Security document comprising a perforated, opaque white-appearing layer over a matrix of colored sub-pixels

Abstract

Security document comprising a perforated, white-appearing opaque layer over a colored sub-pixel matrix. Security document comprising a stack of layers having a colored sub-pixel matrix (101) (SB, SM, SJ), a white-appearing opaque layer (102) over the colored sub-pixel matrix, wherein the white-appearing opaque layer has perforations (PF) opposite sub-pixels of the colored sub-pixel matrix such that when the device is viewed from above, a colored image appears. Figure for the abstract: Fig. 3.

Description

Title of the invention: Security document comprising an opaque, white-appearing layer perforated over a matrix of colored sub-pixels Technical field

[0001] The invention relates to the field of security documents, and in particular to security documents on or within which images can be observed. The invention applies non-exclusively to physical identity documents, such as a passport, an identity card, a driver's license, a residence permit, etc. Prior art

[0002] The identity market today requires increasingly secure physical identity documents (also called identity documents or security documents). This market covers a wide variety of documents, such as identity cards, passports, access badges, driver's licenses, etc., which can come in different formats (cards, booklets, etc.).

[0003] Security documents must be easily and quickly authenticable. They must also be difficult to counterfeit (if possible, unforgeable), in the face of the latest counterfeiting techniques.

[0004] Security documents generally feature coloured images, for example photographs of the faces of a security document bearer.

[0005] Colour image formation techniques for secure identity documents use matrices of coloured sub-pixels (for example with Red-Green-Blue sub-pixels or Cyan-Magenta-Yellow sub-pixels) and techniques for blackening a layer that will mask portions of sub-pixels to obtain pixels of a desired colour.

[0006] For example, it is known to use laserizable layers, as described in prior document FR 2 972 553 in which a laserizable layer is placed on top of a matrix of colored sub-pixels.

[0007] By laserizable, it is understood that the application of a laser beam to the layer (generally called laserizing) generates visible shades of gray through carbonization in that layer. For example, a laserizable layer can be a transparent polycarbonate layer and may contain additives sensitive to the passage of a laser beam because this beam carbonizes them. Such a laserizable layer will be blackened or at least partially grayed throughout its thickness according to the power of the laser since the additives sensitive to the passage of a laser beam are distributed uniformly throughout the thickness of the layer.

[0008] Current color image formation techniques, such as those using laser-etched layers, particularly in secure identity documents, do not always provide satisfactory visual quality. Problems arise especially when the image formation techniques used are limited in their ability to produce certain colors. In other words, the color gamut (the range of achievable colors) of known color image formation techniques is sometimes limited.

[0009] A solution to this problem was described in document FR 3 079 052, which proposes implementing lenses opposite colored pixels to focus light onto white sub-pixels and improve the color gamut. This solution has the drawback of heating the documents, which can produce distortions. Furthermore, the lens magnification is insufficient to achieve a sufficiently wide gamut.

[0010] There is a need for security documents with coloured images that present a less limited colour gamut. Description of the invention

[0011] To this end, the present invention proposes a safety document comprising a stack of layers having a matrix of colored sub-pixels, an opaque layer with a white appearance above the matrix of colored sub-pixels, in which the opaque layer with a white appearance has perforations opposite (for example above) sub-pixels of the matrix of colored sub-pixels so that when the device is viewed from above, a colored image appears.

[0012] Thus, the invention proposes using an opaque, white-appearing layer that can be perforated to reveal colored sub-pixels that were masked by this opaque, white-appearing layer. This allows for the formation of image pixels with colored sub-pixels and a white contribution from the opaque white layer, as well as entirely white pixels, resulting in a wider color gamut, and in particular, brighter colors.

[0013] The invention also makes it possible to avoid the use of lenses, the manufacture of which can heat up the documents.

[0014] It can be noted that a person skilled in the art will know how to select the opaque, white-appearing layer so that perforations can be made in it. Furthermore, this layer is opaque, so that the matrix of colored sub-pixels is not visible to the naked eye through the paper, except by using, for example, a lamp on the back of the document. Thus, by opaque, we mean a good level of opacity, for example a A layer that hides the matrix of colored sub-pixels without using a lighting device under the device. Also, "opaque" can be defined as meaning that the opaque, white-appearing layer masks the matrix of colored sub-pixels to a user observing it without using a lighting device under the device (for example, lighting above the device is possible).

