JPH01231480A - Still video camera with electronic viewfinder - 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 an electronic viewfinder (hereinafter referred to as EVF).
The present invention relates to a still video camera having a.

(Prior Art) Conventionally, known still video cameras include those using a single-lens reflex optical viewfinder as shown in Figure 6, or those using an EVF as shown in Figure 7. .

In Figures 6 and 7, 1 is a lens, 2 is an aperture, 3 is a shutter, 4 is an area sensor, 5 is an eyepiece, 6 is a quick return mirror, 7 is a pentaprism, and 8 is a CRT (finder display). 9 is an infrared cut filter.

Although they are shown in almost the same size in Figures 6 and 7, the method in Figure 7 does not require a mirror box (where the quick return mirror is located), and the back focus of the lens is can be made shorter, so it can be much smaller than the one shown in FIG.

Furthermore, EVFs are often used in handheld VTRs.

[Problem to be solved by the invention]

However, unlike a VTR, a still video camera is slower than the so-called video readout rate (at long exposure times).
Shutter speeds of 1 to 3 are sometimes used, while images are taken using supplementary lighting means such as strobes in darker areas.

Therefore, there may be cases where the EVF cannot be displayed or a sufficient S/N ratio cannot be obtained.

The present invention has been made in view of these inconveniences, and it is an object of the present invention to provide a still video camera that can use an EVF except when the subject is very far away.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a still video camera having an EVF as follows (1).

The configuration is as shown in (2) and (3).

(1) An infrared cut filter disposed on the optical path to the image sensor, and an illumination means for illuminating the subject.

The apparatus includes means for excluding the infrared cut filter from the optical path when a first specific photographing condition is met, and means for energizing the illumination means when a second specific photographing condition is met.

(2) An infrared cut filter placed in the optical path to the image sensor, an illumination means for illuminating the subject, and when the brightness of the subject due to external light is insufficient for use with an electronic viewfinder, the infrared cut filter is removed from the optical path. The illuminating device is provided with a means for excluding the infrared ray cut filter from the optical path and a means for energizing the illumination means when the brightness of the object due to external light is insufficient for use of an electronic viewfinder even after the infrared cut filter is excluded from the optical path.

(3) An infrared cut filter disposed in the optical path to the image sensor, a means for illuminating the subject, and a means for excluding the infrared cut filter from the light path and energizing the illumination means when in the strobe use mode. Be prepared.

[Effect]

With the above configuration, the brightness of the subject can be ensured so that the EVF can be used, except when the subject is dark and far away.

(Example) The present invention will be explained below with reference to Examples.

FIG. 1 is a schematic configuration diagram of a still video camera having an electronic viewfinder, which is an embodiment of the present invention.
FIG. 2 is a block diagram of the same embodiment.

In FIG. 1, 15 is the camera body, and the lens 1
．． Aperture 2. Shutter 3. CCD area sensor 4. Infrared cut filter9. CRT8. Eyepiece 5. Direct photometric element 13. An external light type photometric element 14 is provided. On the other hand, inside the strobe case 10, a strobe 11. An auxiliary illuminator 12 is provided.

The optical image of the subject is created using lens l, aperture 2. The light is guided to the CCD area sensor 4 via an infrared cut filter 9 which is normally inserted into the optical path, and is converted into an electrical signal. CRT
Reference numeral 8 denotes a cathode ray tube that performs display based on the output of the CCD area sensor 4, and together with the eyepiece 5 constitutes an electronic viewfinder EVF.

The infrared cut filter 9 blocks light in the infrared region that would be a hindrance to color imaging, and the direct photometry element 13 measures the brightness of the CCD area sensor 4 and performs so-called direct photometry.

C by the drive circuit of the CCD area sensor 4 (not shown).
The charge accumulation time of the CD area sensor 4 is controlled, and the drive circuit constitutes an electronic shutter.

The shutter 9 is normally closed and the COD area sensor 4
This is a mechanical shield that protects the EVF, and is open when the EVF is in use, and closed after a predetermined time to determine the exposure time, or shutter speed, during actual shooting.The electronic shutter determines this shutter speed. You can also do that.

The auxiliary illuminator 12 is an auxiliary illumination device that illuminates the subject and ensures sufficient brightness to use the electronic viewfinder when the subject is too dark to be photographed using external light alone. However, it can also be used as an illuminator for the output of a still video camera.

Although the auxiliary illuminator 12 is placed inside the strobe case 10, it may be placed inside the camera body 14, or both the auxiliary illuminator and the strobe may be placed inside the camera body 14. .

In Figure 2, BT is the battery of the camera body, SWl
is the normally open switch, SW2, which is entered on the first release stroke.
is a normally open switch that is turned on during the second release stroke.

The output of the battery BT is supplied to all circuits of the camera directly or via a regulator via the transistor switch Trl.

The transistor switch Tri is held in a conductive state by the normally open switch SWI during the first release stroke or by the transistor Tr2 by the CPU's power supply latch control signal. When the normally open switch SW2 closes during the second release stroke, a release instruction is issued through the CPU.

The CPU controls each circuit by transmitting and receiving No. 43 to and from each circuit as shown in the figure. When the normally open switch SWI is turned on, the CPU
performs initialization of each circuit, etc., and starts displaying on the EVF.

Next, operations related to the EVF will be explained using flowcharts shown in FIGS. 3 to 5.

