JPH03155827A - Electronic endoscope device - Google Patents

Abstract

PURPOSE:To obtain a still picture having a correct exposure quantity in a short flash period without opening a diaphragm by increasing the irradiation light quantity to a copying body by a flash light emission during a short switched charge accumulation time, and storing a video signal by the correct exposure quantity in which a peak value of a flash light is controlled in accordance with the charge accumulation time. CONSTITUTION:When a device is switched to an element shutter mode, the exposure quantity becomes T2/(T1+T2) folds. Accordingly, when the light quantity is set to (T1+T2)/T2 folds in this time T2, a correct exposure quantity is obtained. That is, with respect to the light quantity L1 at the time when an illumination current L1 is supplied to a short arc lamp 22, it will suffice that a flash current 12 from which the light quantity L2 which becomes L1X(T1+T2)/T2 is obtained is added to the illumination current L1. A value of a resistance RI is set to the speed of an element shutter so as to obtain such a relation. Accordingly, a charge quantity C2 read out of a CCD 12 by a read-out pulse after this period T2 becomes a correct charge quantity. The video signal of the correct exposure quantity under the flash light emission is stored temporarily in a memory 18, and by reading it out repeatedly from the memory 18, a still picture is displayed on a color monitor 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic endoscope device that takes an i-image of a subject illuminated by flash emission.

[Prior Art] Conventionally, in order to obtain a clear still image without blur in a 7.1 m distance, it has been used to emit light using a flash or a flash.

Shit! As an example using ivy,
As disclosed in Japanese Patent No. 877, the exposure is prevented by using a mechanical shutter for a period shorter than 1/60 [5ccl], but this requires a high-speed movable mechanism. Become.

For this reason, a technique is known in which a similar effect can be achieved by limiting the light accumulation time of a solid-state imaging device such as a COD without using a mechanical movable mechanism.

This technique will be briefly explained with reference to FIG.

Generally, the COD is the vertical synchronizing pulse V shown in FIG. 11(a).
During the period D, the readout pulse shown in (b) of the same figure is applied, and as shown in (C) of the same figure, the charge accumulated before this pulse is applied is transferred and the image is transferred from the COD. Output as a signal.

On the other hand, when using an element shutter, as shown in Fig. 11 (d
), a read pulse is generated and applied to COD during a period different from the interval between vertical synchronizing pulses vom, and
), the charge C1 accumulated in the period T1 from the previous read pulse until this pulse is output is discarded, and only the charge C2 accumulated in the remaining period IT2 is read out in a short period T2. This creates a shutter effect for capturing images.

That is, for one field period, approximately 72/(T1+72
This means that you have obtained a sheet speed of >.

By using the element shutter in this way, it is possible to obtain a still image without blur, but since the accumulation time is short, the charge accumulation time is shortened, resulting in a dark image.

In order to compensate for this, Japanese Patent Application Laid-Open No. 1-106914 has been published.
Using flash light, under this flash light,
In order to obtain the proper exposure, the aperture is operated during the flash period over several fields, and the image is captured into the memory when the proper exposure is achieved.

[Problems to be Solved by the Invention] However, in an attempt to capture a farther point or to obtain a still image with less blur, the method of this publication is used to increase the amount of flash light and fully open the aperture. During the diaphragm operation, the large-intensity flash must be continued, which may lead to temperature rise, lamp deterioration, etc.

Also, if you return to video after obtaining a still image with the appropriate exposure, the aperture will be fully open, so it will take time to return to the correct aperture, and there is a risk that you will not be able to take images in the appropriate state during that time. .

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide an electronic endoscope device that can obtain still images with proper exposure m in a short flash emission period without requiring the operation of fully opening the aperture. do.

[Means and effects for solving the problems] In the present invention, solid! a switching means for shortening the charge accumulation time of the elementary image; a flash light supply means for increasing the amount of light irradiated to a subject by flash emission during the shortened charge accumulation time based on the switching of the switching means; By providing a flash light control means for controlling the peak value of the exposure amount to an appropriate exposure amount according to the charge accumulation time, and a storage means for storing a video signal from an appropriate exposure aperture, an appropriate exposure amount can be achieved in a short flash period without opening the aperture. You can obtain a still image of the exposure amount.

[Example] Hereinafter, the present invention will be specifically described with reference to the drawings.

