JPS6064881A - White page detecting method in both-side laser printer - Google Patents

Abstract

PURPOSE:To enable to calculate the accurate number of passages always without relation to the number of exhausted sheet by detecting white page mixed in both-side printing from the varied state of a photoelectric conversion output level in each page printed area of zero order light of modulated output of a light modulator. CONSTITUTION:A laser light L oscillated from a laser oscillator 1 is modulated by a specific video signal SV, outputted as the primary light L1 and zero order light L0, the light L0 is incident to a photosensor 8, and converted to an electric signal S0 in response to the light amount, and further added to a white sheet passage detector 9. An image presence or absence detector 92 retrieves whether an image exists or not in a print page area extracted from a print area extractor 91 on the basis of a photoelectric conversion signal S0 of the zero light L0, synchronizes with the end timing of the print page area detected from a passage synchronizing signal SP to output a white page detection signal SW.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for detecting a blank page in a double-sided laser printer, and more particularly, to a method for detecting a blank page in a double-sided laser printer. The present invention relates to a blank page detection method in a double-sided laser printer that detects blank pages mixed in double-sided printing in each page print area based on a change state of the photoelectric conversion output level in each page print area of zero-order light that is not used for the page print area.

[Prior art]

In general, many printers such as laser printers are equipped with a function that can count the number of prints (more precisely, the number of print pages) by the printer, and the printing price can be calculated based on the number of prints counted by this function. Basically, it is served. For example, in a conventional Rede printer capable of double-sided printing, the number of printed pages is counted according to the number of recording sheets ejected during recording, and management such as the above-mentioned print price calculation is performed.

In other words, before printing, first set the respective print mode depending on whether it is one-sided printing or two-sided printing. For example, if the one-sided printing mode is specified, a specific counter will set the number of pages to be printed each time a sheet of paper is ejected. They were counting numbers one by one. Separately from this, when the double-sided print mode is specified, the number of printed pages is automatically counted by 2 each time a sheet of paper is ejected, and this counting is continued until each sheet of paper is ejected. The total number of printed pages was calculated. However, in actual printing, even if double-sided printing is specified as described above, if there is no image information for a certain period of time (for example, due to the separation of each page), one-sided printing may be printed on one sheet of paper. A result can occur where only printing is done. In the above-mentioned method of calculating printed pages in the conventional double-sided radar printer, even in such cases, two pages are printed for each sheet of paper ejected, so the number of printed pages is larger than the actual number of printed pages. There is an inconvenience in that the printing fee calculated from the count value must be inaccurate.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and provides a double-sided laser printer that can always accurately calculate the number of printed pages regardless of the number of sheets ejected during recording, and that can contribute to accurate management of printing fees, etc. The purpose of this invention is to provide a blank page detection method.

[Structure of the invention]

Therefore, in the present invention, not only the number of ejected sheets of paper is counted, but also photoelectronization in each page print area of 0th order light, which is not used for scanning to form an electrostatic latent image of image information, of the modulated output of the optical modulator. By detecting blank pages mixed in double-sided printing in each page print area based on the change state of the conversion output level, and calculating appropriate subtraction between the number of printed pages calculated from the number of ejected sheets. This contributes to accurately determining the number of printed pages.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below based on the accompanying drawings. FIG. 1 is a diagram schematically showing the structure of the main parts of a double-sided laser printer that implements the blank page detection method of the present invention. Mirror 3. Lens 41 rotating polygon scanning mirror 5. C + Jy Darrens 6. Photosensitive drum 7, optical sensor 8. It is configured to include a blank page detection circuit 9. In addition, the PAGE 5YNC signal SrC (hereinafter referred to as page synchronization signal), LrNz 5YNC signal SL (hereinafter referred to as line synchronization signal), video signal Sv, primary light L handled by each part of this double-sided laser printer
The photoelectric conversion output signal S is isometric with the light intensity of 1! , zero-order light.

The photoelectric conversion output signal S is isometric to the light amount of . and blank page detection signal Sw are shown in FIGS. 2(a) to 2(f), respectively. First, in FIG. 1, laser light emitted from a laser oscillator 1 is irradiated onto an optical modulator 2, and as shown in FIG.
) and the page synchronization signal S shown in (b).

and synchronously when the line synchronization signal SL is turned on, the light modulator 2) is modulated with a specific video signal Sv (see FIG. 2(C)) applied from an image information supply circuit (not shown). The light is output as light L1 and zero-order light L0. The primary light L8 here is a laser light containing optical image information modulated by the optical modulator 2, and is output after being deflected at a predetermined angle as shown in the figure. On the other hand, the zero-order light Lo is the 1/- laser light that has not been modulated by the optical modulator 2 and is output straight along the incident optical path from the laser oscillator 1. Furthermore, when a black image (image information) exists in the video signal SV during modulation by the optical modulator 2 using the above-mentioned primary light or the video signal Sv (in FIG. 2(C), the output is The amount of light changes only when there is no black image (when the output is at 'L' level in Figure 2 (C)).
It undergoes modulation such that it does not change. Also, 1 above
The light amount of the second order light L0 and the zero order light L0 change in a mutually contradictory increase and decrease relationship, and when the light amount of the first order light L1 increases, the light amount of the zero order light L0 changes.
Next light. When the light amount of L1 decreases, and conversely, the light amount of the primary light L1 decreases, it becomes zero-order light. The amount of light increases. Therefore, the changes in the light intensity of these first-order light L1 and θ-order light L0 are equivalently equivalent to the second
It can be expressed by the photoelectric conversion outputs shown in FIGS. (d) and (e). In other words, the light intensity of the primary light L1 is as shown in FIG.
The zero-order light changes with inverse characteristics to the video signal Sv shown in (,), and is shown as an equal output in (,). The amount of light changes with a completely inverse characteristic to the former characteristic, that is, the same characteristic as the video signal Sv. Now, as mentioned above, the primary light L1 that has been modulated and deflected by the optical modulator 2 is transmitted to the mirror 3.
° It enters the rotating polygonal scanning mirror 5 via the lens 4, is deflected as the rotating polygonal scanning mirror 5 rotates, and enters the cylinder lens 6.
The photoreceptor drum 7 is scanned in a fixed direction through the photoreceptor drum 7. By this scanning, the primary light L is applied onto the photoreceptor drum 7.
An electrostatic latent image is formed according to the image information contained in the image data 1, and recording is performed based on the image. On the other hand, the O-order light L0 straightly output without being deflected from the optical modulator 2 enters the optical sensor 8 disposed in its optical path, is converted into an electrical signal according to the amount of light, and is further transmitted to the blank page. It is added to the detection circuit 9. FIG. 3 is a block diagram showing the details of the configuration of this blank page detection circuit 9. The blank area extraction circuit 91. It consists of an image presence/absence detection circuit 92.

