JPH02126785A - Electronic camera - Google Patents

Abstract

PURPOSE:To automatically regulate a white balance in a simple constitution without providing a special sensor by deciding whether or not subject illumination light is a fluorescent lamp by using an infrared sensor provided for measuring distance, and executing a color balance correction for the illumination of the fluorescent lamp. CONSTITUTION:When a light source to illuminate the subject is the fluorescent lamp, although energy is radiated in a visible area, energy is not radiated in an infrared area, therefore, although output signals can be obtained from a blue sensor 27 and a red sensor 28, the signal output cannot be obtained from an infrared sensor 19. In such a case, a discriminating circuit 53 sends a fluorescent lamp discriminating signal to a color temperature detecting circuit 52. The color temperature detecting circuit 52 is operated in a fluorescent mode, and sends the color temperature detecting signal to a white balance correction control circuit 54. The white balance correction control circuit 54 supplies a correction control signal, which regulates the illumination light of the bluish fluorescent lamp to the light at the standard color temperature, to amplifiers 43 and 44, and the recording is executed by the video signals at the standard color balance.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electronic camera equipped with a white balance adjustment device that automatically adjusts white balance according to the color temperature of a light source illuminating a subject. It is.

[Conventional technology]

Electronic cameras and video cameras generally have a built-in white balance adjustment device. This white balance adjustment device detects the color temperature of a light source illuminating a subject, and corrects primary color signals output from an imaging means such as a CCD according to the color temperature.

By the way, when the light source illuminating the subject is a fluorescent lamp, the amount of illumination light generally tends to be low, and the illumination light blinks in accordance with the commercial frequency, so the white balance adjustment device described above may not work properly. Moreover, in order to eliminate the flickering effect of fluorescent lights, the shutter speed must be controlled to be slower than 1/60 second, so the lighting is caused by fluorescent lights. It is necessary to identify this in advance.

As a device for this purpose, there is a white balance adjusting device (Japanese Patent Application No. 102260/1983) proposed by the present applicant. This white balance adjustment device focuses on the fact that the illumination light from fluorescent lamps contains almost no infrared light, and adjusts the lighting to the fluorescent lamp based on the amount of light received in the infrared region from the shooting screen. It is designed to identify whether or not it is caused by

Using this device, it is possible to effectively detect high-frequency flashing fluorescent lamps with a flashing cycle of several hundred cycles, as well as fluorescent lamps used in foreign countries with different commercial frequencies, and maintain good self-balance. It can be corrected to

[Problem to be solved by the invention]

However, electronic cameras such as those mentioned above are equipped with an infrared sensor dedicated to white balance adjustment in addition to a visible light sensor for white balance adjustment, and because of the large number of sensors, the structure is complicated and costs are high. Ta.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, and provides an electronic camera that can automatically adjust white balance efficiently with a simple configuration without providing a dedicated sensor. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the present invention focuses on the fact that an autofocus sensor is used in a camera, and
An infrared sensor receives infrared light for distance measurement reflected from the subject during distance measurement, and receives illumination light from the subject during color balance correction, and an infrared sensor that receives infrared light reflected from the subject during distance measurement, and an infrared sensor that receives the object illumination light during color balance correction. a determination means for identifying whether or not the illumination light is a fluorescent light; and when the determination means identifies that the subject illumination light is a fluorescent light, the image signal output from the solid-state imaging device is set in a fluorescent light mode. The electronic camera is configured by providing a color correction means for correcting the color.

Another effective solution is to arrange a light-receiving lens in front of the infrared sensor, and to change the distance between the light-receiving lens and the infrared sensor on the optical axis between distance measurement and color balance correction. Become a means.

[Effect]

According to the above, it is possible to determine whether or not the illumination light of the object is a fluorescent lamp using an infrared sensor provided for distance measurement, and depending on the result of this determination, the illumination of the fluorescent lamp is It also becomes possible to perform good color balance correction. Thereby, it is possible to detect whether or not the object illumination light is a fluorescent lamp without providing a new sensor, and the configuration can be simplified.

In addition, when using a light-receiving lens, the infrared sensor is placed at the focal point of the light-receiving lens during distance measurement, and the infrared sensor is moved (for example, forward) during color balance correction to improve the detection accuracy of fluorescent lights. be able to.

Embodiments of the present invention will be described below with reference to the drawings.

