JPS6298973A - Imaging device - Google Patents

Abstract

PURPOSE:To attain a stable picture input by providing a critical level detection means detecting that the maximum level of a picture signal outputted from an image pickup element lies at a critical level beyond a normal level. CONSTITUTION:Since in a normal picture signal 11n and a picture signal 11b causing blooming due to excessiveness of luminous energy the level of the picture signal 11 exceeds a lower limit binarization level 22l for detecting the lack of luminous energy, a luminous energy lack detection circuit 6 outputs a signal at a level 'H' such as luminous energy lack signals 14n and 14b as a luminous energy lack signal 14. In a picture signal 11l lacking luminous energy, the signal at a level 'H' is not outputted as the luminous energy lack signal 14. Then an external outfitting device adjusts lighting luminous energy and exposure one so that the signal at a level 'H' can be outputted but a signal at a level 'H' cannot be outputted as an error signal 14. Thus a normal picture signal can be obtained.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

This invention relates to a so-called -dimensional solid-state image sensor (that is, a device in which a large number of image sensors are arranged in a straight line), which is incorporated into, for example, a facsimile machine or a simple pattern recognition device.
The present invention relates to an image information input device using an LSI (D, MOS type, etc.).

[Prior art and its problems]

In the following description of each figure, the same reference numerals indicate the same or corresponding parts. In addition, "Low" in "old GHL+" will be simply written as "H11", "L". This type of one-dimensional solid-state image sensing device has advanced in resolution due to advances in LSi technology, and has come to be used in various image input devices. However, since it was originally developed for use in facsimile machines with a stable amount of incident light, compared to two-dimensional solid-state image sensors, there is blooming (i.e., the output image signal of the individual image sensor in the area that receives an excessive level of light is saturated and no light is received). Adjacent individual image elements also
Not many countermeasures have been taken to prevent the device from outputting a false signal as if it had received light. Therefore, if there is a bright part in the image, the corresponding image on the individual image sensor will exceed the saturation light level.
Blooming occurs due to carriers overflowing from the element. Figure 4 is a principle waveform diagram to explain this blooming, and (1) and (2) in the figure are image signal 1 during normal conditions.
1n and its binary signal 12n, and (3) and (4) in the same figure.
are an image signal 11b and its binary signal 12b when blooming occurs, respectively. The image signal (1.011n, 1lb) is an image signal output from a one-dimensional solid-state image sensor (a large number of individual image sensors arranged in a row) that receives an image of the object to be imaged, and the horizontal axis represents the image of the subject. Each ([lll) corresponds to the position of the image sensor in the -dimensional solid-state image sensor. This is a signal obtained by binarizing the image signal at a predetermined level after performing intermediate analog processing such as sample and hold.In addition, Kanchu 21 is the saturation level of the image signal, and 22n is the binary value for the image signal. 23 is the black level of the image signal (original level of the non-light receiving area). If the amount of light incident on the image sensor is appropriate, it is shown in the same figure (1). As shown in (2), it is based on the image signal 11n. Binarized signal 12
The bright and dark areas of n almost correspond to those of the image, but when blooming occurs, the image signal 11 in (3) in the same figure, even though the position and size of the image are the same as normal.
The individual image sensor in the dark part of the image as shown in b also outputs the image pseudo signals BSI and BS2 as if it had received light, and the resulting binary signal 12b is as shown in the figure (4).
), resulting in the problem that dark areas are also determined to be bright areas. In recent years, the blooming characteristics of solid-state image sensors, especially two-dimensional solid-state image sensors, have been improved by installing so-called overflow drains as a means to remove carriers overflowing from the individual image sensors caused by blooming, but the blooming characteristics are still being improved. Nothing is perfect. In order to prevent this, a method has been adopted in which an automatic aperture lens (so-called auto iris lens) or the like is used to keep the incident light constant and make it a bell. However, in general, with auto iris lenses, etc., the total amount of light incident on the lens is controlled by the value obtained by integrating the image signal output from the individual image sensor over the entire one-dimensional solid-state image sensor, so even if the average amount of light on the screen is small, the However, there still remains the problem that when there is a particularly bright part, the control becomes insufficient and the saturation light quantity is exceeded in some parts.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned problems and provide an imaging device that can perform stable image input by detecting whether or not blooming occurs based on a signal from an imaging device. shall be.

[Key points of the invention]

The gist of the present invention is to provide an imaging device using a -dimensional solid-state imaging device, including a limit level detection means for detecting that the maximum level of an image signal output from the imaging device is at a limit level outside the normal range. The above-mentioned limit level detection means is an upper limit level binarization detection circuit that binarizes the image signal at the upper limit level, etc.) and a binarization signal from this binarization means. The above-mentioned limit level detecting means is provided with a means (such as a blooming detection circuit) for determining that a warning signal (such as an error signal) has been output and outputting an alarm signal (such as an error signal). (upper limit level binarization) and lower limit level binarization, etc., which binarizes the image signal, and the upper limit level binarization means does not output a binarized signal, and the lower limit level binarization means outputs a binarized signal. A means for variably adjusting the total amount of light input from the object to be imaged to the imaging device so that a binary signal is output. It is in.

