JPH0444463A - Facsimile equipment - Google Patents

Abstract

PURPOSE:To reproduce a half tone picture and a text picture beautifully by providing a means discriminating kinds of a received picture and a control means controlling a recording method in the unit of picture forming being a formed picture in response to the kind of the received picture comprising a text picture and a half tone picture. CONSTITUTION:When a transmission control section 35 receives a connection request from a caller through a line connection section 36, a line is connected to the facsimile equipment, it receives a signal and the signal is stored in a code memory 34. An expansion section 37 decodes a signal of the code memory 34 and the decoded signal is converted into a signal capable of being outputted by a recording section 38. A page memory 40 stores this signal tentatively. A picture mode detection section 41 checks an expanded white/black level picture signal string to discriminate whether the expanded picture is a text picture or an intermediate tone picture. The picture data stored in the page memory 40 is fed to the recording section 38, which forms a picture on paper based on the picture data. Moreover, a control section 39 controls the signal processing above corresponding to a command of an operation display section 51.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a facsimile machine, and more particularly to a facsimile machine whose recording mode can be switched depending on the type of image.

[Prior Art] Conventionally, most facsimile machines were of a thermal recording type. On the other hand, in recent years, electrophotographic recording systems have also been supplied to the market.

[Problems to be Solved by the Invention] In general, images handled by facsimile machines are often text images consisting mainly of characters. , the dots are adjusted to appear larger overall. As a result, when a halftone image is received, the density of the output image becomes higher. In other words, the entire image becomes blackish, making it difficult to bring out grays.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a facsimile device that can reproduce both halftone images and text images beautifully.

[Means for Solving the Problems] An electrophotographic facsimile device that forms an image in response to a received signal according to the present invention as set forth in claim 1 includes means for determining the type of received image. . Types of received images include text images and halftone images, and each image is composed of a plurality of image forming bodies. The facsimile apparatus further includes a control means for controlling a recording method of image forming units according to the type of received image.

In the facsimile apparatus of claim 2, the control means of the facsimile apparatus of claim 1 is characterized by the size of the image forming unit. The control means of the apparatus controls the density of the image forming units.

[Operations] In the facsimile apparatus according to claim 1, since the recording method of image forming units is changed depending on the type of received image at the time of reception, image forming units suitable for each of text mode and halftone mode are used. An image is formed.

In the facsimile apparatus according to claim 2, the size of the image forming unit is changed depending on the type of the received image at the time of reception, so that the size of the image forming unit is suitable for each of the text mode and the halftone mode. An image is formed.

In the facsimile apparatus according to claim 3, since the density of the image forming unit is changed according to the type of the received image at the time of reception, the image is formed with the density of the image forming unit suitable for each of the text mode and the halftone mode. It is formed.

[Example code] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view showing an outline of a document reading section 1 for transmission and a printing section 11 for reception of a laser facsimile apparatus.

In the document reading section 1, a light source 3 illuminates the document on a platen 2 while a scanner 4 moves to scan the document. The light reflected from the original is reflected by a mirror, passes through a lens 5, and enters a linear CCD sensor (for example, 8 pixels/mm) 6. The output signal of the linear CCD sensor 6 is digitized as explained later, and then binarized. Note that if reading is performed using a moving document type, the configuration becomes simpler.

In the printing unit 11 , a laser optical system 12 controls the light emission of a laser diode in response to a received signal, and the light is incident on a photoreceptor 13 . Then, development, transfer, and fixing are performed using a well-known electrophotographic process, and the received signal is printed on plain paper.

The contents of the reading and printing operations described above are similar to those of conventional laser printers, so a detailed explanation thereof will be omitted.

Next, an outline of the operation of the facsimile machine will be explained with reference to FIG. First, the operation when making a call will be explained. The photoelectric conversion section 31 including the linear CCD sensor 6 of the reading section 1 converts the original into an electrical signal. Next, the converted electrical signal is subjected to predetermined binarization processing (dither processing, etc.) by the processing unit 32, and is converted into a binarized time series signal. Next, the data is encoded by the compression unit 33 using a method such as MHSMR. Next, the encoded signal is stored in the code memory 3
It is accumulated in 4. The transmission control unit 35 establishes a connection with the called party, and sends the signal in the memory 34 to the line through the line connection unit 36 according to a predetermined procedure.

Next, the operation at the time of reception will be explained. Line connection section 36
When the transmission control section 35 receives a connection request from the calling side through the transmission control section 35, the line is connected, a signal is received, and the signal is stored in the code memory 34.

