JP2739588B2 - Optical printer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] A printer head having a plurality of light emitting elements arranged therein,
An optical printer device that performs recording by driving the corresponding light emitting element based on print data. With a simple structure, reliability with low density variation based on variation in light emitting element characteristics due to temperature variation of each light emitting element. A temperature detecting unit for detecting the temperature of the printer head, and uniformly disposing the printer head based on the temperature detected by the detecting unit during a non-printing period. This is a configuration in which a driving unit for driving for a predetermined period of time for printing and temperature rise is provided.

[Industrial applications]

The present invention relates to an optical printer device, and more particularly to an optical printer device having a printer head in which a plurality of light emitting elements are arranged, and performing recording by driving the corresponding light emitting elements based on print data.

In recent years, optical printers using electrophotography have been using laser printers.
Printers, LED (light emitting diode) printers, and liquid crystal printers have been developed.

These printers have features of high speed, high resolution, and high image quality, and are expected to greatly develop in the future.

The present invention will be described mainly with respect to an LED printer among the above printers.

The LED printer device has the following features as compared with a laser printer device that has been widely used in the past.

That is, it is a solid-state scan and does not require any mechanical driving parts.

The optical path length can be shortened, and the device can be downsized.

 Advances in semiconductor technology reduce prices.

In the future, LED printers are expected to increase, taking advantage of these features, especially in small printers.

 Another problem is that the output of each LED is not uniform.

 Light output changes with temperature.

Since the luminous efficiency is not large, a large power supply is required.

For the LED, change the emission time for each LED, or
Measures such as changing the current of each LED are considered.
It is possible to make the light output of each LED uniform.

For, the power supply capacity is reduced by dividing the LED into several blocks and emitting light. Alternatively, there is a measure such as reducing the size of the power supply by using a high-efficiency power supply.

 Is a problem to be solved by the present invention.

LEDs are semiconductor elements and have a large temperature dependence. For example, an LED using GaAsP exhibits a temperature dependence of about -0.8% / deg. If the temperature of the LED rises by 30 ° C, about 2
5% lower light output.

For this reason, the change recording density and the dot area change due to the temperature change. This is not so noticeable when outputting normal characters, but it is a problem when outputting graphics or halftone recording.

The sensitivity of the photoconductor also changes with temperature. For this reason, there is a problem that the reproduced recording density changes with the temperature change.

[Conventional technology]

Conventionally, there has been an optical printer device as shown in FIG. 7 to cope with the above-mentioned temperature change.

As shown in the figure, the present apparatus has a printer head 71 in which a plurality of light emitting elements are arranged, a temperature detecting unit 73 for detecting the temperature of the printer head 71, and a temperature detected by the temperature detecting unit 73. Based on the above, when the duty ratio (duty; the ratio of the light emission printing time within a certain period of time) of all the light emitting elements arranged in the printer head 71 is allowed to be printed, the printing and the duty ratio are uniformly increased or reduced. Some have a control drive unit 72.

In the device, when the temperature detected by the temperature detection unit 73 is higher than a predetermined temperature and the light output of the light emitting element of the printer head is low, the printing and duty control driving unit 72 is used. Printer head 71
Control to increase the duty ratio of the light-emitting time when printing is permitted for all the light-emitting elements arranged in
If the temperature detected by 73 is lower than a predetermined temperature, control is performed to decrease the duty ratio.

[Problems to be solved by the invention]

By the way, in the conventional apparatus, based on the temperature detected by the temperature detection unit 73, the printer
Since the duty ratio of all the light emitting elements in the head 71 at the time of printing is controlled by the printing and duty control unit 72, the light output of the entire light emitting elements of the printer head 71 can be stabilized. In addition, it is not possible to eliminate variations in the amount of light due to variations in the temperature between the elements.

For this reason, there has been a problem that the variation in density has a bad influence on the image quality especially in the output of graphic or halftone recording.

This is because each light emitting element is not necessarily used uniformly, and there is a variation in the time used, the temperature used is high when the used time is long, and the temperature is low when the used time is short. As a result, there is a problem that a change in print density due to a local temperature change cannot be eliminated.

In addition, the control of the duty ratio has a problem that the circuit may be complicated in general.

On the other hand, driving control to detect the temperature of each light emitting element and change the light quantity of each light emitting element has a problem that the structure of the control device becomes complicated.

Therefore, the present invention has been made with the object of solving the above problems, and has a simple structure with a small amount of light and thus a small concentration variation based on a variation in the characteristics of the light emitting elements due to a variation in the temperature of each light emitting element. It is intended to provide an optical printer device.

[Means for solving the problem]

In order to solve the above technical problems, the present invention comprises a printer head 1 in which a plurality of light emitting elements are arranged, as shown in FIG. 1, and records by driving the corresponding light emitting elements based on print data. In an optical printer device that performs
A temperature detector 3 for detecting the temperature of the printer head 1
And a printing and temperature increasing drive unit 2 for uniformly driving the printer head 1 for a predetermined time based on the temperature detected by the detection unit 3 during a non-printing period.

