JP2003319291A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably hold the luminance of a back light by preventing the luminance of the back light from being changed due to the temperature of a light source of the back light and to set the luminance of the back light by a power source for use. <P>SOLUTION: A temperature sensor 45 is provided which measures the temperature of a light source 41 of the back light. A light source control circuit 43 is provided which controls the luminance of the back light in accordance with the temperature measured by the temperature sensor 45. The temperature of the light source 41 of the back light is always detected by the temperature sensor 45, and the detected temperature is converted to an electric signal and is sent to the light source control circuit 43. The light source control circuit 43 stably holds the luminance of the back light by the electric signal. A changeover switch 42 is provided with a power discrimination means for discriminating which of a battery and an external power source is used as the power source, and the light source control circuit 43 is provided with a limiting means for setting the luminance of the back light in accordance with the discriminated power source type. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital camera equipped with a liquid crystal display.

[0002]

2. Description of the Related Art A digital camera is provided with a liquid crystal display so that the framing at the time of photographing and the photographed image can be reproduced and observed. The liquid crystal display includes a liquid crystal panel and a light source that provides illumination light from the back surface thereof. The liquid crystal panel is constructed by arranging a large number of minute liquid crystal cells that can vary the transmission density for each pixel together with a micro color filter in a matrix. The transmission density of the liquid crystal cells is controlled according to the image data, and the back side from the back side A color image can be displayed by irradiating a light.

Fluorescent tubes and LEDs are used as the light source of the backlight. The brightness of these light sources can be easily adjusted by adjusting the drive current when they are turned on. In a liquid crystal display, the display image becomes difficult to observe when the surrounding area becomes bright.
As disclosed in Japanese Patent Laid-Open No. 8 and Japanese Patent Application Laid-Open No. 5-241512, by automatically adjusting the brightness of the light source according to the ambient brightness, it is possible to display an image that is easy to observe regardless of the ambient brightness. Becomes

Further, there is an individual difference in how much the brightness of the backlight is set to make it easier to observe the display image on the liquid crystal display. Further, since the light source of the backlight consumes a large amount of power, it may be desirable to set the brightness of the backlight to a low level in advance when the power supply is insufficient. For this reason, generally, a digital camera is also provided with an operation unit for allowing the user to arbitrarily adjust the brightness of the backlight.

[0005]

As described above, in the digital camera, the brightness of the backlight can be adjusted according to the purpose, but the above-mentioned light source for the backlight is generally used in the surroundings or There is a drawback that the brightness increases as the temperature of the device itself rises. Therefore, even if the brightness of the backlight is automatically adjusted according to the brightness of the surroundings, or even if the user sets the brightness in consideration of power saving at the start of use, the brightness gradually increases during use. As a result, it becomes difficult to observe the displayed image, and the desired power saving effect cannot be obtained.

Since the light source of the backlight consumes a large amount of power, the brightness of the backlight has been set to be low in order to save the power of the battery. However, the brightness was the same as when using the battery, although it was not necessary to worry about power consumption when using the external power supply.

The present invention has been made in consideration of the above circumstances, and the brightness of the backlight of the liquid crystal display can be kept stable even if it is continuously used, and the brightness of the backlight is set by the power supply used. The purpose is to provide a digital camera.

[0008]

In order to achieve the above object, the present invention provides a temperature sensor for measuring the temperature of the light source of the backlight. A light source control circuit for adjusting the brightness of the backlight according to the temperature measured by the temperature sensor is provided. The temperature sensor constantly detects the temperature of the light source of the backlight, converts the detected temperature into an electric signal and sends it to the light source control circuit. The light source control circuit keeps the brightness of the backlight stable by an electric signal.

Further, a power supply identifying means for identifying whether a battery or an external power supply is used as a power supply is provided, and a control means for setting the brightness of the backlight according to the identified type of the power supply.

[0010]

1 and 2 are external perspective views showing the configuration of a digital camera 2 which is an electronic apparatus embodying the present invention. The digital camera 2 has a shooting mode for performing still shooting and a playback mode for playing back shot images.