The expansion section 37 decodes the signal in the code memory 34, and the decoded signal is converted into a signal that can be output by the recording section 38. The page memory 40 temporarily stores this signal. The image mode detection unit 41 looks at the expanded white and black image sequences and determines whether the expanded image is a text image or a halftone image. Details of this content will be described later. The image data stored in the page memory 40 is sent to the recording section 38, and the recording section 38 forms an image on paper based on this image data.

Note that the control section 39 controls the above signal processing in response to instructions from the operation display section 51.

FIG. 3 is a circuit diagram of the CPU 71 that controls the facsimile machine. The CPU 71 is connected to a working RAM 72 and a timer clock IC 73.

Further, the CPU 71 is connected to the key matrices 52 to 58 of the operation display section 51, the LCD display section 59, and each control section (see FIG. 2).

■, First Embodiment Next, referring to FIGS. 4A and 4B, the first embodiment according to the present invention will be described.
The operation of the facsimile machine according to the embodiment will be explained.

In the first embodiment of the invention, the dot size of the dots forming the image is switched depending on the type of image. FIG. 4A is a block diagram of a switching circuit that switches the dot size according to an image signal, and FIG. 4B is a timing chart of the circuit shown in FIG. 4A.

In FIG. 4B, waveform a indicates a clock, and this clock synchronizes the reading of print data from the page memory 40 and the triangular wave generation circuit used to control the dot size. The waveform is a triangular waveform generated in synchronization with a clock. Waveform C is a waveform of print data read out in synchronization with the clock. When the value of waveform C is 1, it corresponds to black, and when it is 0, it corresponds to white.

Waveforms d and f are pulse waveforms indicating the dot size. When the dot size switching signal is "0" and the switch 102 is turned on, the comparison voltage input to the comparator 108 becomes low, and the output waveform of the comparator 108 becomes waveform d. When the dot size switching signal is "1" and the switch 102 is turned off,
The comparison voltage input to the comparator 108 increases, and the output waveform of the comparator 108 becomes waveform f. Waveform C and waveform d or waveform f are calculated by AND gate 109. When waveform d is input, waveform e is output from AND gate 109, and when waveform f is input, AND gate 1 is output.
The output waveform of 09 is waveform g. This controls the energization time to the semiconductor laser 101 and controls the dot size.

FIG. 5 is a flowchart showing the main flow of the CPU 71 that controls the facsimile. CP in step S1
Initial settings are performed after U71 is reset. Step S
In step 2, input/output processing of the CPU 71 is performed.

In step S3, the control mode indicating the control state is checked and the program branches depending on the control mode. If the control mode value is O, go to step S4, if it is 1, go to step S5, if it is 2, go to step S
The program advances to step 6. In the standby mode of step S4, the device waits for an incoming signal by key operation or reception. When the device is performing reception processing, the program proceeds to the reception mode subroutine of step S5, and when processing other than reception mode, such as transmission mode or one-touch dial registration, the program proceeds to the other processing routine of S6. move on. After each process ends, the program returns to step S2.

FIG. 6 is a flowchart showing processing in standby mode (step S4). In step 5101, input of an incoming signal is checked. When the arrival m signal is input, the program advances to step 5102, sets the control mode to 1, and returns. If no incoming call signal has been input, the program proceeds to step 5103, performs other processing, and returns.

FIG. 7 is a flowchart showing the operation in reception mode. In step 5200, the value of the internal state in the receive mode is determined, and the flowchart branches to any of steps 5201.5211.5221.5231.5241 according to the determined value.

When the internal state is 0, the program proceeds to step 520.
The process advances to step 1, and the facsimile connection procedure is executed. In step 5202, it is determined whether or not the connection has been completed. If the connection is not completed, the program returns as is. If it is completed, the program updates the internal state in step 5203 and returns.

If the internal state is 1, the program proceeds to step 52.
11, the transmitted image data is stored in code memory 3.
Transfer to 4. In step 5212, it is determined whether or not the transfer is completed. If it is not completed, the program returns as is; if it is completed, the program returns to step 5213.
Update the internal state with and return.

If the internal state is 2, the program goes to step 52.
Proceed to step 21 and execute the cutting procedure. In step 5222, it is determined whether or not the disconnection is completed. If it is not completed, the program returns as is. If it is completed, the program updates the internal state in step 5223 and returns.

