the filters (IFl) IIi on the filter disk 3 can be transparent.

FIG. 4 shows R and G as shown in the second diagram from the color signal obtained by filtering according to the present invention.

FIG. 3 is a diagram showing an example of the configuration of a readout circuit and the like for obtaining a B signal. Further, FIG. 5 is a diagram showing an example of the configuration of the fourth middle block 103.

Components with the same reference numbers as those in the cylinder 111M in the figure indicate the same members.

9) Yo preamplifier, 10 is a mu/D converter, 11 is a channel 7 converter, 15 is an external filter according to the present invention (a) loo to xog are digital memories,
Reference numeral 103 denotes an arithmetic circuit PLUCK; 104 to 106 arithmetic circuits; in the embodiment of the filter configuration shown in FIG. 3, 1o4. to
This is a 5 company subtractor. 12 is the reference ptsu oscillator 0
The operation of the illustrated circuit configured in this manner will be explained.

The synchronous control circuit at; servo-drives the heptad-4 at a predetermined speed synchronized with the output pulse of the reference clock oscillator 12, and the filter desk +S is driven by the motor to filter the light incident on the image sensor 5. .

At this time, the detector 7 installed on the disk detects
A synchronization signal corresponding to the filter switching is output, and together with the output of the clock oscillator 12, the synchronization control circuit 8"
The scan timing and shift timing of the image sensor are controlled through the .

In the present invention, the image sensor is read out sequentially for the light transmitted through each filter. Also, this read time series signal is amplified to a predetermined level via the preamplifier 9, and then converted into a digital signal in the A/D:I inverter.
0 Also, the sequential time-series signal JIl is controlled by a channel selector that is controlled by the synchronization output of the synchronization control circuit a.
Every signal through each filter K, memory 100~lo
g is sequentially distributed and stored.

Then, the images are digitized through the filters IP1 to IP13 shown in Memo Two 101 to io, and the numbers &1 to ol are stored.

Thereafter, the signals in each memory are extracted in parallel from the synchronization control circuit 8, the synchronization signal K, and the arithmetic circuits 104 to 104.
R, G, B as the desired signals calculated at 1o6
I get a signal.

Here, in the case of the filter configuration of fM3 shown in Figure 7, calculation 1
Signal a1 passed through filter 11 through circuit 1o41tc
In the circuit 106, the signal 01 passed through the filter 13 is subtracted from the signal bl, and in the circuit 106 the signal sl
Output in chronological order. The circuit 106 is a delay circuit (good).

With this configuration, B, G, and H digital color signals are output in parallel from the outputs of the arithmetic circuits 104 to 106, respectively.

Also, other color signals can be obtained in the same way by simply changing the arithmetic expression as appropriate.

Figures 6 (a) to 6 (6) are diagrams showing examples of the second combination of filters according to the batting average invention, and (-) in the same figure shows the spectral characteristics of the above-mentioned 7 Ilter IFI having ultraviolet cut-F characteristics, (
b) is the spectral characteristic of the sharp cut filter F5 according to the present invention, (C) is the filter zero spectral characteristic 1 according to the present invention, Cd') Fi is the spectral characteristic of the filter -1F3, (6) - is the image sensor , is a diagram showing the spectral characteristics of the infrared cut filter 14 disposed in front.
.

In this embodiment, one of these filters, IF 1, is used by the photographing lens, but other filters may also be provided at all times in front of the image sensor. The infrared cut filter 15, which is always placed in the
・ ・ .

Therefore, in this embodiment, filter 75, IF6 . , a ramie,
Arrange them sequentially on a filter disk and examine.

Furthermore, when obtaining the threshold R, G, and B signals by using a combination of a sharp cut filter and a band pass filter as in this embodiment, the calculation 1 circuit 103 is omitted in the control circuit as shown in FIG. It has the effect of being able to do things. - That is, through the filters 15, 1F3, and 1F3 respectively. If the images formed on the image pickup device 5 are respectively read out, they are read out as they are as n; a, 11 colors, respectively, so no special arithmetic circuit is required. , ((1) IIi This is a diagram showing a third embodiment of the Filter and Luther combination of the present invention, in which (a) is a characteristic diagram of the filter 11.
b) ti said filter 15? There is a characteristic diagram (・).

In this embodiment, when the filter yla is always disposed in the image pickup optical path or the outer cup filter d is always disposed in the image optical path, #i filter 1 can be a transparent filter.