[0015] In the resulting colored image, pixels are defined as regions comprising colored sub-pixels visible through one or more perforations, possibly a portion of the opaque layer appearing white, or even just a portion of the opaque layer appearing white (which may correspond to a white sub-pixel). The image can be divided into pixels all having the same dimensions. It is understood that one can thus obtain a colored image with pixels that are entirely white or partially white, or even with no portion of the opaque layer appearing white.

[0016] According to a particular embodiment, the document further comprises a laserizable layer arranged above the opaque white-appearing layer and configured to be laserized by application of a laser beam at at least one laserization wavelength.

[0017] As explained above, a laser-etched layer is such that applying a laser beam to this layer generates visible shades of gray through carbonization within the layer. For example, a laser-etched layer can be a transparent polycarbonate layer and may contain additives sensitive to the passage of a laser beam, as this beam carbonizes them. Such a laser-etched layer will be blackened or at least partially grayed throughout its thickness, depending on the laser power, since the additives sensitive to the passage of a laser beam are distributed uniformly throughout the layer's thickness.

[0018] The use of the laserizable layer will make it possible to expand the color gamut towards dark colors, since completely black pixels can be obtained by laserization.

[0019] The laserizable layer can be transparent and therefore the opaque layer with a white appearance is more opaque than this layer.

[0020] According to a particular embodiment, the laserizable layer comprises portions blackened by laserization.

[0021] For example, these blackened areas are placed above colored sub-pixels to affect the perceived hue. Also, these blackened areas can be placed above portions of the opaque layer that appear white or above perforations in this layer. It is therefore clear how the color gamut is thus improved (a black channel is added).

[0022] The blackened portions improve the contrast of the coloured images obtained.

[0023] According to a particular embodiment, the document further includes a filter limiting the passage of at least the laserization wavelength, the filter being arranged between the laserizable layer and the opaque layer with a white appearance or, the laserizable layer is configured to form a filter limiting the passage of at least the laserization wavelength.

[0024] The use of a filter is well suited for fragile opaque layers with a white appearance, for example thin layers of metal oxides, which could be affected, for example perforated by the laser beam at the laserization wavelength.

[0025] The filter can either be a filter layer assembled by lamination, or, alternatively, be the laserizable layer itself.

[0026] By way of example, a laserizable layer that filters ultraviolet (UV) radiation and is sensitive to UV radiation can be used for laserization.

[0027] According to a particular embodiment, the opaque layer with a white appearance is chosen to be perforated by a laser beam of a perforation wavelength.

[0028] This particular embodiment allows the coloured image to be customized in a simple way.

[0029] According to a particular embodiment, the perforation wavelength differs from the laserization wavelength.

[0030] For example, this makes it possible to perforate the opaque layer which appears white without the laserizable layer being laserized.

[0031] A laser beam can be used for laserization with a higher energy than the laser beam used for perforation.

[0032] For example, for a laserization wavelength in the UV range, a perforation wavelength in the infrared range can be used (the filter can be configured to allow this wavelength to pass through).

[0033] According to a particular embodiment, a pixel of the coloured image comprises a coloured sub-pixel visible through a perforation and a white-appearing portion of the opaque white-appearing layer forming a white sub-pixel of the pixel.

[0034] According to a particular embodiment, the opaque, white-appearing layer comprises a metallic oxide.

[0035] The invention also proposes a method for manufacturing a security document in which a matrix of colored sub-pixels is assembled with, above the matrix of colored sub-pixels, an opaque layer with a white appearance,

[0036] the method further comprising the formation of perforations through the opaque white-appearing layer and opposite sub-pixels of the colored sub-pixel matrix so that when the device is viewed from above, a colored image appears.

[0037] This process can be adapted for the manufacture of all embodiments of the safety document as described above.

[0038] According to a particular embodiment, a laserizable layer is further assembled above the opaque layer which appears white and is configured to be laserized by application of a laser beam at at least one laserization wavelength.

[0039] According to a particular embodiment, the laserizable layer is laserized to obtain blackened portions.

[0040] According to a particular embodiment, a filter is further assembled limiting the passage of at least the laserization wavelength, between the laserizable layer and the opaque layer with a white appearance.

