JPH02260974A - Binary signal detecting circuit - Google Patents

Abstract

PURPOSE:To output a binary signal faithful to a picture by providing a driving circuit, which shortens the accumulating time and makes a photoelectric converting element read again when a halation signal is outputted, and a converting circuit, which synthesizes binary data converted from are-read picture signal and the binary data outputted from a memory and converts them into the binary signals. CONSTITUTION:A level voltage setting circuit 29 is connected to the other input terminals of comparators 30 and 31, and voltages L1 and L2 are inputted. The voltages L1 and L2 divide the fluctuation area of a picture signal VD outputted from a line sensor 8 into three areas S1, S2 and S3. The picture signal VD outputted from the line sensor 8 is compared with the voltages L1 and L2 by the comparators 30 and 31, and from which area the signal is outputted is specified. For example, when the picture signal VD is outputted from the area S1, the picture signal VD is classified into an absolute black state, when the signal exists in the area S2, the picture signal VD is classified into a normal state, and further when the signal exists in the area S3, the picture signal VD is classified into a halation state.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a binary signal detection circuit, and more specifically to a binary signal detection circuit that converts an image signal read out by a photoelectric conversion element into a white and black binary signal. This invention relates to a signal detection circuit.

[Conventional technology]

Electronic copying devices are generally used under fluorescent lighting in conference rooms, etc., and when taking images, if they do not have a built-in light source device to illuminate the recording surface, an external light source such as a fluorescent light is required. The brightness of the illuminated recording surface is measured photometrically, and the exposure MtM section is performed according to the photometric output.
Characters, figures, etc. (hereinafter referred to as "images") recorded on a recording surface of a blackboard, whiteboard, etc., using a computer or a line sensor, etc., were converted into image signals. This image signal is converted into a black and white binary signal by a binary signal detection circuit, and is printed out on recording paper via a thermal head.

In the above-mentioned conventional binary signal detection circuit disclosed in Japanese Patent Publication No. 58-13065, as shown in FIG. 6, the rising time constant is larger than the falling time constant, and the image signal (2). a first threshold signal VSO that follows
The image signal (2) is outputted smaller than the first threshold signal VSII, has a rising time constant larger than the rising time constant, and has a rising time constant larger than the rising time constant. A second threshold signal VSL that follows the current level and has a partially secured level is generated, and the first and second threshold signals and the image signal (2) are generated. are compared, two binary data are output, and this binary data is logically processed to convert the image signal (2) into a binary signal (3).

[Problem to be solved by the invention]

However, when using an electronic copying device under illumination from an external light source, depending on the relative positional relationship between the device itself, the recording surface, and the external light source, an image of the external light source reflected on the recording surface may be captured. There is. In such a case,
A part of the recording surface is accompanied by a very high brightness part, that is, halation, and the surrounding image cannot be captured well.For example, the image signal V read from the halation part is The output is as shown in the figure.When this image signal (■) is processed by the binary signal detection circuit described above, it is converted into a binary signal (8) of white level in area B and black level in area C. , is different from the binary signal ■ shown in FIG.

Furthermore, when there is halation on the recording surface, even if photometry is performed, the photometry output will shift due to the halation, and there is also the problem that it is not possible to take an image with an appropriate exposure amount.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a binary signal detection circuit that can correctly convert an image recorded on a recording surface into a binary signal faithful to the image recorded on the recording surface even if halation exists on the recording surface. purpose.

[Means for solving the invention]

In order to achieve the above object, the binary signal detection circuit of the present invention includes a signal generation circuit that outputs a halation signal when the output level of the image signal read out by the photoelectric conversion element is equal to or higher than a predetermined level, and a signal generation circuit that outputs the halation signal and the image signal. a binarization circuit that converts the image signal into binary data by comparing it with a threshold signal that follows the image signal, and converts the image signal into low-level binary data when a halation signal is output; a memory that stores binary data; a drive circuit that shortens the storage time and causes the photoelectric conversion element to read out the data again when a halation signal is output; It is composed of a conversion circuit that combines the converted binary data and the binary data output from the memory and converts it into a binary signal.