This operation, that is, the EVF control sequence, has two sequences: sequence 1, which is determined by the brightness of the subject regardless of the strobe use mode, and sequence 2, which is determined depending on whether or not the strobe use mode is in use. Sequence 1 is
As shown in FIG. 3, the brightness of the subject measured by the external light metering element 14, that is, the EV value, is divided into sequence A, which is sufficient for use with the EVF, and sequence B, which is insufficient. As shown in Figure 3, whether or not it is sufficient for EVF use is
-AVO<TV 1, which means that the aperture 2 is set to the aperture value A
Even with VO, the shutter speed T for proper exposure is determined by the EV value.
V is the charge accumulation time (generally field time -
------1/60~1/50 sec)
That is, when it becomes larger than the TVI, sufficient exposure for use with the EVF cannot be obtained.

In sequence A, as shown in Figure 7J4, the infrared cut filter 9 is inserted into the optical path and the aperture 2 and electronic shutter speeds are controlled to the values AV and TV used in actual shooting, so they are close to the video output of the camera. The image can be viewed using the EVF.

Note that the speed of the electronic shutter is equivalently changed by clearing the CCD area sensor 4 at a high speed since the reading rate of the EVF is constant. For cameras that do not have an automatic focus adjustment mechanism, a large aperture AV and a short shutter speed JiITV may be selected for convenience of focusing.

In sequence B, the infrared cut filter 9 is excluded from the optical path at 5 TEPI, and the aperture 2 is set to the aperture value AVO.
Determine whether the shutter speed TVI for use with F can be secured, and if it is possible, remove the infrared cut filter 9 from the optical path with 5TEP2, brighten it by the difference in brightness EVIR due to the presence or absence of the infrared cut filter, and use this new EV
Using the value (EV1=EV+EVIR), calculate the shutter speed T of the electronic shutter at the opening value AVO of aperture 2 at 5TEP4.
Decide on V and set AVO and TV.

If the EVF shutter speed TVI cannot be secured in 5TEP1, remove the infrared cut filter 9 from the optical path in 5TEP5 as described above, set the aperture 2 to the aperture value AVO in 5TEP6, open the shutter 3 in 5TEP7, and The current of the auxiliary illuminator 12 is energized so that the output of the CCD area sensor 4 becomes appropriate, that is, the surface of the sensor 4 has an appropriate brightness.

Adjust the illumination level by changing the duty, or change the shutter speed of the electronic shutter.

Note that the diaphragm 2 may be adjusted to be closer than the aperture value, but the aperture value makes it easier to focus and the power consumption of the auxiliary illuminator 12 is lower.

As shown in FIG. 5, sequence 2, which is determined depending on whether or not a strobe is used, excludes the infrared cut filter 9 from the optical path and energizes the auxiliary illuminator 12 in the strobe use mode. Then, the illumination level is maximized and it is determined whether the output of the CCD area sensor 4 is an amplifier. If it is an amplifier, the aperture 2 is opened until the output of the sensor 4 becomes appropriate. If it is not an amplifier, the auxiliary illuminator 12. The electronic shutter, aperture 2, etc. are adjusted so that the output of the sensor 4 becomes appropriate.

In this sequence, if you use the strobe aperture as much as possible and change the aperture 2 only when it is impossible (too dark or too bright), you can see an image on the EVF that is close to the actual image.

In addition, since it is possible to know the relationship between the lighting level and the brightness of the subject, it is possible to fire a strobe with a fixed guide number, such as in so-called DV flash control, and to optimize the aperture, as in so-called pre-flash. It can be carried out.

In addition, after shutter 3 is opened, the brightness of the subject is measured by the CCD.
Area sensor 4. Either the direct photometric element 13 or the external light type photometric element 14 may be used for measurement. Furthermore, since the infrared cut filter 9, which was removed from the optical path for use with the EVF, is inserted into the optical path during the second stroke of the release, there is no problem with actual photography.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to use the EVF except when the subject is dark and far away in a non-strobe state, and there is no need to use a large and expensive optical finder.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of an embodiment of the present invention, Fig. 2 is a block diagram of the embodiment, and Fig. 3 is a sequence 1 of the embodiment.
4 is a detailed flowchart of sequence 1 of the same embodiment, FIG. 5 is a flowchart of sequence 2 of the same embodiment, and FIG. 6 is a schematic configuration diagram of a conventional example using an optical finder. FIG. 7 is a schematic diagram of a conventional example using an electronic viewfinder. 1... Lens 2 ------- Aperture 4 ------- CCD area sensor 5... Eyepiece 8... CRT 11... Strobe 12...Auxiliary illuminator 14...External light type photometric element

Claims (3)

[Claims] (1) An infrared cut filter disposed on the optical path to the image sensor, illumination means for illuminating the subject, means for excluding the infrared cut filter from the optical path under a first specific photographing condition, and a second 1. A still video camera having an electronic viewfinder, further comprising means for energizing the illumination means under specific photographing conditions. (2) An infrared cut filter placed in the optical path to the image sensor, an illumination means for illuminating the subject, and when the brightness of the subject due to external light is insufficient for use with an electronic viewfinder, the infrared cut filter is removed from the optical path. and means for energizing the illumination means when the brightness of the subject due to external light is insufficient for use of an electronic viewfinder even after the infrared cut filter is excluded from the optical path. A still video camera with a distinctive electronic viewfinder. (3) An infrared cut filter disposed in the optical path to the image sensor, a means for illuminating the subject, and a means for excluding the infrared cut filter from the light path and energizing the illumination means when in the strobe use mode. A still video camera having an electronic viewfinder.