On the front surface of the digital camera 2, a zoom lens barrel 4 in which a taking lens 3 is incorporated 4, an objective side finder window 6 forming a finder 5, a strobe light emitting section 7 for irradiating a subject with strobe light, and a shutter. Shutter button 8 used for release operation, self-timer light emitting section 9 that blinks at the time of timer shooting to notify shooting timing
Etc. are provided.

When the digital camera 2 is in the power-off state, the zoom lens barrel 4 incorporating the taking lens 3 therein.
Is retracted in the lens barrel housing portion 12 and protected by a lens barrier (not shown) and housed therein. When the power of the digital camera 2 is turned on, the lens barrier opens and the taking lens 3 projects from the front surface of the digital camera 2.

A memory card slot 16 in which a memory card 15 is set is provided on one side surface of the digital camera 2.
Is provided. The memory card slot 16 is protected by an opening-and-closing type protective cover 17 in order to prevent dust and the like from entering. On the other side surface of the digital camera 2, an AC power supply connector 20 to which a power supply terminal of an AC power supply adapter that supplies external power is connected is provided.

On the back surface of the digital camera 2, there are provided an eyepiece side viewfinder window 25 constituting the viewfinder 5, an operation section 26, an image display LCD 27 functioning as a viewfinder, and the like. On the side of the eyepiece finder 25,
Viewfinder light emitting part 2 that informs the status of the digital camera 2.
9 is provided. In the operation unit 26, the power button 3
0, a plurality of operation buttons 31 to 33, and a setting LCD 34 that displays information such as various settings. By operating the operation buttons 31 to 33, the image display LC
The brightness of the image displayed on D27 can be adjusted.

The digital camera 2 is provided with a battery chamber in which a replaceable dry battery 37 is set, and an opening 39 for loading and replacing the battery 37 is provided on the bottom surface of the digital camera 2. Is provided. The opening 39 is opened and closed by the lid member 40. Reference numeral 41 denotes a light source of a backlight that illuminates the image display LCD from the rear surface, and a fluorescent tube is used. In the vicinity of the light source 41 of the backlight, a thermistor that constantly detects the temperature of the light source 41 of the backlight, converts the detected temperature information into an electric signal, and sends the electric signal to the light source control circuit 43 (see FIG. 3) is used. The temperature sensor 45 is provided.

FIG. 3 is a block diagram of the digital camera 2. This digital camera can be used with an external power source by using an AC adapter or the like. When the power button 2 is pressed, the power unit 50 turns the battery 3
7 or an external power source to drive the power. When the power is turned on, the lens barrier of the lens barrel housing portion 12 opens, and the zoom lens barrel 4 with the taking lens 3 incorporated therein comes out. At this time, the changeover switch 42 discriminates whether the battery 37 or the external power source is used for the power source depending on whether the power supply terminal of the external power source is turned on or not, and sends the discriminated information to the light source control circuit 43. The light source control circuit 43 sets the brightness of the backlight from the information sent from the changeover switch 42 in accordance with the power source used. This suppresses power consumption when the battery is used, and when the external power is used, a bright and easy-to-see image is displayed on the image display LCD 27.

The operation unit 26 is used to set a shooting method such as zooming in the moving image mode or the still image mode. After setting the shooting method, framing is performed while viewing the subject image displayed on the image display LCD 27, and the shutter button 8 is pressed to perform shooting.

At this time, the image data taken in from the image pickup section 53 including the taking lens 3 and CCD is sent to the system control section 55. The system control unit 55 converts the image data input from the image pickup unit into an electric signal and sends it to the memory control unit 57. The memory control unit 57 writes the image data sent from the system control unit 55 into the built-in memory 58 or the memory card 15.

The built-in memory 58 is used for the image display LCD 27.
When using as a viewfinder, low resolution image data is temporarily recorded. The image data recorded in the built-in memory 58 is read by the memory control unit 57, sent to the system control unit 55 and the liquid crystal control circuit 60, and the image is displayed on the image display LCD 27 of the liquid crystal panel 62.

When the image display LCD 27 is used for a long time, the temperature of the light source 41 of the backlight illuminating the image display LCD 27 from the rear surface gradually rises. The temperature of the light source 41 is always detected by the temperature sensor 45. The temperature sensor 45 converts the detected temperature information into an electric signal and sends it to the light source control circuit 43. Light source control circuit 43
Uses an electric signal sent from the temperature sensor 45 to keep the brightness of the backlight stable.
By controlling the brightness of the backlight by such a method, it is possible to prevent the brightness of the backlight from increasing due to the temperature rise of the light source 41.