[Action]

 The optical printer device according to the present invention operates as follows.

In order to perform printing by the printer device, print data to be printed is input to the printing and temperature raising drive unit 2.

Then, the drive unit 2 drives the corresponding element of each light emitting element of the printer head 1 based on the print data, and when printing is permitted under conditions such as when recording paper is supplied, Print on the recording paper.

On the other hand, during the non-printing period when printing conditions such as supply of recording paper are not established, the driving unit 2 controls the printer / printer.
All the light emitting elements of the head 1 emit light uniformly, and the temperature of each light emitting element is raised.

Here, “uniform” means the same intensity and the same time for all the light emitting elements.

As a result, constant heat is applied to all the light emitting elements during the non-printing period.

By setting the heat to be a non-negligible amount of heat compared to the heat applied to each light emitting element when printing is allowed, even if there is a temperature variation between the elements due to the difference in the light emission time when printing is allowed, each element has Since the total light emission time including the non-printing period is relatively close to the same length of time, the temperature variation between the elements becomes small.

In order to apply a sufficient amount of heat during the non-printing period, for example, the duty ratio of light emission during the non-printing period may be set sufficiently higher than when printing is permitted.

In parallel with the above operation, the temperature detecting section 3 detects the temperature of the printer head 1, and when the temperature exceeds a predetermined temperature value, the printing and temperature increasing driving section 2
Reduces the light emission time so as to reduce the amount of heat to be applied to all the light emitting elements of the printer head 1 during the non-printing period.

Until the temperature is reached, all the light emitting elements are driven to emit light during the non-printing period.

As described above, it is possible to eliminate the variation in the density based on the temperature dependence of the characteristics of each light emitting element.

〔Example〕

 Next, examples of the present invention will be described.

FIG. 6 schematically shows an entire LED printer as an optical printer according to the embodiment.

As shown in the figure, this apparatus provides a photosensitive layer on a metal substrate, and a cylindrical photoreceptor 66 that rotates at a constant angular velocity, and ionizes gas into positive or negative charge and blows it onto the photoreceptor 66. A charging device 68 for charging the photoreceptor by applying light to the charged photoreceptor 66, based on print data, and irradiating light to remove a charge to form a latent image on the photoreceptor; A printer head 61 in which LEDs (light emitting diodes) are arranged; a developing device 62 for developing the latent image by spraying a charged toner on the charged portion of the photoreceptor 66 with the opposite charge; A sheet cassette 63 for setting a recording sheet for recording the image, and transferring the developed image to the recording sheet by charging the back of the sheet with a charge opposite to that of the charged toner. Transfer device 64 attracted by Coulomb force Comprises a separator 65 for separating the recording sheet from the photosensitive member 66, a fixing device 67 for fixing the toner transferred on the recording paper, and a stacker 69.

The present embodiment relates to a portion that performs printing control of an LED printer as the optical printer.

 FIG. 2 shows a portion for performing print control according to the present embodiment.

As shown in the figure, an LED printer device as an optical printer device according to the present embodiment mainly has an L corresponding to the printer head 1 in which LEDs as the plurality of light emitting elements are arranged.
The LED head 11 which corresponds to the ED head 11, the printing and temperature increasing drive circuit 12, and the temperature detecting unit 3;
And a temperature detection circuit 13b that performs a predetermined process such as amplification of an electric signal whose temperature is detected by the thermistor 13a.

As shown in the drawing, the printing and temperature increasing drive circuit 12 includes a printer controller 12e that outputs a printing signal or a switching signal indicating permission of printing based on an output signal of the temperature detecting circuit 13b, and a printing target. Based on the memory 12c for storing the print data,
A printing circuit 12b that outputs a signal for driving an LED included in the LED head 11, and a signal for uniformly emitting and driving all the LEDs of the LED head 11 based on the output of the temperature detection circuit 13b. It has a temperature raising circuit 12d for outputting, and a signal switch 12a for switching the output of the printing circuit 12b and the temperature raising circuit 12d.

 Next, the operation of the present apparatus will be described.

The operation of the LED printer when the power is turned on will be described with reference to FIG.

The thermistor 13a detects the temperature of the LED head 11, and sends a signal indicating the temperature to the printer controller 12e and the temperature increasing circuit 12d via the temperature detecting circuit 13b.

Since the LED printer is used in various environments, the temperature in the initial state when the power is turned on also varies.

As shown in FIG. 3, when the temperature of the LED head 11 is low, the temperature increasing circuit 12d starts outputting data for driving the LED head 11 to emit light, and the printer controller 12e Immediately after the power is turned on, since a non-printing period is in progress and the temperature of the LED head 11 is low, a switching signal is sent to the signal switch 12a, and a temperature increasing circuit is used instead of the normal printing circuit 12b. Select 12d.

The operation of the temperature raising circuit 12d turns on all the LEDs and sets the light emission duty to 100% continuous lighting so that the LED head
Increase the temperature of 11 rapidly.

