JP3133823B2 - Electronic endoscope device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is an electronic endoscope KagamiSo location BACKGROUND OF THE, in particular based on the R, G, irradiation of each color light of B, and forms a video signal by the solid-state imaging device, the solid-state imaging device in this Endoscope with electronic shutter circuit to control stored charge
The present invention relates to a configuration of a mirror device .

[0002]

2. Description of the Related Art Conventionally, a CCD which is a solid-state imaging device has been used.
2. Description of the Related Art An electronic endoscope apparatus in which a (Charge Coupled Device) is disposed at a distal end of an electronic scope and observes a body cavity such as a digestive tract or a narrow tube of various structures is well known. As the electronic endoscope apparatus, there is a field sequential apparatus, which uses R (red), G (green), and B (blue) color filters for R, G, and B. Are sequentially radiated into the body under observation. Based on the irradiation of each color light, the CCD uses R, R
G and B video signals are formed, and an image is formed on a monitor by the video signals.

FIG. 6 shows a circuit connected to the CCD, and the CCD 1 shown is configured to accumulate charges based on light irradiation for each pixel unit set in a matrix. . The CCD 1 is connected to a CCD drive pulse generator 2 serving as an electronic shutter circuit, and the accumulated charge amount is controlled by a sweep pulse and a read pulse output from the CCD drive pulse generator 2 as control pulses. Is done. That is, as shown in FIG. 7, for example, 1/60 shown by the vertical blanking pulse in FIG.
Within the second vertical scanning period, as shown in FIG. 3B, charges based on light irradiation are accumulated. At this time, for example, when a sweep pulse (gate pulse) P1 and a read pulse P2 shown in FIG. 9C are supplied, unnecessary charges E0 accumulated so far are swept out as shown in FIG. The newly accumulated charge E1 is read out as a signal charge. Therefore, by controlling the above-mentioned sweeping pulse P1 and reading pulse P2, the amount of accumulated charges changes, whereby the level of the video signal can be adjusted and the function of the electronic shutter can be performed.

In FIG. 6, a signal processing circuit 3 is connected to the CCD 1, and the signal processing circuit 3
Signal processing such as amplification processing, gamma correction processing, and the like is performed on the output of No. 1. An A / D converter 4, a memory 5, and a D / A converter 6 are connected to the signal processing circuit 3, and the processed video signal is temporarily stored in the memory 5 and then newly read out. It will be supplied to the monitor, CCD
The image captured in step 1 is finally displayed on the monitor.

[0005]

In the above-mentioned conventional field-sequential type electronic endoscope apparatus, factors that influence the optical characteristics, such as the color temperature of the light source, the wavelength sensitivity of the CCD 1, and the like.
The wavelength sensitivity of a color filter that outputs R, G, and B light, the lens, the light guide that introduces the R, G, and B light, and the wavelength sensitivity of an optical system member such as a near-infrared cut (IR) filter are different. There has been a problem that the R, G, and B signal levels obtained by the CCD 1 change, and the white balance of the video signal cannot be maintained satisfactorily under various conditions.

FIG. 8 shows R, G, and B signals obtained from light sources having two kinds of color temperatures. For example, at a color temperature of 5000 ° K of a xenon lamp or the like, the distribution of each color is represented by a solid line graph I. _The spectrum distribution curve is substantially constant, such as ₅₀₀₀ , and the spectrum distribution curve is substantially constant, as indicated by the broken line. As a result, the level value of the signal proportional to the area in the waveform becomes constant. On the other hand, when the color temperature of a halogen lamp or the like is 3200 ° K, the dotted line graph I
_{As shown in 3200} , it becomes larger in the order of B → G → R, and becomes a curve whose spectral distribution curve rises as shown by a broken line.
The signal level value also increases in the order of B → G → R. Therefore, if the light source changes, the levels of the obtained R, G, B video signals will be different, and the white balance will be lost.

Further, the CCD 1 itself or other optical system members also have unique wavelength sensitivity characteristics, and these factors also affect the levels of the R, G, and B signals.

In the CCD drive pulse generator 2 as an electronic shutter circuit, the color temperature of the lamp changes, for example, from 3200 ° K to 2800 ° K in the case of a halogen lamp, due to aging of the light source lamp. There is a problem in that it needs to be improved.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to switch a control pulse pattern to a solid-state imaging device so that various elements mainly including a color temperature are different. even under, it is to provide an electronic endoscope KagamiSo location capable of obtaining a video signal a white balance is kept good. It is a second object, even if the aging occurs to the light source lamp, the electronic endoscope KagamiSo location that can maintain a good white balance
Is to provide.

