JPH0373369A - Edge-emitting EL printer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an edge-emitting EL printer using a line head comprising an array of edge-emitting EL elements.

2. Description of the Related Art In recent years, line printers are one of the printers developed using electrophotography.

This line printer has devices such as a charger, line head, developer, and transfer device placed close to each other on the circumference of a photosensitive drum. A latent image is formed by scanning light by selectively emitting light from a light emitting element connected to the head, and this latent image on the circumferential surface of the photosensitive drum is developed with toner supplied from a developing device to form this toner image. It is designed to be transferred onto printing paper using a transfer device. LEDs and the like are used as light emitting elements in such line heads, but these have problems such as difficulty in achieving both light emission intensity and responsiveness.

Currently, it is being considered to use an edge emitting type EL element as a light emitting element for a line head. Therefore, a line head consisting of this edge-emitting type EL element was used as the fifth line head.
This will be explained based on the diagram and FIG. First, as illustrated in FIG. 6, the edge-emitting type E7 element 2 of this line head 1 consists of a thin active layer 3 made of zinc sulfide or the like containing an active element, and dielectric layers 4 and 5 from above and below. flat plate electrodes 6 and 7 are formed on the upper and lower surfaces of these dielectric layers 4.5, and extremely flat light is emitted from the end surface of the active layer 3, compared to conventional EL in which the upper surface emits light. It is possible to obtain 0 emission intensity about 100 times. Then, as illustrated in Figure 6,
A line head 1 is formed by arranging the edge-emitting type EL elements 2 having the above structure in an array using a thin film technique and attaching a rod lens array (not shown) or the like.

By arranging the line head 1 formed as described above in close proximity to the circumferential surface of the photosensitive drum together with a charger, a developer, etc., an edge-emitting type EL printer (not shown) can be manufactured.

In such a configuration, by selectively causing each edge emitting type EL element 2 of the line head 1 to emit light, it is possible to form an electrostatic latent image on the photosensitive drum and perform electrophotographic printing.

Problems to be Solved by the Invention The line head 1 described above can contribute to electrophotographic image formation by selectively causing a desired edge-emitting τIEL element 2 to emit light for optical scanning. Here, an edge-emitting type E that can print on A4 paper with a pixel density of 8 pixels/m
Assuming an L printer, the line head 1 will have 1728 or more edge-emitting EL elements 2.

However, when manufacturing a line head 1 consisting of such a huge number of elements, differences in characteristics occur due to differences in manufacturing lots and cumulative errors in the manufacturing process, resulting in differences in the light emission of each edge-emitting type EL module 2. Differences in strength tend to occur.

To compensate for the performance degradation of the line head due to the difference in the characteristics of the light emitting elements, for example, in the case of a device using an FD as the light emitting element, there is a method described in Japanese Patent Application Laid-Open No. 63-31770.
There is a device disclosed in the above publication. This is done by measuring the emitted light intensity of the LEDs forming the line head in advance, recording data on the energization time at which the light amount is uniform in the ROM, and combining this data with the print data using an AND gate for each LED. By controlling the current application time, the light emission intensity of the line head can be made uniform.

However, since it is difficult to control the emission intensity of the edge-emitting type EL element 2 by changing the energization time, it is difficult to control the luminescence intensity of the edge-emitting type EL element 2.
Even if a printer is manufactured, the emitted light intensity becomes non-uniform, making it impossible to manufacture a printer with high printing quality.

Means for Solving the Problem The invention as set forth in claim 1 forms a line head in which a large number of edge-emitting EL elements are arranged in an array, and measures each edge-emitting EL element of the line head in advance. A memory is provided in which element output data based on the emitted light intensity is registered.
Emission intensity correction means is provided for controlling the number of drive pulses applied per unit time to each edge emitting type EL element of the line head in accordance with the element output data and print data registered in this memory.

The invention according to claim 2 provides an edge-emitting type E of the line head.
Emission intensity correction means is provided to control the frequency of the drive pulse applied to the L element.

A line head is formed in which a large number of edge-emitting type EL elements are arranged in an array, and each edge-emitting type EL element of this line head
A memory is provided in which element output data based on the emitted light intensity measured in advance of the L element is registered, and voltage is applied to each edge emitting type Ei and element of the line head per unit time according to the element output data and print data registered in this memory. By providing a light emission intensity correction means to control the number of driving pulses,
Since the difference in characteristics of each edge-emitting type EL element forming the line head is corrected, it is possible to form a line head in which the main scanning light emission intensity is uniform.