〔Example〕

In FIG. 2 showing the external appearance of an electronic camera according to an embodiment of the present invention, a photographing lens 11 having a imaging optical axis 12 is provided on the front surface of a camera body 10 of the electronic camera, and an autofocus portion described later is provided. The function focuses the image of the subject backwards. Above this photographic lens 11, an active AF infrared light projecting section 9 and a distance measuring section 14 are provided, and a distance measuring lens 17 having an optical axis 16 is exposed.

A shutter button 18 is arranged on the top surface of the camera body 10.

In FIG. 1 showing the optical and electrical configuration inside the camera body 10, an infrared sensor 19 is held by a holding lever 21 behind the lens 17. As shown in FIG.

This infrared sensor 19 has an infrared light transmitting filter that transmits light of 700 nm to 11100 nm on the front surface of a plurality of elements divided in the distance measurement base line direction, and has photosensitive characteristics in the infrared region. The focus position is identified by looking at the incident position of the distance measuring infrared light using an imaging position detection circuit. The holding lever 21 is provided with a rack portion 22 that meshes with a gear 23. The gear 23 rotates forward and backward in response to a drive signal from a sensor moving circuit, which will be described later, to move the infrared sensor 19 back and forth. The infrared sensor 19 normally retreats to an initial position, which is the focal position of the lens 17, and moves forward to an out-of-focus position close to the lens 17 during color balance correction. The sensor section 24 includes a diffuser plate 26, and a blue sensor 27 and a red sensor 28 disposed behind the diffuser plate 26. The blue sensor 27 and the red sensor 28 each have a blue transmission filter in front of a light receiving element such as a photodiode.

A red transmission filter is arranged.

The photographing lens 11 is held by a cam barrel 47.

A rack 48 is formed on this cam cylinder 47 and meshes with a gear 49. The gear 49 rotates forward and backward in response to a drive signal from a main lens moving circuit to be described later, and moves the photographing lens 11 back and forth along the photographing optical axis 12. Photography lens 1
1 is usually in a retracted initial position, and a lens 25 . A diaphragm 29 and a beam splitter 31 are provided. The light that has passed through the photographing lens 11 passes through the aperture 29 in the open state, and then enters the beam splitter 31, and a part of it passes through the lens 32 and is sent to the AE
The light is incident on the light receiving section 33. The AE light receiving section 33 sends a photoelectric signal according to the amount of incident light to the exposure control device 34. The exposure control device 34 determines the exposure at the time of photographing based on this photoelectric signal,
The aperture diameter of the diaphragm 29 and the opening time of the shutter 36 are determined.

The light that has passed through the beam splitter 31 is sent to a movable mirror 37. Movable mirror 37 in the lowered position shown
guides the incident light to a well-known pentaprism 38. The light passing through the pentaprism 38 is imaged by an eyepiece lens 39 and observed through a finder. When the shutter 36 is opened after the movable mirror 37 is moved to the raised position by operating the shutter button 18, a subject image is formed on the photocathode of the imaging unit 41 and imaging is performed.

A shutter 36 is provided between the movable mirror 37 and the imaging unit 41. When the shank button 18 is operated, the shutter 36 opens and closes in response to a control signal from the exposure control device 34. Imost image unit 4
1 is a filter face plate with a mosaic arrangement of filters that transmit blue, green, and red, and a CO placed behind it.
The photoelectric signal obtained by photoelectric conversion is supplied to the process circuit 42. The process circuit 42 amplifies the photoelectric signal from the imaging unit 41.
It performs processing such as color demodulation and gamma correction, and outputs primary color signals R, B and luminance signal Y. The primary color signals R and B are supplied via amplifiers 43 and 44, and the luminance signal Y is supplied directly to the video signal processing circuit 46, where matrix calculations and color encoding are performed. The video signal is supplied to the recording device 51 as a video signal of the system. The recording device 51 records the sent video signal on a video floppy.

On the other hand, the blue sensor 27 of the sensor section 24. red sensor 28
The output signals from the color temperature detection circuit 52 are supplied to the color temperature detection circuit 52, and a color temperature detection signal is calculated based on these output signals.

This color temperature detection signal is sent to the white balance correction control circuit 54. The white balance correction control circuit 54 supplies correction control signals for blue and red to the amplifier 4443 in response to the color temperature detection signal. The amplifiers 43 and 44 adjust their respective gains in accordance with the correction control signals, for example, when the color temperature is low, the gain of the primary color signal B is increased and the gain of the primary color signal R is decreased. Therefore, the video signal processing circuit 46 is supplied with a primary color signal corrected according to the color temperature of the illumination light, and the recording device 5
1, a standard color balance video signal is output.