[0010]

According to a first aspect of the present invention, there is provided a solid-state image pickup device which accumulates R, G, and B lights sequentially irradiated from a light source in a light source device. Electronic endoscope system that controls the amount of electric charge by control pulses
In location, the R, G according to the color temperature characteristics of the light source, B
A gate pulse generation circuit for forming a phase control pulse for setting the charge accumulation time for each light irradiation, and the light source
Based on the light source identification information of the device,
Control pulse set according to color temperature on road
And a switching circuit . Also, the second
The invention according to the claims is characterized in that the phase of the control pulse for each of the R, G, and B lights is set based on a condition in which another element that affects the optical characteristics is added to the color temperature. Further, the invention according to a third aspect is characterized in that the gate pulse generating circuit for forming the control pulse is provided with a phase adjusting circuit for adjusting the phase of the control pulse.

[0011]

According to the above arrangement, for example, a color temperature of 5000 °
The control pulse corresponding to K and the control pulse corresponding to the color temperature of 3200 ° K are formed by the gate pulse generation circuit, and are based on the identification information obtained from the light source device.
Any of the control pulse depending on the type of can light source, i.e. the sweep pulse and the read pulse signal (phase) pattern is selected. Then, the charge that has been photoelectrically converted and accumulated by the solid-state imaging device is swept out by sweep pulses having different phases for the R, G, and B signals, and the accumulated charge thereafter is read by the read pulse. As a result, R, G, and B signals having the same level can be obtained, and a good white balance can be maintained even when different light sources are used.

The above-mentioned control pulse is preferably formed in consideration of the wavelength sensitivity characteristics of the solid-state image sensor, the level, the wavelength sensitivity characteristics of the light guide and the like, in addition to the color temperature. Adjustment of the white balance corresponding to various related members constituting the endoscope is easily performed.

The gate pulse generating circuit for forming the control pulse may include, for example, a phase adjusting circuit using a variable resistor,
By providing a phase adjustment circuit that automatically adjusts the phase according to the change in the difference voltage between RG, RB, etc., it is possible to adjust the phase shift of the control pulse and easily change over time. Can respond.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG 1, configuration is shown engaging Ru electronic endoscope apparatus embodiment, the lens 10 for irradiating the tip of the electronic endoscope is disposed in the lens 10 Light guide 11
Is connected. The light guide 11 is connected to a light source device 12, and R, R
A color filter 13 having G and B color filters and a light source 14 are provided, and a control unit 15 for controlling these members is provided. As the light source 14, a xenon lamp or a halogen lamp is used. When the light source 14 is turned on and the color filter 13 is driven, each color light of R, G, and B is formed and output.

A CCD 18 which is a solid-state image pickup device is provided at the tip of the electronic endoscope.
T (emitter follower circuit) 19 and coaxial cable 20
The video amplifier 21 is connected via the
The video signal output from 8 is amplified by the video amplifier 21. On the other hand, a CCD drive pulse generator 23 is connected to the CCD 18, and drive signals HD and VD are input into the CCD drive pulse generator 23 to generate horizontal and vertical transfer pulses (transfer to the storage unit). A transfer pulse generation circuit 24, gate pulse generation circuits 25 and 26 for performing an electronic shutter operation, and a switching circuit 27 are provided.
The gate pulse generation circuit 25 has a color temperature of 5000 ° K.
A gate pulse generating circuit 26 forms a sweep pulse and a read pulse which are control pulses suitable for the color temperature 32.
A sweep pulse and a read pulse suitable for 00 ° K are formed.

The above sweep pulse and read pulse are:
Not only the difference in color temperature, but also the wavelength sensitivity characteristics of the CCD 18,
Considering the wavelength sensitivity characteristics of the color filter 13 and the wavelength sensitivity characteristics of other optical members such as the lens 10 and the light guide 11,
The R, G, and B primary color signals are set so as to maintain white balance. In the embodiment, in particular, a control pulse that matches the above-described color temperature characteristic (FIG. 8) is formed in response to the wavelength sensitivity of the CCD 18 decreasing in the order of R → G → B.