Furthermore, by providing a light emission intensity correction means that controls the frequency of the drive pulse applied to each edge-emitting type EL element of the line head, the light emission intensity of the line head consisting of the edge-emitting type EL element array as described above can be made uniform. can be easily implemented.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 3. The structure of the line head of the edge-emitting EL printer 8 of this embodiment is the same as that of the line head 1 illustrated in FIG. Therefore, the drive circuit of this edge-emitting EL printer 8 will be explained based on the block diagram exemplified in FIG. First, for example, an interface 10 to which a printer controller 9 of another device is connected is connected to a timing controller 16 via a control circuit 15 to which three address counters 11 to 13 and a reference clock 14 are connected. The address counter 13 to which the reference clock 14 is connected is R
It is connected in parallel to a data table 17 which is a memory such as OM.

The interface 10 also includes two RAMs 22 each having three states 18 to 21 connected to an input/output section.
．． 23 via a first data processing circuit 24,
These RAMs 22 and 23 are connected to the control circuit 15 and the address counters 11 and 12 via a selector 25. The data table 17 is connected to a second data processing circuit 26, which is a light emission intensity correction means, to which the RAMs 22 and 23 are connected via the three states 20 and 21.

Furthermore, each latch 27. ~274 and driver 28, ~
284 and the block pole 30 of the line head 29 through
．． Four shift registers 31.~3On are connected. ~
31. On the other hand, the data processing circuits 26 are serially connected in cascade.

Furthermore, the timing controller 16 controls the latches 27 . ~27. and shift registers 31-31. and,
Common electrode 32, ~32m of line head 29 in t1q
The common driver 33 is connected to the common driver 33 .

In such a configuration, in this edge-emitting type EL printer 8, the edge-emitting type EL element 2 of the line head 29 is
The emitted light intensity is measured, and element output data set based on this emitted light intensity is registered in the data table 17. Here, the element output data registered in this data table 17 is formed of, for example, 3 bits, and if the one with the minimum emission intensity is rllllJ, the maximum rooo
, 1 are set sequentially.

Therefore, in this edge-emitting EL printer 8, for example,
Print data including a clock signal input from a device such as a word processor (not shown) through the interface 10 is sent to the first data processing circuit 2 for each main scanning line.
4, it is compressed by processing such as sorting, and the two RAM2
2.23, and the other RAM 23.22 outputs pre-stored print data at high speed. This R.A.
For example, the switching of M22.23 is performed using the reference clock 14.
The selector 25 is controlled by the control circuit 15 which operates according to the clock timing of the RA.
The print data output from M22.23 is input to the second data processing circuit 26 via the three-state circuit 20.21. At this time, the address counter 13 similarly controlled by the control circuit 15 controls the data table 17.
The element output data is output to the second data processing circuit 26 in synchronization with the print data.

Here, in the print data, whether or not to print each edge-emitting type EL element 2 is set in rlJ and rQJ, and as mentioned above, the element output data is 3 bits for each edge-emitting type EL element 2. It is set from roooJ. The second data processing circuit 26 to which these data are input has a function of decoding the 3-bit element output data and combining it with print data.

Therefore, this data processing will be explained with reference to the timing chart exemplified in FIG. 2(a). First, in the edge-emitting type EL printer 8 of 1:, high and low voltage pulses are sent from the common electrode 32 and the block electrode 30 to the line head 29.
is input. Therefore, here, the synchronization of the two pulses is changed by controlling the phase of the low voltage pulse applied from the block electrode 30, and the voltage of the combined drive pulse is adjusted to be larger or smaller than the threshold voltage of the edge-emitting EL element 2. As a result, the light emission of each edge-emitting type EL element 2 is controlled. In this edge-emitting type EL printer 8, the light emission intensity of the edge-emitting type EL element 2 is maximized by six pulse inputs. Further, as illustrated in FIG. 2(b), the emission intensity of the edge-emitting type EL element 2 increases according to the number of input pulses.

Therefore, for example, if the emission intensity of a certain edge-emitting type EL element 2 is the second from the weakest in the level setting, this element output data will be rllOJ. Then, this element output data is decoded by the second data processing circuit 26, and the phase of the low voltage pulse is controlled when the 74 pulses are output, and the edge emitting type EL element 2 emits light when the upper pulses are input.

Further, when the emission intensity is lower than that of the edge-emitting type EL element 2 described above and the element output data is set as rllllJ, this edge-emitting type EL element 2 emits light with six pulse inputs.