When the temperature of the LED head 11 rises and approaches a specified temperature, the temperature increasing circuit 12d intermittently sets the light emission time based on a signal from the temperature detecting circuit 13b as shown in FIG. The temperature of the LED head 11 is maintained at a specified temperature, that is, in the range of 45 ° C to 50 ° C.

Here, the temperature was set in such a range for the following reason.

Generally, the external environment of the device and the temperature inside the device are about 10 ° C
If the maximum value of the external environment of the device is 35 ° C., it is preferable that the specified temperature of the LED head 11 be 45 ° C. to 50 ° C.

As shown in FIG. 4 in more detail the temperature change of the LED head 11 according to this embodiment, when the LED head 11 is lower than this temperature, the temperature of the LED head 11 is maintained at this temperature by the above-mentioned temperature increasing circuit 12d. Will be.

In this way, the process waits until the fixing device 67 of the LED printer device is warmed up to a predetermined temperature (warm-up), and a normal printing operation becomes possible only when the fixing device 67 is warmed up.

In addition, instead of making the light emission time intermittent,
It is also possible to stabilize at a specified temperature by lowering from 100%.

 Normal printing will be described with reference to FIG.

When recording paper is supplied and printing is enabled, and a print command is sent from the host device, the printer controller 12e sends a print signal (FIG. 5 (d)) permitting printing to the printing device. The output of the printing circuit 12b is connected to each LED of the LED head 11 for the signal switch 12e, which has been selected to output to the temperature raising circuit 12d during the non-printing period. A switching signal is sent out as shown in FIG. 5 (e).

As shown in FIGS. 5 (b) and 5 (c), the temperature increasing circuit 12d is provided with the LED from the signal from the temperature detecting circuit 13b.
When the temperature of the head 11 is lower than a predetermined value,
A signal for causing each LED to emit light is output. When a print signal "1" (FIG. 5 (d)) allowing printing is output, the signal switch 12a is sent to the signal switch 12a. Since the printer controller 12e does not output the switching signal (FIG. 5 (e)) for selecting the temperature raising circuit 12d, each LED of the LED head 11 is consequently output.
, The data is not transmitted, and printing is continued.

On the other hand, even if the switching signal ((e)) is received from the printer controller 12e, the temperature detection
The temperature of the ED head 11 is higher than a certain value and the LED head 11
If it is not necessary to raise the temperature of (b),
The data for temperature rise is not output from the temperature rise circuit 12d.

That is, the case where the output result of the temperature increasing circuit 12d is sent to each LED of the LED head 11 and the temperature rises means that the output of the temperature detecting circuit 13b indicates that the temperature of the LED head 11 is lower than a predetermined value. This is limited to the case where the signal is low and the switching signal indicating the non-printing period is being output from the printer controller 12e ((f)).

In this embodiment, the temperature of each element of the LED head 11 is stabilized in this way.

If the external environment is high and the temperature of the LED head 11 is too high, the temperature is notified to the printer controller 12e via the temperature detection circuit 13b,
The printer controller drives the fan for cooling the LED head 11 to perform forced cooling, thereby stabilizing the temperature.

Thus, a latent image is formed on the photoreceptor 66 by the driven LED head 11 (61), developed by the above-described developing device 62, transferred to a recording paper, and fixed by the fixing device 67. Then, printing is completed.

〔The invention's effect〕

As described above, in the present invention, normal printing is performed when printing is permitted, but during the non-printing period, all the light emitting elements of the printer head are uniformly driven to emit light to uniformly control the temperature. Is increased, the temperature variation based on the difference in the light emission time between each light emitting element is eliminated, and the density variation at the time of printing due to the temperature dependency of each light emitting element is removed, and the reliability is improved. An optical printer device can be provided with a simple structure.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of the invention, FIG. 2 is a block diagram according to an embodiment, FIG. 3 is a diagram showing a sequence at the time of power-on according to the embodiment, and FIG. FIG. 5 is a diagram showing the operation of the optical printer device according to the embodiment, FIG. 6 is a diagram showing the optical printer device according to the embodiment and the conventional example, and FIG. 7 is a block diagram according to the conventional example. is there. 1 (11) Printer head (LED head) 2, 12 Printing and temperature rise drive circuit 3 (13a, 13b) Temperature detector (Thermistor 13a, temperature detector 13b)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Inoue 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Mikio Amaya 1015 Kamikodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited ( 56) References JP-A-1-165442 (JP, A) JP-A-2-88260 (JP, A) JP-A 62-134265 (JP, U) JP-A 62-131838 (JP, U)

Claims (1)

(57) [Claims] 1. An optical printer device comprising a printer head (1) in which a plurality of light-emitting elements are arranged, and performing recording by driving the corresponding light-emitting elements based on print data. A temperature detector (3) for detecting the temperature of the printer, and printing and temperature rise for uniformly driving the printer head (1) for a predetermined time based on the temperature detected by the detector (3) during a non-printing period. An optical printer device comprising: a driving unit (2).