JP2009042675A - Camera with liquid crystal lens or liquid lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera for preventing image quality deterioration with a liquid crystal lens or a liquid lens, and to provide a camera for a mobile apparatus correctly reading a bar-code. <P>SOLUTION: The camera has a curved surface lens, a liquid crystal lens or a liquid lens, a switch for setting an imaging mode, a signal processing circuit for processing an image signal, a register for recording the output of the signal processing circuit, and a display monitor for displaying the content of the register. When a normal imaging mode is set, the liquid crystal lens or the liquid lens is in a OFF state. When a macro imaging mode is set by the setting switch, the liquid crystal lens or the liquid lens is in a ON state. The signal processing circuit is provided with a plurality of signal processing methods so that other signal processing method may be selected when the setting switch is changed over. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a camera having a liquid crystal lens or a liquid lens, and more particularly to a camera having a macro photographing mechanism.

Conventionally, with a camera equipped with a macro shooting mechanism, maintaining the image quality when shifting from the normal shooting mode to the macro shooting mode, which is close-up shooting, has been a major problem.
For example, there is a proposal to increase the gain of a circuit that amplifies an image signal at the time of macro photography, while making it easy to focus by narrowing the aperture, that is, to improve the image quality by preventing defocusing (see, for example, Patent Document 1)) .

However, the situation is different for cameras incorporated in small portable devices such as mobile phones.
In a camera incorporated in such a small device, it is necessary to reduce the mechanical size. Therefore, it is desirable not to use an aperture mechanism with a variable aperture amount as well as an autofocus mechanism and a zoom mechanism. On the other hand, in addition to the normal shooting mode that is the normal long-distance shooting mode, the macro shooting mode that is the close-up mode is necessary.

In order to provide a close-up mode in addition to the normal shooting mode, a structure as shown in FIG. 8 has been adopted.
That is, in FIG. 8, light 13 emitted from a subject 11 passes through a lens barrel 12 having a curved lens group in which at least one of the commonly used optical lenses is a curved surface, an IR cut filter 14, and a sensor 16 that is an image sensor. Via the host 17 which is an electronic circuit in the camera. A host (HOST) 17 includes a CPU and controls the entire camera.

In order to provide a close-up mode in addition to the normal shooting mode, a micro lever 15 is provided. By switching the lever 15, the curved lens group in the lens barrel 12 is moved up and down to change the focal length.
However, such a structure has a problem that it becomes an obstacle to miniaturization in a small portable device such as a cellular phone.

For this reason, there is an idea of using a liquid crystal lens or a liquid lens in addition to a normal curved lens having at least one curved surface, and switching the focus (focal length) between the normal shooting mode and the macro shooting mode.
FIG. 9 shows an example of the liquid crystal lens 10.
The liquid crystal lens 10 is configured by sandwiching a liquid crystal material between transparent flat substrates 104 and 106, and concentric transparent electrodes 100 hatched in FIG. 9 are formed on the liquid crystal material side of the flat substrate 104. A common electrode is formed on the entire surface of the flat substrate 106 so as to cover the transparent electrode 100 on the liquid crystal material side. The problem is the extraction electrode 102 for applying a driving voltage to the concentric transparent electrode 100. Since light is also modulated in the extraction electrode portion 102, the image obtained through the liquid crystal lens 10 is whitish, so-called white blur. It is a point that the image quality is degraded.

Although there is a method in which transparent electrodes are multilayered to eliminate such an adverse effect of the extraction electrode, the cost increase due to the increase in the number of processes is large and difficult to realize.
In addition, in the following drawings, the same number is attached | subjected to the same member and description is abbreviate | omitted.

In the liquid lens, two or more kinds of liquids having different refractive indexes are sealed in the same casing, and light is refracted by the difference in the refractive index of the boundary surface to constitute a spherical lens.
Further, the lens can change the shape of the spherical lens by changing the boundary surface of the liquid according to an external signal, thereby changing the light refraction characteristics.
Since this lens can only be configured as a spherical lens due to its characteristics, there is a problem that the focal point between the center of the image and the periphery is likely to be shifted when performing large refraction as in the macro mode photographing as in the present invention.

  In recent years, barcodes have become widespread, and in particular, QR codes with two-dimensionally developed barcodes have appeared, and there has been a demand for reading these barcodes accurately even in small portable devices. However, there is a problem that it is difficult to accurately read a barcode with a conventional camera for a portable device.

JP 05-066644

An object of the present invention is to provide a camera that prevents deterioration in image quality due to the use of a liquid crystal lens or a liquid lens.
Another object of the present invention is to provide a camera for a portable device that can accurately read a barcode.