The output signal from the infrared sensor 19 is input to the discrimination circuit 53 together with the output signal from the red sensor 28. The discrimination circuit 53 sends a fluorescent lamp identification signal to the color temperature detection circuit 52 when the output signal from the red sensor 28 is above a predetermined level and the output signal from the infrared sensor 19 is below a predetermined level. Note that when the output signal from the red sensor 28 is below a predetermined level, the fluorescent lamp identification signal is not output.

When the color temperature detection circuit 52 receives the fluorescent lamp identification signal from the determination circuit 53, the color temperature detection circuit 52 detects the blue sensor 27 and the red sensor 2.
8 is received as input information in the fluorescent lamp mode. Then, the output signals from these sensors 27.2B are evaluated on the assumption that they are illumination light from a fluorescent lamp, and a color temperature detection signal is input to the white balance correction control circuit 54. As a result, the white balance correction control circuit 54 adjusts each amplifier 4 so that the gain of the amplifier 43 is larger than that of the amplifier 44 in order to adjust the strong bluish light peculiar to fluorescent lamps.
3.44 to supply a correction control signal.

Note that when the fluorescent lamp identification signal is not output from the discrimination circuit 53, the color temperature detection circuit 52 operates in the normal mode as described above, and the blue sensor 27. The gains of the amplifiers 43 and 44 are adjusted in accordance with the color temperature detection signal obtained directly from the output signal from the red sensor 28.

The output signal from the infrared sensor 19 in the retracted position is also supplied to the imaging position detection circuit 56. Imaging position detection circuit 56
Then, the imaging position of the subject by the lens 17 is detected from the output signal, and this imaging position signal is supplied to the sensor movement circuit 57 and the main lens movement circuit 58. The main lens moving circuit 5 calculates the lens position of the photographing lens 11 corresponding to the imaging position signal, and outputs a drive signal corresponding to this. The shutter button 18 is connected to a sensor moving circuit 57 and a main lens moving circuit 58, and moves the photographing lens 11 to the in-focus position in response to a drive signal sent from the main lens moving circuit 58 when the shutter button 18 is pressed halfway. Move it back and forth.

The operation of the embodiment configured as described above will be explained below.

When the main switch is turned on, the sensor unit 24 is activated during the framing stage through the eyepiece 39, and the blue sensor 27. The red sensor 28 receives light from the photographic screen and its surroundings through the diffuser plate 26. These output signals are then sent to the color temperature detection circuit 522 and the discrimination circuit 53, respectively.
is input.

Further, as shown in FIG. 3, which is a flowchart illustrating the operation of this embodiment, when the shutter button 18 is pressed halfway, the photographing lens is 11 is detected, and the photographing lens 11 is moved to this focus position. Then, the infrared sensor 19 moves forward.

At this time, the exposure control device 34 calculates the aperture diameter of the diaphragm 29 and the opening/closing time of the shutter 36 so as to provide an appropriate amount of light according to the output from the AE light receiving section 33. After this, when the half-press is released, the photographing lens 11 retreats to the initial position and stops. If the half-press is continued without release, the infrared sensor 19 moves forward and detects the infrared level. At this time, since the infrared sensor 19 is located close to the lens 17, it can receive light from a wide range of surroundings including the subject, and can detect whether the light source of the illumination is a fluorescent lamp.

Then, when the movable mirror 37 rises, the aperture 29 is narrowed down to the aperture diameter calculated by the exposure control device 34 described above.

By opening and closing the shutter 36, the image of the subject is formed on the imaging unit 41, and the imaging unit 41 outputs a photoelectric signal of the subject image.

This photoelectric signal forms primary color signals R and B and a luminance signal Y by passing through a process circuit 42. The luminance signal Y is sent as is, and the primary color signals R and B are sent to a video signal processing circuit 46 via amplifiers 43 and 44. Supplied.

If the subject is illuminated by daylight (natural light),
Since its spectral energy distribution has the characteristics shown in FIG. 4, the blue sensor 27. The output signals from the red sensor 28 each exceed a predetermined level and are input to the color temperature detection circuit 52. Further, the output signal from the red sensor 28 is also input to a discrimination circuit 53.The output of the infrared sensor 19, which is at a predetermined level or higher, is also input to the zero discrimination circuit 53. In this case, the fluorescent lamp identification signal is not output, and the color temperature detection circuit 52 directly compares the signal outputs of the blue sensor 27 and the red sensor 28 to detect the color temperature of the illumination light.

The white balance correction control circuit 54 then adjusts the gains of the amplifiers 43 and 44 in response to this color temperature detection signal.