[0041] This filter prevents degradation of the opaque, white-appearing layer, which can be very fragile because it can be perforated, for example, by the application of a laser beam.

[0042] This filter can be a filter which filters at least the laserization wavelength but which allows other wavelengths to pass through.

[0043] According to a particular embodiment, the opaque white-appearing layer is perforated by a laser beam of a perforation wavelength to obtain the perforations.

[0044] According to a particular embodiment, the perforation wavelength differs from the laserization wavelength (the perforation wavelength is preferably unfiltered by the filter).

[0045] This particular embodiment proposes to use two different laser wavelengths, which is advantageous since the energy required for carbonization can be several times that required for perforation.

[0046] In fact, when a laser beam of a given wavelength is used for carbonization and is subsequently stopped by the filter, it is no longer possible to transmit sufficient energy to penetrate the opaque, white-appearing layer beneath the filter without further carbonizing the laser-capable layer. However, it is desirable to be able to make a colored subpixel visible beneath the opaque, white-appearing layer without carbonization at the subpixel itself. Therefore, using a different wavelength, not stopped by the filter or at least less stopped by the filter, can penetrate the opaque, white-appearing layer without contributing to carbonization. This allows for the independent generation of colors and a black channel that provides contrast.

[0047] According to a particular embodiment, the method includes a registration phase in which the position of a group of colored sub-pixels is observed prior to the formation of the perforations that form the colored image.

[0048] The registration phase is a phase during which the position of the colored sub-pixels of the colored sub-pixel matrix is ​​determined, so that the formation of the perforations takes these positions into account.

[0049] Since the colored sub-pixels are arranged according to a matrix, they are aligned along two orthogonal directions. By way of example, the matrix of colored sub-pixels may comprise sub-pixels having a number N of colors (for example N=3), arranged according to a pattern in which at least N sub-pixels, all of different colors, are repeated along the two orthogonal directions to form the matrix of colored sub-pixels.

[0050] The position of a sub-pixel of a given color at a position allows the position of the other sub-pixels to be deduced during the registration.

[0051] The position of several colored sub-pixels allows for interpolation between these colored sub-pixels to more accurately deduce the position of the other sub-pixels during registration. This allows for the consideration of distortions in the colored sub-pixel matrix.

[0052] The registration step facilitates the subsequent implementation of the perforation formation in the opaque layer appearing white, since it allows us to know the color of the sub-pixels that will be revealed by the perforations.

[0053] According to a particular embodiment, the colored sub-pixels of the colored sub-pixel group are observable through one or more perforations in the opaque layer with a white appearance.

[0054] The perforations used in this step may not be the perforations that will be used to make the colored image appear, but perforations formed before those that will be used to make the colored image appear (although they may be visible within the colored image).

[0055] According to a particular embodiment, a set of trenches are formed in a grid pattern through the opaque, white-appearing layer.

[0056] For example, these trenches are created by a demetallization process at the time of deposition of the opaque, white-appearing layer. Alternatively, the opaque, white-appearing layer can be deposited over the entire surface and the partial removal carried out according, for example, to a grid pattern, before this layer is laminated into the material.

[0057] This set of trenches improves the adhesion of the opaque, white-appearing layer to the other layers of the security document.

[0058] According to a particular embodiment, the position of the group of colored sub-pixels is observed through these trenches.

[0059] This method of implementation is particularly advantageous since it uses trenches which improve the adhesion of the opaque, white-appearing layer to other layers of the security document to observe the sub-pixels and implement a registration.

[0060] It can be noted that the trenches can be made during a step which is not that of perforation formation, in particular, the trenches are made here before the perforations. Brief description of the drawings

[0061] Other features and advantages of the present invention will become apparent from the description below, with reference to the accompanying drawings which illustrate non-limiting examples of embodiments. In the figures:

[0062] [Fig-1] Fig. 1 is a cross-sectional view of a security document before perforation, for example,

[0063] [Fig.2] Fig.2 is a cross-sectional view of the document in Fig.1 after perforation,

[0064] [Fig.3] Fig.3 is a cross-sectional view of the document in Fig.2 after laser cutting.