[Effect]

According to the above configuration, the signal generation circuit monitors the output level of the image signal and generates the halation signal when an image signal of a predetermined level or higher is detected. The binarization circuit converts the image signal read out by the photoelectric conversion element into binary data, and outputs low-level binary data when the halation signal is output. Furthermore, when this halation signal is output, the drive circuit is activated to shorten the storage time and read out data to the photoelectric conversion element again. This re-read image signal is converted into binary data by the binarization circuit, and this converted binary data is combined with the binary data output from the memory by the conversion circuit and converted into a binary signal. and output.

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

〔Example〕

In FIG. 5 showing the external appearance of the electronic copying device of the present invention,
The main body 2 of this electronic copying apparatus has an imaging section 3 formed in the upper front part. An exposure aperture 5 is provided in front of the imaging unit 3.
is formed, and a photographic lens 6 is attached to this frontage 5. Inside the I-most image section 3, a line sensor 8 is attached which is slidable on a pair of shafts 7, as shown by the broken line in the figure. This line sensor 8 slides on the focal plane of the first darkest lens 6 by a motor 9.

Then, the line sensor 8 divides the surface information of the image formed on the focal plane of the photographing lens 6 into a plurality of line information, and converts it into an image signal for each line.

A diaphragm 1O is attached to the top of the photographic lens 6, which serves as both an ultrasonic transmitter and receiver.

This diaphragm 10 emits ultrasonic waves to the whiteboard at an elevation angle of about 10 degrees, receives the ultrasonic waves reflected by the whiteboard, and detects the distance from the main body 2 to the whiteboard. Further, on the top surface of the imaging unit 3, there is a start button 11 for starting imaging. A finder window 12 is provided.

Two large and small lids 15 and 16 are provided on the side surface of the main body 2 so as to be openable and closable. A print unit is built inside the lid 15 to record an image within a print range on the whiteboard surface.

Further, an ejection port 18 is formed between the lower end of the lid 15 and the main body 2 to eject the thermal recording paper 17 on which an image has been recorded. Furthermore, inside the small lid 16, there is provided an operation section in which a main switch, a print mode switch, a density adjustment switch, etc. are arranged.

FIG. 1 shows an example of a binary signal detection circuit according to the present invention, in which a line sensor 8 consisting of an image pickup device such as a CCD is arranged on the focal plane of a photographic lens 6. A pair of comparators 30 and 31 and a binarization circuit 32 are connected to this line sensor 8. This binarization circuit 32 generates a threshold signal that follows the image signal from the line sensor 8 and compares them. When the image signal≧threshold signal,
A high level signal is output, and a low level signal is output when the image signal is a threshold signal.

A level voltage setting circuit 29 is connected to other input terminals of the comparators 30 and 31, and voltages L+ and Lx are input thereto. These voltages L+ and Lx are image signals (2) output from the line sensor 8. The fluctuation range of is divided into three areas: S+, Sz, and Si. Then, the line sensor 8
Image signal output from■. is comparator 30.31
It is compared with the voltages L+ and Lt, and it is specified from which area the output is coming from. For example, image signal■
. When is being output from area SI, the image signal ■
. is in an absolute black state, and when it exists in area S2, the image signal V is in the normal state, and when it exists in area S3, it is in the image signal ■. is classified as a halation state.

The output terminal of the binarization circuit 32 is connected to an OR circuit 33 and a transistor 34. Then, when a high level signal (hereinafter referred to as rHu) is output from the microcomputer 39, which will be described later, when the level of the image signal ■ is in areas St and Ss, the transistor 34 is turned on.
The output from the binarization circuit 32 flows to ground. Note that when the image signal v0 is in the area S2, the microcomputer 39 sends a low level signal (
(hereinafter referred to as "L").

