JPS6285590A - Video camera and interchangeable lenses - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a video camera equipped with an adjustment means for adjusting the white balance of a color imaging signal, and an interchangeable lens that is detachable from the video camera.

<Prior art> Conventionally, in video cameras and other devices, the white balance of a color image signal is determined by setting the spectral characteristic of the most standard lens among the spectral characteristics of commonly used lenses to zero, and then adjusting the spectral characteristic to the set spectral characteristic. It has been adjusted based on color temperature information from the light from the subject.

<Problems to be solved by the invention> However, in conventional video cameras with interchangeable lenses, the spectral characteristics differ depending on the lens used, so it is necessary to set the spectral characteristics of the standard lens and adjust the white balance using color temperature information from the subject. Even after adjustment, the spectral characteristics differ greatly from the standard lens depending on the interchangeable lens actually used, and the white balance cannot be properly adjusted even for the same subject.

By the way, in the imaging system of a video camera, for example, IR
Optical low-pass filters and color filters are installed in front of the image sensor to prevent aliasing distortion due to the output pressure of the cut filter or image sensor, but the spectral characteristics of the filter are not ideal. do not have. For example, it has been necessary to compensate for the spectral characteristics of the video camera's imaging system during use due to the fact that not only the infrared light component but also the red light component of the incident light is cut by the R-cut filter.

The present invention eliminates the above-mentioned drawbacks and provides an interchangeable lens (video camera) and such (
The aim is to provide interchangeable lenses suitable for video cameras.

Means for Solving the Problems In order to achieve the present object, the first invention of the present application is such that the photographing lens is replaceable, and the entire luminous flux incident through the photographing lens and the imaging system is converted into an electrical signal. In the video camera, the photographing lens has a storage means for storing a comprehensive spectral characteristic according to a spectral characteristic peculiar to the lens and a spectral sensitivity characteristic of the imaging system, and the comprehensive spectral characteristic stored by the storage means Information corresponding to '5r: having a reading means, a means for controlling white balance based on the read information, and controlling the white balance based on the read information. shall be.

Further, the second invention of the present application is an interchangeable lens that can be attached to and detached from a video camera, which stores all information corresponding to the spectral characteristics of the photographic lens and the overall spectral characteristics according to the spectral sensitivity characteristics of the imaging system of the camera. All features include readable storage means.

<Function> The storage means for storing information corresponding to the spectral characteristics of the lens provided on the interchangeable lens side and the overall spectral characteristics according to the spectral sensitivity characteristics of the imaging system of the camera is read out by the video camera body side, and this storage means is read out by the video camera body side. The white balance of the color imaging signal is controlled by the white balance control means in accordance with the read output.

Therefore, it is possible to perform excellent white balance adjustment for each interchangeable lens used.

Furthermore, there is no need to store all the spectral sensitivity characteristics of the imaging system on the camera side.

<Embodiment> FIG. 1 is a block diagram of a video camera according to an embodiment of the present invention. In Fig. 1, 1 is a photographic lens that stores color information corresponding to the spectral characteristics of the photographic lens, and 2 is a photographic lens 1.
an image sensor that converts an image incident through the camera into an electrical signal;
3 and 4 are R amplifiers and B amplifiers that amplify the red and blue signals output from the image sensor 2, respectively; 5 is an automatic tracking white balance sensor that detects the color temperature of the light source; ft,'t- around the area, and are arranged so that the light is averaged and received through an achromatic filter. 6 is a digital control voltage value D''/ which controls the gain of the R amplifier 3B amplifier 4 based on the data sent from the lens 1 and the white balance sensor 5.
A system controller that outputs D B/G. 7 converts the digital control voltage values DR/, DB/G obtained by the system Φ controller 6 into analog voltages vR/, v
DD/A converter that converts to B/G. 8 is the signal R', G whose color balance has been adjusted by the R amplifier and the B amplifier.
, B''i is a signal processing system that converts the signal into a predetermined signal.