Therefore, the composite data in which the characteristic difference has been corrected for each end □ light-emitting type El, II element 2 in this way is transferred to the shift register 3.
1 to 314 are serially output to the latch 27. ~2
74, and output to the line head 29 under the control of the timing controller 16 at the point in time when the printing signal for -line is held. And this edge-emitting type E
The L printer 8 performs high-quality printing by emitting main scanning light with uniform light intensity from the line head 29 to which the composite data is input.

Note that in this edge-emitting type EL printer 8, the above-mentioned operation is performed multiple times during the printing time of one line, and the line head 29 repeats line emission multiple times over the width of one main scan. . This corresponds to the fact that the edge-emitting type EL element 2 is extremely flat, and by forming one pixel through multiple light emitting operations in this way, a substantially square pixel can be printed.

Furthermore, an edge-emitting EL printer 8 having the structure described above
Another data processing method for making the light emission intensity of the line head 29 uniform will be explained based on a timing chart and a characteristic diagram illustrated in FIG.

In this method, the frequency of the drive pulse is changed by controlling the phase of the low voltage pulse applied from the block electrode 30 to vary the emission intensity of the edge-emitting type EL element 2.

For example, the element output data is 2 bits for each edge-emitting ELM element 2, rill, rlOJ, roll, ro.
It is set in four stages, such as OJ. Then, these element output data are processed by the second data processing circuit 26 as rlllll11.111J and rlolololool, respectively.
J, rlool, ooloOJ.

It is decoded as rlooolooolJ and combined with print data. Then, this composite data becomes a drive pulse with a frequency corresponding to the element output data, and the emission intensity of the edge-emitting type EL element 2 is controlled in four stages.

Next, a second embodiment of the present invention will be described based on FIG. 4. In the edge-emitting EL printer 34 of this embodiment, the second data processing circuit 35, which is the emission intensity correction means, uses the block electrode 30 of the line head 29. 30n connected to four shift registers 311-31. are connected in parallel.

Note that the other structure is the edge-emitting type EL printer 8 described above.
It is the same as.

In such a configuration, in the edge-emitting type EL printers 3 and 4, the print data output from the RAM 22 and 23 and the element output data output from the data table 17 are combined in the second data processing circuit 35. Processed shift register 31. ~31, are output in parallel.

Then, the following process is completed in the same manner as the edge-emitting type EL printer 8 described above.

In addition, in this edge-emitting type EL printer 34, the second data processing circuit 35 and each shift register 31, to 314 are connected in parallel, so it is easy to increase the speed of data transmission, and it is possible to increase the speed of printing. High resolution is possible.

Effects of the Invention As described above, the present invention forms a line head in which a large number of edge-emitting EL elements are arranged in an array, and calculates the emission intensity based on the emitted light intensity measured in advance of each edge-emitting EL element of this line head. Emission intensity correction that includes a memory in which element output data is registered and controls the number of drive pulses applied per unit time to each edge-emitting EL element of the line head according to the element output data and print data registered in this memory. By providing the means, differences in characteristics of each edge emitting type EL element forming the line head are corrected, so a line head with uniform intensity of main scanning light emission is formed, resulting in an edge emitting type EL element with high quality printing. We can manufacture printers and furthermore,
By providing a light emission intensity correction means that controls the frequency of the drive pulse applied to each edge-emitting type EL element of the line head, it is possible to easily equalize the light emission intensity of the line head consisting of the edge-emitting type EL element array as described above. It has the effect that it can be implemented in many ways.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention, and FIG.
Figure (a) is a timing chart of drive pulses, Figure 2 (
b) is a characteristic diagram of the emission intensity of an edge-emitting type EL element, Fig. 3(a) is a timing chart of drive pulses, Fig. 3(b)
) is a characteristic diagram of the emission intensity of an edge-emitting type EL element, FIG. 4 is a block diagram showing a second embodiment of the present invention, FIG. 5 is a perspective view of a line head showing a conventional example, and FIG. 6 is an end-face diagram. Luminous type E
FIG. 3 is a perspective view of an L element. 2... Edge emitting type EL element, 8, 34... Edge emitting type EL printer, 17... Memory, 26.35...
・Emission intensity correction means

Claims (1)

[Scope of Claims] 1. A line head is formed in which a large number of edge-emitting EL elements are arranged in an array, and element output data is based on the pre-measured emission intensity of each edge-emitting EL element of this line head. a memory in which is registered, and a light emission intensity correction means for controlling the number of drive pulses applied per unit time to each edge emitting type EL element of the line head according to the element output data and print data registered in the memory. An edge-emitting EL printer characterized by: 2. The edge-emitting type EL printer according to claim 1, further comprising a light emission intensity correction means for controlling the frequency of the drive pulse applied to each edge-emitting type EL element of the line head.