  A camera having a liquid crystal lens or a liquid lens according to the present invention includes a curved lens having at least one curved surface and a liquid crystal lens or a liquid lens, and a switch for setting a normal shooting mode or a macro shooting mode. A signal processing circuit for processing the image signal captured through the lens, a register for recording the output of the signal processing circuit, and a display monitor for displaying the contents of the register, and the normal photographing mode is set by the setting switch. The liquid crystal lens or liquid lens is turned off when set, and the liquid crystal lens or liquid lens is turned on when the macro photographing mode is set by the setting switch.

  In the camera having the liquid crystal lens or the liquid lens according to the present invention, the signal processing circuit is configured to be able to select a plurality of signal processing methods, and when the setting switch is switched, the signal processing method is selected again. It is characterized by comprising.

  Further, the camera having the liquid crystal lens or the liquid lens according to the present invention is characterized in that the signal processing method is selected so that at least the liquid crystal lens or the liquid lens is different when the liquid crystal lens or the liquid lens is ON. .

  Further, the camera equipped with the liquid crystal lens or liquid lens according to the present invention is processed so that the output luminance level is lower than the input luminance level in the signal processing method selected when the liquid crystal lens or liquid lens is ON. It is characterized by that.

  In addition, the camera equipped with the liquid crystal lens or the liquid lens according to the present invention has a threshold for the input luminance level in the signal processing method selected when the liquid crystal lens or the liquid lens is ON. When the luminance is high, the output luminance is close to the white level, and when the input luminance is lower than the threshold, the output luminance is close to the black level.

In addition, a camera equipped with a liquid crystal lens or a liquid lens according to the present invention has a switch for setting both a curved lens having at least one curved surface and a liquid crystal lens or a liquid lens, and a normal shooting mode or a macro shooting mode. A signal processing circuit configured to process an image signal captured through the lens and select a plurality of signal processing methods, and a register for recording an output of the signal processing circuit,
A display monitor for displaying the contents of the register, and when the barcode is read, the setting switch is set to a macro shooting mode, and the signal processing method is provided with a threshold value for the input luminance level. However, when the input luminance is high, the output luminance is close to the white level, and when the input luminance is lower than the threshold, the output luminance is close to the black level.

  In the camera equipped with the liquid crystal lens or the liquid lens according to the present invention, the signal processing system has an edge enhancement function.

  In addition, a camera equipped with a liquid crystal lens or a liquid lens according to the present invention has a switch for setting both a curved lens having at least one curved surface and a liquid crystal lens or a liquid lens, and a normal shooting mode or a macro shooting mode. A signal processing circuit configured to process a color image signal captured through the lens and select a plurality of signal processing methods, a register for recording the output of the signal processing circuit, and color display of the contents of the register A display monitor capable of reading, and when reading a barcode, the setting switch is set to a macro shooting mode, and the signal processing method is a method of converting the color image signal into a monochrome signal.

According to the present invention, it is possible to solve a problem peculiar to a camera using a liquid crystal lens or a liquid lens that prevents deterioration of image quality due to the use of the liquid crystal lens or the liquid lens.
In addition, according to the present invention, it is possible to realize a portable device camera that can accurately read a barcode.

At least one of a curved lens having a curved surface and a liquid crystal lens or a liquid lens, a switch for setting a normal shooting mode or a macro shooting mode, and a signal processing circuit for processing an image signal captured through the lens And a register for recording the output of the signal processing circuit and a display monitor for displaying the contents of the register, and when the normal photographing mode is set by the setting switch, the liquid crystal lens or the liquid lens is turned off. When the macro shooting mode is set by the setting switch, the liquid crystal lens or the liquid lens is turned on, the signal processing circuit is configured to select a plurality of signal processing methods, and the setting switch is switched. When selected, the signal processing method is selected again.
Hereinafter, the present invention will be described based on examples.
In the following embodiments, an example of a camera provided with a liquid crystal lens will be described. However, a similar configuration is possible for a camera provided with a liquid lens, and an effect can be expected.

FIG. 1 is a diagram schematically showing an image capturing system of a camera provided with a liquid crystal lens or a liquid lens according to the present invention.
Light 13 emitted from the subject 11 passes through a liquid crystal lens 10, a lens barrel 12 having a curved lens group in which at least one of commonly used optical lenses is a curved surface, an IR cut filter 14, and a sensor 16 that is an image sensor. It is taken in by the host 17 in the camera. A host (HOST) 17 includes a CPU and controls the entire camera.
That is, in the camera of the present invention, the liquid crystal lens 10 is always placed in the photographing optical path, and the curved lens group is not displaced.
The focal length is changed by turning off the liquid crystal lens 10 in the normal photographing mode and turning it on in the close-up mode.