Next, FIG. 2 is a block diagram of the photographing lens 1 and the camera body 2 for explaining a communication method between the photographing lens 1 and the camera body 2 in the embodiment shown in FIG. In the figure, C1 is the camera's microcomputer, C2 is the main interface, C21 is the power output terminal, and C22 is the main interface.
is a data terminal, C2, C3 is a signal terminal, and C24 is a GND terminal. C3 is a ROM in which the main microcomputer program is stored, C4 is a power supply section, C5 is a disk drive section that drives a disk for recording images provided in the camera body 2, C6 is a photometry system, and C7 is a distance measurement system. It is a system. Further, the photographing lens 1 is removably attached to the camera body 2. Ll is the lens microcomputer, L2I Elens interface, L21 is the power terminal, L22 is the data terminal, L23 is the bus terminal, L2
4 is a GND terminal, and L3 is a ROM that stores various information about the lens 10 and programs for the sub-microcomputer, which will be described later.
.

L4 is an aperture drive system, L5 is a focus drive system, and L6 is a zoom drive system.

Next, various information about the lens 1 stored in the ROM L3 of the photographic lens 1 will be explained using FIG. 3.

In FIG. 3, the Rero command sent from the camera 2 via the photographing lens IK data terminals C22 and L22e, the code of the command, the content of the command, the number of bytes of data to be sent from the photographing lens 1, and the data allocated to the bytes. It shows the type. It should be noted that the data indicated by sK "←" in the data content completely indicates that the data is the same as the content shown in the content column.

±Okatsubashi Ashi --＃T
The content read by the command shown as e5t color is the spectral characteristics of the lens, which is L'36°L B7a from the ratio of n, G, and B of the light that passes through the lens gold.
The formula consists of 2 bytes of data indicating . Te5t
The content read by the command shown as Loss is data indicating the transmittance of the photographing lens 1.

Further, the contents read by the command shown as Te5t ID are data indicating the manufacturer, type, and function of the lens, and several bytes are appropriately allocated to each of them, and the data consists of 7 bytes in total.

Here, the data read by Te5teolor will be described in more detail.

The data read by Te5t color is shown below.

That is, ...... (1) Here, Cr r Cg T Cb is, R (λ): Spectral reflectance I (
J): Spectral intensity of standard light source τL(λ): Spectral transmittance of photographic lens 1'L(λ): Spectral transmittance of lens defined as standard τF(λ): IR cut filter attached to camera body 2, Spectral transmittance τj (λ) of various filters excluding color separation filters such as low-pass filters: Spectral transmittance of R, G, and B color separation filters. When j f r is red, when j is g is the transmittance of the green filter, and when j is set to b, it is the transmittance of the blue filter.

(If the camera's color separation filter is not a pure R, G, B type, the R, G, B values obtained from the signal processing circuit that ultimately converts them into R, G, B) S(λ ): When the spectral sensitivity of the image sensor (e.g. image sensor tube, solid-state image sensor) is taken as Cj=fR(λ)I(λ)τL(λ)τF(λ)τj(
λ)S(λ)dλC”j=fR(λ)I(λ)
)τF(λ)τj(λ18(λ)dλ(j=r, g4.
It is.

In other words, the data Cr, Cg, and Cb reflect the image capture system of the photographing lens 1 and the camera body 2, that is, the engineering R cut filter,
R, G, and B obtained from the image sensor through various filters such as low-pass filters, and R, G, and B color separation filters.
This is the output.

Further, the data Cr' r Cg'+ cb' are the R, G, and B outputs obtained from the image sensor when a standard lens is used instead of the above-mentioned photographic lens 1.

Therefore, the data L/G, LB/G obtained by executing "Teat color" is the ratio of the R, G, and B outputs obtained when using the standard lens, and the photographing lens 1 for /G. These are the ratios of R/ and B/G of the R, G, and B outputs obtained when using .

In other words, such data L"7g, L B/G
is data that takes into consideration the spectral characteristics not only of the photographing lens 1 but also of the photographing system within the camera body 1.

By storing the above-mentioned LR/G, LB/Gt in the photographing lens 1, the following effects can be obtained.

- Since the photographing lens IK stores data corresponding to the overall spectral characteristics including the spectral characteristics of the imaging system of the camera body 2, there is no need to store the spectral characteristics of the imaging system on the camera body side.

- Store data corresponding to the spectral characteristics of the camera's compensation system on the camera body 2 side (R/camera body, B/G camera body), and store data corresponding to the spectral characteristics of the photographic lens on the photographic lens l side. b Lens body.

