JPH02258272A - Recording device - Google Patents

Abstract

PURPOSE:To maintain the quality of an image at a high level by outputting information on recording properties which differ for each printer to an external device as a device property signal, then processing image data using an optimal/ image correction technique corresponding to the record properties at the external device and entering the processed image data to a printer. CONSTITUTION:Images arranged in a memory unit 2 are sequentially read by a line buffer 3 with the start of printing by a printed B and the image which has been read is synchronized with a video signal. After this, the image is subject to a digital/digital conversion by means of RAM 5 as a lookup table. The ROM 8 of the printer B stores lookup tables which read input image density data and use this data as addresses, and use density gradation correction data entered to the printer as an output data. The content of the lookup table in ROM 8 selected by a selector 10 is transferred to RAM 5 as a device characteristic signal 25, and the content of RAM 5 is updated. ROM 8 stores lookup tables and corrects the change in the recording properties of the printer B due to its use environments or the change resulting from the use of the printer B.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a recording device that records image data on a recording medium such as paper, and in particular, the present invention relates to a recording device that records image data on a recording medium such as paper. The present invention relates to a recording device that manually outputs high-quality visible images in the form of electrical signals.

[Prior Art] Conventionally, in a recording device (hereinafter referred to as a printer) such as a laser printer that applies electrophotographic technology, when outputting a halftone image, an image signal for recording is first processed by an external device. Generally, a method is adopted in which a host computer or the like performs necessary image processing such as halftone processing and dither processing, and after binarizing the image, the image is manually input to a printer.

In addition, in a laser printer such as the one disclosed in U.S. Pat. It is also possible to output a halftone image by making the time shorter than the normal one-dot ON time.

In this way, performing divine image processing on the host computer side is convenient from the data storage capacity, etc. Also, since it is only necessary to handle binary codes for transmission between the host computer and the printer, data The amount is reduced, making it very convenient for data transfer.

[Problems to be Solved by the Invention] However, in the conventional printers described above, when outputting halftone images, the gradation characteristics generally differ depending on the printer model, so even if the same image data is supplied, In this case, output images with different densities can be obtained. For example, even if a 4 x 4 pixel dither pattern as shown in Figure 2 is output from an external device, when it is actually recorded, a certain printer as shown in Figure 3 will print out the solid line A in this figure. In other printers, the characteristic is similar to the broken line curve B in this figure. As a result, even if the same dither pattern is manually applied to a printer, the white side of the pattern is blown out in some printers, and the side close to black is crushed in other printers, making it impossible to distinguish.

Strictly speaking, not only photographic images, but also character images, especially small character images that are output with thin lines, have different printing line widths depending on the printer, so some printers print the lines thicker while others print them thinner. This caused the inconvenience of

Therefore, due to the reasons mentioned above, when the same host computer is used and multiple types of printers with different characteristics are used to configure one image processing system, the recording medium (generally paper) Problems have arisen in that the resulting image is generally faded and the letters are thin, or conversely, the image is overall dark and the letters are crushed.

An object of the present invention is to eliminate the above-mentioned drawbacks, and even when one system is configured using a common external device and multiple types of printers with different characteristics, the printer can be adjusted to suit the characteristics of each printer. An object of the present invention is to provide a recording device that can always obtain an optimal high-quality visible image output.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a recording device that receives image data as an electrical signal from an external device and outputs a visible image, and provides device characteristics related to image recording characteristics of the recording device. It is characterized by having means for outputting the signal to an external device.

Another object of the present invention is to provide an external device that processes a device characteristic signal from a recording device as a tone correction signal for a halftone image.

A further object of the present invention is to provide an image processing system comprising a recording device having means for outputting a device characteristic signal related to image recording characteristics, and an external device that processes the characteristic signal as a gradation correction signal.

[Function] As described above, the present invention is configured to output information regarding recording characteristics that differ for each printer to an external device such as a host computer or a controller as a device characteristic signal, and the external device can transmit information based on the device characteristic data. This enables image data to be input to the printer after being subjected to the optimal image processing correction corresponding to the recording characteristics of the printer, so that external devices can now control image quality, which differs from printer to printer, regardless of the type of printer. Therefore, it can be maintained at a constant high quality at all times.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Δyu” mouth (i weight) First, a first embodiment of the present invention will be described.