That is, the light spectrum (vs. wavelength) characteristic (color temperature characteristic) of the irradiation light from the light source 14 is L (λ), and the CCD 18
Let C (λ) denote the wavelength sensitivity characteristic of the lens, F (λ) denote the wavelength sensitivity characteristic of the color filter 13, and Lt (λ) denote the wavelength sensitivity characteristics of the lens 10, the light guide 11, and other optical members.
R, G, B primary color signals S output from the CCD 18
R, SG, and SB are represented by the following equations (K: constant).

[0018]

(Equation 1)

[0019]

(Equation 2)

[0020]

(Equation 3)

Therefore, if the constant K is set so that each of the primary color signals SR, SG, and SB has a constant level, the white balance can be adjusted in accordance with various optical characteristics, mainly the color temperature. It can be maintained.

FIGS. 2 and 3 show a configuration for correcting the aging of the color temperature of the light source lamp in the gate pulse generation circuits 25 and 26. In the case of FIG. A well-known phase adjustment circuit including a CR circuit including the circuit 30 is provided. Therefore, the variable resistor 2
The phase of the control pulse can be adjusted by changing the resistances 9 and 30.

In the case of FIG. 3, for example, a voltage memory 32 for storing data corresponding to the RG difference signal voltage VR-G or the BG difference signal voltage VB-G based on the G signal, 3
3 is provided. That is, for example, the color temperature is 3200 ° due to the aging of the lamp of the light source 14.
When it is difficult to obtain white balance due to the change from K to 2800 ° K, the above VR-G, VB-
The data voltage of G is obtained and the voltage is remotely applied to the voltage memories 32 and 33. Then, thereafter, based on the newly input voltage, the sweep pulses P1,
The read pulse P2 is controlled so that the phase can be adjusted automatically.

FIG. 4 shows the overall configuration of the electronic endoscope apparatus. In the electronic endoscope apparatus, an electronic scope 35 on which the CCD 18 is mounted is connected to the CCD driving pulse generator 2.
3. It is connected to an external processor device 36 provided with a signal processing circuit and the like, and a monitor 37 is connected to the external processor device 36. The light source device 12 includes a xenon lamp light source device 12A, a halogen lamp light source device 12B, and the like. These light source devices 12A and 12B are connected to a light guide 11 provided in an electronic scope 35, and are connected to the light guide 11. Identification (ID)
The information is supplied to the CCD drive pulse generator 23 in the external processor device 36.

The embodiment has the above configuration.
The operation will be described based on FIG. First, in the light source device 12 of FIG. 1, ID data indicating the type of the light source 14 is supplied to the gate pulse generation circuit 23. Based on the ID data, the switching circuit 27 uses the color temperature of 5000 ° K in the case of the embodiment.
Or 3200 ° K. When the light source 14 of the light source device 12 is controlled to be turned on and the color filter 13 is driven to rotate, each color light of R, G, and B is sequentially radiated into the body cavity through the light guide 11 and the lens 10. You. On the other hand, in the CCD 18, the reflected light of each color light is received by each element (pixel), and the charge is photoelectrically converted during the 1/60 second vertical scanning period indicated by the vertical blanking pulse shown in FIG. Will be accumulated.

Here, for example, when a xenon lamp is used as the light source 14, the color temperature of 5000 K is selected by the switching circuit 27. Then, the color temperature 5
5 from the gate pulse generation circuit 25 for 000 ° K
The control pulse of the sweep pulse and the read pulse shown in (b) is output to the CCD 18. That is,
The sweep pulses PR1, PG1, and PB1 set for each of the R, G, and B irradiation light have a shorter time from the fall of the vertical blanking pulse in the order of PR1, PG1, and PB1,
The read pulses PR2, PG2, PB2 are at the same time. Therefore, as shown in FIG. 5C, the electric charge (hatched portion) accumulated from the falling of the vertical blanking pulse is:
The discharge pulses PR1, PG1, and PB1 are used to temporarily discharge the charges, and thereafter, the electric charges are accumulated again.
The final charge values ER, EG, EB are read by PG2, PB2.

At this time, when a white pattern is imaged, the charge values ER1, EG1, and EB1 become the same (height) as shown in the figure, and as a result, as shown in FIG. The video signals of G and B have the same level, and a video signal having a good white balance can be obtained.
That is, in the case of a color temperature of 5000 ° K, as shown in FIG.
Since the wavelength sensitivity characteristic of the CCD 18 itself decreases in the order of R, G, and B, it is sufficient to set a longer accumulation time in the order of R, G, and B as described above.

