JPH02233267A - Optical printer - Google Patents

Abstract

PURPOSE:To provide an optical printer having small irregularity of a density due to temperatures of light emitting elements with a simple structure by uniformly driving a printer head based on the temperature detected by a detector during nonprinting period for a predetermined period of time. CONSTITUTION:A printer controller 12e sends a switching signal to a signal switching unit 12a according to the facts of nonprinting period immediately after a printer power source is turned ON and low temperature of a LED head 11, and selects not a normal printing circuit 12b but a temperature rising circuit 12d. The circuit 12d turns ON all the LEDS, and continuously lights them with 100% of light emitting duty to abruptly rise the temperature of the head 11. When the temperature of the head 11 rises to approach a specified temperature, the circuit 12d intermittently lights the LEDs based on a signal from a temperature detector 13b to hold the temperature of the head 11 at a specified temperature, i.e., in a range of 45-50 deg.C.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an optical printer device that is equipped with a printer head in which a plurality of light emitting elements are arranged and performs recording by driving the corresponding light emitting elements based on print data, with a simple structure, Our aim is to provide a reliable optical printer device with small variations in density due to variations in the characteristics of the light emitting elements due to variations in the temperature of each light emitting element, and the present invention includes a temperature detection section for detecting the temperature of the printer head; The printer head is configured to include a printing and temperature increase drive unit that uniformly drives the printer head for a predetermined period of time based on the temperature detected by the detection unit during the non-printing period.

(Industrial Application Field) The present invention relates to an optical printer device, and more particularly, an optical printer device that is equipped with a printer head in which a plurality of light emitting elements are arranged and performs recording by driving the corresponding light emitting elements based on print data. Regarding.

In recent years, various types of electrophotographic optical printer devices have been developed, including laser printers, LED (light emitting diode) printers, and liquid crystal printers.

These printer devices are characterized by high speed, high resolution, and high image quality, and are expected to continue to develop significantly in the future.

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

The LED printer device has the following features compared to conventionally widely used laser printer devices.

That is: (1) It is a solid-state scan and does not require mechanical driving parts.

- The optical path length can be shortened and the device can be made smaller.

■ Prices will become cheaper due to advances in semiconductor technology.

In the future, taking advantage of these features, it is thought that LED printers will become more popular, especially in small printers.

Also, the problem is ■ The output of individual LEDs is not uniform.

■ Light output changes depending on temperature.

■ Requires a large power source because the luminous efficiency is not high.

For ■, change the light emitting time for each LED, or
Countermeasures such as changing the current of each of the four LEDs have been considered, and it is possible to make the light output of each LED uniform.

Regarding (2), the power supply capacity is reduced by dividing L'ED into several blocks and emitting light. Alternatively, there are countermeasures such as using a high-efficiency power source to make the power source smaller.

■This is the problem that we are trying to solve with the invention of wood.

LEDs are semiconductor devices and have large temperature dependence. For example, in an LED using GaAsP, 10. 8
It shows temperature dependence on the order of %/d. LED temperature is 30
As the temperature increases, the light output decreases by approximately 25%.

Therefore, the recording density and dot area change due to temperature changes. This means that when outputting normal characters,
Although it is not very noticeable, it becomes a problem when outputting graphics or halftone recording.

The sensitivity of the photoreceptor also changes depending on the temperature. For this reason,
There is a problem in that the reproduced recording density changes with temperature changes.

(Prior Art) Conventionally, there has been an optical printer device as shown in FIG. 7 in order to cope with the above-mentioned temperature changes.

As shown in the figure, this device includes a printer head 71 in which a plurality of light emitting elements are arranged, and a printer head 71 in which a plurality of light emitting elements are arranged.
a temperature detection unit 73 that detects the temperature of the temperature detection unit 7;
Based on the temperature detected by the printer head 71, each duty ratio (du
Some printers have a printing and duty control drive unit 72 that uniformly increases or reduces ty (ratio of light emitting printing time within a fixed period of time) when printing is permitted.

In this device, when the temperature detected by the temperature detection section 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 drive section 72 In contrast, the duty ratio of the light emission time of all the light emitting elements arranged in the printer head 71 when printing is permitted is controlled to increase, so that the temperature detected by the temperature detection section 73 is higher than a predetermined temperature. If the duty ratio is low, the duty ratio is controlled to be decreased.

[Problem to be solved by the invention]

By the way, in the conventional device, the temperature of the printer is determined based on the temperature detected by the temperature detection section 73.
Since the duty ratio of all the light emitting elements in the head 71 during printing is controlled by the printing and duty control section 72, the light output of the light emitting elements in the entire printer head 71 can be stabilized. It is not possible to eliminate variations in the amount of light caused by variations in temperature between each element.

For this reason, there has been a problem in that variations in density have a negative effect on image quality, particularly in outputs such as graphics or halftone recording.

This is because each light emitting element is not necessarily used uniformly, and the time it is used varies, and those that are used for a long time have a high temperature, and those that are used for a short time have a low temperature. Therefore, there was a problem in that it was not possible to eliminate changes in print density due to local temperature changes.