FIG. 2 is a block diagram of a camera 98 having a liquid crystal lens or a liquid lens according to the present invention.
In FIG. 2, light from a subject passes through a liquid crystal lens 10, a curved lens 18, and various photographing mechanisms 20, and forms an image on a surface of an image pickup device 22 such as a CCD or CMOS sensor and is photoelectrically converted. The image pickup signal output from the image pickup device 22 is converted into a predetermined recording output by the signal processing circuit 24 and recorded in the image recording register 26. The contents of the image recording register 26 are displayed on the display monitor 28 in accordance with an instruction from the CPU 32. Is displayed. The signal processing circuit 24 has a function of amplifying the imaging signal.

  The setting switch 30 is used to set the normal shooting mode or the macro shooting mode. For example, the bi-stable switch is set to the normal shooting mode for long-distance shooting in one stable state, and to the short-distance shooting in the other stable state. Macro shooting mode can be set. A bar code reading state described later can also be included in the macro shooting mode. Further, the setting switch 30 can be a tristable switch, and the third stable state can be set to the bar code reading mode, or a plurality of switches can be provided in the setting switch 30 to be used exclusively for setting the bar code reading mode. . The CPU 32 controls the entire camera system by looking at the state of each block. Of course, the CPU 32 can instruct the display monitor 28 to display the currently selected photographing mode. The release button 34 is a so-called shutter, and when the button 34 is operated, the CPU 32 captures an image and instructs display on the display monitor 28. A portion surrounded by a dotted line is the host 17.

  That is, the camera 98 having the liquid crystal lens of FIG. 2 includes both the curved lens 18 and the liquid crystal lens 10 having at least one curved surface, the switch 30 for setting the normal photographing mode or the macro photographing mode, It has a signal processing circuit 24 for processing an image signal captured through the lens, a register 26 for recording the output of the signal processing circuit, and a display monitor for displaying the contents of the register.

  It should be noted here that the embodiment of the camera 98 equipped with the liquid crystal lens according to the present invention has no autofocus mechanism because it aims to reduce the size. Instead of the autofocus mechanism, it has at least two shooting modes, a normal shooting mode that is a long-distance shooting mode, and a macro shooting mode that is a close-up shooting mode. Is adopted. In the macro photography mode, the liquid crystal lens 10 is turned on to adjust the focus to a short distance. That is, the focal length of the curved lens 18 is made equal in the normal photographing mode and the macro photographing mode, and the focal length is changed only by turning the liquid crystal lens 10 ON or OFF.

FIG. 3 is a diagram showing a configuration of the signal processing circuit 24 shown in FIG.
In FIG. 3, the signal processing circuit 24 has an image processing register 46, and the image processing register 46 selects one of a plurality of N signal processing methods 36, 38, 40, 42 by a selection circuit 44. Read. For example, γ (gamma) correction of a video signal is one type of this signal processing method. Which signal processing method is selected depends on an instruction from the CPU 32.

FIG. 4 is an example of image parameters (that is, a signal processing method) effective in the close-up mode of the camera 98 having a liquid crystal lens or a liquid lens according to the present invention.
As shown in FIG. 4, when switching to the close-up mode, the exposure (AE) is set to the center-weighted photometry window because the main subject is often in the center. For the white balance mode, the main subject is often in the center as well, so the center-weighted metering window setting is also used, and there are many large monochromatic subjects in the subject), so the tracking range is narrow. And For gamma correction, the contrast difference is set large to improve the QR code recognition rate. Regarding the edge emphasis function, it is conceivable to set a stronger setting in order to improve the QR code recognition rate.
These settings are signal processing methods.
That is, the signal processing circuit 24 is configured to be able to select a plurality of signal processing methods.

FIG. 5 is a flowchart showing a control method of the camera 98 having a liquid crystal lens or a liquid lens according to the present invention.
In FIG. 5, when the power of the camera is turned on at 48, initialization is performed at 50. Here, for example, the normal photographing mode is set and the liquid crystal lens is turned off.
Next, at 52, the setting switch 30 is checked to see if it is set to the macro mode.
If the macro mode has been set, the process proceeds to 53, where the liquid crystal lens 10 is turned on, and at 54, the signal processing method when the liquid crystal lens is used is selected. When the signal processing method is selected, the signal processing method selected in the signal processing circuit 24 shown in FIG.
If the macro mode has not been set, the process proceeds to 55, the liquid crystal lens 10 is turned off, and an image processing method for the normal photographing mode is selected at 55.

Next, at 56, it is monitored whether the shutter release button 34 has been operated. If it has been operated, an image is captured via the liquid crystal lens 10, the curved lens 18, the photographing mechanism 20, and the image sensor 22 at 58, and the operation proceeds to 60. The captured image signal is subjected to image signal processing by the signal processing circuit 24, the processed image signal is recorded in the image recording register 26 at 62, and the contents of the image recording register 26 are displayed on the display monitor 28 at 64. Return to 52.
If the release button 34 is not operated, the process returns to 52.
As described above, since the control of the camera according to the present invention stands by in the loop shown in FIG. 5, when the photographing mode is switched by the setting switch 30, the liquid crystal lens is immediately switched on and off, and the signal processing method is also switched. And written in the image processing register 46.

That is, the camera 98 equipped with the liquid crystal lens according to the present invention turns off the liquid crystal lens 10 when the normal photographing mode is set by the setting switch 30 and turns on the liquid crystal lens 10 when the macro photographing mode is set. State.
When macro shooting is set, the liquid crystal lens is turned on and the signal processing method is reread by the image register 46, so that a change in image quality due to the liquid crystal lens is not displayed and the occurrence of a sense of incongruity can be suppressed. It is done.
The signal processing circuit 24 is configured to be able to select a plurality of signal processing methods, and is configured to reselect the signal processing method when the setting switch 30 is switched and the photographing mode is changed.

  When the liquid crystal lens is used, light is also modulated in the extraction electrode unit 102 as described with reference to FIG. 9, so that the obtained image is whitish and is in a so-called white blurring state, and the image quality is deteriorated. However, in the camera 98 having the liquid crystal lens according to the present invention, the signal processing circuit 24 reselects the signal processing method for the liquid crystal lens before displaying the image obtained through the liquid crystal lens 10, so that the white A blurred image can be prevented from being displayed on the display monitor 28, and a situation in which a sense of incongruity is caused can be avoided.

FIG. 6 shows an embodiment of the signal processing method shown in FIG. 3, in which the liquid crystal lens 10 takes measures against image white blur when the liquid crystal lens 10 is ON.
In FIG. 6, the horizontal axis represents input luminance, and the vertical axis represents output luminance. Bw shown on the horizontal axis indicates the width from black to white that the camera can actually recognize.
The dotted line 66 connects the points where the input luminance and the output luminance are equal, but the curve of the signal processing result indicated by the thick line 68 is shifted in a direction where the luminance of the output signal is smaller than that of the dotted line 66.
Such processing is a problem that is specific to the case of using a liquid crystal lens that prevents white blurring caused by the liquid crystal lens, which is the reverse processing of the so-called night mode, in which the output luminance is made larger than the input luminance to increase the resolution of the black portion.
By switching to such a processing method, it is possible to remove the whitishness of an image that has become whitish by using a liquid crystal lens.

On the other hand, signal processing when the liquid crystal lens 10 is OFF performs so-called known γ correction. The signal processing for image white blur countermeasures shown in FIG. 6 is preferably a combination of gamma correction and image white blur countermeasures, and the specific conversion values are the characteristics of the actually used curved lens, liquid crystal lens, etc. by.
That is, the camera equipped with the liquid crystal lens of the present invention is configured to select different signal processing methods at least when the liquid crystal lens is ON and when it is OFF.
In the signal processing method selected when the liquid crystal lens is ON, the output luminance level is processed to be lower than the input luminance level.

FIG. 7 shows a second embodiment of the signal processing system in which a measure for accurately reading a bar code is applied. Since the barcode reading is performed in the macro photographing mode, the signal processing method shown in FIG. 7 is selected in the macro photographing mode.
In FIG. 7, as in FIG. 6, the horizontal axis represents input luminance, the vertical axis represents output luminance, Bw shown on the horizontal axis represents the width from black to white that can be actually recognized by the camera, and the dotted line 66 represents input. The points where the luminance and output luminance are equal are connected.
In the signal processing method shown in FIG. 7, an input luminance threshold Bth is provided. When the input luminance is higher than the threshold Bth, the output luminance is a thick line 72 close to the white level, and the input luminance is higher than the threshold Bth. Is low, the output luminance is processed to be a thick line 70 close to the black level.

By processing the image signal in this way, it is possible to accurately read a barcode represented by binary values of white and black. This signal processing method is particularly effective when used in the barcode reading mode.
In the barcode reading mode, the liquid crystal lens 10 is turned on and the focus is adjusted to a short distance.
It is also effective to provide a known edge enhancement function.

  Furthermore, it is also effective to increase the accuracy of barcode reading by converting an image signal handled in normal color into a monochrome signal of only black and white. Of course, such a conversion method can be provided in the signal processing circuit 24 as one of the signal processing methods.