FIGS. 1 to 4 relate to a first embodiment of the present invention.
FIG. 2 is a block diagram showing the configuration of the electronic endoscope device of the first embodiment, FIG. 2 is a configuration diagram showing the configuration of the flash light supply means, and FIGS. 3 and 4 show different shutter speeds in the element shutter mode. FIG. 4 is a timing diagram for explaining the operation in the case of setting.

As shown in FIG. 1, the electronic endoscope device 1 of the first embodiment includes an electronic endoscope 2 equipped with an imaging means, and an electronic endoscope 11.
A video processor 5 includes a light source section 3 that supplies illumination light to the electronic endoscope 2, and a signal processing section 4 that performs signal processing for the imaging means of the electronic endoscope 2, and this signal processing! ! ! The monitor 6 includes a color monitor 6 that displays standard video signals processed by the unit 4 in color.

The electronic endoscope 2 has an elongated insertion section 7, into which a light guide 8 for transmitting illumination light is inserted. By attaching the incident side end face of the light guide 8 to the video processor 5, illumination light is supplied from the illumination light supply means 9 constituting the light source section 3. This illumination light is emitted from the output end face of the light guide 8 toward the subject.

The illuminated object is imaged by the objective lens 11 on the CCD 12 disposed on its focal plane, photoelectrically converted, and stored as signal charges.

This CCD 12 receives a drive signal (
! 7! signal) is transferred to the preamplifier 1.
After being amplified, the signal is input to the signal processing circuit 15.

The signal processing circuit 15 processes the signal to generate a standard video signal, and the color monitor 6 displays the subject image in color.

In addition to the standard video imaging mode in which one field is imaged at 1/60[5ecl], the apparatus 1 of the first embodiment uses an element shutter to capture an image during an imaging period 'T: captures an image and then remains still. Turn on the special imaging mode to get the image.

For this reason, for example, the front panel of the video processor 5 (
The electronic endoscope 2 may be provided with an element shutter mode switching means 17, and by operating this element shutter mode switching means 17, the scanning circuit 13 is controlled to change the standard positive image period (one field). The drive signal can be output from the scanning circuit 13 during a short imaging period 111J, such as 1/60 [5 ecl).

In addition, the timing at which a still image is stored in the still image storage memory 18 is controlled in accordance with the mode switching of the element shutter mode switching means 17.

Furthermore, when switching to the special imaging mode by switching the mode of the element shutter mode switching means 17, a flash ON signal and a flash current switching signal are supplied to the flash light supply means 19, and the illumination light generated by the flash light is R
We are making it possible to increase.

The configurations of the illumination light supply means 9 and flash light supply means 19 are shown in FIG.

The illumination light supply means 9 is composed of an illumination light power source 21 and a short arc lamp 22 that emits light m according to the supplied current.

This short arc lamp 22 includes a light source 21 for illumination light.
The light is constantly emitted by the current supplied from the flash light supply means 19, and the flash light is emitted by the flash current supplied from the flash light supply means 19.

This flash light supply means 19 includes a flash capacitor 24 that supplies flash current to the short arc lamp 22 via a backflow prevention diode 23, a charging circuit 25 that charges the flash capacitor 24, and a switching circuit that performs 0N10FF of the flash current. Element 26
and a flash control circuit 27 that controls the flash current and switches the flash current. It consists of a flash current switching signal 28.

The short arc lamp 22 has a lamp current (FIG. 3(d)) supplied from the illumination light power source 21.

When the element shutter mode is selected, the flash current from the flash light supply means 19 is further added to this lamp current to emit flash light.

The output terminal of the charging circuit 25 is a flash capacitor 24
and is connected to the collector of a transistor constituting the switching element 26, and the emitter of this transistor is connected to the short arc lamp 22 via a diode 23. The base of this transistor is the changeover switch SW constituting the current switching means 28.
and the flash control 27 via, for example, three resistors R1, R2, and R3, which are selected by this switch swr''i.
is connected to the output end of the This flash control circuit 27 is configured such that its output terminal is, for example, "L" in response to a flash ON signal from the element shutter mode switching means 17.
11 to a constant level or reference level of "H" level, and resistor RI (l is 1.2.
3), a flash current flows between the collector and emitter of the transistor constituting the switching element 26.

Further, the switch SW is outputted with a flash current switching signal corresponding to the element shutter speed selected by the element shutter mode switching means 17, and the switching of the switch SW is controlled by this signal. For example, when selecting a fast element shifting speed, the switch SW is set so that the resistor RI with a small resistance value is selected. That is, by controlling the base current to the transistor forming the switching element 26, the flash current value is controlled.