The line sensor 8 is connected to the output terminal of the OR circuit 33.
A line memo 1J35 having a storage capacity for the number of pixels is connected. An output terminal of this line memory 35 is connected to a thermal head 36 and an input terminal of an AND circuit 50. The other input terminal of the AND circuit 50 is connected to the microcomputer 39, and its output terminal is connected to the input terminal of the OR circuit 33.

The line memory 35 and thermal head 36 are controlled by a microcomputer 39 connected via drivers 37 and 38. microcomputer 39
are connected to the output terminals of the pair of comparators 30 and 31, respectively, and an image signal (2) is output from the output terminals. You can specify which area it is in. Furthermore, the microcomputer 39 connects the line sensors 8. Motor 9 is connected and line sensor 8
and controls the drive of the motor 9. Furthermore, line sensor 8
Only when the storage time is shortened and reading is performed again, the microcomputer 39 causes the AND circuit 50 to
Outputs “H”.

The operation of the binary signal detection circuit of the present invention configured as described above will be explained. In FIG. 5, the finder window 12
When the user looks at the camera, performs framing, and presses the start button 10, a well-known AF mechanism is activated via the diaphragm 9, and the photographing lens 6 is moved to the focusing position. The image written on the whiteboard is then focused on the sliding surface of the line sensor 8 by the imaging lens 6. Further, the microcomputer 39 drives the motor 9 via the driver 41 to move the line sensor 8 to the start position. Next, when the microcomputer 39 drives the line sensor 8 via the driver 40, an image signal (2) as shown in FIG. 2 is generated from the line sensor 8. is output. This image signal■
. is output from the binarization circuit 32 to the OR circuit 33 as a binary data signal of white and black levels.

By the way, this binary data signal is an image signal ■.

Since the transistor 34 is on when is being output from areas S, , S, rl and J are input to the OR circuit 33. Also, the image signal V is in the area S.
, since the transistor 34 is OFF, the binary data signal output from the binarization circuit 32 is OFF.
The signal is now output to the R circuit 33.

The binary signal output from the OR circuit 33 is sent to the line memory 3.
5, the microcomputer 39 drives the Meng Yu 9 via the driver 41 to intermittently feed the line sensor 8. In synchronization with this, the microcomputer 39
drives the driver 40 to cause the line sensor 8 to start reading the second line. The image signal V from the line sensor 8 is converted into a binary data signal by the binarization circuit 32 and output to the OR circuit 33. The microcomputer 39 flushes out the memory of the line memory 35 via the driver 37 in synchronization with the reading of the line sensor 8, and also flushes out the memory of the thermal head 36 via the driver 38.
drive. The thermal head 36 prints on the thermal recording paper 17 based on the binary signal from the line memory 35.

By the way, the case where the line sensor 8 reads out halation will be explained with reference to FIG. 3.

From time T1 to time Tt, the image signal ■ is output from areas St and St. is the binarization circuit 32 as described above.
The signal is converted into a binary data signal and output from the OR circuit 33. Then, when the image signal (2) is output from the area S from 12 o'clock T, the microcomputer 39 turns on the transistor 34. Therefore, the binarization circuit 32
The output flows to ground, and the OR circuit 33 outputs binary signals rl and J. Image signal ■ output from area S2 from T1 o'clock to 14 o'clock. is converted into a binary data signal by the binarization circuit 32, and outputted from the OR circuit 33 as a binary signal. During this time, the line memory 35 is connected to the OR circuit 3.
3, and outputs the binary signals of the previous row to the thermal head 36. This thermal head 36 records a binary signal on the thermosensitive recording paper 17.

Since the microcomputer 39 does not drive the motor 9 at 14:00 when the binary signal converted from the image signal ■ゎ output from the area S is stored in the line memory 35,
Line sensor 8 does not move and remains in its previous position. T5
Image signal from area S, ■. The CCD drive signal whose accumulation time has been shortened based on the microcomputer 3
9 to the driver 40. Therefore, the image signal V2 read out for the second time is outputted from the line sensor 8 with the level lowered overall as shown in the figure.

Further, the microcomputer 39 outputs a drive signal to the driver 37 and rH to the AND circuit 50.