In the blank page detection circuit 9 having such a configuration, the print area extraction circuit 91 to which the above-mentioned page synchronization signal SP and line synchronization signal SL are added converts these two signals into the primary light L1 modulated by the optical modulator 2. The area where each included image should be printed is extracted one line at a time for each page, and the corresponding print 4-
The image area extraction signal is sent to the image presence/absence detection circuit 92.

Therefore, the image presence/absence detection circuit 92 detects the zero-order light applied from the optical sensor 8. photoelectric conversion signal S. Based on this, a search is made to see if the image as described above exists in the print page area extracted by the print area extraction circuit 91. As mentioned above, the zero-order light. The amount of light changes in the same way as the primary light L8 with respect to the image existing in the video signal Sv shown in FIG. 2(C),
Accordingly, the zero-order light can be equivalently expressed as the amount of light. The photoelectric conversion output also changes depending on the presence or absence of an image in the video signal Sv, as shown in FIG.

Therefore, the image presence/absence detection circuit 92 detects the zero-order light.

It is detected that the image is "present" based on the "H" level state of the photoelectric conversion output SO, and when the image "present" is not detected within the print page area extracted by the print area extraction circuit 91. A blank page detection signal SW as shown by the solid line in FIG. 2(f) is output in synchronization with the end timing of the print page area detected from the page synchronization signal S, which is the other input. If it is detected that an image exists in the specific print page area mentioned above during the above search, a blank page detection signal Sw as shown by the dotted line in FIG. Not done.

As described above, according to the blank page detection method of the present invention, zero-order light is detected. In order to search for the presence or absence of an image in a specific print page area based on changes in light intensity within the area, and to detect the absence of the image as a blank page, the effect on the primary light L1 directly used for recording, that is, the primary light It becomes possible to detect the blank page even though the image formation is impaired due to a decrease in the power of the light L1. Furthermore, by appropriately subtracting the number of blank pages calculated from the detection result from the number of print pages calculated from the number of ejected recording sheets, it is possible to calculate the accurate number of print pages during the double-sided printing.

〔Effect of the invention〕

As explained above, according to the method for detecting a blank page in a double-sided laser printer of the present invention, among the first-order light and zero-order light output of the optical modulator, the zero-order light, which is not directly used for recording, is detected within a specific page print area. Since the presence or absence of an image in the print page area is detected from changes in light intensity, it is possible to accurately remove blank pages mixed in double-sided printing without affecting the primary light involved in recording, such as power reduction. By appropriately subtracting the number of blank pages calculated from the detection result from the number of printed pages calculated from the number of recording sheets ejected, the accurate number of printed pages can be determined. This has the excellent effect of contributing to accurate management of printing fees, etc. calculated from numbers.

[Brief explanation of drawings]

FIG. 1 is a schematic structural diagram of a double-sided laser printer that implements the blank page detection method of the present invention, FIG. 2 is a time chart showing the format of signals handled by each part of the device shown in FIG. 1, and FIG. FIG. 1 is a block diagram showing details of the configuration of a blank page detection circuit that constitutes the apparatus shown in FIG. DESCRIPTION OF SYMBOLS 1... Laser oscillator, 2... Optical modulator, 3... Mirror, 4... Lens, 5... Rotating polygonal scanning mirror, 6...
...Cylinder lens, 7...Photosensitive drum, 8...
Optical sensor, 9... Blank page detection circuit, 91... Print area extraction circuit, 92... Image presence/absence detection circuit. Figure 1 Figure 2 Figure 3 L.

Claims (1)

[Claims] an optical modulator that modulates a laser beam oscillated from a Rade oscillator with a specific video signal and outputs it as zero-order light and first-order light whose light amounts reciprocally increase and decrease and whose deflection angles are different; In the method for detecting a blank page in a double-sided radar printer that performs double-sided recording on a predetermined recording paper based on the first-order light modulation output, photoelectric conversion of the zero-order light obtained from a light receiving element disposed in the O-order light optical path is performed. By monitoring changes in the output level, it is possible to search for the presence or absence of an image in each page print area, and to set the page print area to a blank page when the presence of the image is not detected during the search. A method for detecting a blank page in a double-sided laser printer, the method comprising: detecting a blank page in a double-sided laser printer;