The operation of the first embodiment configured in this way will be explained below with reference to FIGS. 3 and 4.

The short arc lamp 22 receives an illumination current from the illumination light power source 21 (shown in FIG. 3 or FIG. 4 (d)) I
I, the short arc lamp 21 emits lamp light ff1L1 shown in FIG. 3 or 4(e), and this light is supplied to the light guide 8.

In this case, a readout pulse is output as shown in FIG. 3 or 4(b) in synchronization with the center of gravity synchronization pulse VD shown in FIG. 3 or 4(a).

When the element shutter mode switching means 17 is operated to switch to the element shutter mode, a flash current switching signal corresponding to the selected shutter speed is output, and the corresponding resistor R1 (in FIG. R2> is turned ON.

Further, as shown in FIG. 3 (or FIG. 4) (b), a read pulse Pi (or P1') is output from the element shutter mode switching means to the element circuit 13, and the read pulses after the read pulse before this pulse P1 are outputted from the element shutter mode switching means to the element circuit 13. , the time Tl until this pulse P1
(or T1') as shown in Fig. 3 or 4 (
The charge amount C1 or C1' shown in f) is completely discharged.

After the readout pulse P1 (or P1') for discharging this charge ICI (or 01') is output, the element shutter mode switching means 17 switches the flash light supplying means 1
A flash ON signal shown in FIG. 3 (or FIG. 4) (C) is output to the flash control circuit 27 of FIG. This flash ON signal is active only for a short time T2 (or T2') until the next read pulse is output.

In response to this flash ON signal, the flash control circuit 27 turns on the switching element 26, and the charge charged in the flash capacitor 24 is supplied to the short arc lamp 22 via the diode 23.

The lamp current at this time is shown in FIG. 3 (or FIG. 4) (d). As can be seen from this figure (d), at times other than time T2,
The short arc lamp 2 is constantly supplied with the illumination current 11 from the illumination light power source 21, and at time T2, the illumination current 11 plus the flash current I2 (or 12') is supplied.

Assume that before entering the element shutter mode, proper exposure has been set using an aperture (not shown) or the like.

At this time, if you switch to element shutter mode, the exposure amount will be (
In the case of FIG. 3) T2/(TI+T2> times. Therefore, if the light amount is made to be (T1 + T2)/T2 times during this time I2, an appropriate exposure amount can be obtained.

That is, as shown in FIG. 3 (or FIG. 4) (f),
When the illumination current 11 is supplied to the short arc lamp 22, the light intensity is 1, LIX(TI +T2>/
It is sufficient to add a flash current I2 to the illumination current 11 to obtain a light amount L2 corresponding to T2.

The value of the resistor R1 is set with respect to the speed of the element shutter so that such a relationship is established.

Therefore, the readout pulse after this period I2 causes the CCD to
The charge ff1c2 (or 02') shown in FIG. 3 (or FIG. 4) (f) read from 12 becomes a proper charge bank. (
An appropriate amount of charge can be stored in the CCD 12 within the period I2. ) In addition, current 11.11-t I2 and 11. Although the relationship of L2 is not necessarily linear, a one-to-one relationship can be obtained by conducting an investigation based on the type of lamp 22 in advance.

As can be seen from the comparison of periods T2 and T2' in d3 in FIGS. 3 and 4, when the shutter speed is made faster, that is, when 72' is shorter than period T2, the flash current f2
' is greater than I2, and any period T2. Charge ff1c2 or C2 read out by readout pulse after T2'
' can be taken as the appropriate electric charge.

The video signal of the appropriate exposure amount at the source of the flash emission is temporarily stored in the memory 18, and is repeatedly read out from this memory 18 to display a still image on the color monitor 6.

Incidentally, even when a plurality of shutter speeds can be selected in the element shutter mode, this can be handled by switching the base current of the transistor constituting the switching element 26 using the flash current switching means 28 as described above.

According to this first embodiment, by using a flash control means with a simple configuration, the flash is emitted according to the shutter speed of the element shitter, so that the flash continues to emit light until the aperture is opened. Since this method does not require the following, the reduction in lamp life can be improved.

Also, even if you return to standard mode after firing the flash,
Since the aperture is not driven wide open or close to it,
If a dimming means using a diaphragm (not shown) is provided, it is possible to quickly shift to the appropriate state in the standard mode.

FIG. 5 shows the configuration of a flash light supply means 31 in a second embodiment of the present invention.