In addition, duty ratio control generally has the problem that the circuit may become complicated.

On the other hand, detecting the temperature of each light emitting element and controlling the drive of each light emitting element to change the amount of light has a problem in that the structure of the control device becomes complicated.

Therefore, the present invention has been made with the aim of solving the above-mentioned problems, and has a simple structure, and has a small variation in light intensity and concentration based on variations in characteristics of light-emitting elements due to variations in temperature of each light-emitting element. This was made for the purpose of providing an optical printer device.

[Means to solve the problem]

In order to solve the above technical problems, the present invention has developed a printer head 1 in which a plurality of light emitting elements are arranged, as shown in FIG.
In an optical printer device that performs recording by driving a corresponding light emitting element based on print data, the temperature detecting section 3 detects the temperature of the printer head 1, and the detecting section 3 detects the temperature of the printer head 1 during a non-printing period. The printer head 1 is provided with a printing and temperature increasing drive unit 2 that uniformly drives the printer head 1 for a predetermined period of time based on the temperature detected by the printer.

[Effect]

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

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

Then, the driving unit 2 drives the corresponding light-emitting elements of the printer head 1 based on the print data, and when printing is permitted when conditions are met, such as when recording paper is being supplied, Print on recording paper.

On the other hand, during the non-printing period when printing conditions such as supply of recording paper are not in place, the driving unit 2 uniformly causes all the light emitting elements of the printer head 1 to emit light to increase the temperature of each light emitting element. It turns out.

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

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

By making the amount of heat non-negligible compared to the heat applied to each light emitting element when printing is permitted, even if there is a temperature variation between each element due to the difference in light emitting time when printing is permitted, the amount of heat applied to each light emitting element is Since the total light emitting time including the non-printing period is relatively close to the same length, the temperature variation between each element is 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 made sufficiently higher than when printing is permitted.

In parallel with the above operations, the temperature detection section 3
The temperature of the head 1 is detected, and if the temperature exceeds a predetermined temperature value, the printing and temperature increase drive section 2 detects the amount of heat that should be applied to all light emitting elements of the printer head 1 during the non-printing period. The light emitting time is shortened to reduce the

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

With the above, it is possible to eliminate variations in concentration due to temperature dependence of characteristics of each light emitting element.

〔Example〕

Next, examples of the present invention will be described.

FIG. 6 shows an outline of the entire LED printer device as an optical printer device according to an embodiment.

As shown in the figure, this device includes a photosensitive layer provided on a metal substrate, a cylindrical photosensitive member 66 that rotates at a constant angular velocity, and a gas that is ionized into positive or negative charges and blown onto the photosensitive member 66. A charger 68 that charges the photoreceptor by applying light to the charged photoreceptor 66 based on print data, and exposure as a plurality of light emitting elements that draw a latent image on the photoreceptor by irradiating the charged photoreceptor 66 with light to remove the charge. a printer head 61 in which LEDs (light emitting diodes) are arranged; a developing device 62 that sprays a 1-toner having an opposite charge to the charged portion of the photoreceptor 66 to develop the latent image; A paper feed cassette 63 is used to set the recording paper on which the image is to be recorded, and in order to transfer the developed image to the recording paper, the back of the paper is charged with a charge opposite to the charged 1 hener. Transfer device 64 that attracts the toner with Coulomb force
, a separator 65 that separates the recording paper from the photoreceptor 66, a fixing device 67 that fixes the toner transferred to the recording paper, and a stacker 69.

This embodiment relates to a part that performs printing control of an LED printer device as the optical printer device.

FIG. 2 shows a portion that performs printing control according to this embodiment.

As shown in the figure, the LED printer device as an optical printer device according to the present example mainly includes an LED head 11 corresponding to the printer head 1 in which LEDs as the plurality of light emitting elements are arranged, and an LED head 11 for printing. and temperature increase drive circuit 12
and corresponds to the temperature detection section 3 and the LE
It has a thermistor 13a provided in the D head 11 and a temperature detection circuit 13b that performs predetermined processing such as amplification of the electric signal detected by the thermistor 13a.

As shown in the figure, the printing and temperature increase drive circuit 12 includes a printer controller 12e that outputs a printing signal or a switching signal indicating permission for printing based on the output signal of the temperature detection circuit 13b, and a printer controller 12e that outputs a printing signal or a switching signal indicating permission for printing based on the output signal of the temperature detection circuit 13b, and a memory 12c that stores print data, a print circuit 12b that outputs a signal for driving the LED of the LED head 11 based on the print data, and an output of the temperature detection circuit 13b. a temperature increase circuit 12d that outputs a signal for uniformly driving all the LEDs of the LED head 11 to emit light based on the above, and a signal switch that switches the outputs of the printing circuit 12b and the temperature increase circuit 12d. It has a container 12a.

Next, the operation of this device will be explained.

The operation of the LED printer device when the power is turned on will be explained based on FIG. 3.

The thermistor 13. a detects the temperature of the LED head 11, and connects the printer controller 1 to the roller 12e and the temperature increase circuit 12 via the temperature detection circuit 13b.
A signal representing the temperature is sent to d.