B4 camera body>, and even if the two are combined, accurate comprehensive spectral characteristics cannot necessarily be obtained.

However, by storing data <LR/=LB/(3>) corresponding to the overall spectral characteristics in the lens IK as in this embodiment, accurate overall spectral characteristics can always be obtained.

Next, the commands and data shown in Figure 3 are sent to the camera body 2.
The order in which data is exchanged between the camera and the lens 1 will be explained using FIGS. 4 and 5. FIG. 4 is a flowchart executed by the camera body 20 microcomputer C1, and FIG. 5 is a flowchart executed by the lens 10 microcomputer L1tC.
This is a flowchart to be executed more easily.

First, the operation of the camera body 2 starts, and the flow starts from the step #θ shown in FIG. 4. Then, 4#1 in FIG. be sent to the lens.

On the other hand, when the operation of the lens 1 is started, steps 70-j and #1 shown in FIG. 5 are started, and step #1 is executed.

The step shown in FIG. 5 #1 determines whether a command is sent from the camera body 2 to the lens 1. If no command is sent, the loop is repeated, and if a command is sent, #1 is determined. Proceed to +2. Therefore, when the operation of the camera body 2 is started and step 4#1 in FIG. Proceed to step 2. Lens 2 determines whether the transmitted command is an executable command or not in #2 of FIG. 5. If the command is executable, the process goes to #3 of FIG. Proceed to $4.

Here, #3 in FIG. 5 is a step in which the command sent from the camera body 2 to the lens 1 is sent as is (return command) from the lens 1 to the camera body 2. Here, Figure 5 4
After executing #1, the lens 1 executes the command (#5 in FIG. 5) and then sends the data designated by the command to the camera 2 (#5 in FIG. 5). Further, FIG. 5 (4) is a step of transmitting data indicating "command error" 1 to the camera 2. In other words, if the command sent from camera body 2 to lens 1 is an executable command, lens 1 transmits the transmitted command from lens 1 to camera body 2 as is. If the command sent from the camera body 2 to the lens 1 is an unexecutable command, the lens 1 sends a "command error" message to the camera 2 indicating that the transmitted command cannot be executed. It shows the flow. In this state, the camera body 2 is in a state to receive the command sent from the lens 1 as shown in FIG. 4I-2, and the lens 1
All the data is sent from the lens 1 to the camera body 2 by executing the steps #3 in FIG. 5 or #4 in FIG. 5 described above.

Next, the camera body 2 is attached to the lens 1 as shown in FIG.
It is determined whether the data sent to the camera body 2 matches the command sent to the lens 1 in #1 of FIG. If they match, the camera body 2 receives the next transmitted data and performs the operation corresponding to the data, as shown in #4 in Figure 4, and the flow ends. However, if they do not match, Then, the flow moves from #3 in FIG. 4 to #5, and in #3 in FIG. 4, it is determined whether the data transmitted from the lens 1 to the camera 2 is data indicating a "command error."

When the sent data is determined to be a "command" error, the Kit flow returns to #1 in Figure 4 and the same command is selected.Also, if "command error 2" is not identified in #5 in Figure 4, the Kit flow returns to #1 in Figure 4. Either the command sent from camera 2 to lens l was incorrectly transmitted to the lens IK, or the data sent from lens l to camera 2 was incorrectly transmitted to camera 2, but in any case, the transmission line This is an error, so the flow stops there.

Here, the data of LR/GL B/G representing the spectral characteristics t of the lens and the image sensor of the camera transmitted from the lens 1 to the camera 2 by the method explained using FIGS. 2 to 5 is the first is sent to the system controller 6 shown in the figure,
Control voltage values VB/, VR are added to the data WR/, WB/G sent from the white balance sensor 5, and are sent via the D/A converter 7 to control the gains of the R amplifier 3 and B amplifier 4. /G, and white balance correction is performed taking into account the spectral characteristics of the lens.

Therefore, according to this embodiment, the lens and the camera body 2
White balance can always be adjusted appropriately regardless of the spectral characteristics of the imaging system.