Next, the eighth part is a diagram showing an example of the configuration of the arithmetic circuit 103 corresponding to this embodiment, and is a diagram showing a filter 15, ? ? , 74 respectively Lf
The signals of the tlili image are sequentially stored in memories 100-102, read out in parallel by the output of the synchronous control circuit 8, and inputted to the arithmetic circuit. Arithmetic U circuit 1031: Consisting of i circuits 104 to 106, if the outputs of memories 1oo to 102 are respectively d, e, e, tz, circuit 104 delays the signal d8 and outputs it as is, i, 10! S'' is a circuit that subtracts the signal e from the signal d1, and a circuit that subtracts the signal f1 from the 106ki signal.

Therefore, each output terminal of the circuit 104~log KtiB % G
Each signal of %R will be output.

As described in detail above, the present invention uses a sharp cut filter as a color separation filter that can switchably apply a plurality of different color filters to the entire imaging surface of an image sensor, and also uses a sharpened infrared cassi filter. By combining them, the number of filters to be changed can be reduced by L, and the occurrence of color blurring can also be suppressed when recording a fast-moving object image in color. Moreover, it is also possible to improve transmission efficiency. In the example, the memory 100 to log is used to perform calculations while synchronizing the signals that have passed through each filter, but it is also possible to synchronize the signals that have passed through each filter by using, for example, a delay m. , you can do the calculation -0, or you can do it as is with the calculation company analog signal.
11 companies Needless to say, when scanning the image formed on the image sensor through each filter, there is a method of over-scanning.
In other words, when scanning the image through each filter, for example, only the Ir1f4'lky yield is scanned, and when scanning the image through the same filter once again, only the Han odd field is scanned. You can also prevent dust by doing this.

Also, the filter disk is not a rotating type but a sliding type, which is good.

Furthermore, the spectral characteristics shown in the third, sixth, and seventh figures are not limited to these; the filter 11 is a sharp cut filter that cuts light with a wavelength shorter than that of blue, and the filter 12 is a sharp cut filter that cuts light with a wavelength shorter than that of green. Sharp cut filter, F
3 is a sharp-cut filter that cuts out light with a shorter wavelength than red, and a band-pass filter with sharp-cut characteristics that cuts out light with a longer wavelength than red.
Note: A sharp cut filter that cuts out long wavelength light is sufficient.

Moreover, even if the image sensor 5 is, for example, an OOD,
``It goes without saying that it may be something like an image pickup tube.

In addition, by using sharp cut filters in combination in this way, the maximum transmittance in the infrared wavelength region is extremely high, and the transmittance in the infrared region is the same as that of fiff. It has the characteristics that the sharp cut characteristics can be selected relatively freely, and it is easy to manufacture. Therefore, the reception of the image sensor is better than that of the conventional one.
Of course, the amount of light increases dramatically and the shooting area expands to the low-brightness side, and it also has the advantage of being able to obtain good color reproducibility at a low cost and completely eliminating noise from infrared light. Have ◎ −

[Brief explanation of the drawing]

Fig. 1 A principle diagram of a field sequential color imaging device according to the present invention, a diagram showing a color signal of the jtgd1%GSB, a fas diagram (&), (1, (・), (1)) according to the present invention A diagram explaining the spectral characteristics of the filter of the first example, #
Figure I4 is a diagram showing an example of the control circuit of the present invention; Figure 5 is a partial configuration diagram of the breakthrough circuit; Figure I4 is a diagram showing the spectral characteristics of the filter of the second embodiment of the present invention; A diagram showing the spectral characteristics of the filter of the third embodiment of the invention,
FIG. 3 is a diagram illustrating a configuration example of an arithmetic circuit corresponding to an embodiment. 101. Shooting lens% 2””Filter% 3 *e+
+ Filter disk, 4*e*゛motor, H*mm
11 spear elements, 6@1111 scissors image processing times imaging processing 0. Synchronous detector, 8006 interphase control circuit, 100~l O3,,
, Memory, 104-l O6, , Arithmetic circuit. Patent applicant: Canon Co., Ltd.

Claims (2)

[Claims] (1) In a color imaging device that obtains different color signals by sequentially switching the number of filters with different transmission characteristics with respect to the imaging surface, an infrared cut filter is provided in the ffiK4, and % FlU Ml
: A color sweeping 9j device 1t0 whose object image is that at least one of the M &'Y filters is a sharp cut filter that cuts wavelengths shorter than red. (2) In a color imaging device that obtains different color signals by sequentially switching a number of filters with different transmission characteristics to the imaging surface, an ultraviolet cut filter is provided in the imaging optical path and the number of %AllKt units is increased. A color imaging device characterized in that at least one of the filters is a sharp cut filter that cuts light with a wavelength longer than W color? t0