When a halogen lamp is used as the light source 14, the switching circuit 2 is operated based on the ID data.
7 switches to the color temperature 3200 ° K side. Then,
The control pulse shown in FIG. 5D is output from the gate pulse generation circuit 26 for the color temperature of 3200 ° K. In this case, the sweep pulses PR1a, PG1a, and PB1a.
Compared to the case where the color temperature is 5000 ° K [FIG. (B)], PR1a is delayed from PR1, PG1a is almost the same as PG1, and PB1a is preceded by PB1. Therefore, as shown in FIG. 5 (e), the charge values ER2, EG2, EB2 which are swept out by the sweep pulses PR1a, PG1a, PB1a having a large time difference and thereafter accumulated are read out. That is, as shown in FIG. 8, when the color temperature is 3200 ° K, the color temperature is increased in the order of B, G, and R. A long accumulation time and a short accumulation time may be set for the R signal. The charge values ER2, EG2, and EB2 obtained in this manner correspond to the charge values ER1, EG1, and E2.
R1, G, and B signals having the same white balance as shown in FIG. 5F are obtained.

In the above embodiment, the case where the color temperature is different has been mainly described. However, the CCD 18 may be connected to a different electronic scope 35. In this case, the ID (identification) data of the electronic scope is transferred to an external processor device. The control pulse can be read and read by changing the control pulse pattern corresponding to different electronic scopes.

[0030]

As described above, according to the first aspect of the present invention, the control pulse for setting the charge accumulation time in the solid-state imaging device is set to R, R in consideration of the color temperature characteristics of the light source in the light source device . The R, G, and B light beams are formed for each G and B light irradiation.
Light source identification of various patterns of control pulse of accumulation time for each light
Since the switching is performed based on the information, there is an advantage that a good white balance can be maintained even when a different light source such as a xenon lamp or a halogen lamp is used.

According to the second aspect of the present invention, the control pulse pattern for each of the R, G, and B lights is set based on the condition in which the color temperature and other factors that influence the optical characteristics are added. The electronic shutter can be controlled in accordance with the wavelength sensitivity characteristics of the solid-state imaging device and the wavelength sensitivity characteristics of optical members such as color filters and light guides, and the maintenance of white balance can be ensured. it can.

Furthermore, according to the third aspect of the present invention, the means for adjusting the phase of the control pulse is provided in the gate pulse generating circuit for forming the control pulse. Even if it occurs, it is possible to maintain a good white balance.

[Brief description of the drawings]

1 is a diagram showing a configuration of an electronic endoscope KagamiSo location according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a gate pulse generation circuit according to the embodiment.

FIG. 3 is a diagram showing another example of the gate pulse generation circuit in the embodiment.

FIG. 4 is an explanatory diagram illustrating an overall configuration of the electronic endoscope apparatus according to the embodiment.

FIG. 5 is a waveform chart showing the operation of the embodiment.

FIG. 6 is a block diagram showing a peripheral circuit of a CCD in a conventional electronic endoscope apparatus.

FIG. 7 is a waveform chart showing the operation of the electronic shutter.

FIG. 8 is a graph showing a difference between color temperature characteristics in a relationship between wavelength and light intensity.

[Explanation of symbols]

 1, 18 CCD, 2, 23 CCD drive pulse generator, 11 light guide, 12 light source device, 13 color filter, 14 light source, 25, 26 gate pulse generation circuit, 27 switching circuit, 29 , 30 ... variable resistor, 32, 33 ... voltage memory.

Continuation of the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 1/00-1/32 G02B 23/24 H04N 9/04-9/11 Practical file (PATOLIS) Patent file (PATOLIS)

Claims (3)

(57) [Claims] An electronic endoscope apparatus for controlling the amount of electric charge accumulated in a solid-state imaging device by a control pulse based on R, G, and B light sequentially emitted from a light source in a light source device. A gate pulse generation circuit for forming a control pulse having a phase for setting the charge accumulation time for each of the R, G, and B light irradiation in accordance with the temperature characteristics; and the gate pulse generation circuit based on the light source identification information of the light source device.
Control pulse set by the color generation circuit in accordance with the color temperature.
An electronic endoscope device comprising a switching circuit for switching . 2. The method according to claim 1, wherein a phase of a control pulse for each of the R, G, and B lights is set based on a condition obtained by adding another element that affects optical characteristics to the color temperature. An electronic endoscope apparatus according to claim 1 . 3. A phase adjusting circuit for adjusting the phase of the control pulse, the gate pulse generating circuit forming the control pulse.
2. The method according to claim 1, further comprising:
Electronic endoscope device .