In this second embodiment, the switching element 26 is controlled by a second switching element 32T, and this second switching element 32 is a timer 3 activated by a flash ON signal.
3. The time constant at which this timer 33 operates is switched by a time constant switching means 34 controlled by a flash current switching signal.

The flash current switching signal of the element shutter mode switching means 17 controls the changeover switch constituting the time constant switching means 34 so that an arbitrary contact can be selected.

Each contact of the changeover switch 34 is connected to, for example, a resistor (not shown) in the timer 33, and the timer output period of the timer 33 is determined depending on the selected resistor.

The output terminal of this timer 33 is connected via a resistor r1 to the base of a transistor constituting the second switching element 32, the collector of this transistor is connected to the power supply terminal VCC, and the emitter is connected via a resistor r2 to the base of a transistor constituting the second switching element 32. ) is connected to the pace of the transistor constituting the switching element 26.

The other configurations are the same as in the first embodiment.

Next, the operation of the second embodiment will be explained below with reference to the timing charts of FIGS. 6 and 7.

Note that FIGS. 6 and 7 show cases where different shutter speeds are selected.

Further, since the operation in the standard mode is the same as that in the first embodiment, the explanation thereof will be omitted, and the operation when the element shutter mode is selected will be explained.

Flash O as shown in Figure 6 (or Figure 7) (C)
When the N signal is output to the timer 33, this flash O
The timer 33 is triggered by the rise of the N signal, and the timer output remains "H" for a time t2 (or t2') according to the time constant switched by the flash current switching signal.
' (see FIG. 6 or FIG. 7(d)), this timer output turns on the second switching element 32, and turning on this switching element further turns on the (first) switching element 26. The charge charged in the flash capacitor 24 is supplied to the short arc lamp 22 at a constant current 2 as shown in FIG. 6 (or FIG. 7) (C) without controlling the peak value.

The time constant at this time is such that the lamp current 11 is maintained for a period T2 (or T
2') During this period t2, there is enough time to fill the shortfall between the amount of light obtained by flowing from show 1 to the arc lamp 22 and the appropriate amount of light with light 1 due to the lamp current ■2 during this period t2. It is set in advance so that

Therefore, in FIG. 7, which corresponds to a faster element shutter speed than in FIG. 6, a longer time constant is selected than in FIG. 6, and after this time constant, the next readout pulse is output. , the charge E! of CCD12! IC2' (same as in the case of FIG. 6) has an appropriate amount of charge as shown in FIG. 7(f). Therefore, even if different shutter speeds are selected as in the first embodiment, images can always be captured with an appropriate amount of charge.

According to the second embodiment, a still image with proper exposure can be obtained with a simple configuration including a timer 33 and means for switching the time constant of the timer 33 in accordance with the shutter speed of the element shutter.

The effect is almost the same as that of the first embodiment.

FIG. 8 shows an electronic endoscope device 41 according to a third embodiment of the present invention.

This third embodiment differs from the first embodiment shown in FIG.
The electronic endoscope 2 has a light receiving element 42 in contact with the CCD 12.
is provided to receive the light reflected by the subject via the photometric lens 43.

The output of this light receiving element 42 is inputted to a flash light supply means 44 as shown in FIG. 8, and when the signal corresponding to the received light σ detected by the light receiving element 42 reaches an appropriate amount, the flash light emission is stopped. I have to.

The configuration of this flash light supply means 44 will be explained below with reference to FIG. 9.

The output of the light receiving element 42 is input to an integrating circuit 46 via a switch circuit 45. This integrating circuit 46 is composed of a resistor R and a capacitor C. The output of this integrating circuit 46 is inputted to the inverting input terminal of a comparator 47, and the reference voltage is input to the non-inverting input terminal of the comparator 47 by a flash current switching signal. A reference voltage from a reference voltage switching means 48 whose level is switched is input.

The output of this comparator 47 is input to an AND circuit 49 together with the flash ON signal.
The second switching element 32 is set to O, N1 by the output of
It's like 0FFI.

Further, the flash ON signal controls 0N10FF of two switches SW1.8W2 constituting the switch circuit 45.

Next, the operation in the element shutter mode according to the third actual flow example will be described below with reference to the timing chart of FIG.

As shown in FIG. 10(C), when the flash ON signal is input to the switch circuit 45, the switch SW1 of this circuit 45 changes from OFF to ON, and the switch SW2 changes from ON to OFF.
The output of the light receiving element 42 is switched to FF, and the output of the light receiving element 42 is sent to the integrating circuit 46.
is input and integrated.