At this time, the gains of the amplifiers 43 and 44 are maintained at standard balance, and the primary color signals are input to the video signal processing circuit 46. At this point, the shutter button 1
When the half-press of 8 is released, the photographing lens 11 and the infrared sensor 19 are moved to the initial position. On the other hand, if the shutter button 18 is pressed fully while the half-press is maintained, the shutter 3
6 is released, and the video signal processing circuit 46 outputs a video signal with well-corrected color balance. This causes the recording device 51 to write this video signal onto the video floppy.

On the other hand, if the light source illuminating the subject is a fluorescent lamp,
Its spectral energy distribution has characteristics as shown in FIG. That is, it radiates energy in the visible region, but hardly radiates energy in the infrared region. In such a case, the blue sensor 27. red sensor 2
Although an output signal with a certain level can be obtained from the infrared sensor 19, almost no signal output can be obtained from the infrared sensor 19.

As described above, when an output signal of a predetermined level is supplied from the red sensor 28 and no output signal is supplied from the infrared sensor 19, the discrimination circuit 53 generates a fluorescent lamp identification signal and sends this to the color temperature detection circuit 52. Send. As a result, the color temperature detection circuit 52 operates in the fluorescent light mode, and the blue sensor 27
．． The output signal from the red sensor 28 is evaluated as being due to light from a fluorescent lamp, the color temperature is detected, and the color temperature detection signal is sent to the white balance correction control circuit 54.

The white balance correction control circuit 54 supplies the amplifiers 43 and 44 with a correction control signal for adjusting the bluish illumination light of the fluorescent lamp to light with a standard color temperature. Therefore, even in this case, recording can be performed using a video signal with standard color balance. The fluorescent lamp identification signal thus generated is also supplied to the exposure control device 34, thereby opening and closing the shutter 36 at a shutter speed for fluorescent lamps, which is slower than 1/60 second, for example. is also possible.

Note that if the red sensor 28 does not supply a signal output of a predetermined level or higher to the discrimination circuit 53, it means that the amount of light on the subject is low. No identification signal is output. In such a state, it is often impossible to obtain a high-quality image due to insufficient light quantity, so it is preferable to issue a warning regarding insufficient light quantity.

Finally, the photographing lens 11 and the infrared sensor 19 are retreated and returned to their initial positions, thereby completing the -times I shadowiest operation.

〔Effect of the invention〕

As explained in detail above, the electronic camera of the present invention includes an infrared sensor that receives infrared light for distance measurement and object illumination light for color balance correction, and an infrared sensor that receives infrared light for distance measurement and object illumination light for color balance correction, and a determining means for identifying whether or not the object illumination light is a fluorescent lamp based on the above; A color correction means for correction is provided. Therefore, it is possible to provide an electronic camera with a simple configuration and good color balance correction without providing a sensor dedicated to detecting fluorescent lamps.

4゜Also, when a light receiving lens is arranged in front of the infrared sensor, and the distance between the light receiving lens and the infrared sensor on the optical axis is changed between distance measurement and color balance correction, , it becomes possible to provide an electronic camera that is convenient for both distance measurement and fluorescent lamp detection.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing an electronic camera according to the present invention. FIG. 2 is an external view of the electronic camera shown in FIG. 1. FIG. 3 is a sequence flowchart of the electronic camera of FIG. FIG. 4 is a schematic diagram showing the energy distribution of natural light. FIG. 5 is a schematic diagram showing the energy distribution of a fluorescent lamp. 10...Camera body 11...The darkest lens 17.25...Lens 18, 19, 21, 27, 28, 29, 33, 34, 36, 37, 38, 54, 53, 58, Shutter button, Infrared sensor, holding lever, blue sensor, red sensor, aperture, AE light receiving unit, exposure control device, shutter, movable mirror, pentaprism, white balance correction control circuit, discrimination circuit, main lens movement circuit. Table 5 Table 1 [nm]

Claims (2)

[Claims] (1) An infrared sensor that receives infrared light reflected from the subject during distance measurement and receives illumination light from the subject during color balance correction; a determination means for identifying whether or not the object illumination light is fluorescent light based on the fluorescent light; and when the determination means identifies that the object illumination light is fluorescent light, An electronic camera characterized by comprising a color correction means for correcting in a light mode. (2) A light receiving lens is arranged in front of the infrared sensor, and the distance between the light receiving lens and the infrared sensor on the optical axis is changed between distance measurement and color balance correction. An electronic camera according to claim 1.