Image signal ■ output from area S1 from time T3 to time T1. is converted into an "L" binary data signal by the binarization circuit 32 and output to the OR circuit 33. Furthermore, since the binary signal output from the line memory 35 is input to the AND circuit 50, the output of the AND circuit 50 is the same as the output of the line memory 35. Since this output is output to the OR circuit 33, the binary signal output from the OR circuit 33 becomes the same as the binary signal stored in the line memory 35 from T1 to 12. Although the binary signal is output from the line memory 35 to the thermal head 36, it is not recorded on the thermal recording paper 17 because the thermal head 36 is not driven.

From 16:00 to T9:00, image signal ■ is output from area S2. is converted into a binary data signal by the binarization circuit 32 and output to the OR circuit 33. At this time, OR circuit 33
The AND circuit 50 outputs the binary signals stored in the memory as rl and J from time T2 to time T1 to other input terminals. Therefore, the output of the OR circuit 33 is the binary data signal just read out as a binary signal.

Image signal ■ output from area SI from 17:00 to T11:00. is output from the binarization circuit 32 as "L".

Therefore, the output of the OR circuit 33 is the binary signal output from the line memory 35. The binary signal outputted from the OR circuit 33 in this manner is stored in the line memory 35. When this line memory 35 is stored, the microcomputer 39 controls the motor 9 via the driver 41.
and sends the line sensor 8 to the next line. When the line sensor 8 is sent to a predetermined position, the microcomputer 39 uses the line memory 35. The thermal head 36° line sensor 8 is driven to perform imaging and printing.

FIG. 4 shows an image signal VD read by the line sensor 8 from an image recorded on a blackboard where halation is occurring. In this case, disulfide may be performed using the method described above, and the line memory 35 can be transferred to the thermal head 36.
When outputting to , the output can be inverted.

(Effects of the Invention) As explained in detail above, the binary signal detection circuit of the present invention functions as a signal generation circuit that outputs a halation signal when the output level of the image signal read out by the photoelectric conversion element is equal to or higher than a predetermined level. , converts the image signal into binary data by comparing the image signal with a threshold signal that follows this image signal, and converts the image signal into low-level binary data when a halation signal is output. a conversion circuit, a memory for storing the binary data, a drive circuit that shortens the storage time and causes the photoelectric conversion element to read out the data again when a halation signal is output, and a drive circuit that causes the photoelectric conversion element to read out the data again; A conversion circuit is provided that combines the binary data converted from the image signal and the binary data output from the memory and converts it into a binary signal.
When an image signal with a predetermined level of 4° or higher is detected, the storage time is shortened and the image signal is read out again, so even if halation occurs on the recording surface due to illumination, etc., a binary signal faithful to the image is output. be able to.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a binary signal detection circuit of the present invention. 2 to 4 are diagrams showing operating waveforms of the binary signal detection signal detection circuit of the present invention. FIG. 5 is a perspective view of an electronic copying device using the present invention. FIGS. 6 and 7 are diagrams showing operating waveforms of a conventional binary signal detection circuit. 39...Microcomputer. 8 ・ ・ 29 ・ 30° 32 ・ 33 ・ 35 ・ Line sensor/level voltage setting circuit l... ・Comparator/binarization circuit/OR circuit/line memory

Claims (1)

[Claims] (1) When the output level of the image signal read out by the photoelectric conversion element is equal to or higher than a predetermined level, a signal generation circuit that outputs a halation signal compares the image signal with a threshold signal that follows this image signal, and generates an image. A binarization circuit that converts the signal into binary data and also converts the image signal into low-level binary data when a halation signal is output, a memory that stores the binary data, and a memory that stores the binary data and outputs the halation signal. When the storage time is shortened, the drive circuit causes the photoelectric conversion element to read again, and the binary data converted from the reread image signal by the binarization circuit and the binary data output from the memory. 1. A binary signal detection circuit comprising: a conversion circuit that synthesizes data and converts the signal into a binary signal.