Next, the operation of this embodiment will be described. When the power button 30 is pressed to turn on the power, the changeover switch 42 identifies whether the battery 37 or the external power source is used, and sends the identified information to the light source control circuit 43. The light source control circuit 43 includes a changeover switch 4
The brightness of the backlight is set from the information sent from 2.

When an external power source is used as the power source, the brightness of the backlight is set so that the brightness of the image displayed on the image display LCD 27 can be seen appropriately. by this,
A bright and easy-to-see image is displayed on the image display LCD 27. Further, when the battery 37 is used as the power source, the power consumption of the battery 37 is saved by setting the brightness of the backlight lower than when the external power source is used. As a result, the battery 37 can be used for a long time.

When the image display LCD 27 is continuously used for a long time, the temperature of the light source 41 of the backlight rises and the brightness of the backlight becomes high. At this time, the temperature sensor 45 detects that the temperature of the light source 41 of the backlight has risen, converts the detected temperature information into an electric signal and sends it to the light source control circuit 43. The light source control circuit 43 adjusts the brightness of the backlight to be low according to the electric signal sent from the temperature 45 sensor. Thereby, the brightness of the backlight can be kept stable and the brightness of the image displayed on the image display LCD 27 can be stabilized.

After using the digital camera, the power button 3
Press 0 to turn off the power. When the power is turned off, the temperature sensor 45 stops detecting the temperature of the light source 41.

In the above embodiment, the brightness of the backlight is prevented from becoming high, but since the ambient temperature of the light source 41 is low, the brightness at the start of using the backlight is low and the image displayed on the image display LCD 27 is low. Can be hard to see.
In this case, the temperature sensor 45 detects that the temperature of the light source 41 is low, converts the detected temperature information into an electric signal, and sends it to the light source control circuit 43. The light source control circuit 43 adjusts the brightness of the backlight to be high according to the electric signal sent from the temperature sensor 45. As a result, an easily viewable image is displayed on the image display LCD 27.

The present invention is not necessarily applied to control the brightness of the backlight for illuminating the image display LCD 27 from the rear surface, but also controls the brightness of the backlight for illuminating the setting display LCD 34 from the rear surface. May be applied to

[0027]

As described above, according to the digital camera of the present invention, since the temperature of the light source of the backlight is constantly detected and the brightness of the backlight is controlled, the temperature of the light source of the backlight changes. Even if occurs, the brightness of the backlight can be kept stable. As a result, an image with stable brightness is displayed on the liquid crystal display. Further, since the brightness of the backlight is controlled to be kept stable, it is possible to prevent the brightness of the backlight from increasing and save power consumption. In addition, the brightness of the backlight can be changed by the battery and external power source, which saves power consumption when using the battery,
It can provide a bright and easy-to-read LCD monitor when using an external power supply.

[Brief description of drawings]

FIG. 1 is a front side external perspective view showing the configuration of a digital camera.

FIG. 2 is a rear side external perspective view showing the configuration of the digital camera.

FIG. 3 is a block diagram of a digital camera.

[Explanation of symbols]

2 digital camera 37 battery 27 LCD for image display 41 light source 42 Changeover switch 43 Light source control circuit 45 Temperature sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 5/225 H04N 5/225 B FF term (reference) 2H088 EA02 EA25 HA07 HA28 MA20 2H093 NC01 NC07 NC42 NC52 NC57 ND02 ND05 ND09 ND39 NG01 5C022 AA13 AB67 AC01 AC03 AC69 AC73 5C058 AA06 AB03 BA05 BA26 BA29

Claims (2)

[Claims] 1. A digital camera equipped with a liquid crystal display for displaying an image by illuminating a backlight, comprising: a temperature sensor for measuring the temperature of a light source of the backlight; and a backlight according to the temperature measured by the temperature sensor. And a control means for adjusting the brightness of the digital camera. 2. A power source identification means for identifying whether the power source used is a replaceable battery or an external power source, and a control for adjusting the brightness of the backlight according to the type of the identified power source. The digital camera according to claim 1, further comprising: