JP2799058B2 - Signal extraction method for luminance adjustment in infrared imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] In an infrared imaging apparatus, a luminance adjustment signal (hereinafter, referred to as a smoothing signal) for automatically adjusting the luminance of an image.
The purpose of this method is to achieve high-speed arithmetic processing with a simple hardware configuration, and to insert an optical means into the incident infrared light path during an invalid scanning period that is invalid for the image acquisition of the scanning mirror to focus the incident infrared light. Is forcibly shifted to obtain a luminance adjustment signal.

[Industrial applications]

The present invention relates to a method for obtaining a smoothed signal for automatically adjusting the luminance of an image in an infrared imaging device.

The infrared imaging device is used when measuring a temperature distribution in a non-contact manner, or when detecting and recognizing a target that is difficult to find with a visible image device. In this case, the average level of the video signal output from the infrared imaging device greatly fluctuates depending on the target and the background, which may cause the display to become black or white and exceed the dynamic range of the display, making it difficult to view. Many. Therefore, brightness adjustment is required to make the display easier to see.

[Conventional technology]

In such brightness adjustment, conventionally, a user operates a brightness adjustment knob to adjust a video signal to fall within a dynamic range of a display. However, in such a configuration in which the manual adjustment is performed, the operation becomes cumbersome. Conventionally, in order to solve the problem, a device that automatically performs the brightness adjustment is known.

FIG. 5 is a block diagram showing an example of a conventional apparatus for obtaining a smoothed signal necessary for automatically performing luminance adjustment.
In the figure, infrared light is incident on a detector 5 via lenses 1 and 2, an operation mirror 3 and a lens 4, and the infrared power is detected. After being amplified by an amplifier 6, the infrared light is smoothed by a microcomputer. The data is AD-converted by an AD converter 7 whose timing is controlled by a signal operation device 9 and is converted into video information, which is stored in a two-dimensional digital memory 8 as video information corresponding to infrared power data. Here, in the smoothing signal operation device 9 composed of a microcomputer or the like, the operation is performed based on the infrared power stored in the digital memory 8 and the preset luminance adjustment coefficient and the like. A smoothed signal corresponding to the obtained infrared power data is output. The smoothed signal is supplied to an automatic brightness adjustment circuit (not shown), and the brightness is automatically adjusted by a known operation so that the video signal corresponding to the infrared power data falls within the dynamic range of the display.

[Problems to be solved by the invention]

Generally, video signals are output at a rate of 30 frames / second, which is a fairly fast operation. The conventional apparatus has to perform high-speed smoothing operation processing such as the above-described rate on the two-dimensional digital memory 8 by the smoothing signal operation device 9, and requires complicated hardware for this operation processing. In addition, there is a problem in that an automatic brightness adjustment cannot be performed with high accuracy because an addition time of one frame or more is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a luminance adjustment signal extraction method capable of performing high-speed arithmetic processing with a simple hardware configuration.

[Means for solving the problem]

FIG. 1 shows a principle diagram of the present invention. According to the present invention, an optical means is inserted into an incident infrared light path during an invalid scanning period (B) ineffective for acquiring a video signal (S ₂ ) of a scanning mirror to forcibly shift the focus of the incident infrared light to adjust the luminance. This is a method for obtaining the signal (S ₁ ).
Incidentally, A is the effective scanning period to obtain a video signal S _2.

[Action]

Infrared light with a so-called out-of-focus state is defocused forces are considered smoothed signal is extracted as luminance adjustment signal S _1. In this case, according to the present invention, a smoothed signal can be obtained simply by shifting the focus, so that the smoothing operation processing unlike the conventional example is not required, the hardware can be simplified, and the smoothing can be performed in a short time. Signal can be extracted.

〔Example〕

FIG. 2 is a block diagram of one embodiment of the present invention, in which the same components as those in FIG. 5 are denoted by the same reference numerals. Second
In the figure, 10 is a transmission type chopper, as shown in FIG. 3, for example, four infrared transmitting material 10a ₁ 10 A ₄ are provided at equal intervals around the rotation shaft 10b, an infrared transmitting material 10a ₁ ~ portions other than 10a ₄ is a cutout portion 10c ₁ ~10c _4, the rotary shaft 10b
It is supported rotatably around. Notch 10c ₁ to 10
ratio of the c ₄ and the infrared transmitting material 10a ₁ 10 A ₄ 3: 7 are set to. Reference numeral 11 denotes a transmission chopper drive mechanism for rotating the transmission chopper 10. Note that transmission-type chopper 10 is positioned so as to face alternately in the optical path connecting the rotation by the drive mechanism 11 is the infrared transmitting material 10a ₁ 10 A ₄ and notches 10c ₁ ~10c ₄ the lens 1 and the lens 2 It is provided in.

Reference numeral 12 denotes a chopper control circuit which controls the operation of the drive mechanism 11. Reference numeral 13 denotes a timing generation circuit which generates a timing signal for controlling the scanning timing of the scanning mirror 3, the AD conversion timing of the AD converter 7, the writing and reading timing of the memory 8, and the control timing of the control circuit 12, respectively.

Next, the operation of the present invention will be described with reference to the operation timing chart shown in FIG.