[0065] [Fig.4] Fig.4 is a top view of the colored sub-pixel matrix,

[0066] [Fig.5] Fig.5 is an illustration of interpolations determined during a registration,

[0067] [Fig.6] Fig.6 is a cross-sectional view of a document with pre-perforated trenches,

[0068] [Fig.7] [Fig.7] is a top view of the document in [Fig.6], and

[0069] [Fig.8] Fig.8 is a cross-sectional view of a document with a laser-etched layer filtering. Description of the embodiments

[0070] We will now describe security documents comprising both matrices of colored sub-pixels and opaque layers of white appearance, with an improved color gamut at least in terms of brightness.

[0071] The images formed by these sub-pixels are customizable images, which can be different for each document, and which can be specific to each document user.

[0072] The documents described herein may be physical identity documents such as a passport, identity card, driver's license, residence permit, etc. In fact, the documents described herein may be associated with a user, and the colored images that will be obtained may be images of the users' faces.

[0073] In [Fig.1], a document 100 obtained by the assembly of different layers, which may have been implemented by means of a lamination, is schematically represented.

[0074] Document 100 particularly includes a matrix of colored sub-pixels 101, for example a transparent or opaque layer on which colored elements have been printed, each forming a colored sub-pixel. Here, the sub- matrix Colored pixels comprise sub-pixels with three possible colors: cyan (SB), magenta (SM), and yellow (SJ). These three colors correspond to the color model well-known to those skilled in the art under the acronym CMY ("Cyan, Magenta, Yellow"). The invention is not limited to this color model and can also use a model such as RGB ("Red, Green, Blue"). Of course, other color triplets that differ from CMY and RGB can be used.

[0075] The subpixels are arranged according to a matrix which will be described in more detail with reference to [Fig. 4]. It can nevertheless be noted that a PM pattern of three subpixels SB, SM, and SJ is repeated several times in the section visible in [Fig. 1].

[0076] Above the array of colored sub-pixels, an opaque layer with a white appearance 102, for example a thin layer of metal oxide, has been assembled. This layer can be chosen so that perforations can be easily formed in it, for example by applying a laser beam with a given wavelength called the perforation wavelength.

[0077] Above the opaque, white-appearing layer 102, a laserizable layer 103 is arranged. This laserizable layer is initially transparent and contains particles that can be carbonized by the application of a laser beam, and more specifically, a laser beam at a given wavelength called the laserization wavelength. The application of the laser beam will create grayscale or even black areas in the laserizable layer. For example, the laserizable layer comprises polycarbonate and the particles that react to the laser beams.

[0078] In order to avoid damaging the white-appearing opaque layer 102 during the laserization of the document 100, a filter 104 is arranged between the laserizable layer 103 and the white-appearing opaque layer 102. This filter is configured to limit the passage of a laser beam at the laserization wavelength, so that this wavelength does not reach the white-appearing opaque layer. Conversely, preferably, this filter is passable for the perforation wavelength mentioned above, which differs from the laserization wavelength.

[0079] For example, the filter may comprise a polymer layer (possibly of the same type of polymer as other layers in the document) but loaded with a substance that absorbs a given spectrum including the laserization wavelength. The filter's transmittance is therefore low at the laserization wavelength and higher at other wavelengths (in particular the perforation wavelength).

[0080] It should be noted that the substance used may differ depending on whether one wishes to stop / filter infrared or ultraviolet radiation. It is also possible to use a layer of laserizable polycarbonate which also filters UV rays and is laserized by UV radiation.

[0081] For example, and as will be described with reference to [Fig.8], a layer of polycarbonate can be used which is carbonized on the surface with a laser having UV radiation, and the perforation of the opaque white-looking layer can be implemented with low-power infrared radiation (so that it does not carbonize the laserizable layer).

[0082] Optionally, an intermediate transparent layer 105, for example made of polycarbonate, is arranged between the opaque white-appearing layer 102 and the filter 104.

[0083] Also, optionally, under the colored sub-pixel matrix 101, a protective layer 107 has been arranged which can be opaque or transparent, for example made of polycarbonate.

[0084] Figure 2 shows document 100 after a step in which perforations PF are formed in the opaque, white-appearing layer has been implemented. This step may involve the application of a laser beam at the perforation wavelength.