Since LED printer devices are 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 increase circuit 12d starts outputting data for driving the LED head 11 to emit light, and the temperature increase circuit 12d starts outputting data for driving the LED head 11 to emit light. The controller 12e switches the signal switching device 1 because the printer is in a non-printing period immediately after the power is turned on and the temperature of the LED head 11 is low.
A switching signal is sent to 2a, and the normal printing circuit 1
The temperature increasing circuit 12d is selected instead of the temperature increasing circuit 2b.

The temperature increase circuit 12d operates by turning on all LEDs and setting the light emission duty to 100% continuous lighting.
E. The temperature of the D head 11 is rapidly increased.

When the temperature of the LED head 11 rises and approaches a predetermined temperature, the temperature increase circuit 12d makes the light emission time intermittently based on the signal from the temperature detection 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 reason why the temperature was set within such a range is as follows.

Generally, the temperature outside the device and the temperature inside the device is approximately 10°
If there is a temperature difference between
This is because it is desirable to set the temperature to 0°C.

As shown in FIG. 4, which shows the temperature change of the LED head 11 according to this embodiment in more detail, when the temperature of the LED head 11 is lower than this temperature, the temperature increase circuit 12d described above causes the LED head to rise.
The temperature of the D head 11 will be maintained at this temperature.

In this way, the fixing device 67 of the LED printer device waits until it is warmed up to a predetermined temperature (heating up), and only when it is warmed up can normal printing operations become possible.

In addition, instead of making the light emission time intermittent, the light emission duty can be set to 1.
It is also possible to stabilize the temperature at a specified temperature by lowering it from 00%.

Normal printing will be explained based on FIG. 5.

When recording paper is supplied and printing becomes possible, and a print command is sent from the host device, the printer controller 12e sends a print signal (FIG. 5(d)) that allows printing.
)) to the printing circuit 12b, and the printing circuit 1
A switching signal is sent to connect the output of 2b to each LED of the LED head 11 (FIG. 5(e)).

As shown in FIGS. 5(b) and (C), when the temperature of the LED head 11 is below a predetermined value, the temperature increasing circuit 12d detects the temperature of the LED head 11 by the signal from the temperature detection circuit 13b.
It outputs a signal to cause each LED of the D head 11 to emit light, and a print signal ``1'' that allows printing is used.
(FIG. 5(d)), the printer controller 1 is output to the signal switch 12a.
Since the switching signal (FIG. 5(e)) for selecting the temperature increase circuit 12d is not outputted from 2e, the data is not sent to each LED of the LED head 11 and is not printed. continues.

On the other hand, the switching signal (
Even if (e)) occurs, the temperature detector 13b detects that the temperature of the LED head 11 is higher than a certain value and the corresponding LED
When there is no need to increase the temperature of the head 11 (same (+
)) ), no temperature increase data is output from the temperature increase circuit 12d.

That is, when the output result of the temperature increase circuit 12d is sent to each LED of the LED head 11 and the temperature rises, the output of the temperature detection circuit 13b is
When the temperature of the ED head 11 is lower than a predetermined value, and when the switching signal representing the non-printing period is output from the printer controller 1-roller 12e ((f)).
It will be limited to.

The purpose of this embodiment is to stabilize the temperature of each element of the LED head 11 in this way.

Note that if the external environment is high and the temperature of the LED head 11 becomes too high, the printer controller 12e is notified of the temperature via the temperature detection circuit 13b, and the printer controller By driving the fan for cooling the LED head 11 and performing forced cooling, the temperature can be stabilized.

In this way, a latent image is created on the photoreceptor 66 by the driven LED head 11 (61), and the above-mentioned developer 62
The issue is developed and transferred onto the recording paper, and the image is fixed by the fixing device 67 to complete printing.

〔Effect of the invention〕

As explained above, the present invention performs normal printing when printing is permitted, but during non-printing periods, all the light emitting elements of the printer head are uniformly driven to emit light to uniformly control the temperature. This increases reliability by eliminating variations in temperature due to differences in light emission time between each light emitting element and eliminating variations in density during printing due to the temperature dependence of each light emitting element. A certain optical printer device can be provided with a simple structure.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the principle of the invention, Fig. 2 is a block diagram of the embodiment, Fig. 3 is a diagram showing the sequence when the power is turned on in the embodiment, and Fig. 4 is the temperature change of the LED according to the embodiment. 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 of the conventional example. be. 1 (11)...Printer head (LED head) 2
, 12...Printing and temperature rise drive circuit 3 (13a,
13b)...Temperature detection section (thermistor 13a, temperature detection circuit 13b) shield, t1 ゛The sequence of the thief's attack is shown by A Tanemi) Bee. Ata '1l goose 2, LED et al.

Claims (1)

[Scope of Claims] 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, comprising: ); and a temperature detection unit (3) that detects the temperature of the printer head (1), which uniformly drives the printer head (1) for a predetermined period of time based on the temperature detected by the detection unit (3) during a non-printing period. An optical printer device characterized in that it is provided with a lifting drive section (2).