The scanning mirror 3 shown in FIG.
The scanning is controlled so that 30% of the scanning is in the invalid scanning period. The image is acquired in the effective scanning period, and the return is performed in the invalid scanning period. In the present invention, the scanning mirror 3 and the chopper control circuit 12 are operated by the timing signal from the timing generation circuit 13 so that the optical path is changed to the transmission type chopper 10.
The effective scanning period scan mirror when facing the notch 10c ₁ ~10c ₄ of, while infrared transmitting material of the light path transmission type chopper 10
Scan timing and transmission type chopper of the scanning mirror 3 as the scanning mirror 3 is disabled scanning period when facing the 10a ₁ 10 A ₄
Each of the ten rotation timings is controlled. In this case, as shown in FIG. 4A, it is assumed that an infrared power exceeding the display dynamic range is incident.

Here, the infrared transmitting material 10a ₁ 10 A ₄ of the transmission type chopper 10
The focus of the infrared light that has passed through the will be connecting to the rear with respect to the focal point of the infrared light that has passed through the notch 10c ₁ ~10c _4, i.e., the infrared having passed through the infrared transmitting material 10a ₁ 10 A ₄ The light enters the scanning mirror 3 in a so-called out-of-focus state. The infrared light in the invalid scanning period (30%) in the out-of-focus state and the infrared light in the valid scanning period (70%) in the normal state are supplied to the AD converter 7 via the detector 5 and the amplifier 6. The data is then A / D converted and written into the digital memory 8. FIG. 4B shows a video signal corresponding to the infrared power written in the digital memory 8 in an analog form. That is, in the period B (invalid scanning period), a smoothed (out-of-focus) signal (smoothed signal) is written.

Subsequently, the video signal (FIG. 4 (B)) written in the digital memory 8 is read out only of the smoothed signal of the period B in the period A (effective scanning period) under the control of the timing generation circuit 13, and the automatic luminance adjustment circuit (Not shown). The automatic brightness adjustment circuit performs automatic brightness adjustment based on the smoothed signal output from the digital memory 8.
As shown in FIG. 3C, a video signal falling within the dynamic range of the display is obtained.

In this case, the present invention does not require the arithmetic processing as in the conventional example to obtain the smoothed signal, so that the hardware can be simplified, the smoothed signal is written in the period A, and the smoothed signal is written in the next period B. , The smoothed signal can be extracted in a short time of one field or less, and the automatic brightness adjustment can be performed with higher accuracy than in the conventional example.

〔The invention's effect〕

As described above, according to the present invention, the focus of the incident infrared light is shifted during the invalid scanning period of the scanning mirror to obtain the luminance adjustment signal, so that the smoothing operation processing as in the conventional example is required. In addition, the hardware can be simplified, a smoothed signal can be obtained in a short time of one field or less, and automatic luminance adjustment can be performed with higher accuracy than in the conventional example.

[Brief description of the drawings]

1 is a principle diagram of the present invention, FIG. 2 is a block diagram of one embodiment of the present invention, FIG. 3 is a schematic diagram of a transmission type chopper used in the present invention, and FIG. 4 is an operation timing chart of the present invention. FIG. 5 is a block diagram of an example of the conventional art. In FIG, 1, 2, 4 denotes a lens, 3 is a scanning mirror, 5 detector, 7 AD converter, the digital memory 8, 10 transmissive chopper, 10a ₁ 10 A ₄ infrared transmitting material, 10c ₁ 10c ₄ is a notch, 11 is a transmission type chopper driving mechanism, 12 is a chopper control circuit, 13 is a timing generation circuit, A is a scanning period, and B is an invalid period.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Sumihiro Uchida 1015 Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-57-124981 (JP, A) JP-A-61- 4389 (JP, A) JP-A-62-298732 (JP, A) JP-A-2-236426 (JP, A) JP-A-63-585 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 5/30-5/335 H04N 5/222-5/257 H04N 9/04-9/11

Claims (3)

(57) [Claims] 1. A method for extracting a signal for brightness adjustment in an infrared imaging apparatus, wherein a signal for brightness adjustment is extracted from infrared light obtained by performing a field scan with a scanning mirror. In the period (B), an optical means is inserted into the incident infrared light path to forcibly shift the focus of the incident infrared light to obtain the luminance adjustment signal (S ₁ ). Adjustment signal extraction method. 2. A notch portion in an effective scanning period (A) effective for acquiring an image of the scanning mirror, and an infrared transmitting material is provided in the incident infrared light path in an invalid scanning period (B) ineffective of acquiring an image of the scanning mirror. luminance adjustment signal extracting method in the infrared imaging apparatus according to claim 1, wherein providing the optical means, characterized in that obtaining the brightness control signal (S ₁₎ so as to face the. 3. The luminance adjustment signal (S ₁ ) is written into a memory during an invalid scanning period (B) of the scanning mirror, and an image is acquired during an effective scanning period (A) of the scanning mirror to obtain a video signal (S 1). ₂ )
3. The method for extracting a signal for luminance adjustment in an infrared imaging apparatus according to claim 1, wherein the signal for luminance adjustment (S ₁ ) is read out from the memory while writing the luminance into the memory.