[0085] At this stage, it is noted that each pattern of colored PM sub-pixels is associated with different perforations. From left to right in the figure: - the first pattern is associated with a unique perforation above its cyan sub-pixel, when viewed from the top of the document, it will have a very bright cyan appearance (it is associated with two white-appearing portions); - the second pattern is associated with two perforations above its cyan sub-pixel and above its yellow sub-pixel, it will have a very bright green appearance (it is associated with a portion of white appearance); - the third motif has no perforations; it will appear white when viewed from above; and - the fourth pattern has perforations above all its sub-pixels, it will have a grey appearance due to the combination of the three components cyan, yellow, and magenta.

[0086] A colored image appears when viewing document 100, with colors brighter than in prior art techniques. It can be noted that the combination of patterns and perforations forms image pixels, but, as will be described below, those obtained after the optional laserization step are called pixels.

[0087] In [Fig. 3], document 100 is shown after a laserization step has been carried out. In this step, a laser beam was applied to the top of the document 100 to form blackened (or at least grey) portions in the thickness of the laserizable layer 103.

[0088] More specifically, a blackened portion PN1 was formed above the yellow subpixel of the leftmost subpixel pattern in the figure, and a blackened portion PN2 was formed above the magenta and yellow subpixels of the third subpixel pattern from the left in the figure. Thus, a colored image is obtained when document 100 is viewed from above, comprising (considering the pixels from left to right in the figure): - a cyan-looking PX1 pixel, less bright than the one obtained for [Fig.2] at the same location; - a PX2 pixel with a green appearance, identical to that of [Fig.2] in the same location; - a gray-appearing pixel PX3, resulting from the presence of the blackened portion PN2 over two-thirds of the surface of pixel PX3; and - a PX4 pixel with a grey appearance, identical to that of [Fig.2] in the same location.

[0089] It is understood that the combination of the opaque, white-appearing layer 102, which is perforated, with the laser-cut layer 103, makes it possible to obtain a very wide color gamut, especially for the brightest colors.

[0090] In [Fig.4], a top view of the colored sub-pixel matrix 101 is shown. For reference, the area occupied by the pixel PX1 described with reference to [Fig.3] is represented by a dashed line rectangle.

[0091] Here, colored lines are aligned in groups of three colors, i.e., three lines.

[0092] It can be noted that in solutions according to the prior art, a fourth line White can be added to obtain brighter colors. However, adding this fourth line will increase the pixel size and decrease image resolution, while also being less satisfactory in terms of color gamut because the maximum possible color saturation will be lower. Indeed, when only three colors are present without white, each covers 1 / 3 of the surface, whereas if white lines are present, each color covers only 1 / 4 of the surface, leading to lower saturation.

[0093] Other arrangements are possible, including with other colours and other matrix formats.

[0094] Figure 5 shows the result of a registration phase.

[0095] This registration phase is implemented prior to the formation of the perforations and aims to determine the position of the colored sub-pixels of the colored sub-pixel matrix, particularly in the event of deformations of this matrix within a document.

[0096] The registration can be implemented automatically, for example by means of a computer system equipped with a camera to observe the documents.

[0097] In this phase, the position of a group of colored subpixels, labeled PO in [Fig. 5], can be observed. For example, these subpixels can be observed through initial perforations used solely for registration. Alternatively, the colored subpixels can be observed by transparency through the document, for example, by using a powerful lighting device under the document.

[0098] From the observed position of the colored sub-pixels PO (which have expected colors in expected locations), one can, for example, deduce polynomial equations by regression that pass through these points and obtain a transformation to apply to the matrix to estimate the position of each colored sub-pixel. This transformation effectively deforms an initially orthonormal grid.

[0099] This step is advantageous for sub-pixels with dimensions on the order of 60 to 70 micrometers, to ensure that a laser beam is applied over the correct sub-pixels to produce a colored image with the correct hues on each document.

[0100] In [Fig.6], a document 100' is shown according to a variant in which A TR trench was formed in an opaque, white-appearing layer 102'. Elements bearing the same references in this figure and in figures 1 to 5 are identical.

[0101] This TR trench improves adhesion between the opaque, white-looking layer 102', which may contain a metal oxide, and the other layers of the document, which are, for example, made of polymer.

[0102] Furthermore, through this trench, which is formed before the perforations, colored sub-pixels can be observed. This allows for registration, as the pixels of the pixel group are visible through the trench (or trenches if there are several, as in [Fig. 7]).

[0103] An advantageous arrangement for TR trenches is shown in [Fig.7], in which, in top view, a grid pattern is seen to be formed by the TR trenches.