If the internal state is 3, the program goes to step 52.
Proceed to step 31 to determine the number of residuals that must be output. If the remainder is 0, the program returns to step 8232.
．． At step 5233, the internal state is set to 0, the control mode is set to 0, and the process returns to standby mode S4. If the remainder is not 0 in step 5231, the program returns 5
234.5235, the contents of the code memory 34 are expanded and transferred to the page memory 40. Here, the image is expanded line by line, the details of which will be described later. Next, in step 5236, it is determined whether the decompression is finished, and if so, the program executes printing and updates the internal state in steps 5237 and 5238.

If the decompression is not completed in step 5236, the program returns directly.

If the internal state is 4, the program goes to step 52.
The program proceeds to step 41 to determine whether printing has been completed, and if it has not been completed, the program returns directly. When completed, the program sets the internal state to 3 in step 5252 and returns.

Next, a method for determining the image mode will be described with reference to FIG. FIG. 8 is a block diagram showing details of the image mode detection section 41. With reference to FIG. 8, the image mode detection unit 4
1 is connected to the decompression unit 37, and outputs a signal for determining the type of image in response to signals from counters A to D that count up in response to a synchronization signal for each line, and from counters C and D. NAND gate 75 and NA
It also includes a determination result memory 76 that records the determination result of the image type based on the signal from the ND gate 75.

Counter A counts the number of consecutive black pixels in response to a synchronization signal for each line. However, it is cleared when a white pixel is input. It is also cleared by the 1-line synchronization signal. Then, when the number of black pixels exceeds a predetermined value, a black pixel continuous signal is generated.

Counter B operates in the same way as counter A for white pixels.

Counter C is connected to counter A and counts the black pixel continuous signals output from counter A. The counter C is also cleared by the 1-line synchronization signal. When the count value exceeds a predetermined value, a first signal is output.

Counter D operates similarly to counter C and receives the second signal a.
I will do it.

9rI! depending on the type of image from NAND gate 75 based on the first and second signals from counters C and D! A dot size switching signal explained in J is output.

The determination result memory 76 records a value indicating whether the image is a halftone image or a text image for each line based on the output signal from the NAND gate 75. When outputting images,
A dot size switching signal is output for the line currently being recorded in response to the image output line synchronization signal.

The image mode detection method shown in FIG. 8 discriminates between halftone images and text images based on the following characteristics.

In a halftone image, black and white pixels are difficult to be continuous.

Generally, when halftone processing is performed using the dither method, it is 8X at most.
A matrix size of 8 is used. Therefore, if the density of the reproduced image is high, the probability of consecutive white pixels is very small, and if the density of the reproduced image is low, the probability of consecutive black pixels is very small.

On the other hand, in text images, black and white images tend to be continuous. In the case of character pixels, unless black and white are inverted, there is a very high probability that white will continue for a long time. Also, even though it is a letter,
If the image signal is read at 8 lines/mm, even vertical lines will be 4 lines/mm.
Black pixels are continuous for about 0.5 mm, and if it is a horizontal line, black pixels are continuous.

Counter C and counter D generate a signal "1" when the probability of consecutive black or white pixels is high. The output signal from this counter C1 counter D and the NAND at that time
FIG. 9 shows the determination of the image type based on the output signal from the gate 75 and the value of the dot size switching signal.

In the embodiments described above, the type of image is determined by the image mode detection unit based on the probability that black pixels and white pixels are consecutive. In addition to this, the following determination method can be considered.

(1) The image mode is determined based on whether the probability that white pixels will continue for a predetermined value or more is high or low. The determination method using only one of the embodiments shown in FIG. 8 lowers the accuracy of the determination result, but is cheaper in terms of cost.

(2) Determine the image mode depending on whether the probability that black pixels will continue for a predetermined value or more is high or low. This also has the same characteristics as the above (1).

(3) For two-dimensional blocks, apply (1) and (2) above.
Alternatively, the determination shown in FIG. 8 is made.

(4) The determination may be made not for each line but for each page.

FIGS. 10 and 11 show diagrams corresponding to FIGS. 2 and 7 of the above embodiment in this case.

Referring to FIG. 10, the image mode detection section 41 determines the type of image (halftone image or text image) for each page, and the determination result is input to the CPU 71. CPU
At step 71, a dot size switching signal is output to the recording section 38 based on the above determination result. In this case, since the image mode is detected for each page, a signal is output to the control section 39 after the image mode is detected for each page, and thereby the image is recorded. Since the other parts are the same as those in the embodiment shown in FIG. 2, the same parts are given the same reference numerals and the explanation thereof will be omitted.