By the way, in the method shown in FIG. 1 described above, the R amplifier 3,
If the control voltage value that controls the gain of the B amplifier 4 is varied over a wide range, the gain of the R amplifier 3° and the gain of the B amplifier 4 will lose linearity with respect to the control voltage (IK).
That is, as shown in FIG. 6, R
The gains of the amplifiers and B amplifiers tend to saturate with respect to the control voltage value, and due to this saturation, the gains of the R amplifiers and B amplifiers differ from the gains for adjusting a proper white balance and begin to contain errors. As a result, the disadvantage is that the white balance is disrupted. - In order to eliminate this drawback, the system controller 6 adds the lens molecule f:, characteristics transmitted from the lens l, and the signal obtained from the white balance sensor 5 to the R amplifier 3. Calculate the gain in the B amplifier 4, and calculate the gain R/1. B/G' to R amplifier 3. B
The control voltage value V is determined in consideration of the characteristics shown in FIG. 6 of the amplifier 4.
B/, VR/.

You can convert it to . The configuration of the system controller 6 having such a function will be explained using FIG. 7. 7th
In the figure, 6-A is the data L transmitted from lens 1.
This is an addition circuit that adds R/, LB/G and data WR/, WB/G transmitted from the white balance sensor 5, respectively. 6-B is a converter that converts the data calculated by the adder circuit 6-A into a digital value corresponding to a control voltage value in consideration of the control voltage-gain characteristics of the R amplifier 3°B amplifier 40.

K as described above from such adder circuit 6-A1 converter 6-BK
R amplifier 3. A control voltage value that takes into consideration the control voltage-gain characteristics of the B amplifier 4 can be obtained.

By the way, according to the above embodiment, it is possible to perform white balance adjustment that is not affected by the spectral characteristics of the lens, but depending on the lens, there is a correction amount that supplements the spectral characteristics of the lens depending on the color temperature of the light source. must be changed.

This will be explained using FIG. 8. In FIG. 8, the light source $1. $2 shows the spectrum distribution of light sources with different color temperatures, R filter and G filter show the transmission characteristics of the red filter and green filter provided in front of the sensor for white balance, and the reference lens person, lens reference 1,
Reference 2 shows the spectral characteristics of the lens. For example,
For a lens with spectral characteristics having almost the same distribution as the reference lens A, such as lens #-1 shown in Figure 8, different correction amounts are applied to the reference lens (a lens that does not require correction of the spectral characteristics of the lens) depending on the light source. It's not necessary.

In other words, the correction amount and light source #1 for light source #1 shown in FIG.
The correction amount for 2 does not change much. However, lens f
In the case of #2, the sensitivity on the short wavelength side is extremely low compared to the reference lens, so the amount of correction differs depending on the light source + i * Ifi 2. In other words, in light source #1 with a low color temperature, the amount of correction for the red component R relative to the green component G is small, but in light source #2 with a high color temperature, the amount of correction must be increased.

My suggestion is that lens #2 shown in Figure 8 has a low color temperature.
Since it is less sensitive to light source #2, which is a bluish light source with a higher color temperature, than light source #1, which is a reddish light source, the correction t of the spectral characteristics of lens #2 is made larger under light source #2. It is necessary to increase the amount of correction for the red signal relative to the green signal.

Therefore, an embodiment of correcting the white balance adjustment for a lens as shown in #2 in FIG. 8 will be described with reference to FIG. 9.

In the embodiment shown in FIG. 9, along with the data LR/ and LB/C3 from the lens 1, a correction coefficient α for correcting the data from the lens 1 is sent to the entire camera body 2 according to the color temperature of the light source. and said data L R/
L B/Q, correction coefficient α, and white rose G.

Data WR/G, WB/G sent from the sensor for
A system controller 6 that appropriately adjusts white balance under a light source of any color temperature will be described below. FIG. 9 is a block diagram of another embodiment of the system controller 6 shown in FIG.

In FIG. 9, 6-C indicates spectral characteristic information LR/, LB/Q from the lens 1, the correction coefficient α, and the output WR/Q of the white balance sensor 5.

This block derives all the control voltages of the R amplifier from WB//G. 1 control signal R obtained in this block
The values of /G' and B/G' are corrected depending on the difference in color temperature of the light source, but the following (1) and (2
It can be expressed by one equation.