FIG. 1 shows a circuit configuration including a printer and a controller (external device) according to an embodiment of the present invention.

Further, FIG. 3 shows the gradation characteristics of the printer outputting with the dither matrix shown in FIG. 2. Curve A in FIG. 3 is for output in a normal environment, and curve B in FIG. 3 is for output in a high temperature environment.

In FIG. 1, controller A and printer B are each separate cylinders, and image data 1 is input from a reader (not shown) or a magnetic disk device (not shown) to controller A, which is an external device. It is stored in page memory 2. In this embodiment, one pixel of the image data 1 will be explained as 4-bit (bit) data. The image data arranged as a 4-bit multilevel signal in the memory 2 is sequentially read out to the line buffer 3 when printer B starts printing, and after being synchronized with the video signal R, it is stored in a look-up table. A RAM (Random Access Memory) 5 undergoes digital-to-digital conversion. This RAM 5 performs density gradation correction according to the recording characteristics of the connected printer B.

On the other hand, in the ROM (read-only memory) 8 of printer B, manual image density data as shown in curves (a) and (b) in Fig. 4 are used as readout addresses, and printer manual gradation correction data is used as output data. Multiple lookup tables are stored. The contents of the lookup table in the ROM 8 selected by the selector IO are transferred to the RAM 5 as the device characteristic signal 25, and the contents of the RAM 5 are updated. The timing at which the signal 25 is loaded into the RAM 5 is preferably immediately after both controller A and printer B are powered on, or when a new lookup table is selected by selector IO.

The reason why the ROM 8 stores a plurality of lookup tables in this way is to correct changes in the recording characteristics of printer B due to the usage environment or changes due to use of printer B. Furthermore, the plurality of lookup tables also has the advantage that even if the configuration of the image data l changes due to a change in the type of reader, etc., it is possible to easily take appropriate measures. In addition, the data of curves (a) and (b) in FIG. 4 in this example are as follows:
Assume that the data is an apparatus characteristic signal for correcting the image density of curves A and B in FIG. 3, which are the output characteristics of printer B.

The following describes the operation when the lookup table corresponding to the curve (a) in FIG. 4 is selected from the plurality of lookup tables in the ROM 8 by the selector IO.

Now, when the conversion data (equipment characteristic signal) 25 of the curve (a) in FIG. 4 is manually entered into the RAM 5 from the ROMB, the R
All data written in AM5 is updated to the contents of the converted data of curve (a) in FIG. 4. Therefore, if, for example, "3" is manually entered into the address line of RAM 5 as image density data, the data converted to "5" will be stored in the RAM.
5 data line.

As a result, the nonlinear output image density characteristic of printer B (see FIG. 3) is corrected to a substantially linear output image density characteristic as shown in FIG.

To explain in more detail, the image data 1 manually input to the controller A is converted in the RAM 5 and then sent to the terminal P of the comparator 7 in synchronization with the reference clock. On the other hand, data of a dither matrix as shown in FIG. 2, for example, is transferred from the dither pattern generation circuit 6 to the terminal Q of the comparator 7 in synchronization with the reference clock.

Here, if the data at the terminal P is P and the data at the terminal Q is Q, the output data R from the converter tough is '1' when P≧Q, and 'O' when P<Q.
sent to. It is assumed that the exchange of signals in each circuit is controlled by a CPII (central control unit) 4 and a CPU 9.

The output signal R of the comparator 7 manually input to the printer B is
The laser driver 11 is powered by the laser driver 11, and the laser driver 11 turns the laser diode 12 ON and OFF according to the output signal R of "1" and "O".

The laser light emitted from the laser diode 12 is converted into scanning light by the rotating polygon mirror 13, and the laser light is applied to the photoreceptor 1.
8. Scan above. A portion of this scanning light is received by a beam detector (not shown), and a signal used as a video signal R and a synchronizing signal for the dither pattern generator 6 is generated from the beam detector. The photoreceptor 18 is uniformly charged by the charger 15, receives the above-mentioned scanning light, forms a latent image on its surface, and then develops the latent image by the developer 17. The developed pattern on the photoreceptor 18 is transferred onto a transfer material (for example, recording paper) 22 by a transfer charger 19, and then transferred to a heat fixing roller 22.
The image is fixed on the transfer material 22 in steps 3 and 24. The developer remaining without being transferred to the surface of the photoreceptor 18 is collected by a cleaner 20. Further, the charge on the photoreceptor 18 is erased by the pre-exposure lamp 21, and the same image forming process as described above is repeated again.