The integrated output of the integrating circuit 46 is input to a comparator 47 and compared with a reference voltage level that is switched according to the shutter speed of the element shutter.

The output of the integrating circuit 46 increases according to the integration time constant from the time when the flash ON signal shown in FIG. 10(C) is output, as shown in FIG. 10(d), and reaches the reference voltage level. Until then, the output of the comparator 47 becomes "H".

Therefore, the output of the AND circuit 49 which takes the logical product of the flash ON signal and the output of the comparator 47 becomes 14 HIt until the integrated output exceeds the reference voltage level. This AND output causes the second switching element 32 and the first switching element 26 to turn ON, and the short arc lamp 22 to flash light with a large lamp current of 11+12.

When the flash light is emitted, the charge amount of the CCD 12 and the output of the light receiving element 42 rapidly increase with time.
The output of the integrating circuit 46 that integrates the output of the light receiving element 42 also increases rapidly. When the output J of the integrating circuit 46 exceeds the reference voltage level as shown in FIG. 10(d), the output of the comparator 47 becomes "H" as shown in FIG. 10(e).
to “L It”.

As mentioned above, the AND circuit 49 takes the logical product of the flash ON signal and the comparator 47, so this AN
The output of the D circuit 49 is also high as shown in FIG. 10(f').
The switching element 32, 26 is turned off, and the short arc lamp 21 changes from the flash light emitting state to the standard constant light emitting state.

Thus, the amount of charge accumulated in the CCD 12 is read out by the readout pulse after the selected period T2.

In this embodiment, the original exposure amount of illumination by flash emission is monitored in real time using the light receiving element 42 according to the shutter speed of the element shutter, and the appropriate exposure amount or an exposure amount close to this is obtained. Since the flash emission is stopped at the same time, a still image with a highly accurate exposure amount can be obtained.

Incidentally, the present invention can be similarly used with an external television camera, in which a television camera with a built-in solid-state image sensor is attached to the eyepiece of a fiber scope.

[Effects of the Invention] As described above, the present invention has the following features: In addition to emitting flash light in the element shutter mode, the amount of light emitted from the flash is controlled or set in accordance with the shutter speed to provide appropriate light 2. Therefore, the flash emission period is shorter than when the aperture is moved, and the reduction in the life span of the lamp that emits flash light can be avoided.

[Brief explanation of the drawing]

FIGS. 1 to 4 relate to a first embodiment of the present invention.
The figure is a block diagram showing the configuration of the electronic endoscopic tA device of the first practical example, Figure 2 is a block diagram showing the configuration of the flash light supply means, and Figures 3 and 4 are different views in the element shutter mode. A timing chart for explaining the operation when the shutter speed is set, FIG. 5 is a configuration diagram of the flash light supply means in the second embodiment of the present invention, and FIGS.
The figures are timing charts when different shutter speeds are set, Fig. 8 is a block diagram of the third embodiment of the present invention, Fig. 9 is a block diagram of the flash light supply means in the third embodiment, and Fig. 10 is a block diagram of the flash light supply means in the third embodiment. The timing chart in the third embodiment, FIG. 11, is an explanatory diagram of the operation in the element shutter mode. 1...Electronic endoscope device 2...Electronic endoscope 3.
...Light source part 4...Signal processing part 5...
Video processor 1 6...Color monitor 9...
Illumination light supply means 12... CCD 17... Element V ivy mode switching means 18... Memory 19... Flash light supply means 22... E+- door clamp 24... Flash capacitor 26... Switching element 27...Flash control circuit 28...Flash current switching means Fig. 1 Fig. 3 Fig. 1 2 Fig. 4 Fig. 1 Fig. Fig. Fig. 9 Fig. 10

Claims (1)

[Scope of Claims] An electronic endoscope apparatus using a solid-state image sensor as an imaging means, comprising: a switching means for switching the charge accumulation time of the solid-state image sensor to a shorter time; and a charge accumulation time that is switched to a shorter time based on switching of the switching means. a flash light supply means for increasing the amount of light irradiated to the subject by flash emission during the time, and the amount of light received by the solid-state image sensor depending on the charge accumulation time of the flash emission becomes an appropriate exposure amount. What is claimed is: 1. An electronic endoscope apparatus comprising: a flash light control means for controlling the amount of light as described above; and a storage means for storing a video signal corresponding to an appropriate amount of exposure.