[0104] Figure 8 shows a document 100" according to another variant. The elements with the same reference numerals in this figure and in Figures 1 to 5 are identical. Here, the laserizable layer 103' reacts, for laserization, to radiation with a laserization wavelength in the ultraviolet (UV) range. This layer is further configured to act as a filter for UV (carbonization can take place on the upper surface in the figure). As a result, the UV radiation does not affect the opaque, white-appearing layer 102 and does not degrade it during laserization.

[0105] The opaque, white-appearing layer can nevertheless be perforated with a laser beam of a wavelength in the infrared range, for example, a low-intensity beam. The laserizable layer 103' can be configured to allow this infrared laser beam to pass through.

[0106] This embodiment is advantageous in that it requires fewer layers to form a document.

[0107] It should be noted that the perforations described here can have dimensions on the order of those of a subpixel or even smaller than those of a subpixel. The blackened areas can also have dimensions on the order of those of a subpixel or even smaller than those of a subpixel. This allows for fine-tuning of the colors of each pixel.

[0108] A person skilled in the art will understand that the embodiments and variants described above are merely non-limiting examples of implementation of the invention. In particular, a person skilled in the art may consider any adaptation or combination of the embodiments and variants described above in order to meet a very specific need in accordance with the claims set forth below.

Claims

Claims

1. A security document comprising a stack of layers comprising a matrix (101) of colored sub-pixels (SB, SM, SJ), an opaque layer of white appearance (102) above the matrix of colored sub-pixels, in which the opaque layer of white appearance comprises perforations (PF) facing sub-pixels of the matrix of colored sub-pixels so that when the device is observed from above, a colored image appears, the document further comprising a laserisable layer (103) arranged above the opaque layer of white appearance and configured to be lasered by applying a laser beam at at least one lasering wavelength, and the document further comprising a filter (104) limiting the passage of at least the lasering wavelength, the filter being arranged between the laserisable layer and the opaque layer of white appearance or,the laserizable layer is configured to form a filter limiting the passage of at least the laserization wavelength.,

2. Document according to claim 1, in which the laserizable layer comprises portions (PN1, PN2) blackened by laserization.

3. A document according to any one of claims 1 or 2, wherein the white-appearing opaque layer is chosen to be perforated by a laser beam of a perforating wavelength.

4. Document according to claims 1 to 3, wherein the perforation wavelength differs from the laserization wavelength.

5. Document according to any one of claims 1 to 4, wherein a pixel (PX1) of the colored image comprises a colored sub-pixel visible through a perforation and a white-appearing portion of the white-appearing opaque layer forming a white sub-pixel of the pixel.

6. A document according to any one of claims 1 to 5, wherein the white-appearing opaque layer comprises a metal oxide.

7. Method for manufacturing a security document in which a matrix (101) of colored sub-pixels (SB, SM, SJ) is assembled with, above the matrix of colored sub-pixels, an opaque layer of white appearance (102),

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14. the method further comprising forming perforations (PF) through the opaque white-appearing layer and facing sub-pixels of the colored sub-pixel array so that when the device is viewed from above, a colored image appears, wherein a laserizable layer (103) is further assembled above the opaque white-appearing layer and configured to be laserized by applying a laser beam at at least one laserizing wavelength, and wherein a filter (104) limiting the passage of at least the laserization wavelength is further assembled between the laserizable layer and the opaque layer of white appearance or, the laserizable layer is configured to form a filter limiting the passage of at least the laserization wavelength. The method of claim 7, wherein the laserizable layer is laserized to obtain blackened portions. A method according to any one of claims 7 or 8, wherein the white-appearing opaque layer is perforated by a laser beam of a perforating wavelength to obtain the perforations. The method of claim 9, wherein the perforation wavelength differs from the lasering wavelength. Method according to any one of claims 7 to 10, comprising a registration phase in which the position of a group of colored sub-pixels is observed prior to the formation of the perforations which form the colored image. The method of claim 11, wherein the colored subpixels of the group of colored subpixels are observable through one or more perforations of the white-appearing opaque layer. The method of any one of claims 7 to 12, wherein a set of trenches (TR) is formed in a grid-like pattern through the white-appearing opaque layer. A method according to claims 12 and 13, wherein the position of the group of colored sub-pixels is observed through the trenches.

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