The above-mentioned look-up table in ROMa may be selected manually by the selector 10, but it may also be automatically switched according to information such as automatic detection of the usage environment using a sensor or memorization of the number of prints using a counter. It is preferable to select . Furthermore, the page memory 2 in the controller A shown in FIG. 1 is not necessarily necessary, and it goes without saying that the page memory 2 may be omitted and image data may be manually processed in sequential processing.

"Yu" wild tribe decoy Next, a second embodiment of the present invention will be described.

The rise speed of the laser light amount in a laser printer is
Particularly in the case of semiconductor lasers, the variation in light emission characteristics is large, and the variation in current rise characteristics of the laser driver is also added to this variation, so it changes significantly. Changes in the rise speed of the laser light amount greatly affect the output image quality of the laser printer.An example of the effect on the output image quality is shown in Figures 6 and 7 (^) and (B).
Explain using.

FIG. 6 shows the rise characteristics of the laser beam/quantity, with time T plotted on the horizontal axis and laser light quantity P plotted on the vertical axis. Here, T=O is the time when the laser ON signal is input to the laser driver. The solid line curve (a) in Figure 6 shows the characteristics of a laser with a fast rise in laser power, and the broken line curve (b) in Figure 6 shows the characteristics of a laser with a slow rise in laser power. Due to variations in characteristics of elements and laser drivers, curve (a) in the same figure
The difference between and (b) is approximately several tens of nanoseconds.

Also, Figure 7 (^) is the curve (a) or (b) in Figure 6.
The photosensitive drum of the laser printer (
This figure schematically shows the shape of the laser spot above the reference numeral 8) in FIG. When using a laser printer with a characteristic of slow rise speed of the laser light amount as shown in the curve (b) of Fig. 6, the laser spot (b) of Fig. 7 (^) may be At the time of the laser ON signal, the shape of the laser spot becomes extremely small compared to the one where the rise speed of the laser light amount is fast (laser spot (a)). This effect occurs when printing small characters or graphic images with many single-dot signals.
This appears as a result of quality deterioration in which the print becomes thinner and the image becomes thinner.

Therefore, in this embodiment, an apparatus having the same configuration as that shown in FIG. 1 is used, and the laser optical system of printer B (semiconductor laser 12 and laser driver 11 in FIG. 1) is ranked in advance according to the rise speed of the laser light amount. The above-mentioned inconvenience is solved by sending a rank identification signal corresponding to the rank to the controller A as the device characteristic signal 25. Therefore, the rise speed of the laser light intensity of the laser optical system used in each printer B is measured in advance, and a rank is displayed on the laser optical system with a label etc. according to the measured value, and the select switch installed in printer B is Switch settings according to rank. By doing so, it becomes possible to easily replace the laser optical system in the market for maintenance work.

The configuration of the second embodiment of the present invention is shown in FIG.
In Figure (8), parts having the same functions as in Figure 1 are given the same reference numerals. Printer B has a select switch 51 that selects a rank, and controller A has a decoder 52 that decodes a device characteristic signal 25° indicating the rank and a pulse width controller 54 that controls the pulse width of the input video signal R°. . The pulse width controller 54 will be explained using FIG. 8(B).

When the rank identification signal is sent as the printer device characteristic signal 25° from the select switch 51 of the printer B mentioned above to the controller A, the pulse width controller 54 of the controller A switches the switch 102 of FIG. Switch to contact A or contact S depending on rank. In the figure, 103 is a pulse signal generator, which generates a pulse signal 103a that remains H (high level) for a predetermined time t1 in synchronization with the fall of an input video signal R'' created from image data ( 9), 104 is an OR gate circuit, and the human video signal R
' and the pulse signal IQ3a output from the pulse signal generator 103, and send the resulting new modulation signal Ml (see FIG. 9) to the printer B. The subsequent steps are the same as in the case of signal R in FIG. Incidentally, FIG. 9 shows the output timing of the signals of each part in FIG. 8(B).