[Embodiments of the invention]

The present invention will be described in detail below based on FIGS. 1(A) and 1(B), and FIGS. 2 and 3. Figure 1 (A), (
B) is a professional circuit diagram showing the configuration of different embodiments of the present invention, and FIGS. 2 and 3 are respectively similar to FIG. 1(A).
, (B) is a waveform diagram for explaining. In FIG. 1(A), reference numeral 1 denotes a conventional linear sensor device, which includes a -dimensional solid-state image sensor 2, a drive circuit 3 that supplies a drive signal 3a to this element 2, and an image signal 11 output from the image sensor 2. It consists of a signal processing circuit 4 that performs intermediate analog processing such as width 1 sample hold, and then outputs it as a video output signal 4a. 5 is a blooming detection circuit which inputs the image signal 11, detects the occurrence of blooming, and outputs an error signal 13 of "H". Next, in FIG. 1(B), reference numeral 6 denotes a light quantity insufficient detection circuit which inputs the image signal 11, detects that the light quantity is insufficient, and outputs a light quantity insufficient signal 14 of "L11". In the figure, (1) to (3) respectively indicate the image signal IH11n) during normal operation, the image signal 11 (11b) when blooming occurs, and the error signal 13 corresponding to the occurrence of blooming.22b (Figure +11. (2+ )
is the upper limit binarization level for the image signal 11, which is set slightly below the saturation level 21, and is a level for detecting the occurrence of blooming. Moreover, in FIG. 3, (1) to (3) are respectively normal times. Image signal IH when blooming occurs or when light intensity is insufficient
11n, llb, and 1N are shown, respectively. Also, Figure 3 (
4) to (6) are the error signals 13. corresponding to (2) in the figure, respectively. The light quantity insufficient signal 14 (14n) during normal operation corresponding to FIG. 21 is a lower limit binarization level for the image signal 11, which is a level for detecting insufficient light quantity. Next, referring to FIG. 2, the operation of FIG. 1(A) will be explained. The blooming detection circuit 5 has an upper limit binarization level of 22 for blooming detection, which is set to the saturation level of 21.
This is a binarization circuit with b. When the level of the image signal 11 from the -dimensional solid-state image sensor 2 exceeds the upper limit binarization level 2b (Fig. 2 (2)), it means that there is a very high possibility that blooming will occur. This outputs an error signal 13 of "H" to the outside ((3) in FIG. 2). Also, to describe the operation of FIG. 1(B) with reference to FIG. 3, the operation of the blooming detection circuit 5 that detects blooming from the image signal 11 and outputs the error signal 13 is the same as that of FIG. 1(8). It is. The light quantity insufficient detection circuit 6 is a binarization circuit that is internally set with a lower limit binarization level 22β for detecting light quantity deficiency, and this lower limit 2
Valorization level 22! can be changed by hardware or software. As shown in Fig. 3 (1) and (2), normal image signal 1
1n and the image signal 11b in which blooming occurs due to excess light intensity, the level of the image signal 11 exceeds the lower limit binary conversion level 221 for detecting insufficient light intensity, so the light intensity detection circuit 6 detects the corresponding light intensity. Shortage signal 14
As shown in 14n and 14b in (5) and (6) of the same figure, a signal of "■(" level is output). An “H” level signal is not output as the signal 14. In this way, an external device not shown in the figure outputs an “H” signal as the insufficient light signal 14, and an “H” signal as the error signal 13. By adjusting the amount of illumination light or the amount of exposure light so that it is not output, it is possible to obtain the image signal 11 (11n) at an optimal level.

【Effect of the invention】

As is clear from the above description, according to the present invention, since the binarization means is provided with a predetermined upper limit level set for determining whether the image signal is excessive, blooming does not occur. In order to return the image signal at the abnormal level to the normal level, an alarm can be issued or the amount of illumination light and the amount of exposure light can be varied with respect to the abnormal image signal by the output signal of the binarization means, This has the effect of making it possible to always obtain a normal image signal.

[Brief explanation of drawings]

FIGS. 1(A) and (B) are block circuit diagrams showing the configurations of different embodiments of the present invention, and FIGS. 2 and 3 are block circuit diagrams for explaining FIGS. 1(A) and (B), respectively. waveform diagram,
FIG. 4 is a principle waveform diagram for explaining blooming. 1: Linear sensor device, 2. One-dimensional solid-state image sensor, 5;
Blooming detection circuit, 6: Insufficient light detection circuit, IHL
ln, llb, IIA): Image signal, 13: Error signal, 14 (14n, 14b): Insufficient light signal, 21
: Saturation level, 22b = Upper limit binarization level, 22! : Lower limit binarization level, 23: Black level. Figure 1 (A)

Claims (1)

[Claims] 1) In an imaging device using a one-dimensional solid-state imaging device, there is provided limit level detection means for detecting that the maximum level of an image signal output from the imaging device is at a limit level outside a normal range. An imaging device comprising: 2) In the apparatus according to claim 1, the limit level detection means includes an upper limit level binarization means for binarizing the image signal at an upper limit level, and an upper limit level binarization means for binarizing the image signal at an upper limit level; An imaging device characterized by comprising means for determining that a digitized signal has been output and outputting an alarm signal. 3) In the apparatus according to claim 1, the limit level detection means includes upper limit level binarization means and lower limit level binarization means for binarizing the image signal at upper and lower limit levels, respectively. means, and a whole that is inputted from the imaged object to the imaging device so that the upper limit level binarization means does not output a binary signal and the lower limit level binarization unit outputs a binary signal. An imaging device comprising means for variably adjusting the amount of light.