FIG. 11 is a flowchart for determining the image mode for each page. The difference from FIG. 7 is that the internal states are 13 and 14. In step 5334, the contents of the code memory 34 are expanded and transferred to the page memory 40, and the image mode is detected using the image mode detection method described above (5335). In step 5336, the image expansion for one page is completed. If the program has not finished, the program returns as is, and if it has finished, the internal state is updated in step 5337 and the program returns.

When the internal state is 14, the program goes to step 53.
The process proceeds to step 41, determines whether the expanded image is a text image or a halftone image, and outputs a dot size switching signal accordingly (S342, S343), and issues a start command to the recording unit 38 to execute printing (S342, S343). 344). Then, in step 5345, the internal state is updated and the program returns. The contents of the parts other than those described above are the same as those explained in FIG. 7, so the explanation thereof will be omitted.

(2) Second Embodiment In the first embodiment, the size of the recording dots was changed depending on the image mode. In the second embodiment, instead of changing the size of the recording dots, the density of the recording dots is changed.

FIG. 12 corresponds to FIG. 4A of the first embodiment,
FIG. 2 is a block diagram of a circuit that switches the density of recording dots by controlling the power of a semiconductor laser. The data to be recorded is read out from the page memory 40 by the successive output circuit 106 in synchronization with the clock, and is applied to the driver 115. The power of the semiconductor laser 101 is
limited by resistors 103 and 104. At this time, if the switch 102 is turned on by the dot density switching signal, it is limited only by the resistor 104, and if it is turned off, it is limited by the resistors 103 and 104. When the power of the semiconductor laser changes, the potential on the photoreceptor drum changes, and the density of the dots when developed by the developing device changes.

A circuit for determining image data for each line in the second embodiment is shown in FIGS. 13 and 14. Since these contents are the same as those shown in FIGS. 8 and 9 described in the first embodiment, the description of the contents will be omitted.

In the second embodiment, the density of the recording dots was changed by controlling the power of the semiconductor laser. In addition to this, the density of the dot size may be changed, for example, by changing the bias voltage during development.

[Effects of the Invention] As described above, according to the present invention, in a facsimile machine using an electrophotographic recording method, the recording method of the image forming unit is switched according to the type of received image at the time of reception, so An image is formed in image forming units suitable for each tone mode. As a result, in an electrophotographic facsimile machine, both halftone images and text images can be reproduced beautifully.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a laser facsimile device.
FIG. 2 is a block diagram for explaining the outline of the operation of a facsimile machine, FIG. 3 is a circuit diagram of a CPU that controls the facsimile machine, and FIGS. 4A and 4B are diagrams showing a first embodiment of the present invention. 5 is a block diagram and a timing chart of a dot size switching circuit according to an example, and FIG. 5 is a main flowchart of a CPU that controls a facsimile;
FIG. 6 is a flowchart showing the standby mode;
FIG. 8 is a block diagram showing the details of the image mode detection section, FIG. 9 is a diagram showing the determination contents of the image mode detection section, and FIG. FIG. 11 is a diagram for explaining the case where the image mode is determined for each page, and FIGS. 12 to 14 are diagrams for explaining the operation contents of the facsimile machine according to the second embodiment of the present invention. This is a diagram. 31 is a photoelectric conversion section, 32 is a processing section, 33 is a compression section, 34
is a code memory, 35 is a transmission control unit, 36 is a line connection unit,
37 is an expansion section, 38 is a recording section, 39 is a control section, 40 is a page memory, 41 is an image mode detection section, 51 is an operation display section, 101 is a semiconductor laser, 106 is a readout circuit, 107
1 is a triangular wave generating circuit, and 109 is an AND gate. In the drawings, the same reference numerals indicate the same or corresponding parts. (2 others) Ta, O O MushiΦ B

Claims (3)

[Claims] (1) An electrophotographic facsimile device that forms an image in response to a received signal, comprising means for determining the type of the received image, and the type of the received image includes a text image and a halftone image. A facsimile apparatus, wherein the formed image is composed of a plurality of image forming units, and a control means for controlling a recording method of the image forming units according to the type of the received image. (2) The facsimile apparatus according to claim 1, wherein the control means controls the size of the image forming unit. (3) The facsimile apparatus according to claim 1, wherein the control means controls the density of the image forming unit.