In this way, the video signal V in FIG. 7(^) (corresponding to signal R' in FIG. 9) is changed to the video signal in FIG. 7(B) in which the laser emission time is increased by the predetermined time tl. v'
(corresponding to signal Ml in FIG. 9).

As a result, the actual laser emission time can be made almost the same as that of the laser (a), which has a fast rise speed in laser light quantity, and the laser spot shape (b') becomes almost the same as that of the laser (a). The situation is shown in the video signal V' in FIG. 7(B).
and is shown by the laser spot (b').

In this embodiment, the signal from the decoder 52 is transmitted to the switch 10.
2, but if this signal controls the pulse width generated by the pulse signal generator 103, the pulse width can be changed in multiple stages.

In addition, in this embodiment, the select switch 51 provided on the printer body B that generates the rank identification signal is manually set according to the rank of the laser light intensity rise speed, but it is also possible to automatically read the rank data of the laser optical system. By providing a sensor or a switch, the rank identification signal may be automatically sent to the controller A when the laser optical system is set in the printer body.

Next, a third embodiment of the present invention will be described with reference to FIGS. 1O and 11.

Figure 1O shows a photosensitive drum, which is the main part of image formation.

This figure shows the external configuration of electrophotographic printers such as laser printers, LED printers, and LCD printers that use so-called process cartridges in which chargers, developers, transfer chargers, cleaners, etc. can be replaced all at once.
The figure also shows the case where the process cartridge 201 is installed and removed from the printer main body P, where S is a paper loading table,
and 202 are paper discharge trays.

The sensitivity of the photosensitive drum built into the process cartridge 201 described above usually varies depending on its manufacturing conditions and environment, depending on its manufacturing loft or product. If the sensitivity of the photosensitive drum varies in this way, for example, in a laser printer, a predetermined latent image potential cannot be obtained with a constant amount of laser light, and as a result, each time the cartridge is replaced, the character line width of the output image becomes thicker or thinner. or the image density becomes darker or lighter.

Furthermore, variations in photosensitive drum sensitivity can be caused by variations in photosensitive drum sensitivity, such as that disclosed in U.S. Pat. No. 4,800,442, among others.
When outputting a halftone image using the pulse width modulation method, this extremely affects the density of the halftone portion and greatly reduces tone reproducibility.

Therefore, in this embodiment, as shown in FIG. 11, one or more sensitivity frames 220b to 224 are provided in a part of the cartridge 201 according to the sensitivity of the photosensitive drum used.
b is attached. These sensitivity frames 220b to 224b
indicates the sensitivity value of the photosensitive drum, and the mounting position, number, etc. are determined in accordance with the sensitivity level code.

When the cartridge 201 is inserted into the printer body P, the sensitivity frames 220b to 224b are connected to the microswitches 2208 to 220 installed in the printer body P.
When the switch 4a is turned on, sensitivity information of the photosensitive drum is output to the controller as an apparatus characteristic signal through an interface cable (not shown).

According to the sensitivity information of this photosensitive drum, the controller
After optimizing the halftone image density by changing the character font and correcting the thickness of the characters, or in the case of a pulse width modulation method, the printer's laser driver (see Figure 1) (equivalent to 11), the corrected image data is output.

Furthermore, in electrophotographic printers, there are variations in characteristics of the developer charged into the developing device depending on manufacturing conditions and the manufacturing environment, which manifests as density changes in the output image. In this case as well, the characteristic information of the developer may be notified to the controller as an apparatus characteristic signal using the same characteristic information input method as in the case of the sensitivity frames 220b to 224b of the above-described embodiment.

In addition, in this embodiment, application to the process cartridge method was explained, but information regarding the image forming characteristics of electrophotographic recording can be output to the controller by manual selector switching instead of the sensitivity frame in non-cartridge methods as well. It is also possible.

Figure 12 shows the first embodiment of the present invention described above. The configuration of a fourth embodiment of the present invention, which is a combination of the second and third embodiments, is shown. In addition,
In FIG. 12, members having the same functions as those in the first to third embodiments are designated by the same reference numerals, and their explanations will be omitted.