"/'=WR/+(W"/, a+LR/G) ---
---(1) GG G B/'=WB/ +(WB/...+LB/G) ・
......(2) GG G Here, as mentioned above, KWR/ and WB/G are the color temperature data of the light source obtained from the sensor for white balance, for example, WR/=4 dB, L R/ /G=1 dB
If α=0.05, the part in parentheses in equation (1) is WR/G・α+LR//G=
=4X0. O5-1-1 = 1.2 dB, and the center is 5.2 dB.

In other words, in this case, the amount of color temperature correction including lens correction, addressed to R, is WR/G in addition to the original lens correction of 11 dB.
, the amount of correction depending on the color temperature expressed by WB/G < w
R/G xα=0.2 dB), which indicates that the correction amount is further adjusted depending on the color temperature of the light source at the time of photographing.

6-B is an exchanger similar to the converter shown in FIG. With the correction blocks 6-C and 6-B, it is possible to correct the color of the lens according to the difference in color temperature of the light source at the time of photographing, as described above.

According to the above-described embodiment, the white balance can always be adjusted appropriately even if the color temperature of the photographing light source is different.

In this embodiment, the storage means t= electrically stores the comprehensive spectral characteristics including the photographing lens and the imaging system of the camera body.
Although ROM C3 is used, other bubble memories or other magnetic memories may be used.

Furthermore, although the microcomputer C1 and interface C2 shown in FIG. 2, which operate according to the flow shown in FIG. 4, are used as means for reading out the boot data stored in the storage means, other hardware logic may be used.

<Effects of the Invention> As explained above, according to the first invention of the present application, in a video camera using an interchangeable lens, the interchangeable lens can store information that is unique to the lens and corresponds to the overall spectral characteristics of the imaging system of the camera body. The comb has a storage means for electrically storing the information,
The video camera is equipped with a readout means for electrically reading out the information stored in the storage means, and a means for adjusting the white balance based on the readout information, so that it can be completely adjusted for each lens used. White balance adjustment tube can be done. Further, according to the second invention of the present application, the means for fully adjusting the white balance within the video camera is provided with a storage means for storing information indicating the comprehensive spectral characteristics of the interchangeable lens and the imaging system of the camera body. Therefore, there is no need to redo the white balance adjustment tube in the video camera every time the entire lens is replaced, resulting in improved operability.

[Brief Description of the Drawings] Fig. 1 is a block diagram of a video camera according to an embodiment of the present invention, and Fig. 2 is a complete explanation of the communication method between the photographing lens l and the camera body 2 in the embodiment shown in Fig. 1. Enokage lens 1 for
A block diagram of the camera body 2 and the camera body 2, and Figure 3 shows the photographing lens 1.
, a diagram showing commands and data exchanged with the camera body 2, FIG. 4 is a flowchart executed by the microcomputer C1 in the camera body 2, and FIG. 5 is a flowchart executed by the microcomputer L1 in the photographic lens 1. The flowchart shown in FIG. 6 is the R amplifier 3. shown in the first part. FIG. 7 shows the relationship between the gain of the B amplifier 4 and the control voltage, and FIG. 7 shows the relationship between the gain of the B amplifier 4 and the control voltage. FIG. 8 is a block diagram showing the configuration of the system controller 6 that performs control considering the characteristics of the B amplifier 4. A diagram showing the spectral characteristics of f#2, R, 0 color filter lenses +1 and +2, and FIG. 9 is a block diagram showing the configuration of the system controller 6 that performs control in consideration of the spectral characteristics of the filter lenses shown in FIG. 8. It is.

Claims (2)

[Claims] (1) In a video camera in which the photographing lens is replaceable and converts the light flux incident through the photographing lens and the imaging system into an electrical signal, the photographing lens has spectral characteristics unique to the lens and the spectral spectral characteristics of the imaging system. and a storage means for storing information corresponding to the comprehensive spectral characteristics according to the sensitivity characteristics, a means for reading out the information corresponding to the comprehensive spectral characteristics stored by the storage means, and a means for reading out the information corresponding to the comprehensive spectral characteristics stored by the storage means, and A video camera comprising means for controlling white balance. (2) An interchangeable lens characterized by comprising a storage means that readably stores information corresponding to the spectral characteristics of the photographic lens and the overall spectral characteristics according to the spectral sensitivity characteristics of the imaging system of the camera.