  In recent years, barcodes have become widespread, and in particular, QR codes in which barcodes are two-dimensionally developed have appeared. Barcodes cannot be read accurately with cameras for small portable devices. In particular, QR codes have many reading errors. However, these problems can be solved by using the signal processing method described in FIG.

  In the embodiments of the present specification, the case where the liquid crystal lens is used has been described. However, the same effect can be obtained by using a liquid lens instead of the liquid crystal lens.

It is the figure which showed typically the image capturing system of the camera provided with the liquid crystal lens or liquid lens by this invention. 1 is a block diagram of a camera according to the present invention. It is the figure which showed the structure of the signal processing circuit of the camera provided with the liquid crystal lens or liquid lens by this invention. It is an example of the signal processing system effective at the time of close-up mode of the camera provided with the liquid crystal lens or liquid lens by this invention. 4 is a flowchart illustrating a control method of a camera including a liquid crystal lens or a liquid lens according to the present invention. It is the 1st Example of the signal processing system of the liquid crystal lens or liquid lens by this invention. It is a 2nd Example of the signal processing system of the liquid crystal lens or liquid lens by this invention. It is a figure which shows the conventional camera structure. It is the figure which showed the example of the liquid crystal lens.

Explanation of symbols

18 Curved Lens 10 Liquid Crystal Lens 30 Setting Switch 24 Signal Processing Circuit 26 Image Recording Register 28 Display Monitor 98 Cameras 36, 38, 40, 42 with Liquid Crystal Lenses Bth Threshold 72 Brightness Near White Level 70 Black Level Brightness close to

Claims (8)

A curved lens and a liquid crystal lens or a liquid lens, at least one of which is a curved surface;
A switch for setting between normal shooting mode and macro shooting mode,
A signal processing circuit for processing an image signal captured through the lens;
A register for recording the output of the signal processing circuit;
A display monitor for displaying the contents of the register;
When the normal shooting mode is set by the setting switch, the liquid crystal lens or the liquid lens is turned off,
A camera having a liquid crystal lens or a liquid lens, wherein the liquid crystal lens or the liquid lens is turned on when a macro shooting mode is set by the setting switch. The signal processing circuit is configured to be able to select a plurality of signal processing methods,
2. A camera having a liquid crystal lens or a liquid lens according to claim 1, wherein the signal processing method is selected again when the setting switch is switched.   3. The camera having a liquid crystal lens or a liquid lens according to claim 2, wherein the signal processing system is configured to select at least a different system when the liquid crystal lens or the liquid lens is ON and OFF.   4. The liquid crystal lens or liquid lens according to claim 3, wherein the signal processing method selected when the liquid crystal lens is ON is processed so that the output luminance level is lower than the input luminance level. camera.   In the signal processing method selected when the liquid crystal lens or the liquid lens is ON, a threshold is provided for the input luminance level. When the input luminance is higher than the threshold, the output luminance is close to the white level, and the threshold 4. The camera with a liquid crystal lens according to claim 3, wherein when the input luminance is lower than the output luminance, the output luminance is processed to be close to a black level. In a camera provided with a liquid crystal lens or a liquid lens, the camera includes:
A curved lens and a liquid crystal lens or a liquid lens, at least one of which is a curved surface;
A switch for setting between normal shooting mode and macro shooting mode,
A signal processing circuit configured to process an image signal captured through the lens and select a plurality of signal processing methods;
A register for recording the output of the signal processing circuit;
A display monitor for displaying the contents of the register;
When reading barcodes,
Set the setting switch to macro shooting mode,
In the signal processing method, a threshold is provided for the input luminance level. When the input luminance is higher than the threshold, the output luminance is close to the white level, and when the input luminance is lower than the threshold, the output luminance is the black level. A camera equipped with a liquid crystal lens or a liquid lens, wherein the camera is processed so as to be close to 7. A camera having a liquid crystal lens or a liquid lens according to claim 6, wherein the signal processing system has an edge enhancement function. In a camera provided with a liquid crystal lens or a liquid lens, the camera includes:
A curved lens and a liquid crystal lens or a liquid lens, at least one of which is a curved surface;
A switch for setting between normal shooting mode and macro shooting mode,
A signal processing circuit configured to process a color image signal captured through the lens and select a plurality of signal processing methods;
A register for recording the output of the signal processing circuit;
A display monitor capable of color-displaying the contents of the register;
When reading barcodes,
Set the setting switch to macro shooting mode,
The camera having a liquid crystal lens or a liquid lens, wherein the signal processing method is a method of converting the color image signal into a monochrome signal.

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