As shown in FIG. 12, the ROM 8 sends a first device characteristic signal 25 indicating a gradation conversion table optimal for the printer B to the RAM 5 of the controller A. Further, a second device characteristic signal 251, which is a combination of the rise characteristic of the laser optical system and the sensitivity characteristic signal of the photoreceptor 18, is sent from the printer B to the decoder 52° of the controller A, and the decoder 52°
The device characteristic signal 251 is analyzed and a control signal is output to the pulse width controller 54°. The pulse [J pottery 54'] optimally controls the pulse width of the video signal R according to this control signal.

Although the fourth embodiment shows a combination of the first to third embodiments, the first. Of course, the combination of the second embodiment and other combinations are also possible.

Of course, the present invention is also applicable to other types of printers in which the line thickness and image density depend on the printing characteristics of the printer.

[Effects of the Invention] As explained above, according to the present invention, information regarding recording characteristics that differ from printer to printer is configured to be output as a device characteristic signal to an external device such as a host computer or a controller, and the external device can output the information regarding recording characteristics that differ from printer to printer. Based on the device characteristic data, the image data can be input to the printer after being subjected to the optimal image processing correction corresponding to the printer's recording characteristics, so the image quality, which used to vary from printer to printer, can now be maintained at a constant high quality. The effect is that maintenance can be performed at all times.

In addition, since host computers and controllers are originally designed mainly for signal processing, they can easily perform complex image processing corrections, and have relatively large storage capacities, so if the present invention is applied, they can be used for image processing corrections. This has the advantage that the memory cost burden can be reduced, and as a result, the image quality can be made constant for each printer at a low cost in the entire system including the printer, controller, etc.

Further, according to the present invention, although the printer input image data is binary data, gradation correction can be performed in accordance with the printer characteristics, and a high-quality image can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention, FIG. 2 is a diagram showing an example of a dither matrix, FIG. 3 is a diagram showing an example of the gradation characteristics of a printer, and FIG. A diagram showing the contents of a lookup table for correcting gradation characteristics in an embodiment of the present invention, FIG. 5 is a diagram showing gradation characteristics after correction in an embodiment of the invention, and FIG. 6 is a rise characteristic of the laser light amount of the laser optical system. Figures 7(^) and (B) are diagrams illustrating the influence of the laser light intensity rise characteristic on images; Figure 8(^) shows the configuration of the second embodiment of the present invention. 8(B) is a block diagram showing the configuration of the signal correction processing circuit in the second embodiment of the present invention; FIG. 9 is a timing chart showing the output timing of signals in each part of FIG. 8; FIG. 10 is a perspective view showing the external appearance of a cartridge type printer, FIG. 11 is a perspective view showing the configuration of a cartridge in a third embodiment of the present invention, and FIG. 12 is a block diagram showing a fourth embodiment of the present invention. It is a diagram. 1... Image data, 2... Page memory, 3... Buffer, 4.9... CPU. 6... Dither pattern generation circuit, 7... Comparator, 8... ROM. lO... Selector, 11... Laser driver, 12... Laser diode, 14... Charger, 17... Developer, 18... Photosensitive drum, 19... Transfer charger, 20 ...Cleaner, 25...Device characteristic signal, 51...Select switch, 52, 52°...Decoder, 54, 54°...Pulse width controller, 103...
- Pulse signal generator, 104... OR gate circuit, 201... Process cartridge, 202... Paper ejection tray, 220a, 221a, 223a, 224a---Micro switch, 220b, 221b, 223b, 224b
...Cartridge sensitivity frame, S...Paper loading table, P...Printer. Figure 2 Figure 3 Figure 11 Cheetah Cheetah Figure 4 Good data Figure 5 Figure 6 Caesars book 4 (a) ○ ○ Figure 7 ('A) Figure 7 (B') Figure 10

Claims (1)

[Scope of Claims] 1) A recording device that receives image data as an electrical signal from an external device and outputs a visible image, comprising means for outputting a device characteristic signal related to image recording characteristics of the recording device to the external device. A recording device comprising: 2) The recording apparatus according to claim 1, wherein the device characteristic signal is processed by the external device as a tone correction signal for a halftone image. 3) The device characteristic signal is information regarding a light intensity rise characteristic of a light source of scanning light in an electrophotographic method or an image forming condition of a photoreceptor.
Recording device described in . 4) The recording apparatus according to claim 1 or 2, wherein the device characteristic signal is information for correcting variations in characteristics of each replaceable process cartridge including a photoreceptor.